PART II. Reptilia

REPTILIA

"Cada uno es como Dios le hizo, y aun peor muchas vezes."

"We are all as God made us and many even worse."

SANCHO PANZA, Don Quixote.

{277}CHAPTER VII

REPTILIA

DEFINITION AND CHARACTERS–POSITION OF THE CLASS REPTILIA IN THE PHYLUM VERTEBRATA–CLASSIFICATION–SKULL AND VERTEBRAE.

The recent Reptiles comprise, broadly speaking, the Crocodiles, Tortoises, Lizards, and Snakes. They are the only Vertebrates which are cold-blooded, breathe by lungs, and have a median occipital condyle. Another equally sufficient diagnosis is the following:–Tetrapoda, with a median occipital condyle, with nucleated red blood-corpuscles, and with complete right and left functional aortic arches. A still shorter diagnosis is:–Monocondylia with a scaly skin.

If our diagnosis is to include the fossil Reptiles we have not only to discard the characters drawn from the soft parts as unavailable, but we are forced to treat the condition of the occipital condyle with caution, since there exist, or must have existed, transitional stages between Reptiles and Amphibia and Mammals; and the winged class Pterosauria does not permit us to use the wings as a differential character for the Birds. In fact, while the Reptilia are sufficiently separated from the Amphibia by their absolutely gastrocentrous vertebrae, it is difficult to distinguish them as a class from the Birds; hence the term SAUROPSIDA, which is intended to indicate the close relationship of the Reptiles to the Birds in opposition to the Mammalia, and to the ICHTHYOPSIDA or Amphibia and Fishes. However, the Reptilia take up a very central position in the evolution of the main classes of the Vertebrata. On the one hand, there is not the slightest doubt that they are evolved from some branch of {278}the Stegocephali, whilst on the other hand the Reptiles, probably through some branch of the Theromorpha, have given rise to the Mammals; some other Reptilian branch, at present unknown, has blossomed out into the Birds.

PRINCIPAL CHARACTERS OF THE REPTILIA.

1. The vertebrae are gastrocentrous.

2. The skull articulates with the atlas by one condyle, which is formed mainly by the basioccipital.

3. The mandible consists of many pieces and articulates with the cranium through the quadrate bones.

4. There is an auditory columellar apparatus fitting into the fenestra ovalis.

5. The limbs are of the tetrapodous, pentadactyle type.

6. There is an intracranial hypoglossal nerve.

7. The ribs form a true sternum.

8. The ilio-sacral connexion is post-acetabular.

9. The skin is covered (a) with scales, but (b) neither with feathers nor with hairs; and there is a great paucity of glands.

10. Reptiles are poikilothermous.

11. The red blood-corpuscles are nucleated, biconvex, and oval.

12. The heart is divided into two atria and an imperfectly divided ventricle. It has no conus, but semilunar valves exist at the base of the tripartite aortic trunk.

13. The right and left aortic arch are complete and remain functional.

14. Respiration is effected by lungs; and gills are entirely absent, even during embryonic life.

15. Lateral sense-organs are absent.

16. The kidneys have no nephrostomes. Each kidney has one separate ureter.

17. There is always a typical cloaca.

18. The eggs are meroblastic.

19. Fertilisation is internal, and is effected, with the single exception of Sphenodon, by means of male copulatory organs.

20. An amnion and an allantois are formed during development.

Numbers 1, 2, 6, 7, 8, 14, 16, 18, 20 separate the Reptiles from the Amphibia. Cf. also pp. 4 and 5.

Numbers 9 (b), 10, 12, and 13 separate them from the Birds and Mammals.

Numbers 3, 8, and 11 separate them from the Mammals.

The EVOLUTION OF THE CLASSIFICATION OF THE REPTILES has to a certain extent been already treated on pp. 7-9. For a long time only Chelonia or Tortoises, Ophidia or Snakes, and Saurii were recognised as their principal divisions. Then the Crocodiles were separated from the Lizards; later the Coeciliae were removed from the Snakes and referred to the Amphibia, {279}and ultimately Sphenodon was recognised as deserving a separate position, equal in rank to the other groups. Stannius showed that the Crocodiles and Tortoises are relatively near allies in opposition to the likewise closely allied Lizards and Snakes (Sphenodon was then unknown), and he expressed this by the term Monimostylica, or creatures with fixed quadrate bones, for the former, and Streptostylica, creatures with movable quadrates, for the latter combination. The fossil Reptiles were hardly allowed proper places in the system. In various zoological text-books they were, or are even now, treated as inconvenient, outlying, or supernumerary members. A long time elapsed before, thanks to the labours of H. von Meyer, Owen, Huxley, Marsh, Cope, Zittel, and Seeley, it was recognised that the extinct groups form the preponderant mass of Reptiles, and that it is the recent groups which, in spite of the bewildering number of species of Lizards and Snakes, are the comparatively few and much-reduced members of a once flourishing class. With the exception of the Lizards and Snakes, which are on the ascending branch, the modern Sphenodon, the Crocodiles and the Tortoises are a mere fraction, comprising a few survivals of richly-developed groups, while all the others, the overwhelming majority, have died out.

The classification adopted in this volume is as follows:–

CLASS REPTILIA.

Sub-Class I. Proreptilia.

" II. Prosauria. Orders: Microsauri, Prosauri.

" III. Theromorpha. Orders: Pareiasauri, Theriodontia, Anomodontia, Placodontia.

" IV. Chelonia. Orders: Athecae, Thecophora.

" V. Dinosauria. Orders: Sauropoda, Theropoda, Orthopoda, Ceratopsia.

" VI. Crocodilia. Orders: Pseudosuchia, Parasuchia, Eusuchia.

" VII. Plesiosauria. Orders: Nothosauri, Plesiosauri.

" VIII. Ichthyosauria.

" IX. Pterosauria.

" X. Pythonomorpha. Orders: Dolichosauri, Mosasauri.

" XI. Sauria. Orders: Lacertilia, Ophidia.

The eleven principal groups are here called "sub-classes" to emphasise the undeniable fact that these Reptilian groups are of much greater morphological value than those which are most generally called "Orders" in the Mammalia, that class which we consider as the standard or model of classificatory units.

{280}[Illustration: FIG. 54.–Diagrams of skulls, showing especially the composition of the bony arches of the orbito-temporal region.

A, C, D, E, THEROMORPHA. A, Elginia, p. 305; C, Cynognathus, p. 306; D, Gordonia, p. 310; E, Dicynodon, p. 310.

B, G, PROSAURIA. B, Sphenodon, p. 294; G, Palaeohatteria, p. 291.

F, CROCODILIA, p. 434.

H, I, K, CHELONIA, p. 316. H, Chelydra, p. 338; I, Chrysemys, p. 346; K, Cistudo, p. 361.

E, Epiotic; F, frontal; IT, infratemporal fossa; J, jugal, shaded vertically; L, lacrymal; M, maxillary; N, nasal groove; Na, nasal bone; O, orbit; P, parietal; Po, postorbital, dotted; Pf, post-frontal; Pm, premaxillary; Pr, prefrontal; Ptg, pterygoid; Q, quadrate; Qj, quadrato-jugal; So, supra-occipital; Sq, squamosal, shaded obliquely; St (in B-E), supratemporal fossa; St (in A), Supratemporal bone.]

{281}[Illustration: FIG. 55.–Diagrams of skulls, showing especially the composition of the bony arches of the orbito-temporal region.

L, PYTHONOMORPHA. Clidastes, p. 490.

M, N, O, LACERTILIA, p. 496. M, Varanus, p. 543; N, Uromastix, p. 524; O, Lacerta, p. 550.

P, ICHTHYOSAURIA, p. 479. Ichthyosaurus, p. 483.

Q, PTEROSAURIA, p. 484. Dimorphodon, p. 486.

R, AVES, generalised, for comparison.

S, MAMMALIA, generalised, for comparison.

T, OPHIDIA, p. 581.

C, Condyle of mandible; Col, columella cranii; F, frontal; I, interparietal or pineal foramen; I.A, Inner angle of mandible; J, jugal, shaded vertically; L, lacrymal; M, maxillary; N, nasal groove; Na, nasal bone; O, orbit; O{1}, preorbital fossa; P, parietal; Pf, postfrontal; Pm, premaxillary; Pr, prefrontal; Ptg, pterygoid; Q, quadrate; Qj, quadrato-jugal; Sq, squamosal, shaded obliquely; St_, supratemporal bone.]

{282}The families cannot well be changed, and terms like super-families and super-orders are sometimes resorted to by those who do not like to look stern facts in the face.

The sequence of the groups, although arranged as much as possible in ascending order, is of necessity as unnatural as that of the maps in an atlas. We cannot yet construct a satisfactory phyletic tree of the Reptiles. The Proreptilia connect them with the Amphibia. Next follow the Prosauria with Sphenodon among the Prosauri as the key to most other groups. Then follow the Theromorpha, and it is probable that from various branches of these have arisen the Chelonia, Dinosauria, Crocodilia, and Plesiosauria. The descent of the Ichthyosauria is very problematic. The same applies to the Pterosauria and to the Pythonomorpha, but it is possible that they, together with the Sauria, are connected with the Prosauria.

With all reserve these hypothetical affinities may be expressed by the following diagram:–

Lacertilia Ophidia | / Ichthyosauria Plesiosauria | / \ \ | / \ \ Crocodilia |/ ? \ | Sauria \ | | Chelonia \| | Pterosauria \ Dinosauria Sphenodon | / \ | | | / \ | | | / Pythonomorpha \ | | |/ | Theromorpha |––––––––––––––– | | Prosauria | Proreptilia

The eleven sub-classes of the Reptilia present so many important differences that it is not advisable to give here a further general account of their structure. The diagrammatic figures A to T on pp. 280, 281, representing various types of skulls, are intended to explain their chief modifications, all referable to Proreptilian and to certain Theromorphous conditions. One of the most important features is that the mandible, which is always composed of many pieces (cf. Fig. 142, p. 550), is invariably carried by the quadrate bone. Diagrams of the generalised skulls of a Bird and a Mammal have been added for comparison.

{283}[Illustration: FIG. 56.–Composition of vertebrae of Reptiles, illustrated by the first and second cervical vertebrae. (1) Atlas (first cervical) and axis (second) vertebra of Crocodilus. (2) Atlas and axis of Metriorhynchus, a Jurassic Crocodile. (3) Analysis of the first two cervical vertebrae of a Crocodile; 2, second basiventral complex or "intercentrum" continued upwards into the meniscus or intervertebral pad. (4) Diagram of the fundamental composition of a Reptilian vertebra; compare this and (6) with Fig. 1 (8 and 9) on p. 13. (5) The first three cervical vertebrae of Sphenodon. (6) Trunk-vertebrae of Eryops, a Permian Proreptile; typically temnospondylous; cp, articular facet of the capitulum of a rib. (7) The complete atlas of an adult Trionyx hurum; the second basiventral (intercentrum) is attached to the posterior end of the first centrum, which, not being fused with the second centrum, is not yet an odontoid process. (8) The complete atlas of an adult Trionyx gangeticus; still typically temnospondylous. (9) The first and second cervical vertebrae of an adult Platemys. (10) The complete atlas of a Chelys fimbriata. Az, Anterior zygapophysis; B.D, basidorsal; B.V, basiventral; C{1}, C{2}, C{3}, first, second, and third centra, formed by the interventralia; Cp^1, Cp^2, articular facets of the capitular portions of the first and second ribs; I.V, interventral; N{1}, N{2}, N{3}, first, second, and third neural arch, formed by basidorsalia (B.D); Od, odontoid process = first centrum; Pz, posterior zygapophysis; R{1}, R{2}, ribs; Sp, detached spinous process of the first neural arch; t{1}, t{2}, tubercular attachments of the first and second ribs; 1, 2, 3, 4, "intercentra" = basiventrals; I, II, III, position of the exit of the first, second, and third spinal nerves.]

As mentioned on p. 278 the vertebrae of the Reptilia and those of all other Amniota are gastrocentrous; that is to say the centra or bodies of the vertebrae are formed by the pairs of interventralia, while the basiventralia are reduced, persisting either as so-called intercentra or wedge-bones, or as intervertebral pads, or disappearing altogether. At the earlier stages of development the gastrocentrous vertebrae behave in the {284}same way as that described on p. 12 (Fig. 1), except that the interdorsal elements are suppressed from the beginning. If the remaining three pairs of constituent elements of each vertebra (the basidorsalia, forming the neural arch; the interventralia, forming the body or centrum; and the basiventralia) remain separate, the vertebrae are called temnospondylous (τέμνω, I cut, σπόνδυλος, a vertebra). If the neural arches and the centra are suturally united or are fused with each other, the vertebrae are called stereospondylous (στερεός, solid). In many Amniota the atlas or first vertebra remains in a relatively primitive, embryonic condition, and is temnospondylous but for the usual modification that its centrum becomes attached to that of the second vertebra, and forms the odontoid process of the latter. The composition of gastrocentrous vertebrae (cf. p. 282) is best illustrated by the first and second cervical vertebrae of the Crocodile (Fig. 56, 3, p. 283).

Concerning GEOGRAPHICAL DISTRIBUTION, even a cursory study shows that the sub-classes have come into existence at very different geological periods, and have each followed their own lines of dispersal.

{285}CHAPTER VIII

PROREPTILIA–PROSAURIA–THEROMORPHA

SUB-CLASS I.–PROREPTILIA.

Permian Temnospondylous Reptiles with well-developed limbs and girdles of the terrestrial type.

The two genera Eryops and Cricotus of the North-American Permian formation had until recently been relegated to the Stegocephali. By grouping them and their nearest allies together as Proreptilia it is intended to indicate that they are the lowest known Reptiles and that they probably link this class to the Amphibia. The superficial resemblance of their tri- or bi-partite vertebrae, and their occurrence in the Lower Permian, have caused the error of classing them with the Stegocephali, but the composition of their typically gastrocentrous vertebrae leaves no doubt as to their affinities. After all, we feel certain that Reptiles have arisen from Stegocephalous Amphibia, and it is in the Lower Permian, exactly where these debatable creatures lived side by side with Stegocephali, undoubtedly likewise temnospondylous, that the change from Amphibia into Reptiles seems to have taken place. Both are referable to Amphibia with quadripartite vertebrae. The condition of the occipital condyles determines nothing. This greatly exaggerated character has lost in importance since we have known the condylar modifications of the Theromorpha; moreover, Cricotus itself seems to have possessed a single condyle. We should even expect the Proreptilia to present many Stegocephalous inheritances, for instance the condition of the skull roofed in by dermal bones, a ventral dermal armour, a very complete pectoral arch still without a sternum, and only one sacral vertebra.

{286}Until more genera are better known than they are now, it is premature to divide the present sub-class into orders.

Eryops, with several species in Texas and New Mexico. E. megacephalus is the most abundant and the largest species, its broad and flattened skull measuring more than 18 inches in length and 12 in width. With the exception of the nostrils and the small orbits, the skull is entirely encased in bone, with a rough, pitted surface, but without any distinguishable sutures. The absence of mucous canals, so common in the Stegocephali, is worthy of note. The quadrates extend obliquely outwards and backwards, so that the joint with the mandible lies in a plane behind the occiput. The mandibles are devoid of a projecting angular process. The teeth are numerous, small, and pointed. The vertebrae are typically temnospondylous, consisting each of three pairs of separately ossified pieces, which, although closely packed together, are not suturally connected. The neural arches possess high spinous processes, they articulate by short and broad zygapophyses and are, with their triangular bases, wedged in between the two ventral pieces, the posterior of which (the united interventralia) is in broader contact with the neural arch and lies behind it; the anterior piece (the united basiventrals) appear as typical, but large, intercentra, and bear on their posterior, dorsal margin the facets for the ribs. The latter are short, but are broad at their proximal ends, which are not bifurcated; they extend their articulation from the "intercentra" upon the short lateral processes of the neural arches. The tail is short and ends in a pointed coccyx, owing to fusion of the last vertebrae.

The pubes and ischia are heavy, the former flattened and broadened out. The limbs are of an almost ideal pentadactyloid type; strongly developed for terrestrial locomotion. The ulna possesses a large olecranon. The carpus consists of ten separate pieces, ulnare, intermedium, radiale, two centralia and five distal carpalia. The latter support only four metacarpals and fingers, the second finger being completely abolished, an explanation suggested by Cope and corroborated by Emery.

{287}Cricotus, with several species in Texas and Illinois. C. heteroclitus was perhaps 10 feet long and probably aquatic. The skull has a long, narrow, depressed snout, the margins overhanging those of the lower jaw; its surface is encased in dermal bones, most of which still show sutures, so that for instance postfrontals, postorbitals, supratemporals and squamosals can be distinguished; all these are in contact with the long parietals and with the quadrato-jugal arch, covering the temporal region; but the supratemporals have a free projecting border, like the squamosals of the crocodiles. According to Cope's description the basioccipital is connected with the first vertebra by an undivided discoid "intercentrum," probably the true centrum, while the first basiventral mass, which would be, if independent, the first true intercentrum, is more probably connected with the first neural arch, thus constituting the ring of the atlas.

The vertebrae are still temnospondylous, but no longer tripartite. The neural arch is fused with the interventralia into one mass, which carries the capitula and tubercula of the ribs, while the united basiventrals still remain as separate intercentral wedges. In the tail these wedges carry chevron-bones, and are enlarged into thick almost complete discs, or rather rings, while the whole vertebral column is still perforated, as also in Eryops, by the chorda dorsalis. The tail is long. The digits are devoid of claws.

Remains of dermal armour exist on the throat in the shape of several large gular plates, while the whole belly is covered with many closely packed bony scales, which are arranged in chevron-shaped transverse rows.

Probably several other genera of American Permian and also of European Permian strata will, when better known and critically examined, have to be referred to the Proreptilia. Thus for instance the European Melosaurus may have affinities with Eryops, while Diplovertebron of Bohemia seems to be allied to Cricotus. The difficulty of division will lie with those Lower Permian Amphibia which, like Archegosaurus, Euchirosaurus, Actinodon, possess tripartite vertebrae, which at first sight are strikingly like those of Eryops. But the tail-vertebrae permit of no mistake, and since these are quadripartite in Archegosaurus, Chelydosaurus, and Sphenosaurus, these genera are safely to be classed with the Amphibia, unless, indeed, for mere argument's {288}sake, it be assumed that the intercentral discs of Diplovertebron and Cricotus are formed by the fusion of Amphibian interdorsals with interventrals. Anyhow, simply to state that the tripartite vertebrae of Eryops are the same as those of Actinodon, would be as convincing as saying that the English and French flags are essentially the same, both containing the same colours, but one is white, red, and blue, the other blue, white, and red. Tripartite Amphibian vertebrae are composed of basidorsals + basiventrals + interdorsals, those of Reptiles are made up of basidorsals + basiventrals + interventrals. (Cf. Fig. 56, p. 283, and Fig. 1, p. 13.)

SUB-CLASS II.–PROSAURIA.

Mostly extinct Reptiles, with deeply amphicoelous but stereospondylous vertebrae, with movable chevron-bones in the tail and frequently with intercentra in the trunk. Sphenodon, the only recent genus, has no copulatory organs.

ORDER I. MICROSAURI.

Extinct, small Reptiles, mostly Carboniferous and Permian, with dermal armour on the dorsal and ventral side and with bifurcated ribs.

We retain this term of Dawson's for those small, newt-shaped, chiefly Permian reptiles, which are allied to Hylonomus, after elimination of contemporary forms like Keraterpeton and Urocordylus, which belong to the Branchiosaurian order of the Stegocephali. Until recently all these creatures had been classed with the Stegocephali. The Microsauri in the present restricted sense reveal themselves, however, as reptiles by the movable chevron-bones in their tail, their broad neurocentral sutures, the possession of two sacral vertebrae (Petrobates), the bifurcated ribs which always articulate with the centra (most clearly shown in Orthocosta), and the possession of five fingers and toes.

Considering the age of these little creatures and their low position in the reptilian scale–in fact, they stand almost as low {289}as the Proreptilia–it is not to be wondered at that they still retain a number of amphibian features. The skull is encased in dermal bones as in the Stegocephali, and the dermal armour of the trunk and tail is composed of many bony, sculptured scales, which cover back, sides, and under surface. The middle rows on the back are the largest, while the scales on the belly are arranged in transverse rows, which imbricate and converge obliquely headwards. Special gular plates seem to be absent. The skull has an interparietal foramen. The jaws and the palate are furnished with small, simple teeth, and there is a large parasphenoid bone, an eminently amphibian character. The occipital condylar articulation is supposed to be double. The centra of the vertebrae are deeply amphicoelous, elongated, and constricted in the middle, just like those of the Aistopoda and Branchiosauri. The dorsal spinous processes are strongly developed, and with the zygapophyses are very reptilian. Transverse processes are absent or very short, the tubercular portions of the ribs articulating with the centra, the capitula mostly intervertebrally, in any case close to the anterior end of the centra. The tail-vertebrae possess very typical, movable chevrons, placed intervertebrally, and bear an extraordinary resemblance to those of Geckos. The ribs are long and slender, but there is no sternum. The fore- and hind-limbs are pentadactyle, in opposition to the invariably four-fingered Stegocephali. The shoulder-girdle consists of scapulae, coracoids, clavicles, cleithra, and a T-shaped interclavicle. The pelvis also resembles that of certain Stegocephali by the separately ossified, somewhat disc-shaped, flat ischia and pubes, which seem to have been joined together by cartilage into one broad mass.

Hylonomus, Dawson's type of Microsauri, was found in the Coal-measures of Nova Scotia, within decayed tree-stumps. Closely allied, if not identical, but much better known is Hyloplesion, e.g. H. longicostatum of the uppermost Permian of Nyrschan in Bohemia. Total length under 4 inches; eyes with bony sclerotic rings; neck short. The truly Permian genera Dawsonia, Melanerpeton, Orthocosta, and Seeleya are allied forms, the last scarcely one inch in length, but well preserved. Petrobates of the Triassic Lower Red Sandstone of Saxony has an arrangement of the ventral dermal armour closely resembling abdominal ribs.

{290}ORDER II. PROSAURI

Mostly extinct, chiefly Permian and Triassic, terrestrial, unarmoured reptiles with deeply biconcave vertebrae, numerous intercentra and chevron-bones, fixed quadrates, complete pentadactyle limbs and shoulder-girdle, entepicondylar foramina, acrodont teeth, and many small abdominal ossifications.

The Prosauri differ from the Microsauri, with which they are closely allied, by the more advanced solidification of the vertebrae, the reduction of the tubercular portions of the ribs, the presence of an entepicondylar foramen in the humerus, and the loss of the dermal ossifications on the upper surface.

Their ancestors are the Microsauri, whilst they themselves seem to be very near the root whence have sprung most, if not all, other main branches of the reptiles, notably Crocodilia, Dinosauria, and Sauria. In fact the Prosauri, although apparently few in number, seem to represent the central stem of the reptilian tree. Only one of them is still surviving, the famous Sphenodon, now represented by a single species in New Zealand.

SUB-ORDER 1. PROTOROSAURI.–The ventral half of the pelvis seems to have formed one broad, continuous mass of cartilage in which the pubic bones are represented by a pair of oval, rather disc-shaped ossifications, while the ischia are more elongated. The pelvis consequently still bears a great resemblance to that of the Microsauri, and thereby also to the Stegocephalous condition, but the ilium seems to be attached to more than two vertebrae. The vertebrae are deeply biconcave, perhaps even with a persistent continuous chorda. The neural arches bear high, laterally compressed spines, but no diapophysial or lateral processes, the ribs being placed mostly intervertebrally and having lost their tubercular portions. The ribs are continued to about the sixth caudal vertebra. Intercentral wedges exist in an unbroken series between all the vertebrae from the atlas to the tail, where they are represented by movable chevrons. A costal sternum seems to be absent, unless it was quite cartilaginous. The shoulder-girdle is complete, consisting of a long interclavicle, clavicles, disc-shaped coracoids, and scapulae; but there are no cleithra, and no indication of precoracoids or even notches in the coracoids. The fore- and hind-limbs are complete and primitive, with five digits. The abdomen is protected by numerous oat-shaped little {291}ossifications, which are arranged in many transverse or rather chevron-shaped rows, still greatly resembling the condition prevailing in the Microsauri, except that they have sunk deeper into the skin, being no longer directly covered by the scales. The skull, being no longer completely encased by bones, and possessing now wide supra- and infra-temporal fossae, appears at first sight much like that of a generalised lizard, except that it possesses three very conspicuous and distinct arcades in the temporal region: namely, the orbito-squamosal bridge across the temporal fossa, formed by the postorbital and squamosal; the arch formed by the squamosal with the postero-lateral buttress of the parietal; and the infratemporal arch or jugal bridge. The jugal itself is long, connecting the quadrato-jugal with the maxillary and lacrymal, and sending up an ascending process to the postorbital bone, thus taking a considerable share in the formation of the orbit. The quadrato-jugal is small, apparently fused with the quadrate, which itself is firmly overlaid by the squamosal. The quadrates are further fixed by being buttressed by the pterygoids, which rest upon short basisphenoid processes and extend far forwards, meeting the vomers and separating the palatines. The premaxillae are short, the nares small and terminal, the nasal bones are large. There is a small interparietal foramen. The teeth are acrodont and pointed, forming unbroken series on the premaxillaries, maxillaries, palatines and dentaries, and there are scattered little teeth on the vomers.

Palaeohatteria longicaudata from the Lower Red Sandstone of Saxony. Total length about 18 inches, with six cervical, twenty trunk, three or four sacral, and about fifty caudal vertebrae. The teeth are ankylosed with the supporting bones. The five fingers have 2, 3, 4, 5, 3 phalanges respectively. For the skull see Fig. 54, G, p. 280. Telerpeton elginense from the Triassic sandstone of Scotland, and perhaps Saurosternon of the South African Karroo sandstone seem to be allied.

Protorosaurus (πρῶτος = first, ὤρα = spring, or dawn, not Proterosaurus) apparently several species, e.g. P. lincki in the Upper Permian (marl-slate and magnesian limestone) of Thuringia and Durham. About 4 or 5 feet long, and in its general appearance rather like a Monitor-lizard, with about eight cervical vertebrae, most of which carry slender backwardly-pointing ribs, sixteen long-ribbed trunk-vertebrae, followed by three or four {292}sacrals and more than thirty caudals, some of which have bifurcated spinous processes.

SUB-ORDER 2. RHYNCHOCEPHALI.–The ventral pelvic bones resemble those of lizards and enclose a wide pubo-ischiadic foramen. There are only two sacral vertebrae. The abdominal ribs are closely packed, each transverse set consisting of only three rod-shaped pieces instead of many small oat-shaped nodules. The intercentra are sometimes suppressed in the trunk-region.

Rhynchosaurus from the Upper Trias of Warwickshire and Shropshire, and Hyperodapedon of the same age, found at Elgin, in Warwickshire, and also in Central India, are rather large, H. gordoni measuring 6 feet in length. Both have a short, broad, and stout cranium, and curved down, toothless premaxillae, hence the name Rhynchocephali; the nares are confluent; the teeth are numerous and small, and are liable to be worn down so that the animals ultimately bite with the edges of the jaws, to which the teeth are ankylosed. The premaxillaries of Rhynchosaurus are curved downwards over a slightly upcurved, likewise toothless process of the mandibles, which form a strong symphysis. All the teeth are very small, absent, or minute on the mandibles, forming one series on the maxillae, several rows on the vomers and especially on the palatines, which latter remain separated from each other. Hyperodapedon seems to have lost the intercentra; its vertebrae are solid, those of the neck are opisthocoelous. The interparietal foramen is likewise abolished. The hook-shaped end of the curved-down premaxillae fits into a bifurcation of the mandibles in front of their stout symphysis. The teeth are similar to those of the other genus. Whilst these, the earliest known genera of Rhynchocephali, are already in various ways rather specialised, e.g. the hooked beak and the loss of the intercentra, the two following fossil genera, although of much later date, namely Upper Triassic, are more closely allied to the recent Sphenodon.

Homoeosaurus pulchellus and other species in Germany are only 6 to 8 inches long. The vertebral column consists of twenty-three presacral and many caudal vertebrae. The first five cervicals are devoid of ribs. Intercentra are restricted to the neck and the anterior portion of the tail. The mandibles are not fused together. The nares are divided by a bony septum. Each premaxillary has one rather broad tooth.

{293}[Illustration: FIG. 58.–Sphenodon punctatum. × ⅓.]

{294}The teeth of the maxillaries and mandibles are triangular, much worn down in front. The ribs are devoid of uncinate processes. Closely allied but larger is Sauranodon of France, which has lost the upper teeth and uses the sharp margins of the jaws instead.

Pleurosaurus of Germany and France, about 5 feet in length, is remarkable for the shortness of its still pentadactyle extremities, for its short neck, and very long tail;–an interesting parallel to what has happened in many genera of recent lizards.

Sphenodon s. Hatteria is the sole surviving member of the whole group of Prosauria, and is represented by one species only, S. punctatum, in New Zealand. As the last living witness of bygone ages this primitive, almost ideally generalised type of reptiles, this "living fossil," deserves a detailed description.

Total length of very large male specimens up to two feet and a half; in general appearance like many a stoutly built lizard. The general colour of the skin is dark olive-green with small white or yellowish specks on the sides. A series of slightly erectile spines of yellowish colour extends from the top of the head to the end of the tail, but is interrupted on the neck; they are cutaneous, covered with a thin sheath of horn. The under surface is covered with numerous scales, arranged in transverse rows; the rest of the body is rather granular. The tail is thick, slightly compressed laterally. The eye is large, dark brown, with a vertical pupil.

Those who are satisfied with superficial resemblances still group this creature with the lizards, but it reveals itself as a primitive reptile or Prosaurian by the following characters, every one of which distinguishes it from the lizards:–The temporal region is bridged by three bony arcades. The large vomers, palatines, and pterygoids form a broad bony roof to the mouth; the large quadrates are firmly fixed by the pterygoids, squamosals, lateral occipital bones, and by the jugal bridge. The vertebrae possess an unbroken series of intercentral wedge-bones. There is an elaborate system of abdominal ribs. The humerus has an entepicondylar foramen, and there is also, in contradistinction to the fossil Rhynchocephalia, an ectepicondylar foramen for the passage of the radial nerve. The carpus still has the primitive number of ten bones, all of which remain separate, including the intermedium. Of soft parts are to be mentioned above all the entire absence of external copulatory organs, Sphenodon being the {295}only recent reptile which is devoid of them; a most primitive condition, sufficient by itself to separate this creature from all the other living reptiles.

The supratemporal bridge is formed by the squamosal and postorbital (Fig. 59, C, Pt.f), the latter being continued forwards and fused with the postfrontal (A, Pt.f). The postorbital joins the ascending branch of the jugal, both together forming the hinder border of the orbit; this is bordered below chiefly by {296}the maxillary, which is long, while the anterior process of the jugal is much reduced. There is no pre-orbital fossa. The nares are terminal and lateral, well separated by the premaxillaries. The posterior temporal bridge is formed by the squamosal and parietal, the bridge extending laterally over the quadrate and enclosing a wide space between itself and the buttress-like expansion of the lateral occipital bone. The space enclosed between this occipital buttress, the quadrate, and the pterygoid support of the latter is likewise very large; it is of course the cavity of the middle ear, and as such is crossed by the columellar chain of the ear. The infratemporal bridge or jugal arch is formed by the jugal, which joins the descending process of the squamosal, and by the quadrato-jugal, which is small and fused with the quadrate. The latter is consequently very firmly fixed.

The teeth are acrodont, ankylosed in one series with the supporting bones, triangular and much worn down in older specimens. Originally there seem to be several in the premaxilla, but the adult bite with the somewhat curved-down portions of the premaxillaries themselves, or with what remains of the fused bases of the original teeth, which then, together with the bone, look like one pair of large chisel-shaped incisors. The lateral edges of the palatines likewise carry teeth, those of the mandibles fit into the long slit-like space between the palatine and the maxillary teeth. Young specimens have a few small teeth on the vomers, which are large, and separate the long choanae from each other. The pterygoids form an anterior symphysis, posteriorly they rest upon short processes of the basisphenoid and send short flanges to the quadrates.

The vertebral column is very primitive. The atlas is still typically temnospondylous. The first intercentrum or fused pair of basiventrals is broad and thick, and forms the ventral half of the atlas-ring, which articulates with the first centrum and with the second intercentrum. The irregularly shaped neural arches remain separate from each other and from the centrum; they carry on the dorsal side a pair of disconnected supradorsals, the so-called pro-atlas. The second intercentrum is fused with the first and second centrum. The second to ninth intercentra have low median ridges or knobs, and are as a rule more firmly attached to the cranial ends of the centra. Those of the trunk are small. From the third or fourth caudal vertebra {297}backwards they appear as chevrons, articulating more with the vertebra in front than with the one behind. The bases of the right and left chevrons are frequently fused across so that the caudal canal is completely surrounded by bone, a feature common in Dinosaurs. Every intercentrum, be it a pair of chevrons, or an unpaired nodule, or crescent, extends dorsalwards into a fibro-cartilaginous ring which surrounds the chorda. The centra of the vertebrae are deeply amphicoelous, the cavity being filled throughout life by the chorda; but the middle of the centra is solid. Most of the caudal vertebrae are transversely divided into two parts, the posterior of which carries the greater share of the arches; they resemble in this respect those of lizards, and the lost tail is likewise reproduced. The first three ribs are represented by bands of connective tissue. The first is attached to the side of the first intercentrum; the second arises from the second intercentrum, and forms a small tubercle on the side of the second centrum; the third behaves similarly. The vertebral arteries and lateral strands of the sympathetic nerve-chain pass through these double basal attachments of the reduced ribs. The other ribs are osseous; they possess short capitula which retain their partly intercentral attachment, while the short tubercula are carried by low processes of the centra, not of the neural arches. Already in the thoracic region both capitulum and tuberculum merge into one facet, at first dumb-bell shaped, further towards the tail oval, gradually shifted backwards and dorsalwards upon the middle of the centrum, until the facet reaches and ultimately lies right across the neuro-central suture. The first few caudal vertebrae also possess ribs, which are however very short and fuse with the diapophyses, immediately below which lies the neuro-central suture.

The whole column consists of twenty-five presacral, two sacral, and about thirty caudal vertebrae. Some of the thoracic ribs have cartilaginous uncinate processes. Three or four pairs of ribs join a typical sternum, into the antero-lateral portion of which are let in the coracoids. The sternum is raised into a low median crest which fuses with the posterior branch of the {298}T-shaped interclavicle, while the lateral branches of the latter fuse with the clavicles. The coracoids are broad and entire, still without fenestrae or notches indicative of precoracoids. The parasternum is very elaborate; it extends from the sternum to the pubic bones, and consists of about twenty-four transverse rows, each of which is composed of a median and two lateral splint-bones. They are irregularly shaped, partly with imbricating hooks, and are firmly attached to, in fact still connected with, the deeper portions of the cutaneous scales of the belly. The three pairs of pelvic bones are fused together at the acetabulum. Pubes and ischia each form one symphysis, and these are connected with each other by partly ossified cartilage and ligaments, so that the originally heart-shaped space is divided into a pair of ovals. The lateral processes of the pubes are thick, but very short. The ischia have postero-lateral processes. There is also a mostly cartilaginous, unpaired hypo-ischium.

The fore- and hind-limbs are still primitive in structure; both pentadactyle. The carpus consists of ten, sometimes eleven pieces, according to the single or double nature of the central element. The proximal series is formed by the radiale, intermedian, and ulnare, with a pisiform. The ulna and radius remain separate. The humerus has the usual ectepicondylar in addition to the entepicondylar foramen common to all the Prosauri and Theromorpha. The hind-limbs are typically plantigrade.

The tail is capable of regeneration, as in many lizards.

The development of this reptile has recently been studied and described by Howes, who quotes the literature bearing upon the whole subject.

A good account of the occurrence and habits of the "Tuatera" has been given by Newman. The Maoris call it "ruatara," "tuatete," or "tuatara," the latter meaning "having spines." Formerly common on the main islands of New Zealand, they are now apparently restricted to some of the islets in the Bay of Plenty, North Island. Bush-fires, wild pigs, dogs and cats, reptile-eating Maori tribes, and the advance of civilisation, have swept them away except on some of the small uninhabited islands, difficult of access, where they dig burrows, into which they retreat at the slightest sign of danger. They sleep during the {299}greater part of the day, are very fond of lying in the water, and they can remain below for hours without breathing. They live strictly upon animals, but these are only taken when alive and moving about. The kind of food seems to vary according to the custom or fancy of the individuals. Sir W. L. Buller observed that some of his captives stubbornly refused to eat until one day, rather accidentally, minnows were offered. Others eat insects and worms; those which live near the seashore not improbably eat also crustaceans. From November to January they lay about ten eggs–white, hard-shelled, long and oval–about 28 mm. long, in holes in the sand, where they can be warmed by the sun. They are as a rule lazy in their movements. The usual pace is a slow crawl, the belly and tail trailing on the ground, but when chasing prey they lift the whole trunk off the ground. After running, or rather "wobbling" three or four yards, they grow weary and stop. They cannot jump the smallest obstacle.

Von Haast has carefully examined their habitations on the Chicken Islands. The Tuatara excavates its own hole, and this is shared sociably by various kinds of Petrels. The entrance to the chamber is generally 4 or 5 inches in diameter, and the passage leading into the inner chamber is 2 to 3 feet long, first descending and then ascending again. The chamber itself is one foot and a half long, by one foot wide and 6 inches high, lined with grass and leaves. The petrel lives usually on the left side, the Tuatara on the right side of the inner chamber. Whilst very tolerant of the bird with its egg and young, it does not allow another of its own kind to live in the same hole, which it is ready to defend by lying in such a manner that the head is placed where the passage widens out into the chamber. On putting one's hand or a stick into the burrow the Tuatara bites at them furiously. They can run very fast, and defend themselves with great pluck against dog or man by biting or scratching. As soon as the sun has set they leave their holes to seek food. During the night, and especially during the pairing season, they croak or grunt.

The eggs, having been deposited during the Southern summer, from November to January or February, in holes on a sunny and sandy spot, contain nearly ripe embryos in the following August. They are, however, not hatched until about thirteen {300}months old. In the meantime they seem to undergo a kind of aestivation. The nasal chambers become blocked with proliferating epithelium, which is resorbed shortly before hatching.

I have kept half-a-dozen specimens in a green-house for several years, and have come to the conclusion that they are dull, not companionable creatures, in spite of their imposing, rather noble appearance when, with their heads erect, they calmly look about with their large, quiet eyes. Each dug its own hole in the hard ground underneath and between large stones. At dusk they sat in front of the holes or walked leisurely to the pan with the earthworms which formed their principal food. Meat they did not touch, but they killed and chewed up lizards and blind-worms. Sometimes they soaked themselves for many hours in the shallow, warm water. The skin is shed in flakes. I never found them basking in the sun, and the pineal eye, still so well developed in these strange creatures, caused them no distress when bright light was thrown upon it. They grew tame enough not to run away when found roaming about at night, but they did not like being handled, and they inflicted the most painful bites when taken up carelessly. The biggest, a male, was rather quarrelsome, grunted much, and worried the others.

SUB-CLASS III.–THEROMORPHA.

The Theromorpha comprise a great number of extraordinary, extinct reptiles, which as a group had a wide range in space and time. The earliest known occur in the Lower Red Sandstone of Thuringia and Bohemia, and in the middle Permian strata of Russia. The majority have been found in strata transitional between the Permian and the Triassic age, notably in the Karroo sandstone of South Africa and in corresponding levels of North America. Closely allied to them are those of the Triassic sandstone of Elgin in Scotland, and of India. They seem to have died out with the Muschelkalk or Middle Trias.

The various genera exhibit such a diversity of structure, shape, and size, and many are still so imperfectly known, that {301}any diagnosis is liable to be faulty, even assuming that they are a homogeneous group. To avoid confusion, we characterise the Theromorpha as Reptiles with a firmly fixed quadrate, a single temporal arch, an interparietal foramen, and a pelvis in which the pubes and ischia form one stout, ventral symphysis.

The dentition is most abnormal, and permits the division of the Theromorpha into two or three main groups. In the Pareiasauri the teeth of the upper and lower jaws form rather even series of nearly equal size; smaller teeth are carried by the palatal bones. In the Theriodontia the teeth are differentiated in a truly Mammalian fashion into incisors, prominent canines, and multicuspid or tubercular molars. Each tooth, and this applies to all Theromorpha, is implanted in a separate alveolus; Tritylodon only seems to have double-rooted molars. The lower canines cross in front of the upper, just as in Mammals. In Placodus, which probably belongs to this assembly, the teeth are few in numbers, very broad and flat, especially those of the palate. In Dicynodon and Gordonia the teeth are restricted to a pair of conical, sometimes very large, tusk-like upper canines, and in Oudenodon the whole mouth is toothless.

The configuration of the skull shows two main types. In the Pareiasauri it is completely roofed in by dermal bones, the only holes on the surface being the nostrils, orbits, and the interparietal foramen.

The most striking feature of the second type of skull is the tendency to form an almost Mammalian zygomatic arch by the junction of the much elongated squamosal with the jugal bone, both abutting against a downward process of the postfrontal bone. The skull shows a pair of wide supratemporal foramina bordered by the parietals, squamosals, and postfrontals. The composition of the temporal arch varies considerably in detail, and in Cynognathus crateronotus at least there is a small hole within the arch, between the squamosal and jugal, probably the last remnant of the otherwise absent infratemporal foramen. Except in the roofed-in skulls of Pareiasaurus and Elginia there is no separate quadrato-jugal element. The quadrate is firmly fixed by the overlapping squamosal, and the whole pedicle for the support of the mandible is rather elongated, and either stands vertically or slants forwards. The mandible itself is compound. The pterygoids extend backwards so as to approach or reach the {302}distal portion of the quadrate; separate ectopterygoids do not seem to be developed. The shoulder-girdle consists on either side of a large scapula, which is mostly directed obliquely backwards, and is fused with the coracoid; a precoracoid is present or at least indicated by a notch or foramen; it is usually fused with the other bones. At least some genera possess a T-shaped interclavicle and clavicles; Pareiasaurus possesses also a pair of cleithra.

The pelvis is in every respect constructed upon the Mammalian plan. The three constituent parts meet at the acetabulum, and the ventral bones, pubes and ischia, form one broad symphysis, leaving two, sometimes very small, obturator-foramina. The ilium is attached to one to five sacral vertebrae, and since the whole pelvis slants obliquely downwards and backwards, this sacral attachment is distinctly pre-acetabular, perhaps most markedly so in Dicynodon. The limbs are mostly stout, humerus and femur with strong crests; the feet are thoroughly plantigrade, with five fingers and toes. The details of the carpus and tarsus are not well enough known to permit of generalisation, but there is a tendency to form a heel, and to develop the cruro-tarsal joint into the chief joint of the hind feet. The vertebrae are amphicoelous, sometimes with rather thin-walled centra, so that in these cases the chorda was continuous. Intercentral wedges, or basiventral elements, are frequent in the cervical and caudal regions. Most of the ribs, especially those of the neck, have a tuberculum attached to the neural arch, and a distinct capitulum which articulates either with the centrum or with the intercentrum, or lastly, if the latter is absent, between two centra. The axis and atlas vertebrae are united.

The occipital condyle exhibits every stage between the single median knob (Pareiasaurus) formed almost entirely by the basioccipital bone, a triple condyle (Dicynodon) to which both lateral and the basioccipital bones contribute, and a kidney-shaped or double condyle (Cynognathus) from which the middle or basioccipital portion is more or less withdrawn.

Dermal bony armour reached an extraordinary development on the head of Pareisaurus and Elginia; whether other parts of the body were protected is doubtful, but the flattened tops of the neural spines of Pareiasaurus suggest that they carried bony scutes. Abdominal protective ossifications are unknown. {303}Many of the Theromorpha reached a considerable size, massive skulls of one foot in length being not uncommon. The tail was comparatively short.

The many resemblances of these strange creatures to Mammals have naturally suggested that the Mammalia have sprung from some such Theromorpha or "beast-shaped" animals. The resemblances are chiefly the dentition, the zygomatic arch, the pelvis, the cruro-tarsal joint, the scapula which is sometimes possessed of a spine, and the occasionally double occipital condyle. The general shape of the skull of Cynognathus is indeed strikingly like that of a Carnivorous Mammal, and the shape of the whole body suggests rather a Mammal than a reptile; and when we have to deal with the fragmentary skulls of Tritylodon (cf. p. 309) it is, indeed, difficult to decide to which of the two classes such a creature belongs. But the Theromorpha possess a number of important characters by which they reveal themselves at once as reptiles: (1) the large and fixed quadrate bone, which is still the sole support of the lower jaw; (2) the compound mandible, which is composed of at least an articular, dentary, angular, supra-angular, and splenial element; (3) the interparietal foramen; (4) the possession of prefrontal and postfrontal bones, sometimes also postorbital, supratemporal, and quadrato-jugal bones. Of course, any of these ancestral bones may be lost, and the interparietal hole may be closed as in tortoises and crocodiles. We can also imagine that the quadrate may be relieved of its jaw-bearing function and become loosened, but this is not easy, considering the strong development of the squamoso-quadrate pedicle. Those Theromorpha in which the quadrate itself is small, whilst the squamosal reaches down, or at least approaches the mandible, as in Dicynodon and Gordonia, are so hopelessly pledged, or specialised in other directions, that it is impossible to connect them ancestrally with Mammals.

However, it is beyond reasonable question that the Mammals have sprung from some reptilian stock (the attempts to derive {304}them from Amphibia, without the intervention of Reptiles, are as gratuitous as they have proved futile), and the Theromorpha undoubtedly comprise creatures which of all animals approach nearest to Mammals, and coincide with them in most important features. But we have not yet found a single Theromorph which can claim to be a direct ancestor of Mammals. Since the latter occur already in the Trias, we have to look for their reptilian forefathers at least in the Lower Permian, and this naturally excludes all the known forms. The filling up of this gap is but a question of time.

The ancestry of the Theromorpha themselves is also shrouded in mystery. Attempts have been made to connect them with the Permian Protorosaurus, Palaeohatteria, and Eryops. On the other hand, some retain various Stegocephalous reminiscences (e.g. the roofed-in condition of the skull by membrane-bones, amongst which, besides others, supratemporals and postorbitals can be recognised; occurrence of cleithra in Pareiasaurus; distinct epiotic bones in Elginia). Although they have died out as a group, they have perhaps given rise to several side-branches, one of which (leaving aside the question of Mammalian origin) seems to have flourished as the Dinosauria.

We divide the Theromorpha into four orders, which are, however, liable to run into each other, and it is reasonably to be hoped that many forms may be discovered which will connect not only these provisional orders with each other, but also with other sub-classes.

ORDER I. PAREIASAURI

Cranium completely roofed in by membrane-bones. The only foramina are the nostrils, orbits, and the interparietal foramen. The teeth are comparatively small, and stand in even series in both jaws.

Pareiasaurus, several species from the Karroo sandstone of South Africa. P. baini was an extremely clumsy brute, of most uncouth appearance, standing between 2 and 3 feet high, and measuring with the short tail nearly 8 feet in length. The skull is very massive, 18 inches long and slightly broader, with a rugose, deeply pitted surface. The teeth are thickly enamelled, serrated at the margin, with many pointed cusps; those {305}of the vomer, palatines, and pterygoids are recurved and arranged in several longitudinal rows. There is a small incisive foramen in the premaxilla; the choanae lie within the pterygoids. The palate has a pair of large lateral vacuities. Between the squamosal and quadrate is a small foramen, as in Belodon and Sphenodon. The nares are terminal, bordered behind by the nasals, and divided by the premaxillaries. The occipital condyle is a single knob, but the lateral occipital bones also partake in its formation. The shoulder-girdle is strong. The scapula slants backwards, is broad, and possesses a longitudinal spine, an almost exclusively Mammalian character. The scapula, coracoid and precoracoid are fused together, and are united ventrally with those of the other side. There is a T-shaped interclavicle, a pair of clavicles, and a pair of slender, long cleithra, which extend along the upper anterior margin of the scapulae. The humerus possesses enormous crests. The broad ilium is attached to two, or perhaps three, sacral ribs. The acetabulum is closed. The pubes and ischia are united into one broad mass of bone, and the obturator-foramina seem to be just large enough to permit of the passage of the nerve. Both fore- and hind-limbs are plantigrade and five-toed. The tibia articulates with one large bone, which is supposed to represent the united astragalus and calcaneum, the latter being without an indication of a prominent heel, although there is a tendency to develop the crurotarsal into the chief joint. The number of vertebrae amounts to eighteen presacrals, eight to ten of which are cervicals. There are two or three sacral and about twenty-four mostly shortened caudal vertebrae. The latter possess intercentral wedges and chevron-bones; wedges occur also between the cervical and some thoracic vertebrae. Some of the posterior cervical ribs are very peculiar–straight, broadened out, turned backwards, partly overlapped by one another, and 18 inches long, recalling the first two ribs of the crocodiles. Sternum and abdominal ribs are unknown.

Elginia mirabilis.–The skull (Fig. 54, A, p. 280)–nothing else is known–indicates one of the most remarkable reptiles hitherto found on this side of the Atlantic. It was discovered in the Red Sandstone of Elgin (Lower Trias). The skull reminds us in its general shape and by its spikes and horns of the little American Iguanoid lizard, Phrynosoma. The length of the cranium is about 6 inches, the distance between the tips of the two largest {306}horns measures 9 inches. The teeth are small and resemble those of an Iguana in their shape and finely serrated edges, indicating herbivorous habits, but there are also several rows of smaller teeth on the palate, the configuration of which is not unlike that of Sphenodon. The top and sides of the skull, except the interparietal foramen, the orbits, and nostrils, are completely encased by rugose, pitted, dermal bones, most of them with strange, horn-like spikes. In the encasement of the temporal region can be discerned a postfrontal, parietal and squamosal, a conically projecting epiotic, a postorbital and supratemporal, a jugal and a quadrato-jugal, which latter almost completely covers the quadrate bone. The interparietal foramen lies far forwards, almost on a level with the orbits. The nostrils are terminal, surrounded by the short nasals, the maxillaries and the premaxillaries, which latter divide them.

ORDER II. THERIODONTIA.

The cranium is not roofed in, but shows a pair of large supratemporal fossae, bordered below by the zygoma, which is formed mainly by the squamoso-jugal bridge, and is shut off from the orbit by the postfrontal joining the bridge. The teeth are differentiated into incisors, canines, and molars (Fig. 54, C, p. 280). The lower canines close in front of the upper.

Cynognathus, Karroo formation of South Africa. C. crateronotus has a skull about 16 inches long, looking like that of a ferocious Carnivore; there are four incisors, huge canines, and nine molars, the latter with serrated edges and anterior and posterior cusps. The wide supratemporal fossa is bordered and closed behind by the broad lateral extension of the parietal, which joins a similar extension of the squamosal bone. The latter is very long, extending to the postfrontal and to a bone which, bordering the orbit posteriorly, is either an upward branch of the jugal, or a postorbital bone; the latter interpretation is made probable by the occurrence of a suture with the jugal in C. platyceps. The jugal bone is very long, beginning at the quadrate, running along the squamosal, and forming the lower border of the orbit.

The number of vertebrae is large, there being as many as twenty-nine presacrals, six of which belong to the cervical region. {307}The atlas is fused with the axis; most of the thoracic ribs articulate partly upon the intercentra. The lumbar ribs are very peculiar; they are much expanded horizontally, and overlap each other, forming thereby intercostal foramina. The broad ilium is attached to three or four sacral ribs. The acetabulum is closed. The ventral side of the pelvis shows a broad symphysis and has a pair of obturator-foramina. The scapula is large, directed backwards, and shows a distinct, very Mammalian spine; it is fused with the coracoid and precoracoid.

The occipital condyle of C. platyceps is kidney-shaped, with the concavity directed upwards; in C. berryi it is separated into two distinct knobs, the middle, basioccipital portion being apparently wanting. The mandible possesses a long coronoid process which ascends obliquely into the temporal fossa.

Aelurosaurus, Lycosaurus, Galesaurus, and many others, likewise of the Karroo formation. In the first genus the splenial bones help to form the symphysis of the lower jaw; teeth are also found on the palate, in opposition to Lycosaurus. This has a skull 6 inches in length; the dental formula on either side is i. 4/3, c. 1/1, m. 5/5; the molars are slender, conical, and recurved. Galesaurus seems to have been rather small, the low, triangular skull measuring only 2 to 3 inches in length, with four or five sharply pointed incisors, prominent canines and four or five small multicuspid or deeply serrated little molars.

Endothiodon, with several species from the Karroo formation, is of uncertain systematic position, only imperfect skulls being known. The animals must have been large and bulky, the skulls being very massive and at least one foot in length. The premaxillaries and the maxillaries are toothless, their alveolar borders forming cutting, prominent edges. The same applies to the very strong lower jaw; but there is a pair of tooth-like stout projections in the upper and lower jaws in the place of canine teeth. True, enamelled, small, apparently conical or low and perhaps blunt teeth occur on either side in one or three longitudinal series upon the palate, and in corresponding positions on the inner sides of the two halves of the lower jaw. It is doubtful if the upper teeth are carried by the palatines or by the broadened inner flanges of the maxillaries. The choanae seem to lie between the pterygoids and the palatines, incompletely roofed in by ventral extensions of the latter towards the middle line.

{308}Direct affinity of Endothiodon (ἐνδοθί, within) with Placodus is unlikely; the same applies to the Dicynodontia, although the restriction of the teeth to the palate seems to point as much to the former genus as do the toothless cutting edges of the jaws to the forms like Oudenodon.

Other Theriodont reptiles have been described from the upper Permian of Russia, for instance Deuterosaurus and Brithopus, but the determination rests upon insufficient fragments. North America has yielded many strange Theromorphous fossils, some of which may belong to the Theriodont order, while others seem to be intermediate between this and the other orders. Diadectes of Texas, for instance, seems to be a Theriodont creature; while in Empedias molaris, with a skull about 8 inches in length, the teeth form an uninterrupted series without distinct canine tusks, and the incisors are distinguished from the molars only by the transversely broadened shape of the latter. Very small teeth are arranged along the median line of the vomer and united palatine bones. In Clepsydrops, Dimetrodon, and Naosaurus of Texas the teeth are differentiated into incisors, canines, and molars, although not so regularly as in the typical Theriodont forms described above, one or more pairs of teeth being enlarged into canine-like tusks. In the latter two genera the spinous processes of the thoracic vertebrae are enormously elongated, standing up vertically to a height of 2 feet, while the centra of the vertebrae measure only one inch in diameter. In Naosaurus claviger these upright spines carry on either side half a dozen transverse projections. Stereorhachis of the Permian of France is typically Theriodont in the structure of its shoulder-girdle, humerus, and pelvis, but the dentition is composed of 3/3 incisors, no canines, and 6/10 pointed molars.

The following genera have been placed by Seeley in the family Gomphognathidae. Microgomphodon, with broader and less prominently multicuspid teeth than those of the typical Theriodonts, seems to lead to Gomphognathus, which has the following dentition: i. 3/3, c. 1/1, m. 12/12, with a long diastema between the canines and molars, some of which latter are nearly as broad as they are long, and have comparatively low tubercles on the crowns. The skull is remarkably like that of a Carnivorous Mammal. There are incisive foramina behind the premaxilla. The maxillaries and palatines form a united palatal roof, and behind them open the {309}choanae. The occipital condyle is kidney-shaped. The mandible is most extraordinary, approaching that of the Mammalian, especially the Marsupial type, except that it is still composed of several pieces. The articular facet for the mandible is borne by an outward or lateral projection, while the bulk of the posterior half of the jaw projects inwards like a broad flange, undoubtedly recalling the so-called inner inverted angle of the Marsupial jaw. The coronoid process is large and extends far into the temporal fossa. Nearly the whole skeleton of Microgomphodon is known; the lumbar ribs are broadened and overlap as in Cynognathus, and the mandible is typically compound, so that there is no doubt about the affinities of this genus with the Theriodontia. It throws light upon Gomphognathus and the three likewise South African genera Diademodon, Trirachiodon and Tritylodon, which are all known from imperfect skulls only. Their teeth are restricted to the jaws, the molars have flat, multitubercular crowns and bear an extraordinary resemblance to those of Mammals. Some of the molars of Tritylodon are said even to possess two roots, but this point, absolutely unique in Reptiles, but common in Mammals, is not certain. The few upper incisors of Tritylodon are rather large, chisel-shaped, and extend like those of the Rodent-type back into the maxillaries; canines are absent, leaving a diastema. Trirachiodon has prominent canines, the five upper molars are multitubercular, rather flat, and much broader transversely than in the longitudinal direction. Still, even these creatures, with skulls of the size of that of a small fox, possessed distinct prefrontal and postfrontal bones, and are, at least in this respect, typical Reptiles.

ORDER III. ANOMODONTIA.

The cranium is not roofed in. The pedicle for the suspension of the lower jaw is much elongated, slants slightly forwards, and is composed of the long quadrate, which is laterally overgrown by the squamosal bone. The teeth are restricted to a pair of strong, tusk-like canines, or they are altogether absent. The margins of the upper and especially those of the lower jaw are trenchant, and were possibly furnished with a thick horny armature like those of tortoises.

{310}Dicynodon, with many species from the Karroo formation of South Africa, reached formidable dimensions. The thick, curved skull is in size and outline not unlike that of a large lion, hence D. leoniceps, D. tigriceps, etc. The zygomatic arch is almost mammalian, except that the posterior boundary of the orbit is formed by a distinct postfrontal bone. The nostrils are lateral. The canine tusks (Fig. 54, E, p. 280) are very large. The choanae open behind the rhomboid vomer and between the separated palatine bones, which are posteriorly confluent with the medially united pterygoids. The latter send out flat extensions, along the lateral side of the palatines; these extensions reach the maxillaries and probably represent the ectopterygoids. The occipital condyle is distinctly triple, being equally composed of the basi- and latero-occipital bones.

The three bones of the shoulder-girdle meet at the glenoid fossa; the scapula has the indication of a spine. The pelvis is stout, attached to four or five vertebrae, converting the latter into a very Mammalian-like sacrum, the position of which lies distinctly in front of the acetabulum. The latter is closed, composed by the three pelvic bones. The pubes and ischia are fused together, leaving only a very small obturator-foramen. The limbs are plantigrade and pentadactyle, very stout; the humerus and femur have enormous crests.

Oudenodon, of which several species have been described, is so much like Dicynodon, except for the complete absence of teeth, that it has been suggested that these skulls belong to females of this genus. This view is strengthened by the fact that tusk-like canines exist, or are absent in some of the species which have been described as Cistecephalus, a genus closely allied to Dicynodon. The latter, which, like Oudenodon and Cistecephalus, occurred in Africa, extended also into India, D. orientalis having been found in the Panchet formation of Bengal, of transitional age between the Permian and Triassic epochs. Oudenodon rugosus, on the other hand, has been described from the Ural.

Gordonia and Geikia, of the New Red Sandstone of Elgin, are known from their skulls only, but these are so well preserved that there is no doubt about their close relationship to the typical South African Dicynodontia. The skull of Gordonia is about 7 inches long and 4 inches high. The canines (Fig. 54, D, p. 280) are reduced to short, but thick, conical tusks. The most {311}remarkable feature is the very elongated squamoso-jugal arch, which arises moreover from the dorsal end of the long squamoso-quadrate pedicle. The two wide and long temporal fossae are dorsally divided by narrow parietal crests. There is a distinct interparietal bone, and the usual interparietal foramen. The choanae are united and lie within the palatines, which themselves are united; the large lateral palatal foramina are otherwise enclosed by the pterygoids, quadrates, and laterally by the squamoso-jugal arch.

ORDER IV. PLACODONTIA.

These are the latest and last members of the Theromorpha, unfortunately known from skulls only, from the Muschelkalk or Middle Trias of Germany and Russia. The skull of Placodus gigas is about one foot long, rather high and triangular owing to the lateral expansion of the temporal arches, which diverge posteriorly. The squamoso-jugal arch is very broad, and most of the posterior border of the orbit is formed by the large postorbital bone. The maxillary bone seems to extend back to beyond the level of the orbits. The choanae lie behind the premaxillaries. The palatines and pterygoids are fused in the middle line, forming a broad bony palate, which, owing to the broad, posteriorly extended wings of the pterygoids, much resembles that of the crocodiles. The teeth are very remarkable. There are two or three stout, conical, or chisel-like teeth in each premaxillary bone, and three to five broad and flat maxillary teeth; three pairs of huge, broad, and quite flat teeth are crowded together and fill up the whole vomerine and palatine portion of the palate. These crushing teeth indicate that Placodus probably lived upon hard-shelled molluscs, and this would be in conformity with its occurrence in the Muschelkalk, which is a strictly marine deposit and full of shells. Another closely allied genus is Cyamodus, one species of which is known from Russia. The teeth are fewer in number and not so large as those of Placodus.

{312}CHAPTER IX

CHELONIA–ATHECAE–THECOPHORA

SUB-CLASS IV.–CHELONIA.

There is no mistaking a tortoise. The shell and the horn-covered toothless jaws separate them from all other four-footed creatures.

They may be described as terrestrial or aquatic, pentadactyle reptiles, with walking limbs or with paddles; ribs with capitular portions only, two sacral vertebrae, humerus with entepicondylar foramen, pubes and ischia forming symphyses, quadrate bones fixed, jaws without teeth, but with cutting horny sheaths. Trunk encased in a bony shell, composed of numerous dorsal and ventral dermal bones, forming a carapace and a plastron, which may or may not be covered with horny shields. Copulatory organ unpaired, cloacal opening more longitudinal than round, never transverse. Oviparous.

It is customary to distinguish the marine, paddle-limbed kinds as Turtles, the others as Land- and Water-tortoises.

Tortoises occur already in the Trias. They reached their greatest development towards the end of the Mesozoic and in the earlier Tertiary periods. They are now comparatively reduced in the number of families and genera, although they are still represented by about 200 species. The sub-class as a whole is cosmopolitan, but does not occur in the colder regions.

Their origin is quite unknown. Of recent groups only the Crocodilia and the Rhynchocephalia come into consideration. Combination of these groups with the Chelonia leads to some unknown forms whence also the Theromorpha have arisen. Palaeontology does not help us, all the leading, main groups of Chelonia having been in existence in the earlier Mesozoic ages, {313}and Palaeozoic Chelonia are still unknown. We can, however, to a certain extent, reconstruct an ideal primordial Chelonian by assigning to it all the ancestral characters actually observed in recent and fossil kinds, and by reducing to simpler conditions those features which we know to be more or less exaggerated specialisations. It is reasonable to assume that originally each metamere, except those of the anterior half of the neck and the posterior half of the tail, carried a transverse series of dermal plates, covered with horny shields, while the trunk, according to the greater bulk of the body, increased in size, converging towards the root of the neck and tail. By concentration, reduction of the number, and increase in the size of some of the remaining plates and shields, the skull assumed its characteristic box-like shape, the neck and tail becoming at the same time free. Chelonia are without doubt descendants of terrestrial, or at least semi-aquatic reptiles, and the marine paddled forms subsequently developed from terrestrial kinds.

CLASSIFICATION OF CHELONIA.–After many vicissitudes it was recognised that the Chelonia cannot naturally be divided according to the modification of their feet. The TRIONYCHOIDEA were clearly separated from the rest by Stannius in 1854. Cope, in 1870, was the first to emphasise the important character of the mode in which the neck is either bent sidewards (PLEURODIRA) or withdrawn in an S-shaped curve in a vertical plane (CRYPTODIRA); and he also separated Sphargis as ATHECAE from all the other Chelonians, for which Dollo in 1886 proposed the term THECOPHORA. The division of the latter into recognisable families, based upon reliable, chiefly internal, skeletal, characters, has been effected by Boulenger; and his classification has been adopted in the present volume, after intercalation of the more important fossil forms. The relationships between these various families may perhaps be indicated as follows:–

{ ATHECAE Sphargidae { { { Pleurodira { Pelomedusidae { { { Chelydidae–Carettochelydidae { { CHELONIA { THECOPHORA { Cryptodira { Chelydridae–Dermatemydidae– { { { Cinosternidae { { { Platysternidae { { { Testudinidae–Chelonidae { { { { Trionychoidea Trionychidae

{314}The guiding taxonomic characters are fully mentioned at the head of the different families, and are mostly internal. The following "key," adapted from Boulenger, and based upon external characters, is preferable for practical purposes.

For the position and names of the horny shields see Fig. 61 on p. 315.

Shell covered with horny shields. Digits distinct, with 5 or 4 claws. Pectoral shields separated from the marginals by inframarginals. Tail long and crested. Plastron small and cruciform. North America Chelydridae, p. 338. Tail long, covered with rings of shields. Plastron large. Indo-China Platysternidae, p. 345. Tail short. North and { Dermatemydidae, p. 341. Central America { Cinosternidae, p. 342. Pectoral shields in contact with the marginals. Plastral shields 11 or 12, without an intergular. Neck retractile in an p. S-shaped vertical curve Testudinidae, p. 345. Plastral shields 13, an intergular being present. Neck bending sideways under the shell { Chelydidae, p. 399. { Pelomedusidae, p. 390. Limbs paddle-shaped, with one or two claws Chelonidae, p. 378. Shell without horny shields, covered with soft, leathery skin. Digits distinct, broadly webbed, but with only three claws Trionychoidea, p. 404. Limbs paddle-shaped. Shell composed of regular series of bony plates. Two claws Carettochelydidae, p. 404. Shell composed of very many small plates arranged like mosaic. No claws Sphargidae, p. 333.

The VERTEBRAE are, sometimes in the various regions of the same individual, amphi-, opistho- or pro-coelous, or even biconvex. Traces of the chorda remain longest in the middle of the centra. Intercentra occur regularly on the first two or three cervicals, and then again in the tail as paired or unpaired nodules, or as short chevrons. The latter occasionally fuse with the caudal end of their centra. Intercentral discs of fibrous cartilage occur regularly in the neck and tail. The ribs develop originally in the same transverse level with these discs, and frequently the anterior thoracic vertebrae retain this intercentral or intervertebral position throughout life. Farther back they often show a gradual change from the intercentral to a more central and ultimately {315}remarkable to a purely neural attachment. In all the Chelonia the ribs are devoid of the tubercular portion.

The cervical vertebrae have no ribs, except mere traces in the shape of small nodules. On the tail the ribs are often large, and, when fused with their neural supports, look like transverse processes; the whole arrangement exactly resembles that of Crocodilia. The first pair of thoracic ribs, those borne by the ninth vertebra, are peculiar. They arise from the anterior portion of the centrum, are much reduced, sometimes to mere threads of bone, and lean against the anterior rim of the second pair of ribs, in many cases without reaching the carapace. The next following ribs, those of the tenth to the sixteenth vertebra, are intimately involved in the formation of the first to seventh costal plates. The ribs of the two sacral vertebrae sometimes remain quite distinct throughout life, just touching the upper {316}ends of the iliac bones; but since these find a much more effective support in the shell, the distal ends of the sacral vertebrae fuse with the eighth, or so-called last, pair of costal plates.

The neural arch of the ninth vertebra rests upon its centrum; but the neural arches of the other trunk-vertebrae, although long, rest upon two centra; retaining, like the ribs, their original intercentral position; and in most cases the neuro-central sutures remain throughout life. The atlas and the last cervical vertebra deserve special attention. In many tortoises, e.g. Trionyx, Clemmys, Testudo, the three constituent parts of the atlas, namely, the neural arch, the centrum, and the intercentrum or first pair of united basiventralia, do not ankylose, but remain loosely connected; and the first centrum, instead of forming an odontoid process, remains movably attached to the second centrum, although it sometimes carries, and fuses with, the second intercentral piece. In other tortoises, e.g. Platemys and Chelys, however, all the parts of the atlas co-ossify and form a complete, solid vertebra which articulates by a concavo-convex joint with the centrum of the second vertebra. The normal number of cervical vertebrae is eight in all Chelonians. The first spinal nerve issues between occiput and atlas, all the others behind the neural arches of their vertebrae. The last, or eighth cervical, owing to the retractility of the neck, forms elaborate joints; its centre fits with a knob into a cup of the ninth, and its post-zygapophyses form broad, curved articulating concave facets for the reception of the anterior zygapophyses of the fixed ninth vertebra. In the Trionychidae the zygapophyses are most elaborate, and they alone articulate with the ninth vertebra, while the centra do not join, but remain, or rather become, separated by partial resorption. In the Chelonidae, in conformity with the non-retractile and short neck, all the cervical joints are much reduced.

{317}[Illustration: FIG. 63.–Skull of Chelone mydas. A, from the left side; in B, the postfrontal and squamosal bones have been removed, and the broad expansions of the jugal, quadrato-jugal, parietal, and quadrate bones have been reduced in order to reduce the skull to more primitive conditions. F, Frontal; J, jugal; L.o, lateral occipital; Mx, maxillary; Op, opisthotic; Pal, palatine; Par, parietal; Prf, prefrontal; Pro, pro-otic; Pt.f, postfrontal; Ptg, pterygoid; Q, quadrate; Qj, quadrato-jugal; S.o, supra-occipital; Sq, squamosal.]

The SKULL (cf. Fig. 54, H, I, K, p. 280) agrees fundamentally with that of Sphenodon and of the Crocodilia, but it is characterised by several special features. There are no ectopterygoids or ossa transversa; no lacrymal bones, no interparietal or pineal foramen; the vomer is unpaired and the nasal bones are mostly absent, unless they are fused with the prefrontals. The premaxillae are very small. The single vomer forms a septum between the choanae; and these are, except in Sphargis, ventrally roofed over by wings sent out by the palatines. The latter form a continuous bony roof to the mouth with the pterygoids, and these diverge posteriorly, being connected suturally with the quadrates, lateral and basi-occipital bones, and with the unpaired basi-sphenoid, which appears between the basi-occipital and the diverging pterygoids, but is in most cases to a great extent overlapped by the latter. The occipital condyle is distinctly triple; the basi-occipital sometimes helps to border the foramen magnum. The supra-occipital sends out a long vertical blade, directed backwards and generally projecting far over the neck, for the attachment of the powerful cranio-cervical muscles. The quadrate is very peculiar. Firmly attached, and hemmed in on nearly all sides by the neighbouring bones, it stands nearly vertically and forms a broad articulating surface for the mandible. Its posterior side shows either a transverse, horizontal groove, in which lies the columella auris, or the groove is transformed into a more or less closed canal. Moreover, the hinder lateral margin of the quadrate forms most of the tympanic frame; its margins being curved backwards, leaving in the Cryptodira, however, a {318}wide notch behind; in the Pleurodira this part of the quadrate is transformed into a trumpet, the wide rim of which, forming a complete ring, carries the tympanic membrane. The tympanic cavity thus formed often leads into a deep recess which extends beneath the squamosal towards the opisthotic and bears some resemblance to the intricate tympanic recesses which pervade that region of the Crocodilian skull.

Dorsally the quadrate is broadly overlaid by the squamosal, which frequently forms an arch with the parietal. Anteriorly the quadrate is connected through a variably sized quadrato-jugal with the jugal; and this, by joining the maxilla and postfrontal, helps normally to form the posterior rim of the orbit. All the bones which border the temporal fossa vary much in extent in the different groups of Chelonia. The extremes are represented by Cistudo and Geoemyda, in which the bony infratemporal arch is absent, owing to the loss of the quadrato-jugal; and on the other hand by the Chelonidae and by Sphargis, in which the whole temporal region is covered over by an additional "false cranial" roof. This roof is produced chiefly by lateral wing-like expansions of the parietal and postfrontal bones, which meet the likewise much expanded jugal, quadrato-jugal, and squamosal bones. In the lower diagram of Fig. 63 (Chelone mydas) the squamosal has been removed, and the other bones have been reduced to their normal, or rather primitive condition, for comparison with the external view of the complete skull of the same animal. The lower diagram shows also the connexion of the pterygoid with a descending process of the parietal; this column, paired of course, usually contains a separate bone, the epipterygoid, the portion between Ptg and Par.

The hyoidean apparatus is well developed, and sometimes assumes large dimensions, especially in Chelys. The two pairs of "horns" are the first and second branchial arches, whilst the hyoid arches are reduced to a pair of small, frequently only cartilaginous, nodules attached near the anterior corners of the basis linguae, which generally fuses with the os entoglossum in the tip of the tongue.

The PECTORAL ARCH consists of a pair of long coracoids sloping obliquely backwards, the distal cartilages of which scarcely touch each other in the middle line, and the scapulae. The upper end of the scapula frequently touches the inside of the {319}first costal plate, protected by a cartilaginous pad. Near the glenoid cavity arises a long process (PC in Fig. 65), placed transversely and approaching its fellow. The distal end is connected with that of the coracoid by a fibro-cartilaginous band. The homology of this scapular process is not quite clear. The band just mentioned favours the idea that the process represents the precoracoid, but its being an outgrowth from the scapula suggests that it is merely the much enlarged acromion. It certainly does not represent the clavicle, which forms part of the plastron: and this is not in contact with the shoulder-girdle at all.

The PELVIS is strong. Ilium, pubis, and ischium meet at the acetabulum. The dorsal end of the ilium is generally broadened, and is attached to one or both sacral vertebrae, but it is also in contact with the superimposed last costal plate. This additional connexion often becomes predominant and the sacral vertebrae are partly or completely relieved of the iliac support, fusing in this case more or less with the costal plates. The pubes have strong lateral processes, directed obliquely forwards and downwards. The pubes and the ischia, which latter are much smaller, form broad symphyses, and these are connected with each other by a longitudinal cartilaginous band (Chelone, Trionyx); or the connecting bridge is broad and quite ossified (Testudo), forming in the latter case two roundish obturator-foramina. Cartilage frequently remains at the anterior end of {320}the pubic symphysis, and a smaller, longer, and narrow piece of cartilage extends sometimes backwards from the ischiadic symphysis, as the so-called hypo-ischium. In the Pleurodira the ends of the ilia, and those of the lateral processes of the pubes, are much broadened and firmly ankylosed with the posterior costal plates and with the xiphiplastron respectively.

The LIMBS are typically pentadactyle and complete, and are most primitive in water-tortoises, e.g. Chelydra and Emys, in which the carpus consists of the typical ten separate elements, including the pisiform. In Testudo the centrale is fused with the intermedium, and the first three distal carpals are also fused together. In the marine turtles the limbs are transformed into paddles, but all the bones retain their independence; the pisiform {321}and the first metacarpal are enlarged and flattened, thereby giving additional width to the paddle. The tarsus remains less primitive; the centrale and the proximal elements have a tendency to fuse together, most completely in land-tortoises; the fifth distal carpal is enlarged, and stands out hook-like from the rest. The number of the phalanges of the fingers and toes varies slightly. It is noteworthy that none of the Chelonia possess more than three phalanges. The three middle fingers and toes have mostly three phalanges; the pollex and hallux have always two; the number of phalanges of the fifth finger varies from three to one, of the fifth toe from two to none. The greatest reduction occurs in Testudo and its allied genera of typical land-tortoises, Homopus, Pyxis, and Cinixys, the formula for the fingers being 2, 2, 2, 2, 2 or 1, and 2, 2, 2, 2, 0 for the toes. In Pelomedusa all the fingers possess two phalanges only, owing to fusion of the first and second phalanges with each other.

The SHELL, which is the most characteristic feature of the Chelonia, consists of the dorsal "carapace" and the ventral "plastron." Each is composed of a considerable number of bony plates which arise as ossifications of nearly the whole thickness of the cutis, only a thin layer of subcutaneous connective tissue remaining soft and lining the inside of the shell. We restrict ourselves to a description of the shell of the Thecophora, leaving the discussion of the peculiar shell of Sphargis to p. 336 f. Very young tortoises are still soft, and the plates which are beginning to ossify are not yet suturally united. The plastron (Figs. 66 and 67) consists of the paired epi-, hyo-, hypo-, and xiphi-plastral plates, and the unpaired endo-plastral plate.

{322}[Illustration: FIG. 67.–Bony shell of Testudo ibera. A, Ventral; B, dorsal; C, left-side view. In B, and on the right half of A, the position of the horny shields is indicated by dotted lines. The underlying bony plates are marked by strong lines. In B the 1st neural and costal plates, the 4th neural, costal, and 6th marginal plates, and the 7th neural plate are shaded. 1, 4, 6, First, fourth, and sixth neural plate; M, in C, fifth left marginal plate; Nu, nuchal plate.]

The latter is homologous with the interclavicle, the epi-plastra are homologous with the clavicles of other Reptiles, while the other pieces are genetically derived from, and are further modifications of, the so-called abdominal ribs of the Crocodilia and Prosauria, These plastral plates are never in direct contact with the shoulder-girdle or with any other parts of the internal skeleton. In the young of all tortoises, and in the adult of the Chelonidae and Trionychidae, the several plastral plates enclose large, irregularly-shaped fontanelles. These are more or less filled up in the other groups; and in the Testudinidae especially the whole plastron forms one continuous mass. The navel is situated between the hyo- and hypo-plastrals. Both these pairs are broader than the others, and are connected with the carapace by {323}means of several marginals. The connecting region is called the bridge. In several tortoises, e.g. Emys, the connexion with the marginals is formed by ligaments only and remains movable. In others, transverse, more or less perfect hinges are formed across the plastron. A rather imperfect joint between the hypo- and xiphi-plastrals develops with age in Testudo ibera. In Cistudo and Cyclemys a very effective hinge lies below the hyo- and hypo-plastrals, just in front of the bridge; and the anterior and posterior lobes of the plastron can be closed against the inner rim of the box, fitting tightly in Cistudo. In Pyxis the front lobe only is movable.

The carapace is composed of one median series, a right and left lateral series of costal plates, and a series of marginals which surround the whole. The median series consists of one large nuchal plate, normally eight neurals and one to three supracaudal plates. The characteristic feature of the neural plates is that they are firmly fused with the broadened neural spinous processes of the underlying vertebrae. The nuchal plate lies in front of the first thoracic or ninth vertebra; it overlies the last cervical vertebrae, with the eighth of which it is connected by ligament only; but the posterior corner of the plate often fuses with the spine of the ninth vertebra. In the Chelydridae, and still {324}more in the Trionychidae, the nuchal sends out a pair of long rib-like processes, which either extend to below some of the neighbouring marginals, or their ends overlap those of the ribs of the second thoracic vertebra (e.g. Trionyx), or, lastly, they are in turn overlapped by the first costal plates (e.g. Cyclanorbis). Such rib-like processes are also present, well developed in the young, shorter in the adult, in the Dermatemydidae and Cinosternidae. It is possible that the nuchal plate represents the fused neural of the eighth and the costal plates of the ninth vertebrae. An indication of the compound nature of the nuchal may be found in the fact that two nuchals have been described in Chelydropsis carinata, a Miocene relation of Chelydra. Somewhat similar modifications have taken place in the post-sacral region. The one to three supracaudal plates are, namely, neurals which have lost their connexion with, or perhaps have never been fused with, the spinous processes of the movable tail-vertebrae. The number of neural plates is mostly eight, but there are sometimes individually nine or ten, the gradual suppression taking place first in the sacral region. When such a plate is suppressed the neighbouring costal plates usually close up and meet in the median line. In Cistudo, for instance, there are only seven normal neurals, the eighth pair of costals meet, and the original eighth neural is transformed into a supracaudal. In Cinosternum the sixth to eighth costals meet, separating the one supracaudal widely from the remaining five neurals. The meeting of the last pair of costals, with co-ordinate reduction of the neurals to seven, is almost universal in the Pleurodira; and this tendency is carried out to an extreme in the Brazilian Platemys and in the Australian Chelodina and its allies, in which all the costals meet in the middle line, and the neurals are completely suppressed. Every stage intermediate between complete neurals (Sternothaerus) and interrupted, vestigial, and vanished neurals, is still represented by some genus. This process takes place independently, both in America and in Australia, and is one of the most recently introduced modifications.

The costal plates arise, like the neurals, independently in the cutis, but they soon come into contact with the underlying cartilage of the ribs, which are long enough to reach the marginals. The ribs flatten, become surrounded by the growing membrane-bone of the plates, and the cartilage of the ribs, {325}instead of ossifying, undergoes a process of calcification. Ultimately this is more or less absorbed, its place is taken by the dermal bone, which forms so to speak a cast of the rib, preserving in many cases the shape of the vanished rib, only the capitular portions of which remain unaffected. The number of costal plates is very constant, namely eight on each side, but some fossils have nine or ten, and there are still individual variations in recent forms, indicative of that number. In a large Chrysemys concinna I find the last pair of costals clearly composed of at least two pairs, and this same specimen has nine distinct neural plates.

The marginal plates are originally paired, almost always eleven pairs, very rarely ten or twelve; an unpaired posterior plate, the pygal, is always present, and is probably the result of fusion. In the Chelonidae large fenestrae remain between the costal and marginal plates, only covered by leathery unossified cutis, and of course by the horny shields. In the Indian fresh-water genus Batagur similar windows are gradually filled up with age, and the horny shields become extremely thin and almost confluent. On the other hand, in Testudo polyphemus, the bony shell, always very thin, becomes still thinner with age and finally fenestrated by absorption.

Great reduction has taken place in the carapace of the Trionychidae. The American species of Trionyx have only seven pairs of costal plates; in Cyclanorbis the neurals are reduced to two. The whole dorsal shell is much smaller than the body, and marginal plates are absent or merely vestigial. It is doubtful if the ossifications in the posterior half of the marginal flap of some genera are homologous with true marginals.

Externally the whole shell is covered, except in the Trionychidae, in Sphargis and Carettochelys with horny, epidermal shields. These are phylogenetically older than the dermal plates, and they do not correspond with them either in numbers or in position, although there exists a general resemblance in their arrangement. On the plastron we distinguish an unpaired or paired gular, and a pair of gular, humeral, pectoral, abdominal, femoral, and anal shields (Fig. 66). Sometimes there are also intergulars, paired in Macroclemmys and Chelys, unpaired in Chelone; in many of the Pleurodira an unpaired intergular lies behind the gulars.

{326}The carapace of most Chelonians is covered with five neural, four pairs of costal and twelve pairs of marginal shields, the last of which often forms an unpaired pygal. In front of the first neural lies the nuchal shield, very variable in size, often absent. The Chelydridae, Dermatemydidae, Platysternidae, and Cinosternidae possess moreover several inframarginals, intercalated on the bridge between the marginal and some of the plastral shields. In many of the other families these inframarginals are restricted to the anterior and posterior corners of the bridge, as the so-called axillaries and inguinals, mostly small and variable. Lastly, Macroclemmys has several small supramarginals.

There are consequently eleven longitudinal rows of shields in all; by elimination of the supra- and infra-marginals they are reduced to seven rows. It is absolutely certain that the number of transverse rows also was originally much greater than it is now. The mode of reduction of the number of the neural and costal shields has been studied in Thalassochelys caretta (cf. p. 388.) The accompanying illustration (Fig. 69) shows some of the main stages actually observed in the reduction of these shields. The chief point is that certain shields are squeezed out, or suppressed by their enlarging neighbours. The ultimate result is the formation of fewer, but larger shields.

Each shield grows individually as follows. Every year, or rather during every periodically recurring period of growth, the area of the Malpighian layer belonging to each shield increases peripherally in size, and at the same time produces a new layer of horn. The original little shield, with which the tortoise is born, remains for years, often throughout life, as the so-called "areola;" it increases in thickness owing to the new layer of horn added from below, and peripherally the increase in size is indicated by the overlapping concentric rings. Each ring represents a year's growth, at least in tortoises which live in temperate zones, where hibernation means a complete suspension of growth. It is not known if the same applies to tropical species, which grow either throughout the year, or which undergo one or more periods of rest. The areola does not remain central; the growth is uneven. With age the oldest layers of the areola are frequently rubbed off, and the areola then appears enlarged.

{327}[Illustration: FIG. 69.–Diagrams illustrating the progressive reduction of the horny shields in various Chelonians. The shields, the fate of which it is desired to follow, are indicated by distinctive shading. I. Hypothetical, primitive stage. Eight neural (including the nuchal) and eight costal shields. Both neurals and costals lie in the same transverse planes. II.-VII. Successive stages in the reduction and suppression of various shields, observed in specimens of Thalassochelys, the normal condition of which is represented by VII. VIII. Six neurals and only four costals. The normal condition of Chelone. IX. The nuchal shield has become very small and the resulting gap has been filled up by an enlargement of the first pair of marginals. This is the normal condition of most Cryptodirous tortoises. X. The first marginals meet in front and the nuchal is either suppressed (Xa[X^a in diag]), e.g. in several species of Testudo, or it is surrounded by the marginals (Xb), e.g. in Sternothaerus. (From Willey's Zool. Results, 1899.)]

{328}For the first dozen years or so the annual rings can be easily followed, but when the creature approaches maturity each shield adds very little to its growth, and the rings become very fine, crowded and irregular. Only by careful counting and comparison of the rings on the costals, marginals, and plastrals, can a reliable average be arrived at. In some tortoises, e.g. Chrysemys, the whole outer layer of the shields peels off periodically; only a thin smooth layer like mica or tracing-paper remains, of course without any indication of rings. The pigment is formed in the Malpighian layer, but it frequently diffuses into the horny shields themselves, notably in Chelone imbricata, which yields the beautiful "tortoise-shell." The colour of the pigment is either black, yellow, or red, with resulting combinations. The green colour, often so beautiful in baby-specimens of Chrysemys, is optical, produced, according to Agassiz, by a network of black pigment, spread over a layer of yellow oil.

Horny scales, sometimes forming spines, and covering a nodule of dermal ossification, are also common on other parts of the skin, especially on the limbs of land-tortoises, and also on the tail of Chelydra. Sometimes the end of the tail is protected by a claw-like nail, for instance in Pyxis. In some of the gigantic land-tortoises, and in Chelone mydas, this nail assumes large dimensions, and several of the terminal caudal vertebrae are fused together into a regular urostyle. In some subfossil specimens of Mauritian tortoises, these ankylosed complexes are 12 cm. long and more than 5 cm. broad!

Before leaving the description of the shell, it is worth while to draw attention to the enormous correlative changes in other organs produced by this case. Nearly the whole organism has been altered. The hard, firm carapace has partly rendered the supporting functions of the vertebral column unnecessary or impossible. In many tortoises, especially in the large land-tortoises, the vertebrae and the capitular portions of the ribs are reduced to mere bony outlines; the reduction to thin paper-like bony lamellae proceeds with age. The iliac bones find a better support in the costal plates; the contact with the sacral ribs is given up, and these ribs fuse partly with the costal plates, or they are absorbed. The whole mass of muscles of the trunk is completely lost in the region of the shell, but traces of them exist in young specimens. Neck, limbs, and tail can in most cases be withdrawn and hidden in the shell. When this is not possible it is due to secondary changes. The neck is withdrawn either by being tucked away {329}sideways (Pleurodira), or by being bent in an S-shaped curve in a vertical plane. In a left-sided profile-view of the animal, the head represents the tail of the S. The neck is withdrawn by long muscles, which are inserted into the ventral side of the middle of the neck, and extend in the shape of vertical ribbons far back into the shell, arising from the centra of some of the middle or even more posterior thoracic vertebrae.

Lastly, a few remarks on the PARTIAL REGENERATION, or the mending of injuries to the shell. If part of the horny covering is badly bruised, torn off, or rubbed through, or if part of the shell is crushed, the underlying portion of the bony plate becomes necrotic, and the horny covering also dies so far as its Malpighian layer is destroyed. Soon, however, the uninjured Malpighian cells, around the margin of the wound, multiply, grow into and beneath the injured portion of the bone, and form a new horny layer, casting off the necrotic portion. After several months the deficiency is patched up; new bone has grown in the deeper remaining strata of the cutis, and the outside is covered by a continuous horny layer, without, however, reproducing the original concentric moulding of the shields. In badly crushed shells sometimes almost one-third of the whole shell is thus cast off and mended within one or two years. The regeneration of the forcibly stripped-off shields of Chelone imbricata is described on p. 386. Bitten-off tails and limbs, rather frequent occurrences in water-tortoises, are of course not reproduced, but the wounds are healed and covered again with scaly skin.

SENSE-ORGANS.–The EYE is by far the best developed sense-organ. It is comparatively small. The pupil is round. The iris is mostly dark in terrestrial forms, while in water-tortoises it is often brightly coloured, for instance pale yellow in Chelodina, greenish and mottled with black, pale grey, brown, etc., in various species of Chrysemys. Cistudo presents a curious sexual dimorphism; the males have red, the females brown, eyes. The sclerotic wall contains a ring of numerous small ossified plates. There is no trace of a pecten. The eye is protected externally by the two lids and the nictitating membrane. In some water-tortoises, notably in Chelodina, the lower lid is transparent. Lacrymal and Harderian glands are present.

{330}The SENSE OF HEARING is apparently not very acute, although tortoises and turtles are frightened by noise, and can distinguish sounds; otherwise they would have no voice, which is very tiny and piping in most tortoises during the pairing season. In most water-tortoises the tympanic membrane is thin and quite exposed; in land-tortoises it is often thick and covered by the ordinary skin; lastly, in Chelone the tympanic cavity is filled with a plug of the much-thickened skin, possibly in adaptation to the water-pressure when these creatures dive to considerable depths. The ossicular chain is mostly reduced to a long, bony, columellar rod.

The SENSE OF SMELL is well developed. All Chelonians carefully smell their food, in the air as well as under water. The individual predilection shown by many species for different kinds of animal and vegetable food,–since they are, for instance, able to distinguish between the various sorts of cabbage, cauliflower, sprouts, etc.,–proves that they possess a considerable amount of smell and taste.

Tortoises have a fine sense of touch; even the slightest tap on the shell is noticed, and the skin of the soft parts is extremely sensitive. Tickling of the sides of the tail, or of the hinder surface of a thigh, produces ridiculous scratching actions of the same or of the opposite foot.

The DIGESTIVE APPARATUS is simple. Only a few peculiarities need be mentioned. The tongue is mostly broad and soft; it cannot be protruded. The oesophagus of the Chelonidae is covered with many conical projections pointing towards the stomach. The latter is simple, except in Sphargis. The intestine is devoid of a caecum, but the difference between the small intestine and the rectum is very marked and often abrupt. The cloaca is very roomy. It contains the large copulatory organ, which is unpaired, grooved on its dorsal side, and is altogether constructed like that of the Crocodilia. The large bladder opens ventrally into the urodaeum, a recess of the cloaca; near its base open the urinary and genital ducts. Many water-tortoises possess also a pair of lateral thin-walled sacs, the so-called anal sacs, dorso-lateral diverticula of the walls of the urodaeum. These sacs, which have highly vascularised walls, are incessantly filled and emptied with water through the vent, and act as important respiratory organs. When such a water-tortoise, for instance an Emys or a Clemmys, is suddenly taken out of the water, it squirts out a {331}stream of this water, which is not, as is generally supposed, the urine from the bladder.

The mode of RESPIRATION is interesting. The lungs are very complicated, highly-developed, spongy structures. They are attached by their whole dorsal surface to the inner lining of the shell. As they cannot expand through their own initiative, and since the shell has made costal and abdominal expansion impossible, the tortoise has to resort to other means of producing the necessary vacuum. This is done partly by the neck and the limbs, which act like pistons in being drawn in and out; partly by the greatly developed hyoidean apparatus, by which, when the neck is stretched out, the throat is alternately inflated and emptied, the air being swallowed, or pumped into the lungs. Additional respiration, besides that of the anal sacs mentioned above, is effected in various aquatic tortoises by slightly vascularised recesses of the pharyngeal region. Most Chelonians can exist for a very long time without breathing; sulky individuals remain for hours or days under water. Cistudo can shut itself up for an equally long time. Nevertheless this and other land-tortoises easily get drowned.

All Chelonians lay white EGGS, round or oval, according to their kind, but the shape of the eggs of one set sometimes varies within the greatest limits. The shell varies from a parchment-like, flexible, scarcely calcareous cover to a hard, well-polished case. As a rule the eggs, imbedded in the ground, are hatched after a few months, but in some of the northern kinds, e.g. Emys orbicularis, the hatching is deferred until the next spring, the embryo's development being arrested during the winter. How such eggs, buried a few inches only below the surface, withstand the often very severe North German and Russian winter is a mystery. Whilst the plastron is generally flat, it is more or less concave in the males of many species, notably in Testudo, Cistudo, and Emys.

The general conclusions which can be drawn from the present GEOGRAPHICAL DISTRIBUTION of the Chelonia are as few and unsatisfactory as those applying to the Crocodilia, since all the main groups of Chelonians, and many more extinct families, occurred together in bygone ages in the same countries, for instance in Europe.

{332}[Illustration: FIG. 70.–Geographical distribution of Cryptodirous tortoises.]

The marine forms are naturally cosmopolitan, but the Testudinidae are likewise cosmopolitan, except in the Australian region. The Chelydridae, now restricted to North and Central America, occurred formerly also in Europe. The Pleurodira, in Mesozoic times plentiful in Europe, India, and North America, are now restricted to South America, Australia, and Africa; the Pelomedusidae to Africa, Madagascar, and South America; the Chelydidae to South America and Australia. In the latter country all the Chelonians belong to the Chelydidae. The Trionychoidea, occurring since the Cretaceous epoch in North America, in Early and Mid-Tertiary times in Europe, are now restricted to North America, Asia, and Africa. The country richest in Chelonians is America; North and Central America together possessing representatives of all the families except the Pleurodira, and these we know to have died out there. The Dermatemydidae, {333}Cinosternidae, and Chelydridae are now restricted to the Nearctic sub-region (including Central America). Poorest in genera and species, all of them Chelydidae, is the Australian region, where no fossils of other families have yet been discovered. Europe, with its few Testudinidae, does not come into consideration; Asia has at least Testudinidae and Trionychidae, and in addition the solitary Platysternum in Indo-China, representative of a family whose affinities with the Chelydridae again proclaim the validity of the Periarctic region.

ORDER I. ATHECAE.

The vertebrae and ribs are not fused with, but are free from, the carapace, which consists of numerous small polygonal plates and is covered with leathery skin without any epidermal shields. The limbs are transformed into paddles. The neck is not retractile. Marine.

FAM. SPHARGIDAE.–Sphargis s. Dermatochelys coriacea, the Leathery Turtle or Luth, is the only recent species and is the largest of all recent Chelonians. The biggest specimen in the national collection is about six feet and a half long, from the nose to the end of the shell, which latter is about four feet long; such a specimen may weigh half a ton. Agassiz, however, says that he has seen some "weighing over a ton." The general colour is dark brown, either uniform or with yellow spots. The Leathery Turtle has a wide distribution, ranging over all the intertropical seas, but it is rare everywhere; least so perhaps in the Western Atlantic from Florida to Brazil and in the Indian Ocean.

{334}[Illustration: FIG. 73.–Sphargis coriacea, the "Leathery Turtle," young specimens, ventral and dorsal views. × 1.]

According to Agassiz it breeds regularly every year in the spring on the Bahamas, on the Tortugas, and on the coast of Brazil, depositing its many eggs on the sandy shore like other turtles. Accidentally it visits the northern coast up to Long Island, and specimens, perhaps carried with the Gulf Stream, have been caught on the coasts of Europe, for instance off Dorsetshire. One was caught near Nantes in 1729, and is said to have made a terrible noise when being killed. This is perhaps the reason why Merrem in 1820 invented the generic name Sphargis, supposed to be derived from σφαραγέω (I make a noise). It has also been recorded from the Mediterranean. It seems to be entirely carnivorous, living upon Molluscs, Crustacea, and fish. The flesh is supposed to be unwholesome. It is a very curious fact that of this rare species only large specimens, besides a very few baby-turtles, are known or preserved in collections, while individuals of intermediate size, say from four inches to three feet in length, have never been recorded. If it were not for the fact that they are still known to breed, it would look as if the {335}species were dying out. Perhaps they are very shy, leading a pelagic life, diving at the least sign of danger, and coming near the land only for the sake of breeding.

The structure of Sphargis is so peculiar in many respects that it deserves a somewhat full account. The neuro-central sutures persist on all the vertebrae. The eight cervicals are short. All the ten trunk-vertebrae carry ribs, and these, with the exception of the last, articulate between the centra and with the neural arches; the first and tenth ribs are short, the others are long and flattened, but not broad, with wide spaces between them. The tail is short, although it consists of about twenty vertebrae; these are devoid of chevrons.

The skull superficially resembles that of Chelone, chiefly owing to the completely roofed-in temporal region. The supraoccipital crest is rather short, covered completely by the parietals, the posterior margin of which is rounded off instead of forming, as in the Chelonidae, a long projecting triangular crest with the supra-occipital. The parietals are in broad contact with the postfrontals, posteriorly they are just reached by the squamosals. The quadrato-jugal is small, separated from the postfrontal by the meeting of the squamosal with the jugal. The quadrate is notched behind, and it separates the opisthotic from the squamosal. The basisphenoid is large and broad, extending far forwards so as to separate the pterygoids widely from each other except in their anterior portions, which, instead of sending a lateral arm to the jugal and maxillary, as in Chelone, are widely separated from these bones by the palatines. The choanae lie on either side of the anterior half of the vomer, and are not roofed over by ventral vomero-palatine wings.

The limbs and their girdles are essentially like those of the Chelonidae, but are not derivable from them. The most remarkable feature is the shell. The dorsal and ventral halves are directly continuous, forming one unbroken case all round, which is composed of many hundreds of little bony plates, irregularly polygonal, fitting closely into each other with their sutural edges, and giving the shell a beautiful mosaic appearance. On the dorsal side are a median row and three pairs of lateral rows of larger plates, and these form seven longitudinal blunt ridges which all converge towards the triangularly pointed tail-end of the shell. The ridges are not so much produced by thickened {336}or spine-like edges of the plates, but by the right and left halves of the plates being actually bent at an angle. This is most conspicuous at the sides of the shell where it passes into the ventral portion. The latter has two pairs of lateral and one median ridge. The whole shell has consequently twelve ridges. The mosaic plates are deeply imbedded in the cutis, being externally as well as internally covered or lined with dense leathery skin. The epiderm is thin, and shows no indications of horny scales. In young specimens the whole shell is soft and very imperfectly ossified, later on it is quite rigid, although comparatively thin. It is nowhere in contact with the internal skeleton, except by a nuchal bone, which by a descending process articulates with the neural arch of the eighth cervical vertebra.

The affinities of the Sphargidae and their position in the system are still debatable. Whilst some authorities, e.g. Cope, Dollo, and Boulenger look upon Sphargis as the sole remnant of a primitive group in opposition to all the other recent Chelonia, Baur considered it the most specialised descendant of the Chelonidae. Dames agreed with him. Van Bemmelen has modified this view in so far as he regards Sphargis as the most specialised Chelonian, but considers the differences between it and the Chelonidae great enough to conclude that both Sphargidae and Chelonidae represent two independent, partly parallel, branches which have arisen from two different groups of terrestrial tortoises. Case, from the study of Protostega and other fossil forms, tends towards Baur's view. He believes that Sphargis is the culminating form of a branch which through Psephophorus and with Eosphargis has sprung from some creature like Lytoloma, which at the same time is the starting-point of another branch which culminates in the genera Thalassochelys and Chelone, while lastly a third branch contains Protostega, Protosphargis, and Pseudosphargis. In other words, he considers them all Chelonidae. If he is right we have of course no business to separate Sphargis with its fossil allies from the rest of the Chelonia as "Athecae."

However, Case has not proved his point. It is easy enough to understand that the characters of the cranium and plastron of Sphargis are in a condition which by partial reduction can be derived from that of typical Chelonidae. The structure of the {337}cervical vertebrae, the absence of the marginal plates and the peculiar articulation of the nuchal with the last cervical vertebra can be explained as convergent analogies, just like the paddles of Carettochelys. But the shell of Sphargis is fundamentally different from and not homologous with that of the others. Cope was therefore quite justified in distinguishing the Sphargidae as "Athecae" in opposition to the others which Dollo later on, by contrast, named "Thecophora." Unfortunate names, since both groups are undeniably in possession of a θήκη or shell. Both authors meant, however, by Theca the epidermal shields, but even this distinction is rendered invalid by Carettochelys.

The most reasonable explanation has been suggested by Hay. The mosaic polygonal components of the shell of Sphargis are, so to speak, an earlier generation of osteodermal plates than the later generation of longer and broader bony plates which in the Thecophora come into contact, and fuse with, the neural arches and ribs. The osteoderms of Sphargis belong to the same category as the dermal ossifications in the scutes of Crocodilia, whilst the plates of the carapace and plastron of the Thecophora belong to the category of the abdominal ribs. Sphargis has the first kind in its peculiar shell, the second kind in the deeper lying plastron and in its nuchal plate. But it has lost, or perhaps had never developed, the horny shields. The only difficulty is, however, the presence of a plastron and of a typical neural plate in Sphargis. This difficulty is not very serious. The plastron is a very old institution. It occurs together with the more superficial osteoderms in Caiman, and the nuchal plate may be the oldest of all dorsals. We can scarcely imagine that the direct ancestors of Sphargis had developed both kinds of shells, and that comparatively recently the inner shell of the carapace was lost, leaving only the nuchal plate. Fossils do not support such an assumption. Undoubted ancestral forms of Sphargis are very rare. Psephophorus of the Oligocene and Miocene of Europe had a continuous mosaic shell much resembling that of Sphargis; Eosphargis is represented by a well-preserved skull from the London clay. Then follows a wide gap until we come to Psephoderma of the Rhaetic, or Upper Trias of Bavaria; the large fragment of whose dorsal shell is composed of about 200 mosaic pieces. If this fragment really formed part of the shell {338}of a Chelonian, its age would speak greatly in favour of the Athecae being a very primitive and independent group.

ORDER II. THECOPHORA.

Thoracic vertebrae and ribs united with a series of median or neural and a paired series of lateral or costal plates. Parietals prolonged downwards, meeting the pterygoids directly or by interposition of an epipterygoid.

SUB-ORDER 1. CRYPTODIRA.–The carapace is covered with horny shields. The neck, if retractile, bends in an S-shaped curve in a vertical plane. The pelvis is not fused with the shell.

FAM. 1. CHELYDRIDAE.–The plastron is small and cross-shaped (Fig. 61, 2, p. 315); the bridge is very narrow, and the displaced abdominal shields are widely separated from the marginals by a few irregularly shaped inframarginals. The tail is long. The limbs, neck, and head are so stout that they cannot be completely withdrawn into the shell. Snout with a powerful hooked beak. American; only two genera, each with one species.

The temporal region is roofed very incompletely and only anteriorly by the expanded parietals and postfrontals, which form a long suture. The plastron consists of nine bony plates, a small entoplastron being present; there are lacunae in the middle line, the plates meeting imperfectly, and the horny abdominal shields are likewise separated by soft skin. The carapace has a nuchal with long rib-like processes which underlie the marginals; the neural plates form a continuous series. There are twenty-three marginal plates. The pubic and ischiadic symphyses remain separate, enclosing one large heart-shaped foramen. The five fingers and toes are webbed and are protected by claws except the outer toe, the nail of which is usually suppressed.

Chelydra serpentina, the Snapping Turtle, attains a large size, namely, a shell-length of more than one foot, and a total length from the nose to the tip of the tail of more than three feet. Its range extends from the Canadian lakes east of the Rocky Mountains, through the United States and Central America. The carapace of young specimens has three very marked series of keels, which gradually disappear with age, until in very old individuals the shell becomes quite smooth. The skin is very warty, especially on the neck, and there is a pair of minute {339}barbels on the chin. The tail carries three series of originally triangular horny crests, which with age are transformed into blunt knobs. The general colour of this rather ugly creature is olive, mottled with dark brown above and with yellowish below.

According to Holbrook the Snapping Turtle is found in stagnant pools, or in streams where the waters are of sluggish motion. Generally they prefer deep water, and live at the bottom of rivers; at times, however, they approach the surface, above which they elevate the tip of their pointed snout, all other parts being concealed; and in this way they float slowly with the current, but if disturbed they descend speedily to the bottom. They are extremely voracious, feeding on fish, reptiles, or any animal substance that falls in their way. They take the hook readily, whatever may be the bait, though most attracted by pieces of fish; in this way many are caught for the market. It is, however, necessary to have strong hooks and tackle, otherwise they would be broken, for the animal puts forth great strength in his struggles to escape, both with his firm jaws and by bringing his anterior extremities across the line. When caught they always give out an odour of musk, which in very old animals is sometimes disagreeably strong.

Occasionally the Snapping Turtle leaves the water, and is seen on the banks of rivers or in meadows, even at a distance from its accustomed element. On land his motions are awkward; he walks slowly, with his head, neck, and long tail extended, elevating himself on his legs like the Alligator, which at that time he greatly resembles in his motions; like the Alligator also, after having walked a short distance, he falls down to rest for a few moments, and then proceeds on his journey. In captivity they prefer dark places, and are exceedingly ferocious; they will seize upon and bite severely anything that is offered them, and their grasp upon the object with their strong jaws is most tenacious.

The Snapping Turtles, or "Snappers," are feared on account of the ferocious bites which they inflict, and they are hated because of the destruction of valuable fish and water-fowl. They in turn atone for this damage by being eaten, especially the younger half-grown individuals, the flesh of the older ones being too much tainted with the odour of musk. The round eggs, which are laid to the number of twenty to thirty in the summer {340}(in the Northern States about June), are likewise good to eat. The first act of the young creature on leaving the shell is said to be snapping and biting. In captivity they are often very sulky, and refuse food stubbornly for many months, perhaps for a whole year, and apparently without much harm to themselves, since they lie quietly in the distant corner of the tank, now and then slowly rising to the surface to breathe. Fresh-water algae grow on the shell and in the mud which settles on it, and since this happens also in the wild state, they are rendered as inconspicuous as old rotten logs. In order to attract fishes they protrude a pair of worm-like, pale pink filaments from the tip of the tongue.

Macroclemmys temmincki, the "Alligator Turtle."–In size and general appearance much like the other Snapping Turtle, but the dorsal shields have each a strong and prominent keel, and these three series increase in size with age. The costal shields are separated from the marginals by an additional series of about four supramarginals, well shown in the illustration. The shields of {341}the cross-shaped plastron are subject to much individual variation, small shields being frequently intercalated, or rather retained, between the usual ones, especially between the pectorals and abdominals, in the gular region, and on the narrow bridge, where the inframarginals number one to three or even more. This species inhabits, broadly speaking, the whole basin of the Mississippi and Missouri rivers.

This beast is as vicious as the other Snapping Turtle. According to Agassiz it does not withdraw its head and limbs on the approach of danger, but resorts to more active defence. It raises itself upon the legs and tail, highest behind, opens the mouth widely, and throwing out the head quickly as far as the long neck will allow, snaps the jaws forcibly upon the assailant, at the same time throwing the body forward so powerfully as often to come down to the ground when it has missed its object.

It lives mostly in the water, but makes considerable journeys overland. Both in the water and on dry land the limbs move nearly perpendicularly, and the body is raised high. On dry land a considerable part of the weight of the body is borne by the long, strong tail.

"They are as ferocious as the wildest beast of prey, but the slowness of their motions, their inability to repeat the attack immediately, their awkwardness in attempting to recover their balance when they have missed their object, their haggard look, and the hideous appearance of their gaping mouth, constitute at such times a picture as ludicrous as it is fearful and revolting. Their strength is truly wonderful. I have seen a large specimen bite off a piece of a plank more than an inch thick. They take hold of a stick with such tenacity that they may be carried for a considerable distance suspended to it free above the ground. Fishes and young ducks are their ordinary prey. They lay from twenty to forty or more round eggs only about the size of a small walnut in holes which they dig in sloping banks not far from the water" (Agassiz).

FAM. 2. DERMATEMYDIDAE.–The pectoral shields are widely separated from the marginals by inframarginals, the gular shields are very small or absent, and the tail is extremely short. Only two or three genera, with three or four species in Central America.

The plastron is composed of nine plates. In Dermatemys mawi it is large, firmly joined to the carapace, covered with {342}eleven or more shields, and there are four inframarginals; in Staurotypus salvini of Mexico the plastron is cruciform, with the anterior lobe movable, covered with seven or more shields, according to the fusion of the anal shields and the presence or absence of the gulars; there are only two inframarginals. The pubic and ischiadic symphyses remain separate; the temporal fossa remains widely open, the postfrontals scarcely touching the parietals. There are 23 marginal shields in Staurotypus, 25 in Dermatemys, including the unpaired nuchal. The nuchal plate has a pair of rib-like processes like those of the Chelydridae, but some of the posterior costal plates, sometimes only one pair, meet in the middle line, overlying or suppressing the corresponding neural plates. The shell of these aquatic tortoises is rather flat, more or less keeled, especially in young specimens, and in the fully adult condition is about one foot in length.

FAM. 3. CINOSTERNIDAE, represented by the single genus Cinosternum, with about ten species in North and Central America, and one in Guiana. Closely allied to the two previous families, with which it agrees by the separation of the pubic and ischiadic symphyses, the presence of an ento-plastral plate, the possession of inframarginal shields (Fig. 61, 3, p. 315), the widely open temporal fossae, and the rib-like pair of processes to the nuchal plate. It agrees with the Dermatemydidae in the interruption of the neural plates by the meeting of several pairs of the costal plates. There are 23 marginal shields; five or four shields, according to the presence or absence of the gular on the plastron, and in some species these plastral shields become, with age, more and more separated from each other by soft skin (see Fig. 75). The shape and size of the plastron differ considerably in the various species; in most of them, e.g. in C. pennsylvanicum and C. leucostomum, but not in C. odoratum, the anterior and posterior lobes are movable, with transverse soft hinges, so that the animal can completely close its shell. The skin of the legs and neck is so baggy and loose that these parts slip in, the skin rolling off, when the creature withdraws into its shell. They lay only a few–from three to five–elliptical eggs, which have a shining, glazed, and thick, but very brittle shell.

{343}[Illustration: FIG. 75.–Cinosternum odoratum, young specimens. × ⅔. A and B, males; C, female.]

Cinosternum odoratum, the Mud-Turtle, or Stinkpot Terrapin, so called on account of the disagreeable smell which exudes from the inguinal glands. The head is disproportionately large, with the snout rather compressed laterally, and pointed underneath, with several short barbels. The neck is long and slender. The carapace of the young is keeled, each of the neural shields being raised in the middle line; but in full-grown specimens the shell becomes quite smooth and rounded. The horny shields of the plastron are relatively largest in the young, but they soon leave ever-increasing spaces between them, which are then filled with soft skin only, which thinly covers the underlying bone. The {344}fore- and hind-limbs, especially the latter, are extensively webbed, and are provided with five short claws. The general colour of the shell is horny brown, either uniform or with darker spots or streaks. The neck and limbs are mottled brown. The only ornamental colouring is a pair of clear yellow broad lines on each side of the head, and a similar streak on each side of the lower jaw. On the chin and upper throat are two pairs of small tentacles. The tail of the male is of about the length of the hind-limbs, while that of the female is so short that its tip scarcely reaches beyond the hinder margin of the carapace. Length of the shell of full-grown specimens between four and five inches. Very young specimens have a rather droll appearance, owing to the long and slender neck with the large head, and the humpy back.

This species is common in the eastern half of North America, from Canada to Texas. It is mainly aquatic, and is one of the dullest and shyest species. My own specimens spend most of their time in the water, invariably in the darkest corners, preferably under a stone or a log, and they do not leave their hiding places until dark, in search of worms, meat, and all sorts of animal food. For months I could never induce them to take food from a stick, or even to eat in my presence, and it was not until after many weeks that one of them at last protruded its head far enough to exhibit the yellow stripes. When taken out of the water they draw in their heads, just allowing the vicious little eyes to be visible, and opening the sharp-edged mouth widely to bite deliberately and furiously at the unwary finger. Some spent the winter in the water, in the greenhouses, feeding as usual, others crept on land, hiding under moss, half buried in the soil, where they slept for several months, but with interruptions in order to soak and to drink. When spring is well advanced they prefer the water for their regular sojourn. Some which had been sent over from New York arrived in a deplorably dried-up condition, the skin being quite flabby and shrivelled, but after a few hours' soaking they came round, and increased considerably in weight, the limbs and neck becoming turgid.

C. pennsylvanicum of Eastern North America has a larger, more oval plastron. The head is not so strikingly large as in the other species and, like the neck, is brown with yellowish spots, and often has streaks on the sides. The tail of the male ends in a {345}nail-like horny point. The lobes of the plastron are well hinged in the adult.

C. leucostomum of Central America is larger, with a shell-length of six inches. The plastron is not at all cruciform, but has a broad bridge, and fills the box, moreover it has an anterior and a posterior hinge, so that the box can be completely closed. Hence the vernacular name of the Box-Terrapin.

FAM. 4. PLATYSTERNIDAE, represented by the single species Platysternum megacephalum in Burma, Siam, and Southern China.

The pectoral shields are widely separated from the marginals by inframarginals, the plastron is large, oblong, not cruciform, and the tail is long.

The plastron consists of nine plates, and is covered with six pairs of shields, the most anterior of which are the broad gulars. The nuchal plate has no rib-like processes. The neurals form a continuous series, and there are twenty-three marginal scutes. The temporal fossae are completely roofed over, owing to the long sutures formed by the parietals with the postfrontals, moreover the postfrontals expand laterally so much that they posteriorly come into broad contact with the quadrato-jugals and squamosals, anteriorly with the maxillaries, so that the jugals are completely surrounded by bones, and are shut off from the orbits and from the temporal fossae. This is a unique arrangement, found nowhere else in Tortoises. The pubic and ischiadic symphyses are connected with each other by ligaments only.

The general appearance of this water-tortoise is rather curious, since the carapace is much depressed, looking, especially in younger specimens, as if it had been crushed in. The head, provided with very strong hooked jaws, is strikingly heavy and large, and is covered above with one single large shield. The tail is longer than the shell, which, in full-grown specimens, reaches about six inches in length; it is, throughout its length, covered with rings of squarish shields. A large specimen measures 14 inches in total length, of which only five fall to the shell.

FAM. 5. TESTUDINIDAE.–The shell is always covered with well-developed horny shields. Those which form the plastral bridge are in direct contact with the marginals. The plastron is composed of nine bones. The digits have four or five claws. The neck is completely retractile. The skull is devoid of parieto-squamosal arches.

{346}This large family is cosmopolitan, with the exception of the Australian and the adjoining Austro-Malayan countries. It contains genera which form a continuous gradation between absolutely terrestrial and thoroughly aquatic tortoises; and many are truly amphibious. As a general rule the typically terrestrial kinds have a more curved or arched shell, the digits are short, the eggs are more oval or round, and they are chiefly herbivorous; the essentially aquatic kinds have a flatter or depressed shell, webbed feet, with longer, often slender claws, the eggs are more cylindrical, and they live on animal diet. About 20 genera, with more than 110 species, are recognised by Boulenger, but their essential characters are nearly all internal, and therefore of no avail for the determination of live or entire specimens.

Chrysemys.–One of the most typical and widely distributed genera of American Terrapins or water-tortoises. The carapace is flat; the plastron is quite immovable, with a strongly developed bridge. Feet well webbed. Tail short. Skull with a broad, complete, lateral, temporal arch. About one dozen species, mostly in the eastern half of the United States, but the whole genus ranges from Canada to Argentina.

Most of the young Chrysemys are very pretty, the ground-colour of the upper shields being green, variegated with yellowish-brown or blackish markings, which often form exquisitely delicate patterns, either concentrical (Ch. concinna, Ch. rubriventris), or more longitudinal (Ch. elegans), or apparently quite irregular. The ground-colour of the plastron is yellow, but the various species are best distinguished, at least in very young individuals, by the arrangement of the dark brown spots and patches. There are, for instance, several pairs of bold lateral and several median patches in Ch. rubriventris; five pairs of ocellated spots in Ch. elegans; only small median patches, where four plastral shields meet, in Ch. concinna; while the plastron of Ch. picta is uniformly yellow.

These water-tortoises are very lively and shy, most so perhaps Ch. picta, which is very quick and active. The food varies, often according to individual fancy. Most of them eat fish. Ch. picta is partial to insects, but it also takes worms. Some of my specimens refused meat for a long time, but ultimately they became so fond of it and of worms, that they came out of the pond to take the food from the fingers; those in the Zoological {347}Gardens of London have developed a taste for biscuits. One of my largest Ch. concinna fasted deliberately for eight months, refusing worms, insects, meat, and frogs, only occasionally sniffing at the food, until it was tempted with whitebait, which it took greedily. It refused, however, smelts and pieces of soles, but after another month it condescended to take meat regularly. Very young individuals live chiefly on flies, which they watch for near the surface of the water; and they are fond of smooth caterpillars, maggots, the larvae of humble-bees, and similar soft creatures. They all spend most of their time in the water, preferably floating near the surface, hidden between weeds; and they are fond of basking. Some of them spend the night in the water, lying motionless on the bottom, with heads and limbs turned in. Others prefer hiding under moss. Those species, which, like Ch. concinna and Ch. picta, are common in the North, are of course perfectly hardy. For the winter they dig themselves holes in the banks near the water, and they do not come out again until the spring is well advanced. The eggs are hard-shelled, mostly long and oval, and they are hatched before the end of the summer. The larger species of Terrapin are eaten.

Ch. picta (Fig. 76), the "Painted Terrapin," of the Eastern United States, e.g. of New York and Long Island, is easily recognised by the much depressed shell, which is absolutely smooth, and without a trace of a keel. The colour above is dark olive-brown or blackish, with broad yellow bands across the anterior ends of the neural and costal shields. Three or four of these transverse bands are very conspicuous. The marginals are red, with more or less concentric black and yellow markings. The pretty red colour, with some black stripes, extends over the bridge, but the plastron itself is uniformly yellow. The soft parts are likewise prettily marked, the ground-colour is black-brown, with delicate bright yellow and red stripes on the sides of the neck, limbs, and tail. The stripes are originally yellow, but they develop an orange or red line in the middle, so that each red stripe is ultimately narrowly edged with yellow; or the yellow and red stripes alternate, for instance on the tail, which is short, narrow, and pointed. The head is further adorned with a pair of conspicuous bright yellow patches behind the eyes, and a smaller pair on the occiput. The black and yellow stripes run across the gape of the mouth, some of the lines even looking as if they had been {348}painted across. The nuchal shield is elongated and very narrow, its anterior edge and that of the neighbouring marginals are finely serrated. Very young individuals are at once recognised by the prominent longitudinal median stripe of bright orange extending over the nuchal and neural shields; the yellow transverse bands are still absent; they appear when the longitudinal line vanishes.

The "Painted Terrapin" is one of the few species of which, thanks to L. Agassiz, complete data of growth from the new born to old age are known. During the first six or seven years the rate of growth is so uniform that numerous specimens collected at the same time are readily arranged in sets of the same age, simply by the differences they show in their size. The successive lines of growth on the shields indicate the number of years. After the seventh year the age is much more difficult to distinguish in those tortoises, which, like Ch. picta, have a perfectly smooth epidermis. This smoothness is due to the fact that the shields undergo a process of moulting. An upper, quite {349}transparent layer of each shield peels off completely like a piece of mica. I have been able to confirm Agassiz' statement on Ch. concinna in their third and fourth springs, and on a number of adult Ch. picta. The latter were not allowed to hibernate, being kept in a warm tank; they peeled completely during the late autumn, and then the red and yellow colours underlying the newly formed shields appeared very vividly; others moult at midsummer.

Growth of Ch. picta, after Agassiz.

+––––––––––––––––––––––+––––––––––-+––––––––––––+––––––––––-+––––––––––-+ | Year. | Length of | Breadth of | Height of | Length of | | | carapace. | carapace. | box. | tail. | +––––––––––––––––––––––+––––––––––-+––––––––––––+––––––––––-+––––––––––-+ | | millim. | millim. | millim. | millim. | | Second | 26.5 | 25 | 12 | 16.5 | | Third | 42 | 39.5 | 17 | 17.5 | | Fourth | 51 | 49 | 21.5 | 20.5 | | Fifth | 54 | 51 | 23.5 | 21.5 | | Sixth | 59 | 56 | 25 | 23.5 | | Seventh | 66 | 60 | 26.5 | 26 | | Eighth (♂) | 72.5 | 61 | 28 | 27.5 | | Ninth (♂) | 74 | 62 | 28 | 27.5 | | Tenth (♂) | 77 | 64 | 30 | 28 | | Eleventh (♂) | 80 | 67 | 30 | 28.5 | | Fourteenth (♂) | 92 | 74.5 | 33 | 28.5 | | Twenty-fifth (♀) | 121 | 92 | 43 | 34 | | Old ♀ | 129 | 96 | 47 | 37 | | Very old ♀ | 163 | 113 | 59 | 53 | +––––––––––––––––––––––+––––––––––-+––––––––––––+––––––––––-+––––––––––-+

The size of the eggs varies considerably, from 26 by 17 to 30 by 16 millimeters; sometimes they are perfectly round, 17 mm. in diameter.

Ch. concinna.–The specific character by which this Terrapin may be easily recognised is a pair of orange-red broad streaks, which extend from above the eye to the sides of the neck. The general colour is olive-brown above, variegated with yellowish dark-edged lines, which, together with numerous rugosities, radiate from the middle field of each shield. The plastron is yellow, often with blackish symmetrical patches, and sometimes these become confluent and preponderant. Very young specimens are extremely pretty, the ground-colour of the carapace being green, each shield with darker, somewhat concentric markings, most conspicuous and regular on the upper surface of the marginals, where the marks of the adjoining shields form one pattern-system across the dividing lines. The plastron is either uniform yellow or has a few pairs of blackish spots {350}which stand so closely together that they form almost median patches.

The carapace is rough. The horny shields become very thin with age. The anterior margin of the small nuchal and the neighbouring marginals is faintly serrated. The posterior marginals form slight notches or indentations between their edges. The plastron is almost square behind. The edges of the jaws are nearly smooth, without hook and receiving-notch. The tail is short.

This species inhabits the South-Eastern States of North America, from Missouri and North Carolina to the Gulf of Mexico. Very large female specimens have a shell sixteen inches in length. The eggs measure from 33 by 25 to 39 by 25 mm. or about 1½ inch in the long diameter.

Emys.–The plastron is movably united to the carapace by ligament, and in the adult has a slightly flexible hinge across the middle, between the hyo- and hypo-plastral plates and the pectoral and abdominal shields. The plastron is large, but does not quite close the box. Besides the small nuchal there are twelve pairs {351}of marginal shields. The head is covered with smooth skin; the temporal arch is complete. The limbs are extensively webbed. The tail of the very young is nearly as long as the shell, but it becomes relatively shorter with age, being reduced in the males to about two-thirds, in the females to half the length of the shell. Only two species are found in Europe, the other, E. blandingi, in Canada and north-eastern U.S.A.

E. orbicularis s. europaea s. lutaria, the European Pond-tortoise.–The shape and coloration of the shell change likewise much with age. In the very young the shell is round, and the shields are rough and slightly keeled, uniform dark brown above, black below, with a yellow spot on each marginal and plastral shield. When half grown the dorsal shields become quite smooth, and are striated or spotted, with yellow upon a dark ground. The head, limbs, and tail are dark, with yellow or light brown spots and small dots. In very old specimens all these yellow marks disappear on the shell, which then becomes uniform brown or almost black. The coloration is subject to much local and individual variation, and there are two main types, the spotted and the radiate. It is difficult to say which of the two is the prettier. One male which I caught in the Alemtejo was very beautiful. The shell was almost black with a greenish shine when in the water, and had many bright yellow and whitish spots. In the radiate type the yellow is sometimes preponderant, so that each shield becomes a study of delicately painted yellow, brown, and blackish lines radiating from the centre. This variety seems to prevail in the south of Spain, decidedly so in the Marismas, also in Northern Italy, whence most of the European markets are supplied. The largest shell in the British Museum is 19 cm. = 7½ inches long. Fischer Sigwart received one from Naples which was about 9 inches long, and this seems to have been kept as a pet, since its shell had been gilt. Specimens about 5 inches in length may be considered as fully adult. There are very few reliable observations on the growth of individuals. One of F. Sigwart's grew in eleven years only about 2.5 cm. = 1 inch, when its shell was 13.4 cm. = 5¼ inches long–total weight of the tortoise 491 grammes, about 1 lb. One of my own grew from 11 to 13.2 cm. shell-length, and 8.3 to 10.6 cm. in width within eight years, but this was one of the specimens which, living in a greenhouse, {352}did not hibernate. This European pond-tortoise is now restricted to Southern and Middle Europe, extending eastwards towards St. Petersburg and into Asia Minor, southwards into Algeria. Formerly it had a much wider range, having been found in post-glacial deposits in Southern Sweden, Denmark, the Netherlands, and in East Anglia. Specimens have been found in the peat of the fens of Norfolk and Cambridgeshire, contemporary with bones of the Beaver, Roe-deer, and Pelican. The same applies to North Germany, where its gradual disappearance from the western and central parts is obvious. Except in Central France it is now practically unknown to the west of the Elbe river. The country between the Elbe and Oder is now debatable ground, Emys being exceedingly rare. Some fifty years ago this seems to have been different, to judge from the fact that farmers were rather fond of keeping a tortoise in the water-troughs of the cattle to keep the water free from worms and other impurities. Hence arose a silly superstitious custom. It was considered equally conducive to the health of the pigs to keep a tortoise in the foul tub into which all the dish-water and kitchen-refuse–as potato-peels, sour milk, etc.,–were collected before the mess was given to the pigs.

A specimen is still occasionally caught in the Havel and Spree rivers. I myself have heard of one or two in the backwaters of the Oder near Frankfurt, but they are vanishing, and it is difficult to say exactly why. The universal lowering of the water-level owing to better drainage cannot quite account for it, since there are thousands of suitable ponds, swamps, and backwaters left. In Poland and in Eastern Prussia the tortoise is still common.

This creature lives on a strictly animal diet. Worms, insects, frogs, fishes form its main sustenance. Fishes are regularly stalked. The tortoise watches its opportunity, slowly it half crawls, half swims along the bottom, rises imperceptibly by a few gentle movements of the widely spread-out webbed feet, then opens its sharp cutting jaws wide, and makes a grab at the belly of the fish. Frogs are most easily stalked when they sit upon a floating leaf. The tortoise rises from below, and often waits with the nostrils and eyes just above the water and close to the frog. After a while it sinks, and rises again, this time actually touching the toes of the non-suspecting frog, smelling at them and deliberately biting with a sideward turn of the head.

{353}[Illustration: FIG. 79.–Emys orbicularis, European Pond-tortoise (left), and Clemmys leprosa, Iberian Water-tortoise (right). × ½.]

{354}What the jaws have got hold of is not allowed to escape again. The tortoise holds on and tears the prey to pieces with the sharp-clawed fingers. This takes a long time, only the scraped-off flesh and the intestines being eaten. The skeleton remains and sinks to the bottom, while in the case of a fish, the air-bladder floats away on the surface, and remains there as one of the surest signs of the existence of tortoises in that locality. The bones are cleaned with wonderful neatness. Some of my grass-snakes shared this fate, their backbones, with the hundreds of pairs of ribs, being picked or rather scraped clean, scarcely less well than if they had been prepared for a museum.

As a rule the prey must be in motion to be seized, unless the tortoise has watched it before, and even then the latter prefers to smell it before biting. In captivity they soon learn to eat meat, and they become very tame, but in their native haunts they are extremely shy and cautious. Fond of basking upon a stone or on the banks, with the four limbs sprawling, or with the hind-limbs stretched backwards, and with the webs spread out so as to offer as large a surface as possible to the rays of the sun, they lie motionless for hours and appear fast asleep. But the slightest noise, or any other sign of our approach, is sufficient to send them plumping into the water, and to make them scuttle along with unsuspected agility. Nothing but the audible plump of the flat body and the widening rings of the disturbed water indicate their presence. After a long time of waiting we give it up, and turn away. That very instant we see a little ripple, caused by the withdrawing of the tortoise, which had come to the surface and had been watching us, with only the nose and eyes peeping out of the water, the rest being concealed between the floating vegetation. Apparently they cannot see us well with their eyes still under water, owing to the difference of refraction, otherwise they would not peep out and then at once turn back. It is certainly not for the want of air, since they can remain below for many hours without breathing.

Although they generally feed in the water, they come on land when tame and hungry enough to take the offered food. Sometimes they make long migrations, perhaps because their old home is dried up or does not yield food enough. They hibernate during the cold season, buried in the mud, and they do not appear until {355}the spring is well advanced. During the pairing season, on warm spring nights, they emit short piping sounds, and when they have found each other, the couple swim about together. The white, hard-shelled, long, oval eggs, averaging 25 to 15 mm., and about ten in number, are laid on land. This is a very laborious and curious business. The female having selected a suitable spot, not loose sand, but rather hard soil free from grass and other dense vegetation, prepares the ground by moistening it from the bladder and the anal water-sacs. Then it stiffens the tail and bores a hole with it, moving the tail but not the body. The hind-limbs then scoop out the hole, the broad feet moving alternately and heaping up the soil on the side, until the hole is about five inches deep, that is as far as the hind legs will reach. The eggs are laid at the bottom in one layer, divided and distributed by the feet. Lastly, the soil is put in again, and the tortoise, by repeatedly raising its body and falling down, stamps the soil firm and flat, roughens the surface a little with its claws, and leaves the nest to its fate. Nothing but an accident leads to its discovery. The young are hatched, according to locality and the kind of season, either in the same autumn or not until the next spring. Eggs laid in a garden at Kieff, in Russia, were hatched eleven months later. This implies hibernation of the embryo within the egg, and this is probably the usual course of events, resembling the conditions of the development of Sphenodon (cf. p. 299). The pretty little creatures, scarcely larger than a shilling-piece, are exceedingly difficult to rear. They require a tank with green vegetation, stones to bask on and to hide under, and also dry ground and moss for a change. They eat flies, tiny worms, tadpoles, etc., greedily enough, but for some occult reasons they do less well than many another kind of water-tortoise. Miss Durham has, however, succeeded in rearing one, which is now in its fourth year; the shell is 2 inches long, and each shield shows three annual rings around the areola. This specimen spent the winters in an unheated room under moss, not in the water.

E. blandingi, the North American species, has a more elongated and decidedly higher carapace than its smaller European relation. The carapace is dull black with many pale yellowish spots; the plastron is yellow, with a large dark patch on the outer and hinder corner of each shield. The head is dark brown above, bright {356}yellow below and on the throat, a contrast which gives this tortoise a striking appearance. This species is extremely voracious, becomes easily tame, and spends a great part of the day on land, hiding under grass to avoid great heat, and withdrawing into the water for the night.

Clemmys.–The plastron is immovably united with the carapace, and is devoid of any transverse hinge. The skull has a complete bony temporal arch. This genus, consisting of eight species, is otherwise very much like Emys, and is truly Periarctic.

C. leprosa s. sigris (Fig. 79).–The upper jaw has a median notch for the reception of the upturned point of the lower jaw; the cutting edges of the powerful beak are smooth. The shell is flat and long-oval, nowhere serrated. The plastron does not quite fill the box. In the young the shell is nearly round, and the horny shields form three series of keels, of which the lateral pair disappear early; the shields are olive-brown, each with an orange spot or streak; the plastron is dark brown, with a yellowish margin. The adult looks very different. The shell has become much more oval, with the greatest width behind the bridge. The long shields are smooth, and in elderly specimens are without any trace of the original connective rings of growth. The general colour of the shell is uniform pale olive-grey, inclining to yellow on the plastron. The ground-colour of the soft parts is olive-grey, but the sides of the head are adorned with orange-red or yellow marks, the patch between the eye and ear and three or {357}four stripes on the neck being especially conspicuous. The limbs have pale yellowish streaks. All these markings are, however, subject to much individual variation. While, for instance, the half-grown creatures are distinctly agreeably coloured, often with a rich brown, nicely sculptured shell, and with conspicuous orange and yellow marks on the skin, the very old ones become rather ugly, the prevailing colour varying more and more into dull uniform pale olive-grey.

The "Iberian Water-tortoise" is typical of the Iberian Peninsula, and extends through Morocco and Algeria far into North-Western Africa. Unknown to the north of the Cantabrian range, decidedly scarcer than its cousin Emys in the northern half of the Peninsula, it becomes common in the south. In the Alemtejo, in the lower parts of Andalucia and in Morocco, there is scarcely a pool, stream, or river in which it is not found, feeding on any living thing it can master, although fishes and frogs are its principal prey. When the streams and watercourses run dry, during the hot and dry season, the tortoises crowd together into the remaining pools, which soon become stagnant and filthy. But even these havens of refuge are not of lasting avail. They are soon cleared of anything edible, and the stinking water becomes dirtier and hotter day by day. Ultimately the tortoises leave the pool to hide under ledges of rocks, where they aestivate for months. This life in the muddy, slimy pools renders these tortoises peculiarly liable to the attacks of a certain fresh-water alga, which enters through the cracks in the horny shields and then flourishes in the Malpighian layer, and even in the underlying bone itself. This becomes gangrenous in patches, and the whole shell assumes a leprous appearance, hence the specific name of leprosa. Everything combines in favour of this destructive little alga. The tortoise, covered with mud, basks in the hot sun, the horny shields become brittle and crack, often peeling off in thin flakes. But those happy individuals which inhabit permanent rivers, or pools which do not dry up, are, and remain, as clean as other water-tortoises.

C. leprosa has a most disagreeable, offensive smell, something like concentrated essence of fish, due to the secretion of a pair of large glands situated beneath the skin of the inguinal region, and opening behind the bridge. Freshly caught specimens stink horribly, but when they have become accustomed to being {358}handled, they no longer void these glands. They always withdraw into the water for the night, and the cold season is spent in the mud. Their time of propagation is still somewhat doubtful. Very young tortoises are met with in the Peninsula in March, when they are already in the rivers. Those which I imported in the summer and autumn invariably dug their nests and laid their long, oval eggs (28 to 33 mm. long) in the month of November, pairing having taken place some two or three months previously. The mode of making the nest is exactly the same as that described for Emys. As most of my specimens were kept in a greenhouse with a permanent current of warm water through their tanks, they never hibernated, nor did they pass through a torpid time in the summer, but they showed an irresistible love for the hot-water pipes, huddling together by the dozen, so that the pipes had to be screened off to prevent the creatures from getting burnt. Until this precaution was taken, they heated themselves so much that the shields and even the bones of the plastron were injured. The artificial warm temperature and the complete suppression of seasonal rest had no bad influence, most of the tortoises living with undiminished appetite for more than twelve years, but the sexual period became disturbed, pairing occurring ultimately at all times of the year. The eagerness of the males, however, had a peculiar evil secondary influence upon the females. The male tries to fasten on to its mate by biting into the collar-like fold of the neck into which the head is withdrawn, and this repeated irritation produces sores and swellings, which latter in their turn prevent the female from wiping the eyes with the back of the fore-limbs, a habit common to most, if not all, tortoises. Ultimately the eyes fester, and the tortoise, becoming practically blind, falls off its feed, leaves the water, which makes matters worse, and is very difficult to cure.

In other respects they are very hardy, and they stand acclimatisation in England perfectly. Some, thriving in a deep concreted pond, passed through the very severe winters of several years ago, hiding in the mud below the ice, and appeared in the spring in perfect health. They can also successfully pass the winter under moss and a heap of loose garden-rubbish.

C. caspica is closely allied to C. leprosa, which it represents in the Balkan Peninsula and in Asia Minor. It differs from the south-western species chiefly by having the cutting edges of the {359}upper jaw finely denticulated, and by its prettier coloration, each shield being ornamented with yellowish streaks which form a kind of ∞ on the costals, and a ring on the marginals. The plastron is black in the young, with yellow and black patches in the adult. The head and sides of the neck are striped with yellow lines, narrowly edged with black, and the rest of the soft parts is marbled dark olive and yellow. A few other species occur in China, Japan, and North America.

Clemmys insculpta, one of the American species, ranging from Maine to Pennsylvania and New Jersey, is easily recognised by the peculiar reddish-brown and brick-dust colour of the soft parts. The strongly keeled, posteriorly emarginate carapace is reddish brown, with radiating yellow lines. Each shield is delicately sculptured. The plastron, which is notched behind, is yellow, with a large black patch on the outer corner of each shield. Length of a full-grown specimen 8 inches. They frequent the rivers and ponds, but are also very fond of leaving the water, sometimes remaining for months in dry places.

Malacoclemmys of North America, with three species only, is closely allied to Clemmys, from which it differs chiefly by the very broad alveolar surface of the upper jaw, and by the more forward position of the entoplastron, this being placed anteriorly to the humero-pectoral suture. We mention this genus since one of its species, M. terrapin, is so extensively eaten in the Eastern United States. The shell is oval, slightly emarginate behind, obtusely carinated along the middle line. The upper parts of the shell are brown or greenish, with dark concentric lines; the marginals are yellow below, each with a ring of dark grey, and forming a peculiarly up-turned rim. The plastron is yellowish, either with concentric stripes and dusky lines or uniform yellow. But it is the colour of the soft parts which gives this otherwise dull-looking creature its delicately pretty appearance. The skin is, namely, greenish white with countless small black dots. The males remain much smaller than the females, and have the concentric stripes more pronounced. This species, the choicest of the edible Terrapins, frequents the salt marshes of the east coast of North America, from Rhode Island to the Gulf of Mexico, being most abundant around Charleston.

The following is a condensed account of an article which appeared in the New York Sun, 18th September 1898, the data {360}of which were supplied by the manager of the terrapin-farm at Beaulieu, Georgia. The continued hunting and the unfailing demand for them are making them very scarce, so that enterprising men have established terrapin-farms or "crawls" for the keeping and breeding of terrapins. The "crawls" in question are near the river. The larger is 310 by 60 feet, and is divided into three compartments for three sizes. The smaller "crawl" is for the babies, and is 100 by 8 feet. Through both "crawls" runs a ditch connected with the river and making a circuit of the farm. The bottom of the "crawls" is on a level with the low tide, and is covered with a layer of mud about six inches deep. Into this the terrapins burrow in the winter. The average population of terrapins is about 40,000, one half "bulls" and the other half "heifers." The latter are much better eating, and grow to a much larger size, namely, eight inches on the plastron, while the "bulls" rarely grow over five inches long. When a female reaches six to eight inches it is called a "count." Those between five-and-a-half to six inches long are known as "two-for-threes," while those from five to five-and-a-half inches are known as "halves." They are fed exclusively on shrimps and crabs on account of the flavour, although they will eat almost anything. The 40,000 consume on an average twenty bushels of crustaceans a day. They are quite indifferent to cold. The manager saw some placed in a block of ice and frozen fast to it; after four or five days they were chopped out, thawed, and were soon as lively as ever. The statement that it takes these terrapins only seven years to attain full commercial growth is surprising, and is probably an underestimate. At the end of the large "crawl" is a board to enable the females to creep into a sand-pit, where they lay the eggs from April to June, eight to twelve forming a set. It is necessary to get the babies away from their parents as soon as they hatch, else they will be eaten. The young must not be exposed to the cold. The old ones have a large amount of curiosity. The best way of catching them is for two men to go out in a boat with a net. They row carefully along until they come to a likely spot. Then one man raps several times sharply on the boat with a stick, and if there are any terrapin about they will come to the surface just as fast as they can get there to see what is going on, and the other man scoops them up with a little net. Another {361}way, used in the salt marshes, is for the negroes to go tramping through the mud and water. If they pass any terrapin these will rise out of the mud to see what the disturbance is. The captives are then fattened in the "crawl." When the men go in to feed them they whistle, and terrapin from all over the "crawl," thousands of them, come swimming through the water, piling over each other in their efforts to get close to the man with the shrimps and crabs.

Cistudo.–The plastron, without forming a bridge, is connected with the carapace by ligaments, and is divided into two movable lobes, the transverse hinge being so perfect that the box can be completely closed after head, legs, and tail have been withdrawn. The nuchal shield is very small; the first four neurals are large and broad, the fifth much broader than long. There are twelve pairs of marginal shields. The carapace is high and arched. The digits are almost completely free. The tail is very short. The skull is without a bony temporal arch, the quadrato-jugal and the jugal being absent. Only two species, in North America.

C. carolina of the Eastern United States is a very interesting species. Closely allied by its internal structure to the water-tortoises, it has become absolutely terrestrial; and the shape of the head, the convex shell which is coloured black and yellow or orange-brown, and the short webless fingers are all terrestrial features. But the rather long toes, provided with long and sharp claws, the broad and flat feet, enlarged by a broad fold of skin on the outer margin, the long oval eggs, the smooth covering of the head, and the preponderant animal diet, still proclaim the aquatic relationship of this tortoise. It is in fact a genus which has changed habits and features from aquatic to terrestrial life. The head is covered with a smooth skin, and the upper beak, especially in old specimens, is strongly and broadly hooked. The eyes of the males are red, those of the females are brown. The plastron of the males is concave, that of the females is flat. Large females reach a length of nearly six inches. The young are nearly round, with high, arched back and prominent keels. The keels of the middle line remain a long time, but they gradually flatten down with age, being prominent only at their posterior ends. Each dorsal shield is originally nicely sculptured, with a well-marked areola and concentric rings. Very old individuals {362}become much flatter on the top of the shell, but the sides remain steep, so that the whole shell roughly resembles a somewhat oblong box with the corners rounded off, and the whole upper surface rubbed down quite smooth. The variations of colour are almost endless, and they occur in the same localities. I have a number of all ages from Long Island, near New York. The half-grown are beautifully reddish or orange-brown with dark patches, median keels prominent, plastron uniform black-brown. In others the dark-brown prevails over the lighter markings, which are yellower and more spotted or dotted than patched. Some of the oldest, with quite smooth shells, are black, with small, round, light yellow spots. Others are vermiculated or striped with yellow and black. The soft parts vary to the same extent, some showing on the neck a beautiful intricate pattern of yellow, reddish and brown, while in others these colours are arranged more or less in longitudinal stripes.

These "Box-tortoises" are often caught in the States and kept as pets in the gardens, and their owners mark them by cutting their initials into the plastron. These marks heal up and widen in time like letters cut into the bark of a tree. One of my specimens, certainly a very old one to judge from his hooked beak, perfectly smooth and flat shell, and from the condition of the marginals, which have the edges rubbed down quite smooth and rounded off, has two initials and the date 1837 on its plastron. Of course there is no proof that the date had been cut in that year, more than sixty-three years ago, but it was done a long time ago. The scars on those parts of the shell which touch the ground are almost effaced, and the letters and figures have become somewhat distorted owing to the usual unequal, not concentrical, peripheral growth. Moreover, this tortoise must have been already adult, although not quite fully grown, since the marks are large and were evidently put in such a size and position as to fit the available space. I may mention that this record tortoise was, when I got it, not kept in confinement, but had been picked up at large.

These Box-tortoises become very tame. Although fond of drinking quantities of water in long and slowly repeated draughts, they do not go into the water, and if they fall in accidentally they are liable to get drowned. They enjoy a mixed diet, but animal food predominates, consisting chiefly of snails, the shells of {363}which are passed, slugs, earthworms, maggots, and soft caterpillars. Their fondness for slugs is all the more remarkable since scarcely any other Vertebrate eats these slimy, sticky molluscs; but a Box-tortoise will make a meal of two or more fat specimens of the black slug Arion, and it will eat dozens of small slugs. It first deliberately smells the prey, turns the head sidewards and gives a bite, whereupon first the intestines and then the rest are eaten. The slime is later on scraped off with the fore-limbs, or the head is rubbed against the grass. The favourite time of feeding is towards dusk or in the early dewy morning, and they are especially lively during a soft, warm rain. They also relish various kinds of fungi and fruit, for instance half-rotten bananas. Close observation of their habits gives us indications as to how the change from carnivorous to herbivorous habits may have taken place. Accidentally many a blade of grass is bitten off and swallowed together with the molluscs, also bits of rotten wood and moss, and their excrements are often full of such more or less digested matter. They are not very fond of basking, although they love warmth, creeping into the grass, where they make a shallow form by moving the shell backwards and forwards. During the cooler nights they frequently retire into a hole or under a log of wood. They require to hibernate. If kept in a warm house they become restless in the autumn, refuse food, drink and feed again after some weeks, but are liable to die during the winter. If they can find a cool place they bury themselves and sleep for several months. If left out of doors they dig into the ground, creep into a hole, at the bottom of which they half bury themselves, or they hide under a heap of garden-rubbish well out of the reach of frost. Warm April days bring them out, and the first requirement is a drink.

When walking about in search of food they assume a curious attitude, with the shell well above the ground, the long neck stretched out and raised high. Their temper varies individually. Some become tame readily and lose all shyness, and creep up to their friend to take food from his fingers. Others are decidedly shy and sulky, withdrawing with a hiss into the shell, which in some specimens shuts almost hermetically all round, and they do not come out until all imaginary danger is past. One of my males sulked thus for several months, at least we never saw anything of it except the closed shell, but it did not starve itself. {364}Propagation takes place in the summer, the long oval hard-shelled eggs being laid in June and July.

The TYPICAL LAND-TORTOISES are easily recognised by their feet. The digits are short, have not more than two joints, and are without any trace of webs; the metacarpals are scarcely longer than broad. The hind-feet are club-footed. The skin on the anterior side of the fore-limbs is covered with strong horny scales, frequently with dermal ossifications. The plastron is united suturally by a broad bridge with the usually strongly arched carapace. The skull has complete postorbital and temporal arches. The top of the head is covered with shields. The tail is short. There are only a few recent genera, modifications of the central and typical genus Testudo. The latter is cosmopolitan in the warmer temperate and tropical regions, except in the Australian and Austro-Malayan countries.

Cinyxis (Fig. 82) with a few species in Tropical Africa from the Gambia and from Abyssinia to the Equator is remarkable for the unique modification of its carapace, the posterior portion of which is movable, the hinge passing between the seventh and eighth marginal and the fourth and fifth costal plates, externally behind the seventh marginal and the second costal shields. In the middle of the back the hinge is imperfect, the parts being merely flexible enough to permit the posterior half of the box to be closed. The head is covered with shields.

C. belliana, of Northern Tropical Africa, has a small nuchal shield, and the margin of the carapace is smooth. Length of shell up to seven or eight inches. C. homeana, of West Africa, has likewise a small nuchal shield, but the posterior portion of the carapace descends vertically, and the marginals are strongly reverted and serrated. C. erosa (Fig. 82), also from West Africa, has no nuchal shield; the marginals are reverted and serrated, but the posterior part of the carapace is sloping, and the anterior {365}portion of the plastron is strongly forked in front, and projects beyond the anterior border of the carapace. This peculiar creature reaches a length of nine inches. When withdrawn within the shell, which is closed behind and depressed in front, with the jagged edges of the plastron and the anterior marginals protecting the drawn-in head, it has a very quaint appearance. It lives entirely on fruit and other vegetable matter, and is said to prefer to lie in the water, while C. belliana is supposed to be entirely terrestrial.

Pyxis arachnoides, of Madagascar, a small land-tortoise, only four inches in length, has an immovable carapace, but the front lobe of the plastron is hinged.

Testudo.–The plastron is immovable, except that in old individuals of some species, e.g. T. ibera, the hinder lobe develops a transverse flexible hinge. They have existed since the Oligocene of North America and Europe; and are now represented by nearly forty species in all the tropical and warmer temperate countries excepting the Austro-Malayan and Australian region. Typically terrestrial, herbivorous and frugivorous, although occasionally varying their diet with worms, molluscs, and insects. The eggs are hard-shelled, mostly less oval than those of the aquatic and semi-aquatic tortoises. The males generally remain smaller than the females, have a slightly longer tail, and have a concave instead of a flat plastron. Most land-tortoises hibernate in the ground during the cool and cold seasons, or they aestivate during the hot and dry months of tropical countries, but this is not an invariable rule.

T. graeca, the common "Greek Tortoise." The shell is very convex, without keels, and has a smooth, not serrated margin. {366}The nuchal shield is narrow. The fifth or last neural shield is much broader than the others. The supracaudal is usually divided in the median line, so that this is really the last pair of marginals. The plastron is notched behind; the axillary and inguinal shields are small. The scales on the anterior surface of the fore-limbs are small, and form from half-a-dozen to ten longitudinal rows. The hinder surface of the thigh is quite smooth. The tip of the tail ends in a conical, horny spur. The coloration of the shell varies somewhat, but the ground-colour is yellow, each shield with a dark brown centre and irregular patches or confluent spots towards the margin. The plastron has an irregular, broad black border. The soft parts are grey-yellowish. Some specimens are rather pale, almost lemon yellow with little black; others incline towards orange with more or less black. The middle fields of the shields of young specimens are granular, although this area is rubbed smooth with age; but the rest shows clearly marked concentric lines of growth. The eyes are dark, with a brown or bluish tinge, sometimes inclining to dark grey in very old specimens.

Full-grown females have a shell six inches in length. This species inhabits the northern half of the Balkan Peninsula, parts of Asia Minor and Syria, Italy, and most of the islands of the Mediterranean, from the Grecian Archipelago to the Balearic Islands.

T. ibera is closely allied to T. graeca, from which it differs chiefly in the following points. The last pair of marginal shields are fused into an unpaired supracaudal, the median line of division being almost obliterated. The fifth neural shield is not broader, and generally a little narrower than the others. The posterior lobe of the plastron develops with age a transverse ligamentous hinge, and is thus rendered slightly movable, especially in the females. The posterior margin of the carapace is slightly expanded in old specimens. The scales of the fore-limb are large and imbricating, and form only four or five longitudinal rows. On the middle of the exposed posterior surface of the thighs the skin carries a strong, conical, horny tubercle. The coloration is much like that of T. graeca, except that the yellow of the young inclines to pale olive. Some specimens are uniform brownish. This species reaches a much larger size than T. graeca, old females often measuring eight inches, {367}rarely more than nine inches in length. Its home is Morocco and Asia Minor, extending into Persia. It also occurs in certain parts of Southern Andalucia, where it breeds regularly, for instance, in the sandy pine-forests of the Marismas, near the mouth of the Guadalquivir. Whether it has been introduced from Morocco, or is indigenous, is an open question. Its specific name refers to its Iberian home.

T. marginata is worth mentioning, since it is the Greek tortoise, although not that of the European markets, which are supplied by the other two species. T. marginata is restricted to Greece proper, where it is the only land-tortoise. It is less closely allied to T. graeca than to T. ibera, of which it may be called an exaggerated form. The posterior margin of the carapace is much expanded or flanged, and serrated. The supracaudal is undivided, the posterior lobe of the plastron is movable, but the large conical spur on the thighs is absent. The dorsal shields of adult specimens are black with a small yellowish patch; the ventral shields are yellowish, each with a large black triangular patch. The British Museum possesses a shell 28 cm. = 11 inches in length.

The habits of these Moorish and Greek tortoises are very much alike, and since they enjoy the distinction of frequently being kept as pets in gardens, where they are allowed to look after themselves, a great many incidental and odd observations have been made on them. They are essentially vegetable feeders, but their taste varies individually and with the season, also according to the vegetation of the country they happen to come from. Most of them enjoy juicy plants, for instance, lettuce and cabbage; the flowers of the dandelion attract them not merely by their bright colour; clover is also a favourite food, and an enclosure of grass-land with clover in it is soon cleared of the latter; grass is also taken, in default of anything better. Some of my specimens gradually bite large holes into gourds and pumpkins; and in Morocco I found them in the autumn feeding entirely on the terribly astringent green fruits of the dwarf palm Chamaerops humilis. The larger specimens bolted the fruit with the stones, passing the latter. In close captivity they often learn to take and to like bread soaked in milk or water. They drink slowly and at length, but scarcely ever when they have succulent food. There is one thing which they do {368}not eat, namely, "black beetles," although they are warranted to do so by the men who hawk them in the streets. Worms, slugs, etc. are often mentioned as part of their occasional diet, but I am not aware that any of the hundreds which I have watched have taken such creatures, in spite of every opportunity. Their habits are very regular. They learn to know the geography of their domain thoroughly, and the spot selected for sleeping will be resorted to over and over again, be it underneath some broad leaves, under a bushy fir-tree, between a cluster of wallflowers, or between some tussocks, or even in an almost bare corner, the attractions of which are not at all obvious. Although their mental capacities cannot possibly be called brilliant, they soon learn to distinguish between different persons, and they will come up to be fed; but their memory for localities is surprising. Here is only one instance. A tortoise which had been put into an outhouse for hibernation was six months later taken to its usual large enclosure, and in the afternoon it tucked itself away on the top of a mound under precisely the same low bush where it used to sleep during the previous autumn. It could not see that spot from where it had been put down, and it did not meander about during the day, but after having enjoyed the warm sun it made straight for its favourite place. Dr. Girtanner of St. Gallen in Switzerland testifies to their appreciation of music. When the town-band began to play on the square adjoining his garden, all his tortoises crept as fast as possible towards the fence and remained there motionless with heads and necks erect. When the piece was finished they moved about, but when the next number began they were again spellbound. This he has observed, not on one but on many occasions. That they can hear, although their ears are not visible, but covered by the ordinary skin, is obvious enough from the fact that during the pairing season they emit feeble piping sounds.

They are extremely fond of basking in the hot sun, sometimes allowing themselves to be almost baked in it, but then again at other times they seem to be anxious to seek the shade. They rise late and go to bed early, being absolutely diurnal. In the summer they leave their quarters when the sun is well up, making for a sunny spot to graze. Then they lie still and bask, unless a shower causes them to retreat under shelter. {369}After some hours' rest they feed again, and in the afternoon, long before sunset, they go to bed. Some winters in England are of course much more severe than any which these tortoises experience in their native countries. Still they manage to survive them, provided they find a place which they can burrow into, deep enough to be out of the reach of frost; and if there is a heap of mould, rotting weeds, and leaves, they are probably safe. Sometimes they are restless, coming out again in unusually mild winters without, however, taking food. If they appear too early in the spring, they run the risk of terrible colds on prolonged wet and cold days, but in the autumn they are hardier, and can stand several degrees of dry frost.

The pairing season begins in May, but lasts far into the summer. In Morocco I found them pairing as late as the month of September. The preliminaries extend over many days. The male becomes unusually active, makes a piping sound, runs after the female, draws in its head, and knocks with its shell against that of the female. This is repeated many times, until the female is excited enough to raise itself upon its hind-limbs. The eggs, only two to four in number, are laid several weeks later, and are buried in the ground. They are roundish-oval, hard-shelled, and vary according to the size of the female. Those of T. graeca measure on the average 30 by 24 mm.; those of a large specimen of T. ibera 32 to 36 by 30 mm. The newly-hatched little creatures are still quite flexible, and apparently soon bury themselves before beginning their active life in the ensuing spring.

The age which these tortoises can reach is quite unknown, but there are reliable data of individuals having been kept for many years. Rumpf kept two T. graeca in his garden at Frankfort-on-the-Main, and let them hibernate in a box with hay in the cellar. One lived 33, the other 23 years. The most famous specimen of T. ibera is "Gilbert White's Tortoise," which had been kept for more than 40 years before it came into his possession. It used to bury itself in November and to come out in April. It died in 1794, having reached an age of fifty-four plus an unknown number of years, since there is no record of its size when it came to England. The same applies to every other specimen which has been, and is being, observed as a pet. My {370}largest Morocco female, which has a shell 7 inches long, shows at least 25 concentric rings of growth on the shields; the last half-dozen rings are very narrow, while some of those of the central area have been rubbed down. This creature is not improbably 30 years old. A small female, which is only 5¼ inches long, has already 14 rings on its still perfect shields. Lastly, a little one, only 4 inches long, shows 7 rings. They grow fastest when they are about 6 to 7 inches long, and they then seem to be at their prime. White's tortoise, now enshrined in the National Collection, was unusually large, the shell measuring 25 cm., or nearly 10 inches; around the much-enlarged, rubbed-down areola of each shield are about 30 very narrow rings.

T. horsfieldi is easily recognised by its possessing only four claws on the fore- and hind-limbs. It is closely allied to the species last mentioned, which it seems to represent in the sandy districts of Transcaspia and the Kirghiz Steppes to Afghanistan.

T. elegans, the "Starred Tortoise" of the southern half of India and Ceylon, is easily recognised by the very convex carapace without a nuchal shield, and by the beautiful markings of the other shields, each of which has a yellow areola, whence radiate yellow streaks upon a black ground. Moreover, the dorsal shields often form humps. It reaches the length of one foot. Old specimens lose the beautiful yellow radiation, owing to a considerable amount of peeling off of the horny layers.

The habits have been carefully watched by Captain Thomas Hutton, who gives the following account. The tortoises live in the grassy jungle at the base of the hills, but owing to their colour being so blended with the rocky nature of the ground, they are with difficulty distinguished. Moreover, they remain concealed beneath shrubs or grass during the heat of the day. In the rainy season they are most active, wandering about all day, feeding and pairing. At the approach of the cold weather they select a sheltered spot and conceal themselves by thrusting their shell into some thick tuft of grass, remaining there in a sort of lethargic, but not torpid, inactivity until the hot season, at which time they remain concealed only during the heat of the day, coming out about sunset to feed.

During the hot season Hutton's captives often soaked themselves {371}in water, and they drank a great deal. Copulation lasted about ten minutes; the females received the males from the end of June to the middle of October. On the 11th of November a female dug a pit at the root of a tuft of grass, having previously watered the spot, then digging with the hind-limbs alternately, and continuing to water the soil. In two hours she had made a hole six inches deep and four wide; she then laid four pure white eggs, each about 1¾ inches or 45 mm. long, and filled the hole again with the prepared mud, pressing it well in with the feet and with the weight of the body. The whole operation took four hours. From December to the beginning of February these tortoises were listless, they then took water and some lucerne, but did not come out again until the middle of April, well in the hot season. Both males and females wrestled in a curious way. One confronted the other, with the head and fore-limbs drawn into the shell, and with the hind-limbs planted firmly on the ground, and in this manner shoving against each other in any narrow space. Sometimes, if one succeeded in placing its shell beneath the other, he tilted his adversary over on his back, from which position he had great difficulty in recovering himself.

T. polyphemus, the "Gopher Tortoise" of the south-eastern States of North America, is one of the few American species. It is characterised by the shape of the front lobe of the plastron, which is bent upwards, and extends beyond the carapace. The nuchal shield is present, not narrow; the supracaudal is undivided. The shell is much depressed, and flattened along the vertebral region, with rounded margins. The fore-limbs are armed with very strong claws. The general colour is very dark brown above, inclining to black; brownish yellow below, with blackish patches. The length of the shell is about one foot, or even eighteen inches.

The Gopher is interesting for its habits, which are described by Agassiz, Schnee, and others. Its domicile consists of an excavation, the mouth of which is just sufficient to admit the animal, the burrow running in an oblique direction to the depth of about four feet. The whole passage is sometimes more than two yards long. It expands from the entrance, and ends in a roomy space, sometimes with a few branches of fir trees which have been dragged in either for food or as a lining. The burrow {372}is inhabited by one pair only. When the dew is on the grass, or after rain, they emerge in search of food, which consists of grass, succulent vegetables, fruit, etc. They also eat the gum that exudes from trees, especially the resin of the pine. The eggs are laid in June, not in their domicile, but in a separate cavity near the entrance; a set consists of five eggs, almost round, and very large, namely, 40 mm., or more than one inch and a half in diameter. To capture the Gopher a deep hole is dug at the mouth of their home, into which they fall as they emerge for food. In Southern Texas and neighbouring parts of Mexico they are represented by a smaller and lighter coloured species.

T. tabulata, widely spread over Tropical South America, whence it is often brought over as a curiosity, reaches a large size, specimens nearly two feet in length being not uncommon. The shell is flat on the top, and is very elongated, without a nuchal, but with an undivided supracaudal shield. The carapace is very dark brown or black, each shield with a yellow or orange centre; the plastron is brown and yellow, the dark colour being mostly confined to the middle portion. The ground-colour of the skin of the limbs is blackish, but the scales are orange or red. The head is yellow and black. This species inhabits the forests, and lives chiefly on the fruits of trees; in captivity they are said to take bread soaked in milk or water, lemons, apples, bananas, cabbage, gourds, and also meat, at least the males.

GIGANTIC LAND-TORTOISES differ from the others in no essential points except their large size. The term gigantic is, however, applied to many of them by courtesy only, since they do not exceed the dimensions of large Turtles. A truly gigantic species, T. atlas, has left its remains in the Sivalik Hills of late Miocene or early Pliocene date. The skull is between seven and eight inches long, and is well preserved, but the correctness of the dimensions of the specimen, as it now stands, restored in the National Collection, is open to doubt. The shell was probably not more than six feet long. Miocene and Pliocene Europe was also inhabited by large tortoises, with shells about four feet long, e.g. T. perpigniana, whose bony plates are one inch thick; others have been found in North America. Such large tortoises are now restricted to two widely separated regions of the world, namely the Galapagos Islands (which have received their name from these creatures, galápago being one of the Spanish terms for {373}tortoise), and the islands in the Western Indian Ocean, namely the Mascarenes (Bourbon, Mauritius, and Rodriguez), the Comoros, Aldabra, the Amirantes, and the Seychelles. When they became extinct in Madagascar is not known, but T. grandidieri was a very large species of apparently very recent date. Of the other islands the Comoros only were inhabited by man, the others were devoid of any but small and harmless Mammals. It was on these peaceful islands that large tortoises lived in incredible numbers, and, like the Dodo of Mauritius and the Solitaire of Rodriguez, grew to a size far beyond that of their less favourably placed continental relations. The same applies to the tortoises of the Galapagos Islands. Plenty of food, a congenial equable climate, and absence of enemies enabled them to enjoy existence to the fullest extent. There was nothing for them to do but to thrive, to feed, to propagate, to grow, and to vary. At least there was nothing to check variation within reasonable limits. Scattered over the many islands, they were prevented from inter-breeding, and thus it has come to pass that not only every group of islands, but in the case of the Galapagos almost every island, has or had its own particular kind, be these called varieties, races, forms, or species.

There are four features of special interest. First, these tortoises grow to a large size, and there are no small species on any of these islands. Secondly, they vary much individually. Thirdly, each island or group of islands has developed its own kind. Lastly, there is the widely spread tendency to reduce the thickness of the bony plates of the carapace, in spite of its size. In some cases, notably T. vosmaeri of Rodriguez, the bony shell is reduced to apparently the utmost limit compatible with mechanical safety. The horny shields are, or were, however, well developed, sometimes much more so than in other recent land-tortoises. Whatever were the original reasons for the development of a strong shell in tortoises, they cannot have prevailed in these islands.

Where did all these tortoises come from, and how did they get to these oceanic islands? Accidental transport or migration are out of the question. Land-tortoises are drowned within a few hours. Moreover, there are none of their kind on the continents of Africa, Asia, and South America, although they had a much wider distribution in past geological ages. Consequently we have to assume that they are descendants of tortoises once populating the land which, except the islands, lies now below {374}the western Indian ocean. The existence of this, "Lemuria" or "Gondwana," came to an end in Mid-Tertiary times. The large tortoises on the remaining continents died out–in any case they are gone, while those which lived on, or retreated to, what became the present islands, survived and flourished.

The tortoises were not left in peace with the advent of man, who found that they were good to eat. They were first exterminated on the Mascarene Islands. In 1759 four small vessels were specially appointed for the service of bringing tortoises from Rodriguez to Mauritius; one vessel carried a cargo of 6000; and altogether more than 30,000 were imported into Mauritius within the space of eighteen months. Dr. Günther very properly remarks that many of these tortoises must have been small-sized specimens, and that many of them were probably used for provisioning passing Government vessels. Anyhow an inter-insular traffic was carried on, and there are records of superfluous tortoises having been turned loose, at the end of the voyage, in distant islands, even in Java. Importation and exchange of choice specimens, by way of presents, seems also to have taken place. All this makes it now actually impossible to trace the original habitat of the few surviving specimens with anything like certainty. At the beginning of this century the large tortoises had been nearly cleared off most of the islands, and at the present time only the south island of Aldabra enjoys the reputation of still possessing some really indigenous tortoises. The few survivors on the other islands are said to have been introduced. The small stock at Aldabra is now under Government protection. Representatives of various species will linger on for a little time to come, when they are kept as pets on some tropical islands, but those which have been brought to Europe are of course doomed.

We can mention only a few of the large tortoises which have become famous, not to say historical. A fascinating résumé of the whole complicated question has been given by Dr. Günther.

Testudo gigantea s. elephantina s. hololissa s. ponderosa, originally confined to the North Island of Aldabra, where this {375}kind has been completely exterminated, is now still to be found in the Seychelles in considerable numbers, introduced there by planters, and kept in a state of semi-domestication. A very large specimen was received by the Hon. Walter Rothschild, at Tring, in 1893. In 1897 its shell measured 40¼ inches in length, 52¼ over the curve, and 50 inches across the curve transversely; it weighed 358 lbs. The measurements taken in previous years are unfortunately not free from mistakes. "Whenever the temperature was over 60° F. this tortoise had a free run of 350 acres of grass park, and when the temperature showed permanently below 58°, it was kept in an orchid house from September to June. When at liberty in the park it lived entirely on grass, but in the hothouse it fed on carrots, cabbage, lettuce, and several other vegetables"; it was also very fond of rotten fruit. To this species belongs the large tortoise which has been living at St. Helena for more than the last hundred years.

T. daudini is the species of the South Island of Aldabra. Voeltzkow, in 1895, succeeded in carrying off seven specimens. He gives the following description:–The island is an atoll, cut through in three places, with a greatest length of about twenty miles. The chief hindrance in the search for the tortoises is the impenetrability of the island. The soil consists entirely of sharp water-worn corals, with their points uppermost, while the whole is covered with such thick masses of low scrub, that a way has to be cut with an axe, so that an extended search over a large area is out of the question. To land on the outside is dangerous, on account of the heavy surf; while landing from the inside of the atoll is much hindered by the dense thickets of mangrove trees. As drinking water, and that very bad, is only found in one place, rainwater has to be collected from the natural hollows, and carried along in tanks. Thousands of mosquitoes prevent one remaining over night in those places which the tortoises frequent. Then at last, when one has discovered, by a stroke of luck, one of these creatures, in the thick scrub, where they hide during the heat of the day, the real hard work begins, namely, the conveyance of the beast. Six reached Europe alive, two of them were sent to Frankfort, and the four others to Hamburg. Mr. Rothschild received a male of T. daudini, which, until its recent death, was the largest living tortoise known. The length {376}of its shell was 55 inches, or 67½ inches over the curve; total weight 560 lbs. This specimen had a chequered career. Although its original home must have been the Aldabra atoll, it had been known for many years on Egmont Island, one of the Chagos Islands. According to tradition, it had been there some 150 years, but the first settlement on that island was formed from Mauritius only at the beginning of this century. The owner of the tortoise, M. Antelme, took it to Mauritius, whence it came to England. On the Egmont Island it used to bury itself for six months in the ground without eating anything.

T. sumeirei.–This kind is supposed to have been the species peculiar to the Seychelles. In 1766 five large tortoises were brought from the Seychelles to Mauritius by Chevalier Marion de Tresne. Of these only three were alive in 1898, two in {377}Mauritius and one in London; the latter specimen soon died in the Zoological Gardens. One of the two survivors, the last of their race, is famous. It was kept at Port Louis, and when Mauritius became a British possession in 1810, the tortoise was especially mentioned and taken over. It still lives there in the grounds of the barracks of the garrison. According to the proverbial oldest inhabitants it had in 1810 already reached its present size, namely, a shell-length of about 40 inches with a greatest circumference of 259 cm. = 8 feet 6 inches. Total weight 160 kilo = about 358 lbs. When walking it stands 63.5 cm. = 25.4 inches high, with the plastron about 15 cm. or 6 inches above the ground, and it can then carry with ease two full-grown men on its back. This old male is now nearly blind, but is otherwise of regular habits and in good health. Although it has been known for nearly 150 years it had to wait for its scientific name until the year 1892.

Another famous individual is the Colombo tortoise. It is supposed to have come to Colombo from the Seychelles in 1798. It died in 1897. To judge from photographs, this specimen, a male, may possibly belong to T. sumeirei, in spite of the very flat shell, which is 53½ inches in length.

Leaving aside the remains of sub-fossil tortoises, e.g. the thin-shelled T. vosmaeri of Rodriguez, and several kinds which have been dug out in the Mare-aux-songes of Mauritius, one of which had a markedly forked and prolonged anterior plastral lobe, rather resembling that of the Pliocene Sivalik T. atlas, we now turn to the tortoises of the Galapagos Islands. They existed in enormous numbers towards the end of the seventeenth century, when Dampier visited those islands. Hundreds were exported and scattered early in the nineteenth century. When the islands became a penal settlement of Ecuador, the introduction of convicts and pigs proved detrimental to them, but Darwin found them still present in 1835 on most of the islands. His classical account of these old giants is to be found in the Voyage of the Beagle. They lived on the succulent cactus plants, leaves of trees, berries, and a kind of Usnea, a lichen pendant from the trees. They collected regularly at certain pools and springs, leading to which were regular well-trodden paths, formed by the coming and going of the tortoises. He calculated that they could walk a distance of about four miles in one day. During {378}the time of propagation the males emit a hoarse bark, which can be heard a hundred yards off. The round eggs measure about 5 cm. or 2 inches in diameter, and are laid in the month of October, about one dozen making a set.

Nearly every island had apparently its own kind. They are all remarkable for their small head and the length of their neck, which is decidedly longer and more slender than that of the Eastern tortoises. The most peculiar looking are or were T. ephippium and T. abingdoni, the shell of which is extremely thin, with large lacunae in the osseous plates. The profile of the shell is somewhat saddle-shaped, with the horny shields partly concave and turned upwards at the sides. The general colour of these and the other Galapagos tortoises is black. T. ephippium still survives on Duncan Island. Of T. elephantopus s. vicina Baur collected twenty-one specimens in 1893 on Albemarle Island. Some of them are still comparatively young, only 16 inches long. A large one was killed, and, being hard up for water, Baur and his companions drank the five cups full of fluid contained in the pericardial sac; they found it most refreshing, and tasting somewhat like the white of an egg. One monster is said to have measured 56 inches over the curve, with a skull 7.12 inches in length. Mr. Rothschild received one of this kind alive–a much-travelled specimen. It came to England from Sydney, whether it had been brought in 1880 from Rotuma Island, north of the Fiji group. There it had probably been left with others by Captain Porter, who, on his voyage from the Galapagos in 1813, distributed several young tortoises from his stock among the chiefs, and permitted a great many to escape into the bushes and among the grass. The shell of this specimen measured 49½ inches in length, 56 over the curve.

FAM. 6. CHELONIDAE (Turtles).–The limbs are paddle-shaped, and the shell is covered with horny shields. Only two recent genera, with three species, widely distributed in the seas.

The neck is short and incompletely retractile. The temporal region of the skull is completely roofed over above and laterally by the parietals, postfrontals, squamosals, quadrato-jugals and jugals. All these bones are much expanded, and form the additional or false roof. The parietals are especially large, and are in broad contact with the squamosals. Nasals are absent. The nares are bordered by the small premaxillaries, the maxillaries, {379}and the prefrontals. The choanae are enclosed by the palatines, which are separated by the vomer, and are posteriorly in broad contact with the pterygoids. The latter are connected with descending processes of the parietals by epipterygoids. The foramen magnum is bounded not only by the supra-occipital and the lateral occipitals, but also by the basi-occipital. For the skeleton see Fig. 65, p. 320. The pubic and ischiadic symphyses are connected by a narrow cartilaginous band. The pubis has a large, broad, lateral process, but the ischium is devoid of such a process. The paddles of the fore- and hind-limbs are produced by an elongation of the metacarpal and metatarsal bones and of most of the phalanges, and these have no condyles; most of the carpal and tarsal elements are flattened, and additional width is given to the hands by the much enlarged pisiform bone. The number of phalanges of the five fingers is 2, 3, 3, 2, 2; that of the five toes, 2, 3, 3, 3, 2.

The carapace is heart-shaped and very flat. The nuchal plate has no rib-like processes. The eight neurals form a continuous series, and the short tail is covered by two or three pygal plates besides the unpaired last marginal. The number of all the {380}marginals is 23, sometimes 25 individually. The plastron (Fig. 66, p. 321) is composed of the usual nine plates, which, however, remain entirely free from the marginals, and are only loosely connected with each other, enclosing a very large unossified space. The horny shields covering the plastron number 13, and there is a series of about 5 inframarginals (Fig. 61, 6, p. 315). There are normally 12 pairs of marginal shields, a nuchal, 5 neural, and 5 or 7 costal shields. Whilst the number of these dorsal shields is pretty constant in Chelone, it is subject to an astonishing amount of individual variation in Thalassochelys.

The Chelonidae are a highly specialised offshoot of the Cryptodira adapted to marine life. Fundamentally they agree most with the Testudinidae, paradoxical as this may appear at first sight. There is nothing primitive about them except the complete series of inframarginal shields. Fossil forerunners of marine turtle-like creatures appear in the Upper Jurassic deposits of Europe and North America. The numerous genera have been grouped together as Thalassemydidae and Chelonemydidae. They are more or less intermediate between Chelonidae and Emys-like Testudinidae, the carapace being not too much flattened and broadened out, the fontanelles between the ribs are mostly small, the plastral bones are still broad, enclose a smaller ossified space, and there is still a bony bridge in most cases. The paddle-shape of the limbs is less pronounced, and sometimes only indicated. In some forms, especially Lytoloma, from the Upper Cretaceous and Eocene of North America and Europe, the anterior portion of the skull is much longer than in the Chelonidae, the vomer and the premaxillaries are elongated, and the anterior portion of the roof of the mouth, with the corresponding parts of the lower jaw, seems to have carried crushing pads. Some of the best-known Upper Jurassic genera are Eurysternum and Idiochelys; Plesiochelys from the Purbeck and Wealden; Allopleuron hofmanni from the Upper Cretaceous of Belgium approaches Chelone by the large fontanelles between the small marginal and the short costal plates. True Chelonidae are very rare and imperfect in the Mid-Tertiary strata, but both recent genera seem to have existed since Pliocene times.

The few recent Chelonidae are entirely marine, going on land only in order to deposit their eggs in the sands of unfrequented shores. Their distribution, in conformity with their oceanic life, {381}is almost cosmopolitan within the warmer zones, but not a few find their way far into the temperate seas. They are all eagerly hunted by man either for food or for the sake of the tortoiseshell.

Chelone.–With only four pairs of costal shields. Carapace with large persisting fontanelles between the costal and marginal plates. Two species.

Ch. mydas (the "Green or Edible Turtle"), has when adult a nearly smooth shell, all the shields being juxtaposed, fitting closely into each other, and becoming quite smooth with age. The neural shields of younger specimens have a feeble keel. The twenty-five shields which surround the carapace form a smooth, or but indistinctly serrated rim. The head is covered with one pair of prefrontal shields, the others are small. The horny beaks of the upper and lower jaws have denticulated outer edges, those of the upper jaw having two pairs of strong denticulated ridges. The limbs have generally only one claw, namely on the first digit. This claw, although sometimes curved and thick, and more than an inch in length, is blunt. The general colour is olive or brown above, with yellowish spots or blotches; the under parts are pale yellowish. This species attains a large size, with a length of shell of nearly four feet, but the usual length of full-grown specimens is three feet, and these weigh, when in good condition, more than three hundredweight. Their home is in the Atlantic, Indian, and Pacific Oceans, but there are certain regions in which they are more common than in others. Famous centres are the Island of Ascension, the West Indies, and the coast of Mosquito, at least for commercial purposes. As they require sandy, easily accessible beaches for the deposition of their eggs, they congregate in certain parts of the world more than in others, and being strictly vegetable feeders, they are naturally bound to the coasts, although they are sometimes met with far out at sea. Their chief food consists of algae, and of Zostera marina, the edible "Dulce," which grows plentifully in the lagoons of the coast of Florida. When they have eaten their fill, they are said to chop off more of these plants, and roll them, together with the adherent mud, into balls of the size of a head, and these balls, receding with the tide, are followed by the Turtles.

Whilst in the water they are caught in various ways, with {382}nets or harpoons. In some parts of the world the natives follow them in a boat, and when they espy a turtle crawling along the bottom, a man, attached to a rope, dives in, clasps it, and is brought up by his companions together with his prey. Turtles are fond of basking asleep, floating on the surface, and they are then harpooned from a stealthily approaching boat. The most original mode of catching them is that used by the natives of Torres Straits, Madagascar, and Cuba. The turtle-fishers go out in the boat to a spot frequented by grazing turtles; a long string is tied to the tail of a fish, Echeneis, a member of the Mackerel family, and the Echeneis, anxious to get away to protective shelter, makes for a turtle, and attaches itself to the turtle's plastron by means of the large sucking apparatus on the top of its head and neck-region. The men are guided by the string, and the turtle is gently coaxed up towards the surface or followed into shallow water, where it is either harpooned or dived for. It is curious that this use of the Echeneis exists in such widely separated parts of the world, the natives of which cannot have any knowledge of each other. These modes of catching turtles are sportsman-like, but the greatest and most wanton destruction is practised at their breeding places. In conformity with the wide distribution of these creatures, the time of breeding is not the same everywhere. In the West Indian region, and in the Straits of Malacca, it falls within the period of April to June; on the coast of West Africa it occurs from September to January. The females come to their breeding places from afar, reconnoitre the beach carefully, are extremely wary and shy, taking alarm at the slightest disturbance, and at last crawl on land. Well out of the reach of the tide the female scoops out a hole in the sand, deposits about one hundred or more of its round, rather parchment-shelled eggs, covers the nest carefully, obliterating all traces of the dug-out sand, and makes again for the sea by another route. At least they are said to make a sort of circuitous route so that nobody can tell the position of the nest, which may be anywhere beneath the broad trail left by the heavy creature on its way from and back to the sea. The nest is discovered by probing the sand with sticks. The time of incubation is not known, but according to Agassiz, lasts at least seven weeks.

{383}[Illustration: FIG. 85.–Three turned Turtles, a Seal, and Albatrosses, Laysan Islands, north-west of the Sandwich Islands. From a photograph belonging to the Hon. W. Rothschild.]

{384}The "turning" of turtles is a cruel and wanton operation, since frequently many more are turned over and left to perish than are taken away. Men lying in ambush watch the beast, or they approach the lonely sandy shore by boat, and rush the helpless creatures when these are surprised in sufficient numbers. It takes several men to lift a full-grown specimen. It is therefore necessary to secure them by turning them over with poles or by their flippers, lest they should crawl away. On board ship they are either put into tanks or tied with ropes on deck, covered with a moistened cloth; and occasionally a piece of bread, soaked in sea-water, is thrust into the parched mouth. In London they are kept in large tanks, often in considerable numbers, but since they take no food in captivity, or rather because it is difficult to supply them with the right sort, they are not kept long. After the head has been cut off, the body is suspended for a day or two, in order to drain it of the blood. It is not only the meat and the fat which are used for the making of the famous soup, but also the thick and dense layer of subcutaneous tissue which lines the inside of the shell.

Tennent describes a revolting spectacle exhibited in the markets of Jaffna, in Ceylon. The flesh of the turtles is sold piecemeal by the Tamil fishermen, while the animals are still alive. At certain seasons, says the same authority, the flesh of turtle on the south-west coast of Ceylon is usually avoided as poisonous, but some lamentable instances are recorded of neglect of this, and consequent sickness, followed by coma and death. In the Gulf of Manaar specimens are frequently found between four and five feet in length; and on one occasion, in riding along the seashore north of Putlam, he saw a man in charge of some sheep, resting under the shade of a turtle shell, which he had erected on sticks to protect him from the sun. In connexion with this curious sight, Tennent quotes Aelian's statements, copied by him from Megasthenes' Indica Frag. lix. 31, that in the Indian ocean turtles occur which measure fifteen ells, so that not a few people may find ample shelter beneath a single shell.

Ch. imbricata ("Hawksbill Turtle").–The number of shields covering the carapace is the same as in Ch. mydas, but they strongly imbricate, or overlap each other from before backwards, until the animal is very old, when the shields become juxtaposed.

{385}[Illustration: FIG. 86.–Chelone imbricata ("Hawksbill Turtle"), young. × ½.]

In young specimens, under one foot in length, each of the neural and costal shields is strongly keeled, the three rows of keels converging towards the posterior end of the shell. The neural series of keels is almost continuous, and remains longest, even in half-grown specimens. The twelve pairs of marginal shields form at first a strongly serrated sharp edge; the serrations disappear gradually on the front portion, but remain on the posterior half of the shell. The horny covers of the jaws form a hooked beak, with sharp but smooth or feebly denticulated margins. The fore- and hind-flippers have two claws. The young are pale brown above, blackish below; the shell of the adult is beautifully marbled with yellow on a rich dark-brown ground; the plastron is yellow. The shields and scales of the head and limbs are dark brown, with yellow margins. The top of the head is covered by a large unpaired frontal and a pair of prefrontal or interorbital shields. This Turtle does not reach the size of the green or edible kind; the largest shell on record is in the National Collection, and measures 85 cm. = 34 inches in length. They range over all the tropical and subtropical seas. They are apparently strictly {386}carnivorous, living upon fish and molluscs, the shells of which they crunch. Although not eaten, they are much persecuted on account of their shells, the horny shields of which are the "tortoiseshell" of commerce. A large specimen yields up to 8 lbs. Few of the shields are, however, thick enough to be manufactured into the larger articles which art and fashion delight in, but if heated in oil, or boiled, they can be welded together under pressure, and be given any desired shape. In genuine articles of Oriental manufacture these welds can generally be detected, or their compound nature is indicated by the beautiful pattern, which is too regular in the imitations now common. Even the shavings and leavings can be welded and moulded into large pieces. The stripping of the shields has been described by Sir E. Tennent. "If taken from the animal after death and decomposition, the colour of the shell becomes clouded and milky, and hence the cruel expedient is resorted to of seizing the turtles as they repair to the shore to deposit their eggs, and suspending them over fires till heat makes the plates on the dorsal shields start from the bone of the carapace, after which the creature is permitted to escape to the water. At Celebes, where the finest tortoise-shell is exported to China, the natives kill the turtles by blows on the head, and immerse the shell in boiling water to detach the shields. Dry heat is only resorted to by the unskilful, who frequently destroy the tortoise-shell in the operation." The cruel process described above is resorted to "for economy's sake," the Singhalese believing that such maltreated turtles regenerate the shields, to be caught and shipped again. Since none of them are actually re-caught in the mutilated condition, this is looked upon as a proof of the correctness of the treatment. It is more likely that they die.

New shields can be reproduced only if the underlying Malpighian layer of cells (cf. Fig. 68, B, p. 323) is not killed by the roasting. However, Dr. Charles Hose, with his long experience in Borneo, is positive that numerous individuals are there caught which have imperfectly mended shells, the shields of which do not imbricate, are thin, and almost worthless.

It is commonly believed that the same individuals return again and again to the same spot for laying. This is very likely the case. Tennent mentions that in the year 1826 a Hawksbill was taken near Hambangtotte, which bore a ring attached to one of its fins, that had been placed there by a Dutch {387}officer thirty years before, with a view of establishing the fact of these recurring visits to the same beach. The same homing instinct has been observed in some females of the Green Turtle, which, having been brought from the Tortugas Keys to Key West off the south end of Florida, escaped, and were, a few days later, re-caught at the Tortugas. On the other hand, experiments made with turtles at Ascension are said to have had no result.

Thalassochelys, with five pairs of costal shields. The carapace is completely ossified in the adult, leaving no fontanelles between the ribs and the marginals.

Th. caretta (the "Loggerhead Turtle").–The shields of the carapace imbricate only in young specimens, in the adult they become smooth and juxtaposed. The margin is serrated posteriorly. The carapace of the young has three strong keels. The intergular shield is very small or absent. The marginals, including the nuchal, usually number 23, rarely 25. The large head is armed with hooked jaws, the crushing surface of the horny upper beak has a median prominent ridge. The top of the head has a pair of shields in front of the unpaired frontal. The flippers of the young have claws on the first and second digits; in the adult usually only that of the first digit remains. The general colour of the shell is uniform brown above, yellowish below. Very young specimens are uniform dark brown or blackish above and below.

Large individuals have a shell about three feet and a half in length. The Loggerhead is carnivorous, and is commercially of no value. Its habits seem to be the same as those of the other Turtles, but it has a much wider distribution. Besides all the tropical and intertropical seas, it inhabits the Mediterranean, and is an accidental visitor to the western coasts of Europe, especially Portugal and the Bay of Biscay. It has been caught several times on the coast of Belgium, and an old female containing 1150 eggs was captured in 1894 on the Dutch coast. In 1861 one was caught near Penman, on the coast of Banffshire, and a second in the completely land-locked Loch Lomond. It has been more frequently recorded from the coast of Devon and Cornwall.

The most interesting feature of the Loggerhead is the {388}astonishing variability in the number of the horny shields of the carapace. The normal number of shields of the carapace, leaving out the marginals and counting the nuchal as the first neural, is 6 neurals and 5 pairs of costals, in all 16. The greatest number of dorsal shields observed is 8 neurals and 8 pairs of costals, in all 24. Many of the intermediate combinations have been observed, there being, for instance, specimens with 8 neurals and 16, 14, 13, 12, or 11 costals, the latter not being always in pairs, but unequal on the right and left sides; or there are 7 neurals with 20 to 16 costals, or 6 neurals with 20, 19, 18, 17, or 16 costals. The interesting fact in connexion with these variations is, moreover, that some of the shields are much smaller than the others, sometimes mere vestiges in all stages of gradual suppression, and that the abnormalities are much more common in babies and small specimens than in adults. The importance of these "orthogenetic" variations has been discussed on p. 326.

SUB-ORDER 2. PLEURODIRA.–Neck bending laterally and tucked away in the niche formed between the anterior portion of the carapace and plastron. Pelvis ankylosed to the shell, the broadened tops of the ilia to the carapace, the distal ends of the pubes and ischia to the plastron.

Freshwater tortoises, almost entirely carnivorous, inhabiting South America, Australia, Africa, and Madagascar. Fossil forms are known from the Jurassic epoch onwards.

Owing to the strong connexion of the iliac bones with the costal plates the sacrum has become practically abolished, the sacral ribs being reduced to one pair (the posterior of the original two pairs) or being absent. The centra of the cervical vertebrae articulate by cup and ball joints. The formation of the temporal region of the skull varies considerably in the three families, some genera lacking the complete zygomatic arch, while others have a narrow parieto-squamosal arch bridging over the temporal fossa, or the latter is completely roofed over by the laterally expanded parietal, which meets the jugal and quadrato-jugal. The quadrate is always trumpet-shaped; the rim of the tympanum is complete, but the posterior part of the trumpet remains open. The basisphenoid, pterygoids, and palatines form a broad and flat roof to the mouth. The vomer is large, and separates the palatines in the Chelydidae; it is very much {389}reduced or absent in the Pelomedusidae, in which the palatines meet. All the Chelydidae, except Chelys, have nasal bones which remain distinct from the prefrontals. The choanae lie in front of the palatines, divided by the vomer when this is present, but they are not roofed in ventrally.

The ilia are solidly ankylosed in the adult with the neighbouring costal plates, mostly with the last two pairs, sometimes also with the pygal plate. The lateral processes of the pubes fuse with the xiphiplastra. The ischia are also attached to the same plastral elements.

The carapace is flat and completely ossified. The nuchal plate is always conspicuous, much larger than the neurals, and these are often reduced by being encroached upon by the eight pairs of costal plates, which then meet in the dorsal line. In Sternothaerus all the eight neurals are present and form a continuous row. In most of the other genera they are reduced to seven, the last being squeezed out. In Rhinemys they are reduced to the second, third and fourth and an isolated fifth, and in Hydraspis they are all gone. The pygal plate is always, even in Sternothaerus, separated from the last neural by the eighth pair of costals. The marginals number 23, but in Carettochelys only 21.

The carapace is covered with horny shields, except in Carettochelys. The nuchal is absent in the Pelomedusidae and in a few Chelydidae (Elseya and a few species of Emydura). In Hydromedusa the nuchal is shut in by the anterior marginals, simulating a sixth neural. The plastron is composed of the usual nine elements, but the Pelomedusidae possess an additional pair, the meso-plastra, inserted between the hyo- and hypo-plastra. The bridge is strong, connected with the carapace by suture. In Sternothaerus the front lobe of the plastron is movable. The intergular shield is always present; it is terminal, forming part of the front margin, except in Chelodina, where this shield, although large, is shut in behind the gulars (cf. Fig. 61, 4 and 5, p. 315).

Although the Pleurodira are a peculiarly specialised group, one of the oldest Chelonian fossils known seems to belong to them. Proganochelys, represented by a complete shell, nearly 2 feet long, has been found in the Upper Keuper Sandstone of Würtemberg. Plesiochelys, of the Upper Jurassic of Switzerland, has eight neural and three supracaudal plates, but is without the {390}ischiadic plastral ankylosis. Pleurosternum, of the English and Continental Purbeck beds, has meso-plastral plates like the recent Pelomedusidae. Rhinochelys, of the Cambridge Greensand, has a broad parieto-postfrontal roof, and large nasal bones. Forms like Podocnemis, now restricted to South America, occur in the Eocene of Europe. One of the most aberrant Chelonians is Miolania, from the Plistocene of Queensland and from Lord Howe's Island, remarkable for its huge size and the thick armour on the head and tail; the head especially carries large paired projections, one pair of which extends horizontally like powerful horns, recalling the queer Theromorphous Elginia.

We divide the recent Pleurodira into three families, of which that of Carettochelys stands apart by its paddle-shaped limbs and the absence of horny shields. The Pelomedusidae and Chelydidae are closely allied. The former are not Australian, and are externally distinguished by the absence of a nuchal shield.

FAM. 1. PELOMEDUSIDAE.–Neck completely retractile within the shell. Carapace without a nuchal shield. The plastron is composed of eleven plates, there being besides the unpaired endo-plastron a pair of meso-plastra, situated between the hyo- and hypo-plastra; but these meso-plastra meet in the middle line in Sternothaerus only, while in Podocnemis and Pelomedusa they are restricted to small pieces on the bridge, widely separated from each other by the usual hyo- and hypo-plastral suture. A nuchal shield is absent; there are twenty-four marginal and thirteen plastral shields, inclusive of the conspicuous intergular. The temporal fossa is widely open, except in Podocnemis, where it is partly roofed in by the meeting of the much-expanded quadrato-jugal with the parietal. The palatine bones are in median contact, not separated by the vomer. Nasal bones being absent, the large prefrontals meet in the middle line. The second cervical vertebra is biconvex.

This family is now represented by only three genera, with about fifteen species in Africa, Madagascar, and South America.

Sternothaerus.–Skull without a bony supratemporal roof. Meso-plastra large, extending right across the plastron. Anterior lobe of the plastron movable, the hinge passing between the hyo- and meso-plastral plates, and between the pectoral and abdominal shields. Fore- and hind-limbs with five short digits and claws. Several species in tropical and southern Africa, and {391}in Madagascar. S. derbianus in West Africa, from the Gambia to Angola, is the largest species, with a shell nearly one foot in length.

Pelomedusa.–Skull with a slender parieto-squamosal arch. Meso-plastra small and lateral. Plastron without a hinge. Fore- and hind-limbs with five very short digits and five claws. Top of the head with one pair of shields between the eyes, and with a large interparietal and a pair of parietals behind.

P. galeata, the only species, occurs in Madagascar and nearly the whole of Africa south of the Sahara, from the Cape to Abyssinia, and in the Sinaitic peninsula. The shell, less than one foot in length, is much depressed and is obtusely keeled; brown above with black spots; brownish-yellow below. The short and broad head is coloured like the rest, without ornamentation. In Somaliland this species sleeps hidden on land during the dry seasons, from July to the end of September, and from January to March, and appears at once after the rains have set in.

Podocnemis.–With a supratemporal roof formed by the junction of the parietal with the quadrato-jugal. Meso-plastra small and lateral. Fore- and hind-limbs broadly webbed, with five and four claws respectively. The fore-arms and the outer edges of the hind-feet with several conspicuous shields, hence the generic name. Head with an interparietal, two parietals, and a narrow unpaired shield between the eyes. The tail is very short. The carapace is flat and broad, strongly serrated on the posterior margin. Chin with one or two short barbels. Several species in South America, chiefly in the basin of the Amazon, and one in Madagascar.

P. expansa.–Very common in Tropical South America, east of the Andes. The female, which is much larger than the male, has a shell nearly three feet in length. Olive-brown above with darker patches; yellowish below. With a few yellow spots above and behind the eyes, and on the parietal region. The "Arrau" turtle is of great commercial importance on account of the eggs, which are periodically collected in enormous quantities, chiefly for the oil. This is either eaten, like the eggs themselves, or used for burning in lamps, or as an addition to tar. The turtles are likewise eaten by man and beast. Thousands of the little creatures are snapped up by Jabiru storks, alligators, and fishes; the adults fall an easy prey {392}to the prowling jaguar, which turns them over on to their backs and neatly cleans out the flesh with its sharp and powerful claws.

Fertilisation takes place in the water, the eggs are deposited on land, in sand-banks, the female digging a hole about two feet deep and covering up the numerous soft-shelled eggs with sand. The time of deposition is the early hours of the morning, but the season depends upon the beginning of the principal rains, since the young are hatched shortly before the torrential rains. This season differs considerably in the various countries. The hatching takes about forty days; the eggs are consequently laid in the Amazon countries during the months of September to November, in the Orinoco district in March. This species lives in the pools of the inundated forests, and when these are dried up, the animals retire into the rivers themselves. Their food consists mainly of the fruit dropping down from the trees.

Bates, in his delightful book, The Naturalist on the River Amazon, gives the following lively and exhaustive account of his experience with these turtles:–

"I accompanied Cardozo in many wanderings on the Solimoes, during which we visited the 'praias' (sand islands), the turtle pools in the forests, and the by-streams and lakes of the great desert river. His object was mainly to superintend the business of digging up turtle eggs on the sandbanks, having been elected commandant for the year by the municipal council of Ega, of the 'praia real' of Shimuni, the one lying nearest to Ega. There are four of these royal praias within the Ega district, a distance of 150 miles from the town, all of which are visited annually by the Ega people for the purpose of collecting eggs and extracting oil from their yolks. Each has its commander, whose business is to make arrangements for securing to every inhabitant an equal chance in the egg harvest, by placing sentinels to protect the turtles whilst laying, and so forth. The pregnant turtles descend from the interior pools to the main river in July and August, before the outlets dry up, and there seek in countless swarms their favourite sand-islands; for it is only a few praias that are selected by them out of the great number existing. The young animals remain in the pools throughout the dry season. These breeding places of turtles then lie 20 to 30 or more feet above the level of the river, {393}and are accessible only by cutting roads through the dense forest....

"We found the two sentinels lodged in a corner of the praia, where it commences at the foot of the towering forest-wall of the island, having built for themselves a little rancho with poles and palm-leaves. Great precautions are obliged to be taken to avoid disturbing the sensitive turtles, who, previous to crawling ashore to lay, assemble in great shoals off the sand-bank. The men, during this time, take care not to show themselves, and warn off any fisherman who wishes to pass near the place....

"I rose from my hammock by daylight, shivering with cold; a praia, on account of the great radiation of heat in the night from the sand, being towards the dawn the coldest place that can be found in this climate. Cardozo and the men were already up watching the turtles. The sentinels had erected for this purpose a stage about fifty feet high, on a tall tree near their station, the ascent to which was by a roughly made ladder of woody lianas. They are enabled, by observing the turtles from their watch-tower, to ascertain the date of successive deposits of eggs, and thus guide the commandant in fixing the time for the general invitation to the Ega people.

"The turtles lay their eggs by night, leaving the water, when nothing disturbs them, in vast crowds, and crawling to the central and highest part of the praia. These places are, of course, the last to go under water when, in unusually wet seasons, the river rises before the eggs are hatched by the heat of the sand.... The hours between midnight and dawn are the busiest. The turtles excavate with their broad webbed paws deep holes in the fine sand; the first-comer, in each case, making a pit about three feet deep, laying its eggs (about 120 in number), and covering them with sand; the next making its deposit at the top of that of its predecessor, and so on until every pit is full. The whole body of turtles frequenting a praia does not finish laying in less than fourteen or fifteen days, even when there is no interruption. When all have done, the area (called by the Brazilians 'taboleiro') over which they have excavated is distinguishable from the rest of the praia only by signs of the sand having been a little disturbed.

"I mounted the sentinel's stage just in time to see the turtles retreating to the water on the opposite side of the sand-bank, {394}after having laid their eggs. The sight was well worth the trouble of ascending the shaky ladder. They were about a mile off, but the surface of the sands was blackened with the multitudes which were waddling towards the river; the margin of the praia was rather steep, and they all seemed to tumble head first down the declivity into the water.... Placards were posted up on the church doors at Ega, announcing that the excavation on Shimuni would commence on the 17th of October, and on Catuá, sixty miles below Shimuni, on the 25th. By the morning of the 17th some 400 persons were assembled on the borders of the sand-bank, each family having erected a rude temporary shed of poles and palm-leaves to protect themselves from the sun and rain. Large copper kettles to prepare the oil, and hundreds of red earthenware jars, were scattered about on the sand.

"The excavation of the taboleiro, collecting the eggs, and purifying the oil, occupied four days. All was done on a system established by the old Portuguese governors, probably more than a century ago. The commandant first took down the names of all the masters of households, with the number of persons each intended to employ in digging; he then exacted a payment of 140 reis (about 4d.) a head towards defraying the expense of sentinels. The whole were then allowed to go to the taboleiro. They ranged themselves round the circle, each person armed with a paddle, to be used as a spade, and then all began simultaneously to dig on a signal being given–the roll of drums–by order of the commandant. It was an animating sight to behold the wide circle of rival diggers throwing up clouds of sand in their energetic labours, and working gradually towards the centre of the ring. A little rest was taken during the great heat of mid-day, and in the evening the eggs were carried to the huts in baskets. By the end of the second day the taboleiro was exhausted; large mounds of eggs, some of them four to five feet in height, were then seen by the side of each hut, the produce of the labour of the family.

"In the hurry of digging, some of the deeper nests are passed over; to find these out, the people go about provided with a long steel or wooden probe, the presence of the eggs being discoverable by the ease with which the spit enters the sand. When no more eggs are to be found, the mashing process begins. {395}The egg, it may be here mentioned, has a flexible or leathery shell; it is quite round, and somewhat larger than a hen's egg. The whole heap is thrown into an empty canoe and mashed with wooden prongs; but sometimes naked Indians and children jump into the mass and tread it down, besmearing themselves with yolk, and making about as filthy a scene as can well be imagined. This being finished, water is poured into the canoe, and the fatty mass is then left for a few hours to be heated by the sun, on which the oil separates and rises to the surface. The floating oil is afterwards skimmed off with long spoons, made by tying large mussel-shells to the end of rods, and purified over the fire in copper kettles.

"The destruction of turtle eggs every year by these proceedings is enormous. At least 6000 jars, holding each three gallons of the oil, are exported annually from the Upper Amazons and the Madeira to Para, where it is used for lighting, frying fish, and other purposes. It may be fairly estimated that 2000 more jarfuls are consumed by the inhabitants of the villages on the river. Now, it takes twelve basketfuls of eggs, or about 6000, by the wasteful process followed, to make one jar of oil. The total number of eggs annually destroyed amounts, therefore, to 48 millions. As each turtle lays about 120, it follows that the yearly offspring of 400,000 turtles is thus annihilated. A vast number, nevertheless, remain undetected; and these would probably be sufficient to keep the turtle population of these rivers up to the mark, if the people did not follow the wasteful practice of lying in wait for the newly-hatched young, and collecting them by thousands for eating; their tender flesh, and the remains of yolk in their entrails, being considered a great delicacy. The chief natural enemies of the turtle are vultures and alligators, which devour the newly-hatched young as they descend in shoals to the water. These must have destroyed an immensely greater number before the European settlers began to appropriate the eggs than they do now. It is almost doubtful if this natural persecution did not act as effectively in checking the increase of the turtle as the artificial destruction now does. If we are to believe the tradition of the Indians, however, it had not this result; for they say that formerly the waters teemed as thickly with turtles as the air does now with mosquitoes. The universal {396}opinion of the settlers on the Upper Amazon is, that the turtle has very greatly decreased in numbers, and is still annually decreasing.

"The principal object of another expedition was to search certain pools in the forest for young turtle. We started from the praia at sunrise on the 7th of October in two canoes, containing twenty-three persons, nineteen of whom were Indians. The pool covered an area of about four or five acres, and was closely hemmed in by the forest, which, in picturesque variety and grouping of trees and foliage, exceeded almost everything I had yet witnessed. The margins for some distance were swampy, and covered with large tufts of fine grass. The pool was nowhere more than five feet deep, one foot of which was not water, but extremely fine and soft mud.

"Cardozo and I spent an hour paddling about. The Indians seemed to think that netting the animals, as Cardozo proposed doing, was not lawful sport, and wished first to have an hour or two's old-fashioned practice with their weapons. I was astonished at the skill which they displayed in shooting turtles from little stages made of poles and cross pieces of wood. They did not wait for their coming to the surface to breathe, but watched for the slight movements in the water which revealed their presence underneath. These little tracts on the water are called the siriré; the instant one was perceived an arrow flew from the bow of the nearest man, and never failed to pierce the shell of the submerged animal. When the turtle was very distant, of course the aim had to be taken at a considerable elevation, but the marksmen preferred a longish range, because the arrow then fell more perpendicularly on the shell, and entered it more deeply.

"The arrow used in turtle-shooting has a strong lancet-shaped steel point fitted into a peg, which enters the tip of the shaft. The peg is secured to the shaft by twine, being some thirty or forty yards in length, and neatly wound round the body of the arrow. When the missile enters the shell the peg drops out, and the pierced animal descends with it towards the bottom, leaving the shaft floating on the surface. This being done the sportsman paddles in his canoe to the place, and gently draws the animal by the twine, humouring it by giving it the rein when it plunges, until it is brought again near the surface, when {397}he strikes it with a second arrow. With the increased hold given by the two cords he has then no difficulty in landing his game.

"By mid-day the men had shot about a score of nearly full-grown turtles. Cardozo then gave orders to spread the net.... Three boat loads, or about eighty, were secured in about twenty minutes. They were then taken ashore and each one secured by the men tying the legs with thongs of bast.

"When the canoes had been twice filled we desisted after a very hard day's work. Nearly all the animals were young ones, chiefly, according to the statement of Pedro, from three to ten years of age; they varied from 6 to 18 inches in length, and were very fat. Cardozo and I lived almost exclusively on them for several months afterwards. Roasted in the shell they form a most appetising dish. These younger turtles never migrate with their elders on the sinking of the waters, but remain in the tepid pools, fattening on fallen fruits, and, according to the natives, on the fine nutritious mud. We captured a few full-grown mother turtles, which were known at once by the horny skin of their breast plates being worn, telling of their having crawled on the sand to lay eggs the previous year. They had evidently made a mistake in not leaving the pool at the proper time, for they were full of eggs, which, we were told, they would, before the season was over, scatter in despair over the swamp. We also found several male turtles, or capitaris, as they are called by the natives. These are immensely less numerous than the females, and are distinguishable by their much smaller size, more circular shape, and the greater length and thickness of their tails. Their flesh is considered unwholesome, especially to sick people having external signs of inflammation."

The most recent account of these water tortoises is that published by Dr. Goeldi from the MS. of João Martins da Silva Continho, a former resident at Manáos on the Middle Amazon. The "Tartaruga" (the Portuguese name for turtles) live from January to July in the inundated, quiet backwaters of the forest-region, feeding upon the various seeds of palms as these ripen and drop successively; rarely, and only when hard up, they are carnivorous. The creatures hide under water below the trees, when they are espied by the Indians, who dive down to a depth of twenty and more feet to catch them in their arms. The {398}civilised Indians use a steel-pointed lance of hard wood, about 10 feet in length. A string connects the point with the shaft around which it is wound. When stuck into the tortoise the shaft and point part; the string is either tied to the boat or to a little float of light wood. In other districts an arrow with a string is employed.

In August, when the water subsides, the tortoises return to the rivers, and the entrance of the lagoon is closed with nets. A number of boats with long poles drive them with much noise towards the entrance. On their way to the rivers the tortoises always go up-stream, and this is called the "arribaçaõ das tartarugas," the ascent of the turtles. The fishermen post themselves at shallow spots or on sand-banks, and wait for the creatures which come up to find a place for landing and laying. The arrows employed are called sararaca, i.e. a thing which can be disjointed; they are about 4 feet long, and consist of a gomo or internodium of wood 9 inches long with a one- or two-barbed steel point, and the shaft into which the gomo fits loosely. The gomo is, moreover, connected with the shaft by a string made of palm-fibres about 30 feet in length, partly wound round the shaft, which ultimately acts as a float.

The laying takes place from the end of September into October. Some of the parents seem to reconnoitre on land for a few days. As a rule only females do this, and the natives say that they are led by a "mestra." The laying takes place early in the morning. The number of females is so great that they often block the way of the boats, and make a great noise by knocking against their neighbours' shells. Each digs a hole about 18 inches or 2 feet deep, and lays from 80 to 200 eggs. Sometimes the laying individual is entirely buried by its neighbours which are scraping their own holes.

In some districts the eggs are wanted for "manteiga" (Portuguese for butter); and the turning over, or viraçaõ of the tortoises takes place later. In other districts they are caught before the eggs are laid, and this barbaric and destructive custom was formerly forbidden by the people themselves. Although the provincial assembly tried to reinstitute the old reasonable customs, the inspectors are often got over by bribery.

There are two ways of extracting the oil from the eggs. To get the thick oil used, mixed with tar, for shipbuilding, caulking, {399}etc., the eggs are heaped up for five days and then worked. The fluid oil for lighting is made from fresh eggs, which are put into a boat and then trampled out with the feet. The oil is drawn off into large earthen jars and put on the fire. Then it is rapidly cooled. The best oil, used for frying fish, is that which is gained from the roasted tortoises themselves. Fresh eggs are either fried or taken with sugar, or mixed with manioca-flour and water. The young, which are hatched in January, are likewise eaten fried, or they are preserved in the fat of the parents.

An average tortoise yields 5 lbs. of fat, costing on the spot two milreis. The whole full-grown animal, of one yard in length, costs the same, and its meat is sufficient to sustain a family of six people for three days. To make 24 lbs. of oil requires 3000 eggs. Two or three tortoises would yield the same amount from their fat. Consequently the destruction of the eggs causes an enormous waste, and is after all the least economical procedure. In the year 1719, 192,000 lbs. were exported from the Alto Amazonas, representing 24,000,000 eggs. In 1700 there were still plenty of tortoises 50 leagues above the mouth of the Para river. Now there is no assembly of more than fifteen tortoises to be found anywhere within 300 leagues from Para to the mouth of the Rio Negro. On the Rio Madeira, from the mouth to the first cataract, 186 leagues distance, there are now only two regular nesting localities. The upper Solimoes and the Rio Yapura are still rich. Near Ega are regular tortoise-ponds, called "curral," which yield sufficient support to their owners; the animals are fed with manioca-flour and leguminous plants.

FAM. 2. CHELYDIDAE.–The neck bends under the margin of the carapace, but remains partly exposed. The nuchal shield is absent except in two Northern Australian species. There are twelve pairs of marginal shields. The plastron is composed of nine plates, and is covered with thirteen shields, one of which is the conspicuous intergular. The temporal region of the skull shows great diversity. It is quite open in Chelodina, covered in by broad expansions of the parietal bones in Platemys, Emydura, and Elseya, or bridged over by a parieto-squamosal arch, which is very slender in Rhinemys, strong in Chelys and Hydraspis. The palatine bones are separated by the vomer; the nasals are variable, mostly present, but the prefrontals are always small, and separated {400}by the frontals. The fifth and eighth cervical vertebrae are biconvex.

This family, still represented by nearly thirty species, which are divided into eight genera, is restricted to Notogaea, namely, South America and Australia.

Chelys fimbriata, the "Matamata," the only species of this genus, inhabits the rivers of Guiana and Northern Brazil. Besides the nuchal, there are seven neural plates; the last pair of costals form a median suture. Nasal bones are absent. The jaws are very weak. The Matamata has a very peculiar appearance. The nose is produced into a long, soft tube, at the end of which open the tiny nostrils. The eyes are very small, and the orbits are placed very near the anterior end of the skull, while the parietal {401}region is broad and much elongated (Fig. 87, p. 400). The quadrates are drawn out into trumpet-shaped tubes. The hyoid apparatus is very large, with enormous anterior and posterior horns. The head and neck are as long as or even longer than the carapace, which is covered with thick, lumpy shields. The skin of the thick neck, of the sides and under parts of the head, is produced into many soft arborescent excrescences or fimbriae, those of the chin and throat and the large ear-flaps being movable at will, and probably used to attract fishes and other prey. The tail is very short. The fore- and hind-limbs are webbed, the former with five, the latter with four claws. Old specimens, which reach a total length of three feet, are uniformly dark brown, and look like a log covered with rough bark. The young are far less ugly, with black and yellow spots on the shell, and with dark stripes along the neck.

Very little is known about the habits of this peculiar creature. It is said to lie submerged in the water, waiting for fishes, frogs, or tadpoles, which are attracted by the playing motions of its cutaneous excrescences. The jaws being so weak, and being covered with a partly soft lip-like skin, it is probable that they are not used for seizing the prey, but that the latter is engulfed into the mouth with the inrush of water into the throat. {402}That this can be widened enormously is indicated by the greatly developed hyoid apparatus.

Chelodina.–The neck is long and slender, the head small and smooth. The nuchal is terminal; the intergular is large. The neural plates are completely suppressed, all the eight pairs of costal plates meeting in the middle line. The shell is very flat. Anterior and posterior limbs entirely webbed, and with only four claws. The tail is very short. Three species in Australia, one in New Guinea.

Ch. longicollis reaches a shell-length of ten inches. It inhabits Southern Australia. The illustrations make a detailed description unnecessary. The colour of the dorsal shield is uniformly dark rich brown, while the shields of the under surface are yellow, with broad dark brown lines along the sutures. These "long-necked Chelodines" have a striking appearance, when they swim or creep about, with the neck either stretched out straight or bent horizontally in an S-shape. The whole creature looks neat and elegant; the iris is pale yellow, and gives the eye a very intelligent expression. They keep well in captivity, provided they are given the choice of land and water. My own prefer to spend most of the day on land, preferably under the ledge of a stone, or perched upon the stone itself if the latter is in the shade, and not too much exposed to view. There they lie motionless, with the neck neatly tucked under the shell, either to the right or to the left. Although the eyelids may be closed, they can see well enough, owing to the transparent condition of the lower lid. They feed in the water upon soft animals, as for instance worms, smooth caterpillars, cockroaches or little frogs; and they also take meat readily, provided this is moved about. The food is invariably taken with a quick sideward jerk of the neck and head.

{403}[Illustration: FIG. 90.–Chelodina longicollis (Australian long-necked Chelodines). × ¼.]

My specimens soon became so tame that they left the water, and ran up to me with the necks stretched to their full length, then snatching the bit of food, and retiring into the pond to swallow it. When left to themselves they are rather nocturnal in their feeding habits. Now and then they tuck themselves away for weeks without feeding, for instance when they go through a regular term of {404}aestivation in the summer. The last winter they spent buried in the moss, but occasionally, especially on bright and sunny days, they went into the water for a few hours, chiefly to drink, but sometimes also to take a little food.

Hydromedusa, a South American genus, has a neck even longer than that of Chelodina, which it much resembles externally. But the nuchal shield, large and broad transversely, is situated behind the anterior marginals, looking therefore like a sixth neural shield. The neural plates form a continuous row, only the last pair of costal plates meeting in the middle line. H. tectifera occurs in Southern Brazil, and in the La Plata. The shell is dark brown above; yellowish, with dark spots, below; the head and neck are olive-coloured, adorned with a broad white, black-edged band on either side. Fore- and hind-limbs broadly webbed, and with four claws. Total length of the shell about eight inches.

FAM. 3. CARETTOCHELYDIDAE.–The shell is covered with soft skin instead of horny shields. The limbs are transformed into paddles, with elongated digits, and have only two claws. The neck is short, and not retractile. In other respects the skeleton, notably the plastron, pelvis, and skull, conform with the Pleurodirous type. Only one species, Carettochelys insculpta, still imperfectly known, from the Fly River, New Guinea. Length of the shell of the only complete specimen about 18 inches. This peculiar creature seems to stand in the same relation to the typical Pleurodira, as do the Chelonidae to the Testudinidae, except for the complete reduction of the horny shields upon the shell, recalling in this respect Sphargis and Trionyx.

SUB-ORDER 3. TRIONYCHOIDEA.–The shell is very flat, oval, or almost round, and is covered with soft, leathery skin instead of with horny shields. The limbs are broadly webbed, and only the three inner digits are provided with claws. Carnivorous, found in the rivers of Asia, Africa, and North America.

The head and neck are completely retractile, bending by a sigmoid curve in a vertical plane like that of the Cryptodira. The jaws are concealed by soft, lip-like flaps, and the nose forms a soft short proboscis. The ear is hidden. The skull, Fig. 91, is flat, with three long posterior processes, formed by the supra-occipital above, and the squamosals on either side. The whole temporal region forms a wide, shallow fossa, without any {405}indication of being arched or bridged over. The premaxilla is extremely small, unpaired, not even reaching the nasal cavity or the vomer. The maxillaries are correspondingly enlarged, surrounding the choanae, which are separated by the narrow vomer. The palatines form a median suture, and are joined behind by the long basisphenoid, which separates the long pterygoids from each other. The quadrate is trumpet-shaped, with a posterior notch for the stapes. The zygomatic arch is complete, and is formed by the quadrato-jugal and the jugal; the latter joins the maxillary and postfrontal, mostly reaching the orbit; in some cases it also just meets the parietal, thereby adding to the strength of the postorbital arch. The prefrontals are large; nasals are absent. The mandible is remarkable for the great development of the coronoid process.

The pubic and ischiadic bones enclose a large heart-shaped foramen, and are free from the plastron; the ilia are attached only to the sacral ribs. The carapace is peculiar in so far as it is very incomplete peripherally, the ribs extending considerably beyond the costal plates, nor are they joined by marginal plates, which are absent, unless they are represented by a few small ossifications imbedded in the posterior marginal flap of the disc (Emyda of India). The rim of the disc is always formed by a horizontal, cutaneous, very flexible flap. All the dorsal plates have a rough upper surface, vermiculated or rugose, as usual with such dermal bones, which have lost most of or all their horny covering, and have sunk more deeply into the skin. The {406}nuchal plate has usually a pair of rib-like processes. The neurals form a continuous series, except in the African Cyclanorbis, in which they are much reduced in size, and separated by the costal plates.

The plastron is imperfect, all its constituent nine elements being only loosely connected with each other, and there remains a wide median vacuity between the lateral elements. Most of these plastral bones are reduced to splints, which, instead of meeting by regular sutures, loosely interdigitate with their jagged edges. In the young all these ventral elements are deeply imbedded in the soft, leathery skin, and they do not at all resemble in appearance those of the dorsal side. With age they develop upon their ventral surface stronger and denser ossifications, which ultimately broaden out, sometimes beyond the original underlying bone, and assume the characteristic vermiculated surface-appearance. This is undoubtedly a process of exostosis, a step towards revival of that armour which had been much reduced ancestrally. To appreciate this condition, it is at least suggestive that these mud-tortoises, when kept in the usual hard-bottomed tanks, invariably become sore, the skin wearing through where the imbedded plastral bones touch the ground. Thus what is crammed into the short life of a captive individual, is in the natural course of events spread over many generations, whereby it has ceased to be pathological, and has become a comparatively new, tertiary, but regular feature.

It is not open to much doubt that the characteristic features of the Trionychoidea are not primitive but secondary. This is indicated by the whole structure and behaviour of the carapace and plastron. The softening of the whole shell, the loss of the horny shields, the reduction of the claws, are the direct and almost unavoidable results of life in muddy waters.

Geologically they do not seem to be very old. They appear, already referable to the genus Trionyx, in the Upper Cretaceous strata of North America. In the Lower and Middle Tertiary strata many species existed in North America and in Europe, and it is of great importance that in these species the costal plates were much broader, and the marginal plates better developed, than in the recent forms. Now their half-dozen genera, with about twenty-four species, are confined to North America, the tropical and warmer parts of Asia, and the Malay {407}Islands, and to Africa from the Nile to the Senegal and to the Congo.

The habits of Trionychoidea have found few observers. According to L. Agassiz, they live in the muddy bottom of shallow waters, burying themselves in the soft mud, with only the head, or a small part of it, exposed. They breathe without moving the body, by raising up the long neck and carrying the leathery snout above water. When moving through the water they strike horizontally with both pairs of limbs, alternating, however, the right and left; but when they start suddenly, the front limbs are seen moving together towards the tip of the snout, and then striking simultaneously backward with great power. As the shield does not project forward, the fore-limbs usually move beyond the shield, and as its outer edge is sharp, and the feet are broad, their webs reach above as well as below the plane of that edge, so that the water is driven partly over and partly under it. When they move along the bottom, the limbs still move horizontally, the webs striking against the water, and the inner toes, those with the claws, against the bottom. They also bury themselves horizontally, becoming covered by only a thin layer of mud. They readily resort to the shell for protection. The neck and head are withdrawn entirely, the loose skin rolling off from the greater part of the neck; and the skin of the legs also slips off, as far as the elbows and knees. In confinement they exhibit great quickness; their movements are abrupt and unsteady, except when they swim rapidly in one direction. They then dart their long and slender neck quickly forwards or sideways and upwards, as snakes do, and bite in the same way, striking suddenly. Their temper is bad or even ferocious, and large specimens are quite dangerous.

Their food consists of all sorts of aquatic animals, fish, frogs, and molluscs, for instance Anodonta and Paludina. According to the different diet, many species develop a peculiar kind of dimorphism, a reasonable explanation of which has been given by Boulenger. In the young the horny coverings of the jaws are sharp, with cutting edges, and in those specimens which keep to a diet of fish and other soft creatures, the jaws remain in the same condition. But in those which take to living upon molluscs, the hard shells of which they have to crush, the horny edges are {408}worn down; and broad, thick, horny, crushing pads are developed in their stead, the supporting parts of the jaws becoming more massive. The masticatory muscles are likewise enlarged, and a tubercle grows upon the lower border of the jugal bone, whence arises part of the masseter muscle.

The eggs are round, thick-shelled, but very brittle; they are laid in the sand above the level of the water, and this is the chief occasion on which these tortoises creep on land.

Trionyx.–The plastron has no special cutaneous valves for the concealment of the hind-limbs. This is the principal genus, with the greatest number of species and the widest distribution, the latter coinciding with that of the whole family. The upper surface of the shell of young specimens frequently forms numerous longitudinal ridges or series of little horny tubercles which disappear with age.

T. ferox, the commonest "Soft-shelled Turtle" of the United States. Olive above with scattered, small, round, black spots; young with conical, spine-like tubercles, especially on the nuchal border and on the posterior portion of the shell, which has a pale, black-edged border. A light, black-edged streak passes through the eye and joins its fellow on the snout. The limbs are olive brown, spotted and marbled with black. The under parts of the shell are white. Very large specimens have a shell 18 inches in length and 16 inches wide. Holbrook gives the following account of its habits:–

"A voracious, carnivorous creature. They reside most constantly in the water, swim with rapidity, and choose for their retreat holes under the banks of rivers, or under rocks; and not unfrequently the trunk of some huge forest tree, fallen into the stream, affords them shelter. Sometimes they leave the water and conceal themselves in the mud: I have frequently seen them thus buried to the depth of 2 or 3 inches, leaving only a small breathing hole for the long neck and narrow head, which is occasionally thrust out, but most commonly it is retracted so that one would pass near without observing their habitation; and if seen, it might easily be mistaken for the residence of some large insect. At other times they may be seen in numbers on rocks in shallow water, basking in the sun, apparently asleep. They bite severely when provoked, darting forward with great velocity the long neck and head, and not unfrequently spring upward at the same time and make a loud hiss.

{409}[Illustration: FIG. 92.–Trionyx ferox (American Soft-shelled Turtle). × ⅒.]

In the month of May the females seek sandy places along the banks of the waters they inhabit to lay their eggs, generally about sixty in number; and it is remarkable that, though their motions are slow and difficult on dry land, yet at this season they sometimes mount hillocks several feet high. The flesh affords the most delicate food, surpassing that even of the Green Turtle. The geographical distribution is interesting. It inhabits the Savannah as well as all those rivers that empty into the northern borders of the Gulf of Mexico; it ascends up the broad Mississippi, and is found in all its tributaries, even to the very foot of the Rocky Mountains; it abounds in the chain of great northern lakes both above and below the Falls of Niagara, and is common in the Mohawk, a tributary of the {410}Hudson river; but it is not found in any other Atlantic stream between that and the Savannah river, a distance of nearly 800 miles."

T. triunguis, the only African species, ranging from the Senegal and Congo into the Nile-system, but occurring also in Syria, is perhaps the largest of all Trionychidae, reaching a shell-length of almost 3 feet. The adults are olive-brownish above, the throat and under parts of the shell with round, white spots separated by a dark network. The young have whitish specks and spots.

T. gangeticus and T. hurum are the principal Indian species. The former is the larger of the two, with a shell of more than 2 feet in length; olive above, the young with fine black vermiculations; head with a black longitudinal streak from between the eyes to the nape, intersected by two or three chevron-shaped black streaks; under parts yellowish. T. hurum is olive brown above {411}and below, in younger specimens with conspicuous, large, yellow spots on the sides of the head. The young are ornamented with two or three pairs of large round spots on the back, and the same applies to the beautiful young of the Burmese, T. formosa.

The three genera, Cycloderma and Cyclanorbis of Tropical Africa, and Emyda of India, have a pair of cutaneous femoral valves or flaps on the plastron, beneath which the hind-limbs are withdrawn.

{412}CHAPTER X

DINOSAURIA–CROCODILIA

SUB-CLASS V.–DINOSAURIA.

Mesozoic, long-tailed, toothed reptiles, with distal ischiadic symphysis, terrestrial limbs, large fixed quadrate bones and bifurcated ribs.

The Dinosaurs begin and end with the Mesozoic epoch, and have a world-wide distribution. The name, "terrible Reptiles," refers to the gigantic proportions which many of them attained, not a few of them surpassing in size and shape the fantastic pictures of the dragons of our fables. Although these creatures came to an end millions of years before the first man-like beings appeared, it is reasonable to suppose that the widely-spread myths of dragons are based upon the accidentally disclosed skeletons of these monsters.

The skull is built after a plan which may be derived from a combination of the Crocodilian and Rhynchocephalian skulls, but the detail varies considerably in the many and much diversified members of this large sub-class. There is as a rule a pre-orbital foramen, which is smallest in the Ornithopoda. The orbit is completely encircled by bones, and the temporal fossa is divided by a squamoso-postfrontal or post-orbital bridge into a smaller supra-, and a much wider infra-temporal portion, the latter being bordered below by the jugal and quadrato-jugal, and this is firmly connected with the quadrate by an ascending process. The quadrate is long, more or less vertical in position, slanting either forwards or backwards, and firmly fixed above by the squamosal, perhaps also by a supra-temporal bone. The orbit is bordered by the jugal, lacrymal, pre- and post-frontals. The interparietal foramen seems to be {413}abolished. Teeth, mostly alveolar and laterally compressed, are restricted to the dentary, maxillary, and premaxillary bones. In the Orthopoda the latter carry no teeth, or these are restricted to the lateral portion, leaving a wide diastema. This toothless part plays upon a peculiar crescent-shaped bone, the so-called predentary, which rests loosely upon the anterior ends of the mandibular rami, which latter do not as a rule form an osseous symphysis. The Ceratopsia possess in addition a similar upper toothless piece, the prerostral, a kind of pre-premaxilla. The morphological value of these extra pieces is quite obscure; they were in all probability provided with thick, horny pads. The bones of the roof of the mouth recall in their arrangement that prevailing in the Rhynchocephalia and the Parasuchia. There are two pairs of large vacuities; one between the maxillae, ectopterygoids and palatines; the other between the latter, the maxillae and the usually small or slender vomers. The pterygoids are perhaps the largest bones, and form a rather long symphysis; laterally and behind they abut against the quadrate, anteriorly against the ectopterygoids and the palatines, which latter they sometimes separate. A peculiar feature of some skulls, e.g. Ceratosaurus and Triceratops is the great size of the groove in which the large hypophysis of the brain is lodged.

The vertebrae are very variable, amphicoelous, opisthocoelous, nearly plain, with a slight concavity behind, or occasionally procoelous in the anterior region of the tail. Besides the usual pre- and post-zygapophyses many Sauropoda and Theropoda possess on the posterior trunk-vertebrae additional joints, effected by a vertical wedge, the hyposphene, which extends backwards from between the post-zygapophyses and fits into a notch between and below the anterior zygapophyses of the next following vertebra. These additional articulations are analogous to the zygosphenes and zygantra of snakes and iguanas, except that in these Sauria the wedges are formed on the opposite, namely the anterior ends of the vertebrae. The vertebrae of the neck and trunk are devoid of intercentra, but those of the tail carry long chevron-bones. The number of sacral vertebrae is generally increased to four or five. The ribs have well-developed capitula and tubercula, and the former have the tendency to shift from the centra or from their parapophysial processes on to the usually much elongated diapophyses of the neural arches. This {414}arrangement, recalling the Crocodilian condition, results in an increased capacity of the dorsal portion of the body-cavity. Intervertebral articulation of the ribs does not occur except sometimes in the sacral region. Abdominal ribs are rare, but they occur in some of the Theropoda, e.g. in Compsognathus.

The sternum seems to have been mainly cartilaginous, with a pair of irregular, disc-shaped ossifications. How the coracoids were attached is unknown; they are small, generally with a foramen, but the scapulae are always very strong and slant backwards. Clavicles and interclavicles seem to be absent.

The fore-limbs are as a rule powerful, although often much shorter than the hind-limbs, which are then enormously developed, and in many genera of two of the main groups show a tendency towards a semi-erect gait. Some of the Dinosaurs, e.g. Iguanodon and Brontozoum, were absolutely bipedal. Others seem to have hopped like Kangaroos. In correlation with this more or less erect mode of progression the iliac bones are very strong, much elongated horizontally, and attached to more than three, often to five or even more, vertebrae. The pubic bones show two main types. Each consists either of a single strong shaft, which is connected distally with its fellow; or (Orthopoda) this main shaft sends out, below its point of contact with the ischium, a long process, the so-called post-pubis, which is directed downwards and backwards. In the latter case it runs parallel and in close contact with the ischium. Such bifurcated pubic bones never meet in the middle line. The ischia, on the other hand, are always connected with each other, not so much by fusion as by syndesmosis.

The hind-limbs exhibit all stages from a simple, plantigrade and five-toed state to a decidedly digitigrade, four, and even three-toed arrangement. Many genera exhibit the tendency to form an intertarsal joint, a feature elsewhere known in birds only, where it is typical and universal. The astragalus sends up an ascending process which tends to fuse with the anterior aspect of the distal end of the tibia, and the calcaneum is sometimes more or less firmly attached to the fibula. In Compsognathus even the distal tarsalia have begun to fuse with the metatarsalia, so that this reptile at least has a typical intertarsal joint. The femur is remarkable for the frequent possession of a "fourth" trochanter on the middle of the inner aspect of the shaft, undoubtedly {415}for the insertion of the long caudi-femoral or long adductor muscle.

Many Dinosaurs possess hollow instead of solid bones. The vertebrae have large cavities in the Sauropoda, notably in Brontosaurus; in many Theropoda, e.g. Coelurus, Anchisaurus, Compsognathus, the limb-bones and the vertebrae are hollow, the latter being reduced to thin-walled shells with a few inner partitions, the bones being at the same time much swollen and enlarged. In the Ornithopoda the vertebrae are solid, but the limb-bones are hollow. The reason of this hollowing out is not easily found. Undoubtedly it results in a saving of material and weight, whilst at the same time, without loss of strength, the surfaces for the attachment of the necessarily powerful muscles are increased. But Compsognathus is a small, Brontozoum a gigantic, creature. On the other hand, the bones of the huge Stegosauri are solid. Most probably these cavities were, as in birds, filled with air-sacs ultimately in communication with the lungs; and it is by no means a baseless suggestion of Haeckel's that the Dinosaurs were warm-blooded. Their mode of propagation can only be guessed at from the circumstance that a rather well-preserved specimen of Compsognathus contains in its abdomen what may possibly be an embryo. There is nothing against the assumption that the Dinosaurs were viviparous; on the contrary, it seems more natural than that, for instance, an Atlantosaurus of more than 100 feet in length and many tons in weight, should have laid eggs.

Some of the herbivorous Dinosaurs, namely, the Stegosauri and the Ceratopsia, had a dermal armour of variable extent; the plates were loosely imbedded in the skin, and reached their greatest size along the middle of the back and tail, and these crested plates were probably covered with horny scutes, obviously weapons of defence. The Ceratopsia were armed with a pair of huge pointed horns on the head, and a smaller one on the nose (see Fig. 102, p. 430). It is difficult to guess the use of the weapons of these terrestrial monsters, unless they were employed against the equally large carnivorous Dinosaurs or in the combats for the possession of their charming mates.

About the ancestry of the Dinosaurs we know nothing except that their affinities lie with the Crocodilia; but it is impossible to derive either from the other. The oldest forms, in the {416}present state of our knowledge–those which have left their three-toed spoors in the Trias of Connecticut–were already much specialised by having attained to an upright bipedal gait, while the Sauropoda, which except for their gigantic size are the most generalised, are of comparatively recent date, none of them being known from strata older than the Upper Jurassic. Twenty years ago, until the discoveries of numerous kinds in the United States, our knowledge of the whole group was very limited. There is a widely spread notion that the birds have sprung from some Dinosaurian stock. Huxley was the first to show clearly that birds were an offshoot of the reptiles, and he said of the Dinosaurs, especially his Ornithoscelida (Iguanodon, Scelidosaurus, Megalosaurus, Compsognathus, and others), that they "present a large series of modifications intermediate in structure between existing reptiles and Aves." Baur proved to his own satisfaction that we have to look for the ancestors of the Ratitae among the herbivorous Dinosaurs, especially the Ornithopodous forms, whilst the Carinatae are descendants of the Ratitae. However, even he had to give up this absolutely unwarrantable view.

It is easy to select a considerable number of characters amongst the various Dinosaurs which also occur in birds, and some of these have until a recent date been considered as peculiar to birds. For instance, the double, bifurcated pubic bones of the Orthopoda; the increased number of vertebrae to which the horizontally elongated ilia are attached, especially in the forms with an upright gait, and the bipedal feature itself; the possession of an ascending process of the astragalus and its fusion with the tibia in Compsognathus and Ceratosaurus among the Theropoda, and in Ornithomimus; the attachment of the distal tarsalia to the metatarsalia, e.g. in Compsognathus,–in fact, the formation of an intertarsal joint, a feature otherwise characteristic of, and peculiar to, birds; the frequent reduction of the fifth metatarsal bone; the backward position of the hallux and the proximal reduction of its metatarsal in Compsognathus; the elongation and partial fusion of the functional metatarsals in the latter genus and in Ceratosaurus; the regular increase of the phalangeal numbers of the first four toes from two to five in many of the Ornithopoda;–in short, the great resemblance between the feet of some of the Dinosaurs and those of the birds. However striking these arguments are, they are instances of {417}convergent analogies. The upright walk, which has been assumed and improved upon independently by members of both Theropoda and Orthopoda, has produced the same, or nearly the same modifications in them as in the birds.

It is easy to show that these features are mere coincidences. The oldest bird known is Archaeopteryx from the Upper Oolite of Bavaria. Consequently all those Dinosaurs, which are of the same and of later date, have to be excluded from the supposed ancestry, and they happen to be those in which (as in Ceratosaurus, Compsognathus, Ornithomimus, Iguanodon) the resemblances are greatest. There remains only Anchisaurus of the Upper Trias, more or less contemporary with the Brontozoum, which left its three-toed footprints (Archaeopteryx has four well-developed toes) with Zanclodon. Moreover, the most bird-like foot is either that of the Theropoda, which, like Anchisaurus and Zanclodon, differ from birds by the formation of the pelvis, or of some of the latest Ornithopoda. What, then, is the good of selecting a number of bird-like features from members of Dinosaurs which we are bound to class in different groups, and which existed, some in the lower, others in the middle, or even in the latest Mesozoic periods?

Lastly, the advocates of the Dinosaurian ancestry of birds cannot have fully appreciated the enormous differences between the wing of Archaeopteryx and the fore-limb of any Dinosaur with the most avian resemblances in the hind-limbs. The fore-limbs of these reptiles are modified in a direction diametrically opposed to that from which a bird-like wing could be developed. The skull presents another difficulty,and here again Compsognathus, a contemporary of Archaeopteryx, comes perhaps nearest to that of a generalised bird's skull. The ancestors of the birds must have combined the following characters:–Of not later than Mid-Oolitic age, with bifurcated pubic bones, four functional toes, elongated metatarsals, complete clavicles, premaxillary teeth, and free, not firmly fixed quadrate bones. But such creatures are not Dinosaurs.

We divide the enormous number of Dinosaurs according to the formation of the pelvis, that of the hind-limbs, and the dentition, into four orders.

{418}ORDER I. SAUROPODA.

Pubes simple, with symphysis. Premaxillae with teeth. Plantigrade.

The teeth are mostly spatulate, laterally compressed, with sharp edges, but without serrations. Skull with a pair of large pre-orbital fossae. The centra of the vertebrae of the trunk have large lateral cavities. The fore- and hind-limbs are pentadactyle, plantigrade, and hoofed, of the typical walking type; the bones of the limbs are stout and solid; the femur is devoid of an inner distal or fourth trochanter. The carpal and tarsal bones are free. Herbivorous. The Sauropoda comprise some of the most gigantic terrestrial creatures which have ever existed, compared with some of which the bulk of an elephant appears almost insignificant. Their range in time extends from the Lower Oolite into the Cretaceous, with a perhaps world-wide distribution, namely, Western Europe, North America, Patagonia, Madagascar, and India. Although they are, except for their size, the least specialised of all Dinosaurs, none of the Sauropoda hitherto discovered are old enough to claim to be the ancestors of the other Dinosaurs.

Brontosaurus excelsus of the Upper Jurassic of Wyoming was a giant at least 60 feet long and about 10 feet high. The head is extremely small in proportion, not so broad as the fourth of the thirteen vertebrae of the long and flexible neck. The trunk is comparatively short, the tail longer than the neck, and provided with numerous chevron-bones. Most of the vertebrae are hollow, especially the five co-ossified sacrals. The spinal canal of the sacral region is very wide, indicating a strong sacral swelling in conformity with the huge posterior limbs. The pubic bones are stronger than the ischia. The long axis of the {419}former stands almost vertically like that of elephants, and the knee is scarcely bent in the erect position. The shoulder-girdle consists of long scapulae, broad at the base and small, almost square and perforated coracoids, which latter fit into a pair of partly ossified plates representing the sternum.

Atlantosaurus immanis of the Upper Jurassic of Wyoming and Colorado, is supposed to have been 115 feet long, perhaps the biggest and bulkiest of all animals, the femur measuring more than 6 feet in length and 2 in width at the upper end.

Morosaurus grandis, of the Upper Jurassic of Wyoming, with allied forms in the Purbeck and Wealden of England, reached a length of 30 feet; in general appearance resembling Brontosaurus, but the sacrum consists of four vertebrae only, and the ischia are bent backwards in their distal halves, so that their symphysis is formed by the shafts instead of by their ends.

Ornithopsis and Cetiosaurus, likewise huge creatures, from the English Wealden and from the Great Oolite respectively, are rather imperfectly known, although several species of each, under many generic synonyms, have been described.

Diplodocus longus, of the Upper Jurassic of Colorado and Wyoming, is almost completely known. More than 40 feet long, it had a head in its general outlines not unlike that of a horse, the skull being about two feet long. The outer nasal openings are confluent, elongated, and lie far back on the top of the skull. There is a pair of large antorbital, and a pair of smaller lacrymal fossae. The teeth, long and slender, are restricted to the anterior portion of the mouth, with many successors, which, decreasing in size, lie on the inner or lingual side of the functional tooth, like the cartridges in a repeating rifle. The {420}functional teeth themselves are implanted in sockets. The generic name refers to the peculiar chevron-bones, each half of which diverges into an anterior and a posterior branch.

It is difficult to understand how these huge, long-necked Sauropoda lived and moved about. The long neck suggests at first sight predacious habits, but the teeth, rather feeble in Diplodocus, and distinctly of the plant-cutting type in other genera, put this out of the question. The high position of the unpaired nasal opening, and the shortened nasal bones of Diplodocus, are features indicative of aquatic habits, but the short-toed, plantigrade limbs are absolutely adapted to terrestrial life, and we cannot well assume that such enormous brutes as Atlantosaurus could possibly have ventured into swampy ground.

ORDER II. THEROPODA.

Pubes simple, with symphysis. Premaxillae with teeth. Digitigrade. Carnivorous.

The teeth are pointed, recurved, laterally compressed and serrated. The nasal openings are large, lateral, and nearly terminal. The vertebrae and the large bones of the limbs are hollow. The fore-limbs are considerably shorter than the hind-limbs, which are distinctly digitigrade, many of the species having a pronouncedly upright gait. The proximal tarsalia show a tendency to fuse with the tibia, and the astragalus has sometimes an ascending process, by which the fusion with the tibia is strengthened. The first and fifth metatarsals are often reduced, while the three middle bones are elongated and sometimes even fused with each other, so that the whole foot assumes a striking resemblance to that of birds. The terminal phalanges are protected by curved claws. Owing to the shortness of the fore-limbs, and the often considerable length of the hind-limbs, which are strongly bent at the knee and the ankle-joint, these animals must have progressed somewhat like clumsy kangaroos.

The Theropoda, of which a great number of genera are now known, from the size of a slender cat to that of an elephant, lived from the Upper Trias to the Upper Oolite, both in Europe and in North America.

Brontozoum giganteum, one of the oldest forms, is known {421}from its foot-spoors only, which, together with other three-toed spoors in the sandstone of the Connecticut valley, were originally described and figured by Hitchcock as Ornithichnites (ἴχνος = track, or spoor). Some of these imprints are more than a foot in length, the right and left spoors following alternately at a distance of from four to six feet. In some cases the long trailing tail has left a furrow behind, and the large tracks are accompanied or crossed by much smaller, and even by quite tiny tracks, otherwise similar, and undoubtedly made by the young.

Anchisaurus, from the same locality, was still Sauropodous, in so far as the metatarsals are still free, with two, three, four, and five phalanges on the first four toes, but the fifth metatarsal is reduced, carrying a vestige of only one phalanx, and the proximal tarsal bones are fused with the tibia and fibula respectively. Total length some seven feet, of which about four belong to the tail.

Zanclodon, from the Keuper of Würtemberg, about ten feet long, with pentadactyle hands and feet. Ischia stronger than the pubic bones, which are distally much broadened. The femur is nearly three feet long, and possesses a fourth trochanter. The astragalus has an ascending process, and is fused with the tibia. The toes are short, strong, and clawed. The shoulder-girdle and fore-limb are strong, the latter well adapted to grasping. The teeth are much compressed laterally, with sharp, finely serrated edges. Several allied genera have been described from the Upper Trias of France and England: others from corresponding strata of India and South Africa.

Megalosaurus, from the Trias to the Wealden in England and France, with other species in Colorado and India, reached a considerable size, larger than that of any other Theropoda, the scapula of M. bucklandi being nearly three feet long, and the femur still longer. The hind-limbs are twice as long as the fore-limbs. The cervical vertebrae are short, the neck being much shorter than the tail. Hands with five fingers, feet with four toes. Pubic bones long and slender, with a broad symphysis. With well-developed abdominal ribs, resembling those of crocodiles.

{422}Allosaurus, from the Upper Jurassic of North America, with only three toes. Ischia and pubes united into one symphysis. Anterior extremities very short. Sacrum consisting of four vertebrae. Total length of some of the larger species about twenty feet.

Ceratosaurus nasicornis, from the Upper Jurassic of Colorado, is about seventeen feet long. The generic and specific names refer to the nasal bones, which are raised into an unpaired longitudinal crest. This, by its rough surface, suggests that it was covered by a horny sheath, or carried a horn. The large skull, about two feet in length, is armed with strong, slightly curved, laterally compressed, sharp teeth, unequal in size. The pre-orbital foramen is large, bordered above by the prefrontals, which are raised into prominent knobs. The supratemporal foramina are extremely small, the lateral foramina very large. The quadrate slants backwards. The sacrum consists of five vertebrae. The caudal vertebrae carry long and slender chevron-bones. The pubes and ischia are long and slender, each forming a separate symphysis at their broadened ends. The three {423}metatarsals are elongated and fused with each other. There seems to have been some dermal armour in the shape of osseous plates, which extended in one series from the occiput over the neck.

Coelurus gracilis, of the Upper Jurassic of Wyoming, and closely allied forms in the Wealden of England, are remarkable for the pneumaticity of the centra and processes of their vertebrae, the bony parts of which are restricted to thin, hollowed-out shells, so that the whole skeleton must have been very light. Computed length of these imperfectly preserved creatures about five feet.

Hallopus victor, of the Upper Jurassic of Colorado. Anterior extremities very short, with only four fingers; posterior limbs very long and slender, especially the tibia; the much elongated metatarsals are separate, the first absent, the fifth much reduced, so that the foot is tridactyle; the calcaneum projects like a heel. The ilium is attached to two sacral vertebrae only; the pubes are slender, forming a narrow symphysis, while that of the ischia is broad. Most of the bones of this creature, which probably progressed by hops, are hollow. Total length about three feet, the length of the hind-limbs being about nine inches.

Compsognathus longipes, of the Upper Jurassic of Bavaria, is one of the smallest of all the Dinosaurs. It is most remarkable on account of its almost bird-like feet. The fibula is much thinner and somewhat shorter than the tibia; the latter is closely attached to, although not fused with the proximal tarsal bones, while the distal tarsals are fused with the united and much elongated second, third, and fourth metatarsals; the fifth is reduced to a short bone near the intertarsal joint; while the first is represented by its distal portion only, which is stowed away on the hinder aspect of the middle of the second metatarsal, and carries two phalanges. The three middle toes consist of three, four, and four phalanges respectively. Whilst the whole hind-limb is typically avian, the pelvis is quite different; the pubic bones are simple, slender, and directed forwards, forming a symphysis with their whole distal halves, and broadening out distally into a horizontal process directed towards the symphysis, which is likewise formed by the fusion of the inner surfaces of the thin and rather flat ischia. The fore-limbs are only half the size of the hind-limbs. The neck consists of about ten vertebrae, mostly with long and {424}pointed ribs. Tail long with well-developed chevrons. The skull is long and pointed, composed of thin bones, which have lost most of the sutures; with large lateral, temporal, and pre-orbital, but without supratemporal, foramina. Premaxillae, maxillae, and mandible with numerous slender and rather long, conical, alveolar teeth.

ORDER III. ORTHOPODA

Each pubic bone consists of an anterior or pre-pubic and a posterior or post-pubic branch, neither of which forms a symphysis. Premaxillae without teeth. With a premandibular predentary piece. Herbivorous.

The so-called pre-pubis is homologous with the pubis of most recent reptiles, and with the pectineal process of birds, while the "post-pubis" is homologous with the processus lateralis of Chelonians and Saurians, and with the "pubis" of birds. The right and left halves of the pubis remain widely asunder ventrally. In many cases the post-pubis, always directed obliquely backwards, lies closely against the shaft of the ischium, which always forms a distal syndesmosis, or a symphysis, with its fellow. The fore-limbs are usually very short, provided with five or four short and strong fingers. The hind-limbs are long and strong, mostly with three, sometimes with four functional short toes, either plantigrade (STEGOSAURI) or digitigrade (ORNITHOPODA). Femur with an inner distal, or fourth, trochanter. The dentition is of the herbivorous type, restricted to the dentaries of the mandible and to the maxillary bones, leaving the whole or the greater part of the premaxillaries free. The additional "predentary" piece of the mandible is possibly a calcified, but originally horny, pad. The teeth are greatly compressed laterally, and finely serrated, but are much ground down by use; several rows of successional teeth lie on the inner or lingual side. The skull is strongly built, with large anterior nasal openings; pre-orbital foramina very small or absent; orbits completely encircled by bones; supratemporal foramina small, lateral foramina large. Quadrate large, vertical or slanting slightly forwards. The vertebrae are solid, not hollow; sacrum consisting of four, five, or more vertebrae; ribs bifurcated, the capitula carried either by the centra, or moved up to the diapophyses of the neural arches; chevron-bones {425}numerous, and frequently long, especially on the anterior half of the long and heavy tail.

Orthopoda occur from the Lias to the Upper Cretaceous, both in Europe and in North America. The name Orthopoda, invented by Cope in 1866, is appropriate for obvious reasons; it comprises the Stegosauri and Ornithopoda of Marsh (1881). The latter term is not very fortunately chosen, considering that the whole hind-limb of the Theropodous Compsognathus is far more ornithic than that of any three-toed Ornithopoda, in which the tarsalia rarely fuse with the tibia and never with the metatarsals. To apply the term Ornithopoda to the whole order is quite unjustifiable, unless it is meant to apply to the strikingly bird-like configuration of the pelvis.

SUB-ORDER 1. STEGOSAURI.–The fore- and hind-feet are plantigrade, or nearly so, the metapodials being but little elongated, with more than three functional digits. The bones of the limbs are solid. The ribs of the trunk are bifurcated, and are carried by the diapophyses of the neural arches. The body, especially the back, is protected by dermal bony plates, which are not connected with the internal skeleton.

Scelidosaurus harrisoni. One nearly complete skeleton, about 11 feet in length, from the Lias of Lyme Regis. About twenty-four pre-sacral vertebrae, of which six or seven belong to the neck, four sacral and about forty caudal vertebrae. Four fingers, four toes, with 2, 3, 4, 5 phalanges, the fifth metapodials being quite vestigial; the hallux and pollex are very short, so that the foot at least is functionally tridactyle. The tarsal bones remain separate. The head is very small. Two rows of ridged bony plates extend from the neck over the back, and converge into one row upon the long tail; smaller plates, arranged in many rows, seem to have protected the sides and under parts. Hylaeosaurus and Polacanthus of the English Wealden are allied forms.

Stegosaurus, with several species from the Upper Jurassic of Colorado and Wyoming, and others, e.g. S. armatus (= Omosaurus), from the Kimmeridge Clay of Wiltshire in England. The head is relatively very small, and the brain is surpassed several times in thickness by the huge sacral swelling of the spinal cord. Teeth numerous and small. All the cervical and trunk-vertebrae carry bifurcated ribs, those of the trunk being carried entirely by the very high neural arches. The fore-limbs are only about half {426}the length of that of the hind-limbs, so that these creatures, which were undoubtedly quadrupedal, must have had a very peculiar gait, standing with the head, neck, and shoulders much lower than the arched back and pelvic region. The ulna has a strong olecranon; the hand has four functional fingers. The pre-acetabular portion of the ilium is much elongated; the pre-pubic branch stands horizontally, while the post-pubis is closely adpressed to the ischium. The astragalus is fused with the tibia, the calcaneum with the fibula. The foot has only three short toes, protected, like the fingers, by hoofs. The dorsal dermal armature consists of very high, crest-like plates. S. ungulatus of North America has a computed length of 28 feet, with the hind-limbs about 7 feet long. This creature was nearly 10 feet high, when measured from the ground to the tips of the dermal crests on the middle of the back. These bony, laterally compressed plates are themselves nearly 3 feet high, and are replaced, on the hinder portion of the tail, by several pairs of pointed spikes about 2 feet in length.

SUB-ORDER 2. ORNITHOPODA.–The hind-limbs are distinctly digitigrade, usually with only three functional toes, protected by claws. The long bones are hollow. Femur with a long fourth trochanter. Without dermal armour-plates.

Camptosaurus.–Several species, up to 10 feet in length, from {427}the Upper Jurassic and the Wealden of North America and England. Five fingers, with 2, 3, 3, 3, 2 phalanges and four toes, with 2, 3, 4, 5 phalanges, but the hallux is much shortened and does not touch the hard ground; astragalus and calcaneum separate.

Laosaurus of Colorado is a smaller form, intermediate in structure between the former genus and Hypsilophodon foxi from the Wealden of the Isle of Wight. A small creature, less than 5 feet in length. Four fingers, with 2, 3, 4, 2 phalanges; fifth metacarpal vestigial. Four toes with 2, 3, 4, 5 phalanges and long claws. Astragalus and calcaneum separate. Post-pubis very slender. Each premaxillary with five pointed alveolar teeth, leaving a wide median diastema; maxillaries with eleven, dentaries with ten laterally compressed blade-like teeth.

Iguanodon from the Wealden of England, Belgium, and Germany. Apparently two species, I. mantelli, about 16 feet, I. bernissartensis nearly 30 feet long. The premaxilla is quite toothless; the teeth of the maxillae and mandibles stand in close series, implanted in alveolae; they are spatulate, laterally compressed, with finely serrated edges, and slightly curved, the lower outwards, the upper inwards, and bear a general resemblance to those of Iguana, hence the generic name. There is only one functional set of teeth, and these are much worn down by use, but in such a way that, owing to the different curvature of the opposed teeth, the worn-down crowns form cutting, and at the same time crushing, almost triturating surfaces, indicating that these animals lived upon herbs. The gait of these creatures was upright, as shown by their spoors; the long almost vertical ischia, which form a padded symphysis, only slightly raised above the ground, suggest that this symphysis was used as a true sitting support, the animal resting upon it, the hind-limbs and the long tail. The latter, to judge from the long chevrons and the high neural spinous processes, must have been furnished with strong muscles. The whole tail was undoubtedly used as a balance during the upright position. Many of the tendons of the dorsal spinal muscles on the back and upper half of the tail are ossified. The post-pubic branches are very slender, distally much reduced, and, except at the obturator-foramen, separated from the ischia; the pre-pubes are very strong and broad. The femur has a fourth trochanter, a feature which {428}induced the unfortunate late Paul Albrecht to declare that Iguanodon was a reptilian Duck! The tarsal bones are separate. The metatarsals and toes are reduced to three, with 3, 4, 5 phalanges respectively, the first being a mere styliform vestige. The anterior limbs are likewise very powerful, but are much shorter; the hands are adapted for grasping, possibly for defence and offence, as indicated by the pollex, which, although short, is transformed into a formidable spur-like weapon, firmly fixed at a right angle to the other four fingers, the phalanges of which number 3, 3, 3, 4; the second and third fingers were protected by hoof-like nails, the fifth finger is feeble, and stands somewhat apart. The whole vertebral column consists of more than eighty vertebrae, of which ten are cervical, eighteen thoracic and lumbar, while five or six are fused into the sacrum. The cervical vertebrae are opisthocoelous, and carry short ribs, except the atlas, which possesses two separate supra-dorsal pieces, which fill the gap between it and the occiput.

Many specimens of I. bernissartensis, which is now completely known, including even the hyoid bones, were discovered in 1878, in the Belgian colliery of Bernissart, between Mons and Tournai, close to the French frontier. The bones were in a fault or crack, filled with clay of Wealden age, about one thousand feet below the present sea-level, and there about thirty Iguanodons, all {429}apparently adult, had become embedded. Five of them are now mounted in one of the public galleries of the Brussels Museum, of which these perfect monsters form one of the chief attractions. Having proved to be such a valuable find, they were claimed by the Government, on the ground that Iguanodons were not included in the license of the Coal Mining Company. The fact that not only I. bernissartensis, but also a few specimens of I. mantelli, already known from England, where the large form likewise occurs, were found in the same place, makes the specific differences somewhat doubtful; they are perhaps sexual.

Claosaurus of the uppermost Cretaceous strata of Wyoming, is one of the latest of Dinosaurs. It is nearly allied to Iguanodon, but has only three functional fingers, the fifth being absent, whilst the pollex is very short.

Hadrosaurus s. Diclonius of the same level as the preceding genus in North America, apparently also in the Middle and Upper Chalk of England and Belgium, has a most peculiar spoon-shaped bill, the premaxilla and the predental bone being spatulate and quite toothless. The teeth in the upper and lower jaws are numerous and small, and whilst one set of teeth is being ground down, the several successional series are already functional. H. mirabilis has in all about 2000 teeth; the total length of the skeleton is 38 feet, of which nearly 4 feet are taken up by the skull; in other respects this genus is allied to Iguanodon.

Ornithomimus, of the Upper Cretaceous of Colorado, is known only from its fore- and hind-limbs. The fore-limbs are short, with three fingers. The hind-limbs are very long and strikingly bird-like. The metatarsals, of which only the second, third, and fourth are developed, are much elongated; the proximal half of the third is pushed back between the second and fourth, and imperfectly fused with them, exactly as in young birds. The astragalus has a long ascending process, and is fused with the tibia. The fibula is very slender, distally much reduced; the calcaneum is represented by a tiny nodule; the terminal phalanges end in pointed claws. O. grandis must have reached a considerable size, to judge from its middle metatarsal, which is 60 cm. or 2 feet long. Until more is known of these extraordinary creatures, nothing definite can be said about their affinities. They may perhaps belong to the Theropoda.

{430}ORDER IV. CERATOPSIA.

Pubic bones simple, forming a symphysis, post-pubic branches being absent. The mandible carries a toothless "pre-dental," and the fused premaxillaries carry a similar, toothless, "rostral" bone.

The teeth of the upper and lower jaws are alveolar, and have two roots. The fore-limbs are little shorter than the hind-limbs; pentadactyle and plantigrade, with broad hoofs. Femur without a fourth trochanter. Limb-bones solid. The skull is large, and remarkable for a pair of long frontal bony cores, which probably carried large, pointed horns; the parietal bones form a huge, horizontally broadened out crest, which extends backwards over the neck. Upon this cranial neck-shield follow small dermal bony plates. These miraculous creatures flourished during the Cretaceous epoch in Europe and in North America. Some, for instance, the American Triceratops flabellatus, reached a huge size, its skull alone measuring more than 5 feet in length, while that of T. prorsus is, including the neck-shield, about 7 feet long. The total length of this monster, the back of which stands about 8 feet high, is more than 20 feet. Other genera seem to have a well-developed dermal armour, e.g. Nodosaurus of the Middle Cretaceous period of Wyoming.

The Ceratopsia combine characters of the Sauropoda and of the Stegosaurian Orthopoda; in their pelvis they agree with the former, in the development of dermal armour and a predental bone they agree with the latter, while they differ from either by the possession of a rostral element.

{431}SUB-CLASS VI.–CROCODILIA.

If we had to deal only with the recent Crocodilia the following would be an all sufficient diagnosis:–Four footed, long-tailed reptiles, with fixed quadrate bones, with teeth separately implanted in alveolae and restricted to the upper and lower jaws.

To define Crocodilia in general and to distinguish them from various extinct groups we have to resort to additional characters. The vertebrae are solid; the ribs of the neck and thorax possess a distinct capitulum and tuberculum; there is a series of loose, compound abdominal ribs; the humerus is devoid of an entepicondylar foramen; the iliac bones are broadened out and attached to two sacral vertebrae; the pubic bones are simple, not bifurcated, and neither they nor the ischia are ventrally united. The skull always has a strong, bony, quadrato-jugal arch. The possession of a longitudinal cloacal opening and of {432}an anterior or ventral single copulatory organ can of course be asserted of recent forms only.

In spite of these many characters common to all Crocodilia, it is very difficult to separate the latter from the Dinosauria, the only absolute difference lying in the ventral pelvic bones. It is therefore most suggestive that the fore-limbs of the Mesozoic Crocodilia are so much shorter and weaker than their hind-limbs, a discrepancy which is not lessened before the Tertiary epoch. The Mesozoic Crocodilia were almost entirely marine; the strongly-developed ankle-joint (indicated already by such early forms as Aetosaurus and Mystriosaurus) must have been inherited from some terrestrial group with digitigrade tendencies and shortened hind-limbs. All this points to some Theropodous Dinosaurian stock of which the Crocodilia may well form an aquatic, further-developed branch. Loss of the pubic and ischiadic ventral symphysis is not a serious modification. So far as modern reptiles are concerned only the Chelonia and Sphenodon are related to the Crocodilia, whilst Monitors and other lizards resemble them only superficially. We divide them into three Orders.

ORDER I. PSEUDOSUCHIA.

The few members of this peculiar group of reptiles are all restricted to the Keuper or variegated marls, although they seem to have had a wide distribution, some having been found in Germany, others in New Mexico. They perhaps form an early side-branch of the generalised Crocodilian stock, which died out with the Jurassic age.

The skull is distinctly short and pointed. The premaxillaries are very small and are dorsally separated from each other by the large nasals, which also keep the maxillae widely asunder. The nostrils are latero-terminal, bordered chiefly by the nasals, below by the premaxillae and part of the maxillae. The orbit is bordered below by the strong jugals, in front by the prefrontal, above by a supra-orbital and a small postfrontal, behind by a postorbital, which, firmly connected with the jugal and squamosal, shuts off a supratemporal foramen. There is also a lateral temporal fossa, and a large hole enclosed by the lacrymal and the maxillary bones. The teeth are restricted to the anterior {433}half of the jaws. The neck, back, and tail are covered by two rows of large and broad, closely-jointed bony plates; smaller plates protect the sides and the ventral surface. The vertebrae are still unknown.

Aëtosaurus ferratus of the Upper Keuper near Stuttgart is the best known. One of the greatest treasures of the Stuttgart Museum is a slab of sandstone, about 2 square yards in size, upon which lie huddled together twenty-four individuals of various sizes, the largest measuring 86 cm. or 2 feet 10 inches. They are in a beautiful state of preservation, and many of them are in the most life-like attitudes, just as if a mass of sand had fallen upon them and crushed them down, and as if they were struggling to get out.

Erpetosuchus and Ornithosuchus of the Elgin sandstone seem to be allied forms.

ORDER II. PARASUCHIA.

As the name implies, a collateral branch of the true Crocodilia. They are, like the Pseudosuchia, restricted to the Keuper formation. The vertebrae are mostly biconcave, sometimes with nearly plain, scarcely concave, central joints. The premaxillae are very long and powerful. The nostrils lie far back, rather near the orbits, on the top of the snout, within the anterior half of each nasal and almost above the choanae. The latter are situated in front of the palatine bones and are divided by a backwardly directed process of the vomer, which is plainly visible on the roof of the mouth. The palatines and pterygoids leave a wide median space between them. The pterygoids are narrow and have three processes, the antero-lateral of which joins the palatines and the maxillary bones (there being no separate ectopterygoid), the inner joins the basi-occipital, and the postero-lateral the quadrate.

The orbit is surrounded by the frontal, prefrontal, lacrymal, postorbital and postfrontal, while the strong jugal is excluded. The temporal region shows a lateral and a dorsal foramen; the latter opens backwards and above the occiput, being bordered in front by the parietal, laterally by the squamoso-occipital bridge.

The vertebrae are amphicoelous. The first and second {434}vertebrae are devoid of ribs; the cervicals and first thoracics carry separate capitular and tubercular processes for the attachment of the ribs, while the ribs of the rest of the trunk are carried entirely by the long diapophyses, as in the modern Crocodiles. The dermal armour consists of two rows of broad, dorsal, and several rows of smaller, lateral, bony plates.

Belodon is by far the best-known genus, with several species in South Germany and North America, some of which reached a length of 10 feet, without ventral armour. The closely allied Stagonolepis of the Elgin sandstone in Scotland had dorsal and ventral armour. Other genera in the Triassic formations of India and North America.

ORDER III. EUSUCHIA.

Crocodilia in the stricter sense. The premaxillae are short and always enclose the nostrils. The choanae lie behind the palatines, in recent forms even within the pterygoids. They occur from the Liassic or Lower Jurassic period to the present time.

The direct ancestors of the Eusuchia are still unknown. They cannot have been developed from the Pseudosuchia, nor do we know intermediate stages which connect them with the Parasuchia. The nostrils, situated within the premaxillaries, always lie in front of the nasals, although these sometimes extend forwards and form a bony internasal septum fusing with the usual cartilaginous septum. The choanae, instead of opening immediately behind the vomer, are carried far back, owing to the formation of a secondary bony palate. In the Jurassic Crocodiles this roof is formed by the meeting of the palatine bones in the medio-ventral line, and the choanae open immediately behind. From Cretaceous times onwards this roofing is continued by the pterygoids, which likewise form a median suture; and the united choanae (which may, or may not, be divided by a thin bony septum) are pushed towards the posterior end of the pterygoids. Since the Jurassic times there exists also a tendency to enclose the Eustachian passages (the remnants of the first gill-clefts) by bone. In the earlier members they were still wide slits or open grooves on the ventral side of the basi-occipital bone. Since the Cretaceous epoch they have been transformed into bony canals and open through one median hole, situated between the basi-occipital and the {435}basisphenoid, immediately behind the posterior symphysis of the dorsal portion of the pterygoids, which latter almost completely cover the basisphenoid. The vomer is not visible (except in Caiman niger), being covered by the ventral junction of the palatines and maxillaries. The broad, lateral wings of the pterygoids are connected by separate bones, the ectopterygoids = transpalatines = transverse bones, with the maxillaries, and in recent forms also with the jugals. Thus an extensive, very firm bony palate is produced; and the large palatal foramina, between the palatines, maxillaries, ectopterygoids and pterygoids, are closed by the same dense mucous membrane which cover the whole roof of the mouth.

The opisthotic and epi-otic bones fuse early with the lateral and with the supra-occipital bones; only the pro-otic remains longer as a separate element, perforated anteriorly by a large hole for the exit of the third branch of the trigeminal nerve. The basisphenoid is scarcely visible, being covered by the pterygoids. The presphenoid is large, continued forwards and upwards into the usually cartilaginous interorbital septum. Near the anterior and upper margin of the presphenoid is a large notch on either side for the passage of the optic nerve, the three eye-muscle nerves and the first branch of the trigeminal nerve. There are no separate orbito-sphenoids, their place being taken by membrane or cartilage in continuation with the interorbital septum, but the alisphenoids are large, abutting upwards against the frontals. Each prefrontal sends down a vertical process which joins the palatine of its side.

The configuration of the snout varies much. There are two parallel lines of development since the Jurassic epoch, namely, long-snouted creatures, of which two still survive as Gavialis and Tomistoma, and more broad and short-snouted members like the rest of the Crocodiles and Alligators. In opposition to the Parasuchia the elongation of the snout is effected by the maxillaries. The length of the nasals varies much, mostly in conformity with that of the maxillaries. As a rule they reach the premaxillaries but not always the nasal groove. In Gavialis they are short, far separated from the premaxillaries by the maxillaries, which meet in the dorso-median line. The orbit is bordered by the frontals, which at an early age fuse into an unpaired piece, and by the prefrontal, lacrymal, jugal, and postfrontal. {436}At a deeper level the orbit is partly divided from the lateral temporal fossa by a strong column which is formed by the meeting of a downward process of the postfrontal with an inner process of the jugal, and an ascending process of the ectopterygoid (cf. Fig. 108, p. 458). This arrangement adds considerably to the strength of the skull. The lateral temporal fossa is bordered in front by the column just described; below by the jugal and the quadrato-jugal, which is firmly wedged in between the jugal and quadrate; behind by the quadrate; above by the postfrontal, which forms a strong superficial bridge with the squamosal. This rests upon and often fuses with the quadrate and an intervening transverse wing-like extension of the lateral occipital bone. By this squamoso-postfrontal bridge part of the original temporal fossa is divided into the lateral one just described, and a dorsal fossa. The latter is bordered by the postfrontal, squamosal, and united parietals. This dorsal temporal fossa is consequently not homologous with that of the Parasuchia, a vestige of which is however present in many, especially in young skulls of Crocodiles, in the shape of a narrow passage which extends backwards from the dorsal fossa, bridged over by the junction of the parietal with the squamosal, and bordered below by the occipitals.

The size of the upper temporal fossae stands in an inverse ratio to that of the lateral fossae. In the older Eusuchia the upper were the larger of the two. The temporo-mandibular muscle which lifts or shuts the lower jaw arises from the walls of the upper fossa, passes beneath the jugal arch, and is inserted into the supra-angular portion of the lower jaw. In the more recent Crocodiles this muscle is more and more superseded by the pterygo-mandibular muscle, which, arising chiefly from the dorsal surface of the much broadened-out pterygoid bone, fills the widened space between the latter and the quadrate, and is inserted into the outer surface of the os angulare of the lower jaw. This muscle, owing to its general disposition, is capable of much more powerful development and leverage than the temporo-maxillary muscle, which latter, being more reduced, allows the dorsal fossae to be more and more closed up by the surrounding bones.

The fossae are still comparatively large in the long-snouted genera Gavialis and Tomistoma, which live entirely upon fish and scarcely chew their food, whilst these holes almost completely {437}disappear in some of the Alligators, namely in the broad- and short-snouted members, which, having a varied diet, taken from every available group of the animal kingdom, chew their prey.

The quadrate extends obliquely backwards, and is immovably wedged in and partly fused with the quadrato-jugal, the squamosal, and the lateral occipital wings. Between the latter and the quadrate remains a slit-like canal, well visible from behind, through which passes the continuation into the mandible of the columellar or ossicular chain of the auditory apparatus. Intricate passages, used as additional enlargements of the space of the middle ear, pervade the proximal portions of the quadrate and the roof of the cranium beneath the parietal bridges mentioned above, the two sides communicating with each other. The supra-occipital bone is visible from behind; its top is covered and partly fused with a continuation of the parietals, which are, like the frontals, fused into an unpaired mass. The occipital condyle is formed entirely by the basi-occipital bone, so far as the articulating facet is concerned, but it is supported on either side by a lamella from the lateral occipitals.

The two halves of the lower jaw form a symphysis of very variable length. Each half is composed of six bones. (1) The articulare, perforated in its upper, posterior, inner corner by a canal for the reception of the siphonium, a narrow tube of connective tissue, which connects the cavities of the middle ear with the large empty space enclosed within the lower jaw; (2) the angulare; (3) the dentary, which alone carries the teeth; (4) the splenial, a long splint-like bone on the surface of the inner or median side of the jaw, of variable length; (5) the operculare, the counterpart of the splenial on the outer side; (6) the supra-angulare, which forms the dorsal border of the lower jaw between the dentary and the angulare.

The teeth, which are more or less conical or compressed laterally, are deeply implanted in separate sockets. They are often shed throughout life, the successors lying on the median side, and with their caps partly fitting into the wide, open roots of the teeth to be expelled. The number of teeth in the premaxilla is universally five on either side in recent forms, but in a few species, e.g. Crocodilus niloticus and C. porosus, the second pair is lost with maturity and is not replaced. In the broad-snouted {438}kinds, especially in the Alligators, most of the upper teeth overlap laterally those of the lower jaw. In most species of Crocodilus the overlapping is less marked and the teeth partly interlock, but the fourth mandibular tooth, generally the strongest and longest, is received into a lateral notch at the junction of the premaxillary and maxillary. Frequently those of the longer lower teeth which fit into pits of the upper jaw, gradually transform the pits into holes by continued pressure upon the bone, and in old specimens the tip of the lower tooth may even perforate and stand out above the skin of the snout.

The vertebrae are solid, but remnants of the notochord persist for a long time in the middle of the centra. These are still amphicoelous in the Jurassic Eusuchia, and there were probably considerable intervertebral portions of the notochord. From the Lower Chalk onwards the vertebrae are procoelous, with the exception of the first caudal vertebra, which has a knob at either end, so that naturally the posterior of the two sacral vertebrae is opisthocoelous. This peculiar formation of the first caudal is probably correlated with the flexibility of the tail.

Cartilaginous intercentral rings, pads or menisci, occur regularly throughout the vertebral column, unless they are abolished by fusion of adjoining vertebrae. It is most instructive to follow the attachment of the ribs in one and the same individual. The position of the capitulum, vertically below the tuberculum in the neck, changes in the thorax into one in which the capitulum lies anterior to the tuberculum and in the same horizontal plane with it. Moreover, whilst on the cervical vertebrae the capitulum is carried by the centrum (enclosing with the tuberculum a typical transverse canal for the vertebral artery, etc.), further back it moves its point of attachment upwards, lying right upon the neuro-central suture on the tenth and eleventh vertebrae. From the twelfth vertebra backwards both capitulum and tuberculum are carried by the transverse process or diapophysis of the neural arch. The ribs of the five or six lumbar vertebrae are merely vestigial or absent. The ribs of the two sacral vertebrae are very stout, fusing in the adult with both centrum and neural arch. Some of the anterior caudal vertebrae also carry ribs, attached across the neuro-central suture; long before maturity they fuse with their vertebrae, and then look like transverse processes. Most of the caudal vertebrae carry also a {439}pair of chevron-bones, and these are continuous with the intercentral rings of cartilage.

The atlas and the epistropheus or axis are of supreme interest. Crocodiles are, in fact, the only animals in which these two vertebrae retain all their constituent hard parts in an almost undisturbed primitive condition (Fig. 103, 1-4). The basal piece of the atlas-ring, the first basiventral or intercentrum, carries a pair of long ribs attached by their capitular portions. A small knob near the dorsal edge of the rib occurs in many specimens, and is the last remnant of the tubercular portion. The latter was still complete in Jurassic Crocodiles, for instance in Metriorhynchus (Fig. 103, 2, t{1}). The first centrum joins that of the second vertebra as its so-called odontoid process, not directly, however, but by the intercalation of the complete second basiventral, represented by a cartilaginous disc, and by a large unpaired pyramidal piece (Fig. 103, 3, ^2). This, serially homologous with the ventral half of the atlas-ring, is the second basiventral intercentrum, wedged in from below between the odontoid process and the second centrum, with which it soon fuses. Moreover, it carries the capitulum of the second rib (2, Cp^2), the tuberculum of which is articulated with a facet of the second neural arch in Jurassic Eusuchia (t{2}). In recent Crocodiles this tubercular portion is much reduced, and, curiously enough, is attached to a knob which belongs to the odontoid piece or first centrum. This shifting explains the apparently anomalous condition that "the atlas of the Crocodiles carries two pairs of ribs, the second vertebra none." To complete the account of the atlas we have to mention the separate unpaired piece which lies upon the two neural arches. It is the detached neural spine, and not the remnant of a "pro-atlas."

The first and second ribs (R{1} and R{2}), at least in the recent forms, are very long and are quite movable. Those of the next five cervical vertebrae are firmly fixed, short, and adze-shaped. The eighth and ninth are again long, and make the transition to the thoracic ribs, which are mostly eight in number, some with uncinate processes. Then follow several shorter or floating ribs, mostly two or three pairs. The next following three presacral vertebrae carry no ribs. The two sacral and the caudal ribs have already been mentioned.

As a rule the vertebral column of recent Crocodiles, Alligators, {440}and Gavials is composed of twenty-six precaudal vertebrae (namely, nine cervical, fifteen thoracic and lumbar, two sacral), and about thirty-four to forty or more caudal vertebrae. Individual variations, including lop-sided attachment of the iliac bones, are by no means uncommon.

The sternum remains cartilaginous. It consists of an anterior rhomboid portion, which carries the coracoids and two pairs of ribs, and a posterior longer and narrower portion formed by the median fusion of the next following five or six ribs. Posteriorly the sternum bifurcates, each half carrying two or three ribs, of which the last sometimes loses its proximal connexion, and thus appears as a xiphisternal process. Ventrally, upon the anterior part of the sternum lies the longitudinal, originally paired, episternum. The shoulder-girdle consists of the coracoids and the scapulae, which fuse with each other into one bony piece on each side. A pre-coracoid is indicated in fossil forms by a notch in the coracoid.

The space between the posterior end of the sternum and the pubic bones is occupied by the so-called abdominal sternum, composed of seven pairs of ossifications, resting upon the ventral side of the rectus abdominis muscle. Each pair consists of two closely apposed pieces, while the right and left remain separate in the median line. The last pair is much stronger than the rest, is more deeply imbedded in the rectus muscle, and is loosely connected with the anterior margin of the two "pubic" bones.

The limbs are built upon the typical terrestrial pentadactyle type, but were in the Jurassic species undoubtedly more adapted to swimming locomotion. The fore-limbs were conspicuously shorter and smaller than the hind-limbs, and it is only since Tertiary times that the difference has decreased to a great extent. Ulna and radius remain separate. The proximal row of carpal bones consists now of the ulnare and radiale, both strong and distinctly elongated. On the outer side, between ulna and ulnare, lies a pisiform bone. Upon the radiale follows a compound bone, often imperfectly ossified towards the median side, and consisting of the first distal carpal, the centrale, and the intermedium. The third, fourth, and fifth carpals are fused into one mass. The second distal carpal remains separate. All five fingers are present and well developed. The number of phalanges of the pollex is two, of {441}the others three, four, four and three respectively. During the embryonic development the number of phalanges of the fourth and fifth finger increases temporarily, to as many as seven on the fourth, to five or six on the fifth finger. Before the young animal is hatched the numbers are reduced again, chiefly by fusion of adjoining phalanges. This hyperphalangeal condition, typical of Plesiosauri, Ichthyosauri, Cetacea, and several other absolutely aquatic animals, naturally suggests the descent of the present Crocodiles from more essentially aquatic ancestors, but hitherto no trace of supernumerary phalanges has been found in any Jurassic Eusuchia, nor in the Parasuchia and Pseudosuchia.

The composition of the pelvis is difficult to understand. It consists in the adult stage of three separate bones, of which two only partake in the formation of the acetabulum. The broad ilium sends out two processes; the posterior and stronger articulates with the ischium, which sends out a short and stout process towards the anterior process of the ilium, enclosing a foramen. This process contains a separate centre of ossification, possibly homologous with the true pubis, while each club-shaped bone, loosely attached to it and directed forwards, generally called the pubis of the Crocodiles, would then be equivalent to an epipubis. Neither the "pubes" nor the ischia form a ventral median symphysis.

The femur is devoid of a prominent inner trochanter. Tibia and fibula are of almost equal strength. The tarsal elements are, in the adult, reduced by fusion to five bones. The fibulare is transformed into a typically projecting, heel-shaped calcaneum, while the intermedium is fused with the tibiale into a broad astragalus. The first, second, and third distal tarsalia are much reduced towards the inner side, and form one wedge-shaped, partly cartilaginous mass. The fourth tarsale lies between the fibulare and the fourth metatarsal, while the fifth tarsale is hook-shaped and loosely attached to the outer side of the fourth. It has lost its metatarsal and the rest of the fifth finger. Embryos are hyperphalangeal, the fourth toe developing six phalanges, and there are traces of the fifth toe. The numbers are ultimately reduced to 2, 3, 4, 4, 0 on the five toes. The fourth toe remains without a claw.

SKIN.–The epidermal horny layer is not shed periodically nor in pieces; the wear and tear is made good imperceptibly. The {442}scales, which cover the whole body, have a hard, horny, waterproof covering, but between them the skin is soft. Each scale of the sides, belly, and tail, and especially those of the lower jaw, shows a little dot or pit. At this spot the epidermis is not cornified or thickened, and a nerve with sensory corpuscles ends beneath the bottom of the pit. Sometimes these pits are filled with débris of cells, and on the lower jaw, especially on the chin, these organs, instead of forming pits, are raised into little wartlike prominences.

The scutes or dermal portions of the scales consist of thickened, cutaneous connective tissue, and are more or less extensively ossified, thus forming a proper dermal armour. In most recent Crocodilia the armour is restricted to the back, with occasional osseous plates on the throat, as in Osteolaemus; regular although thin ossifications in the ventral scutes occur in the Caimans only. The Crocodile and Alligator skins of commerce consist entirely of the tanned cutis, minus the epidermis and the horny coverings of the scutes. In some fossil genera the ventral armour was extensively developed, especially in Teleosaurus, in some genera to the exclusion of dorsal ossifications. The armour of the recent forms consists, so far as the large scutes are concerned, of a considerable number of scutes, which are arranged in transverse rows, each row corresponding with one skeletal segment of the trunk proper. Mostly there is a detached cluster of scutes on the back of the neck. On the trunk some of the scutes are larger and more crested than others, and form in their totality a variable number of longitudinal rows. The median pair is generally the most conspicuous on the back. Some of the more lateral rows of keeled scutes converge more and more towards the tail, the inner rows drop out imperceptibly, and two lateral rows combine on the middle of the tail into an unpaired series of vertical blades. These are no longer bony, but show more strongly developed horny sheaths; they are very flexible, and transform the tail into an effective propelling organ.

Most of the larger scutes and the upper surface of the bones of the skull have a peculiar gnawed-out, almost honeycombed appearance, as is usual wherever most of the cutis itself is transformed into bone or co-ossifies with underlying bone, while the uppermost layers and the horny layer of the epidermis are much reduced and thinned out.

{443}All the recent Crocodilia possess two pairs of skin-glands, both secreting musk. One pair is situated on the throat, on the inner side of the right and left half of the lower jaw. The opening of the gland, visible from below (see the figure of Crocodilus niloticus, p. 461), is slit-like, and leads into a pocket, which in large specimens is of the size of a walnut; the bag is filled with a smeary pale brownish substance, a concentrated essence of musk, much prized by natives. The secretion is most active during the rutting time, when the glands are partly everted. My young Crocodiles and Alligators often turned them inside out, like the finger of a glove, when they were taken up and held by force. The other pair lies within the lips of the cloacal slit, and is not visible from the outside. The use of these strongly scented organs, which are possessed by both sexes, is obviously hedonic. The sexes are probably able to follow and find each other, thanks to the streak of scented water left behind each individual.

The TONGUE is flat and thick, attached by its whole under-surface, so that it can be elevated but not protruded. It fills the whole space between the two halves of the lower jaw behind their symphysis. The dorsal surface shows numerous irregular polygonal fields, in the middle of most of which opens the duct of a large mucous gland. Tactile and gustatory corpuscles are scattered over the surface in the shape of tiny wartlike elevations. The hinder margin of the tongue is raised into a transverse fold, which, by meeting a similar fold from the palate, the velum palatinum, can shut off the mouth completely from the deep and wide cavity of the throat, which leads of course into the gullet. Dorsally the choanae open into this cavity; and since the narial passages are transformed into long tubes, completely surrounded by bone, Crocodiles can lie submerged in the water, with only the nostrils exposed and with the mouth open, and breathe without water entering the windpipe. The opening of the latter, the glottis, is a longitudinal slit, protected by the laryngeal cartilages, opened and closed by muscles. There is also a pair of membranous folds within the glottis, which serve as vocal cords. Ventrally below the larynx lies the cartilaginous, broad, shield-shaped hyoid; on the sides are attached the short hyoid horns. The TRACHEA is long, consists of about sixty or more complete cartilaginous rings, and divides into two short bronchi, likewise protected by complete rings. The trachea is depressed; its transverse diameter decreases {444}from the glottis backwards. The LUNGS have attained a high degree of efficiency. Each lung is an oval sac, and is transformed into a complicated system of tubes, at the end of which are the countless honeycomb-like respiratory cells, the whole lung being spongy. The main bronchus is continued straight down to the posterior end of the lung, and sends off during its course regular secondary bronchi, and these send off tertiary bronchi. The whole arrangement is very regular, the tubes coming off like rows of organ-pipes. Each lung hangs freely in the thoracic cavity. Besides its ventral attachment by its arteries, veins, and the bronchus, it is connected by loose tissue with the liver and the pericardial septum. Each half of the thoracic cavity is partitioned off from the abdominal cavity by a strong transverse mesenteric lamella. The partition between the lungs and the stomach is at first simple, it then divides, to enclose the liver; the anterior partition passing between liver and lung to the inner surface of the sternum; the posterior lamella between the liver and the stomach. Both meet on the ventral surface of the liver, and are continued into or attached to the peculiar "diaphragmatic" muscle. This is covered by the internal rectus muscle of the abdomen, arising from the last pair of abdominal ribs near the pubic bones; it is innervated by a branch of the last precrural nerve, and extends as a broad but thin muscular sheath (always within and unconnected with the abdominal wall) to the ventral posterior vein of the liver; thence it is continued as an aponeurosis, together with the peritoneal lamella mentioned above, to the inner surface of the sternum. Contraction of this singular muscle indirectly widens the pulmonary cavity, and thereby directly aids inspiration. It acts consequently like the diaphragm or midriff of Mammals, although it is morphologically an entirely different muscle.

The STOMACH is smaller than one might expect from the fact that large Crocodiles can eat up nearly a whole man; but a great deal of their prey is stowed away preliminarily in the wide gullet until the rapid, powerful digestion, which dissolves every bone, makes room in the stomach. This consists of a wide, somewhat globular gizzard, rather muscular, with a pair of tendinous centres like those of birds, and a much smaller pyloric, globular, more glandular compartment. It leads into the duodenum, which is coiled up into a double loop, and receives at its end the {445}hepatic and pancreatic ducts. The small intestine is narrow, and is stowed away in a few irregular coils; the rectum is wide; a caecum is absent.

The CLOACA is peculiar. The coprodaeum and urodaeum, cf. p. 498, are confluent, and form a wide, oval bag, closed in front and behind by strong sphincters, and it acts normally as a urinary receptacle. In the dorsal wall open the two ureters; a little towards the sides, and ventrally, open the two oviducts, on the right and left, near the base of the clitoris. Then follows a transverse, soft, muscular fold, which shuts off this cavity from the proctodaeum or outermost chamber. In the latter is stowed away the rather large copulatory organ. It arises out of the medio-ventral wall of the cloaca, and has a deep, longitudinal groove on its morphologically dorsal side for the conduction of the sperma, the vasa deferentia opening near its basal end. On either side of the root of this organ, in both sexes alike, opens a peritoneal canal, wide enough in large specimens to pass a goose-quill. The outer opening of the cloaca forms a longitudinal slit; within it, dorso-laterally, are the openings of the two anal musk-glands.

The KIDNEYS are much lobed. The testes are long and oval; the ovaries are much elongated and flat; and the eggs contained therein in great numbers are extremely small, except those which ripen during the time of propagation.

The VASCULAR SYSTEM has attained the highest state of development of all reptiles. The heart is practically quadrilocular, the partition between the right and left ventricle being complete; but there is still a small communication, the foramen Panizzae, which lies in the middle of the wall common to both aortae, where they leave their respective ventricles. The left aortic arch conveys all the arterialised blood out of the left ventricle, and supplies head, neck, trunk, and tail. The right aortic arch, coming from the right ventricle, supplies venous blood, mixed with what little arterial blood it receives through the foramen Panizzae, to most of the viscera. On a level with the stomach both descending aortic arches are still connected with each other; the left aorta supplies most of the gut; the right, the trunk and the kidneys.

The outer EAR lies in a recess, dorsally overhung by the lateral edge of the bony squamoso-postfrontal bridge; and this {446}carries a flap of skin, provided with muscles, to close the ear tightly. The tympanic membrane is visible at the bottom of the recess; shining through it is part of that cartilage which is homologous with the malleus of the auditory ossicular chain; the outward extension of the latter on its way to the mandible, behind the joint, passes as a partly cartilaginous string through the slit-like hole which is visible at the back of the skull, between the quadrate and the latero-occipital wing.

The EYES have, besides the lower and upper lid, a third, the nictitating membrane, which can be drawn over the front of the eyeball. In the upper lid lies a cup-shaped bony plate of variable size. The pupil contracts into a vertical slit. The iris is greenish.

The recent GEOGRAPHICAL DISTRIBUTION of the various kinds of Crocodilia loses its mystery when we recollect that during the Tertiary period Alligators, Crocodiles, and long-snouted Gavials existed in Europe. The solitary species of Alligator in China is the last living reminder of their former Periarctic distribution. The group, taken as a whole, is otherwise now intertropical, Crocodiles alone inhabiting the Palaeo-tropical region, together with long-snouted forms in the Oriental sub-region, while Alligators and Caimans, with a few Crocodiles, live in America.

They are all rapacious, doing much damage by their predatory habits, and are fierce and sulky in temper. But the danger to man differs much in different countries. While Crocodiles are dreaded in some localities, they are in others considered almost harmless, and men swim through the haunted waters without hesitation. It seems as if certain old and wily individuals turn into man-eaters, just like tigers and lions.

{447}Their home is the water, in which they pass the night, their time of hunting. The prey is either patiently watched or stalked, and nothing falls amiss. Water-birds are seized by the beast, which rises imperceptibly from below. Some species are said to make use of their powerful tails for hitting the victim and even jerking it into the mouth. The strength of their jaws is enormous, and they do not let go what they have seized, unless, in the case of a man, he has the presence of mind and the opportunity to dig his fingers into the monster's eyes whilst being dragged down.

In the morning they crawl on to sandbanks, or on to logs of wood, which they closely resemble, in order to bask, mostly in such a position that on the slightest alarm they can plunge into the water. For this reason they frequently make a half circle before they settle down to rest, with the heads turned towards the river. There they bask all day long, apparently fast asleep, often with gaping mouths. But their sense of hearing and of sight is sharp, and they learn from experience, old individuals being by far the most wary. Commercially the skins are now of considerable value. The flesh is white, and is tolerable eating but for the combination of fishy and musky odour, which, although faint, is not to everybody's liking.

All the species have a voice, a kind of loud, short bark or croak, heard at night and when angered. The female lays several dozen or even three score white, oval, hard-shelled eggs in the sand, well out of the reach of moisture; and some species construct an elaborate kind of nest. The mother watches it, takes care of and fights for her offspring, numbers of which fall an easy prey to large storks, fishes, and to the stronger members of their own kind.

In the cooler countries they hibernate in the ground; and in hot countries, which are subject to drought, some kinds aestivate in the hardened mud; or they migrate. When during a prolonged drought on the island of Marajó, at the mouth of the Amazon, the swamps and lakes were dried up, the Alligators migrated towards the nearest rivers, and many perished in the attempt. On one farm were found 8500 dead, and at the end of Lake Arary more than 4000. Such occurrences in bygone times may perhaps explain the masses of bones found here and there in a fossil state.

{448}The age to which Crocodiles can live is quite beyond calculation. They are capable of propagation long before they are anything like half-grown, maybe at an age of little more than ten years; then they continue to grow perhaps for more than one hundred years, until they die.

It is customary to divide the Eusuchia, most of which are extinct, into a longirostral and a brevirostral section. In the former the snout is much elongated and narrow, and the nasal bones, although they are sometimes very long, do not reach the nasal groove. The mandibular symphysis is very long, and is formed not only by the dentary but also by the splenial bones. In the brevirostral section the snout is shorter, sometimes broad and rounded off, and the nasal bones are supposed to reach the nasal groove, or at least to approach it very nearly; the mandibular symphysis is formed by the dentaries only. But these distinctions are quite arbitrary, and there exist all kinds of intermediate forms. For instance, in Goniopholis and Diplocynodon, which are both undoubtedly near allies of the recent Crocodiles and Alligators, the nasal bones are considerably removed from the nasal groove; and in Crocodilus cataphractus they are separated even from the premaxilla by the medio-dorsal suture of the maxillaries. Again, in Goniopholis the mandibular symphysis is so long that it comprises part of the splenial bones. Both typically long- and short-snouted forms occur already in the Upper Oolite, but in the Lower Jurassic age only long-snouted kinds seem to have existed. The latter cannot easily be connected with Belodon, one of the Parasuchia, on account of the position of the nostrils; the mere shortening of the long premaxillaries of Belodon would not transfer its distinctly paired nostrils to the anterior end of the premaxilla. To account for the position of the nasal groove in the Eusuchia, we have to go back to a primitive condition, such as that of the Pseudosuchian Aëtosaurus, and this consideration shows that the Parasuchia and Eusuchia are collateral branches.

The Eusuchia have been split into many families. Zittel, for instance, divides them into ten, some of them on insufficient grounds, since there are too many intermediate forms; and more, sometimes quite unexpected, modifications are still being found. Several of the accepted families represent collateral or convergent lines of development.

{449}[Illustration: FIG. 105.–Group of Crocodiles. A long-snouted Gharial or Gavial (Gavialis gangeticus) on the top of Crocodilus acutus; a Nile Crocodile (C. vulgaris) in the foreground; C. palustris, a "Mugger," in the right upper corner. Observe the peculiar floating attitude of the young specimen.]

{450}There is the same tendency to transfer the choanae further back, owing to the formation of a solid secondary roofing in of the mouth, to transform the amphicoelous into procoelous vertebrae, to reduce the supratemporal foramina, and to obtain a better development of the dorsal armour, whilst that on the ventral side is gradually reduced. Lastly, there is a tendency towards a shortening and broadening of the snout, a condition which has reached its culmination in the Alligators, while the Gavials are survivals of another branch. The notches in the premaxilla, for the reception of some of the lower teeth, have also been acquired independently. Although the recent Crocodilia cannot now, as has been pointed out by Boulenger, be separated into different families, no valid diagnoses being possible owing to the existence of Tomistoma, their phylogeny shows them to belong to at least two heterogeneous groups.

KEY TO THE GENERA OF RECENT CROCODILIA.

I. Snout very long and slender. The mandibular symphysis extends at least to the fifteenth tooth, and is partly formed by the splenial bones.

a. Nasal bones very small, and widely separated from the premaxillaries .......... Gavialis gangeticus, p. 451.

b. Nasal bones long, in contact with the premaxillaries .......... Tomistoma schlegeli, p. 453.

II. Snout not slender, but triangular or rounded off. The mandibular symphysis does not reach beyond the eighth tooth, and does not reach the splenial bones.

a. Fourth mandibular tooth fitting into a notch in the upper jaw.

1. Without a bony nasal septum .......... Crocodilus, p. 454.

2. Nasal bones dividing the nasal groove .......... Osteolaemus, p. 466.

b. Fourth mandibular tooth fitting into a pit in the upper jaw.

1. Without a bony nasal septum .......... Caiman, p. 471.

2. Nasal bones dividing the nasal groove .......... Alligator, p. 466.

FAM. 1. TELEOSAURIDAE, in the Lias and Oolite of Europe; marine.–Snout very long and slender. Nasals widely separated from the premaxillae by the maxillaries. Choanae at the posterior end of the palatines. In front of the eye a small sub-lacrymal foramen. Supratemporal foramina large. Vertebrae amphicoelous. Anterior limbs scarcely half as long as the posterior pair. The dermal armour consists of two rows of broad scutes on the back, while the belly is protected by a shield of numerous bony scutes, which are connected with each other by sutures. Teeth numerous and rather slender. General appearance like that of Gavials.

{451}Teleosaurus of the Middle and Upper Oolite in England and France. Snout very slender. Nasals narrow and short. The under side is protected by a beautifully finished armour, consisting of a square breast-shield of four rows of bony scutes, and a larger, long, oval shield on the belly, with about six longitudinal and seventeen transverse rows of scutes.

Mystriosaurus, of the Upper Lias in France and Germany, reached a length of 15 feet, and is characterised by an additional series of keeled but smaller caudal plates running parallel with the middle pairs, which are neatly sutured together.

FAM. 2. METRIORHYNCHIDAE, in the Upper Oolite of Europe; marine.–Nasals broad posteriorly, sometimes extending with a pointed wedge very near the premaxillae. Without sub-lacrymal foramina. Eyes with a ring of ossifications in the sclerotic. Dermal armour unknown. Vertebrae and choanae like those of the previous family. Metriorhynchus and Geosaurus.

FAM. 3. MACRORHYNCHIDAE, in the freshwater deposits of the Purbeck, Wealden, and Greensand of Europe. Snout long and slender. The nasals are narrow, and so elongated that they meet a similar long extension of the premaxillaries. Choanae between the palatines and pterygoids. Vertebrae amphicoelous. Dermal armour consisting of two imbricating dorsal and eight ventral rows, e.g. Pholidosaurus of the English Wealden.

FAM. 4. GAVIALIDAE.–Snout long and slender. The choanae are situated entirely within the pterygoids. Vertebrae procoelous. Members of this family make their first appearance in the littoral marine deposits of the Upper Chalk of Europe and North America; others are common in tertiary, marine, and freshwater deposits, whilst only two genera and species occur now in the Oriental sub-region.

Thoracosaurus in the Upper Chalk of New Jersey and France and Belgium is intermediate between Gavialis and Tomistoma. The prefrontal bones are very small, while the lacrymals are very long and surround the nasals posteriorly. The nasals themselves are slender, and reach the posterior likewise long and narrow prolongations of the premaxillaries.

Gavialis.–The snout is extremely long and slender. The mandibular symphysis is so long that it comprises a great portion of the splenial bones, and extends backwards almost to the level of the last teeth and to the palatal foramina. The nasal {452}bones are very short, and are separated from the premaxillaries by the long suture of the maxillaries. About twenty-eight upper and twenty-five lower teeth on each side.

G. gangeticus, the only recent species, is essentially Indian, inhabiting chiefly the basins of the Ganges, Brahmaputra, and Indus; it occurs also in the Mahanadi of Orissa and in Arakan, but does not live in the Irrawaddy, nor in the Narbada, Kistna, and farther south. In spite of its great size, which reaches 20 feet or even more, it is harmless, and lives entirely upon fish; hence its Hindustani name, gharial, meaning fish-eater, of which the generic name is a corruption.

The nuchal and dorsal scutes form a continuous shield, but there are two small postoccipital scutes. General colour, dark olive-brown above; the young are paler, with dark markings. The male is remarkable for several peculiarities. The nose is very much swollen, and can be inflated like a bag when the nostrils are closed. In connexion herewith, probably produced by the recoil of the air in the long narial passages towards the choanae or posterior nares, there is a pair of hollow globular swellings, in large specimens of the size of a goose's egg. The shell of these globes is formed by the dorsal wings of the palatine bones above the floor of the choanae, and they extend forwards to the right and left of the ethmoid almost to the vertical downward process of the prefrontals.

Although the Gharial is common enough, we know next to nothing about its habits, and in zoological gardens it is rather rare. A. Anderson has, however, made the following observations. Forty eggs were dug out of the sand, where they were {453}lying in two tiers, twenty below and twenty above, with a foot of sand between. The young ran with amazing rapidity the moment they were hatched. Some of them actually bit his fingers before he had time to remove the shell from their bodies! The length of these new-born creatures was 15 to 16 inches, 9 of which belonged to the long and slender tail.

Several fossil species have been described from the Pliocene deposits of the Sivalik Hills of India; and in the same district occurred the closely allied Rhamphosuchus crassidens, which reached the gigantic length of about 50 feet!

Tomistoma.–The general configuration of the skull and snout is that of Gavialis, but the nasal bones are long and reach the premaxillaries, although not the nasal groove, thereby separating the maxillaries. The first and fourth mandibular teeth fit into notches of the upper jaw, while most of the others fit into pits between the teeth of the upper jaw. About twenty upper and eighteen lower teeth on each side.

T. schlegeli, the only species, reaches a length of 15 feet; it inhabits the rivers and swamps of Borneo, Malacca, and Sumatra. Fossil specimens of Tomistoma have been found in the Miocene of Malta and Sardinia. Gavialosuchus of the Miocene of Hungary is closely allied.

FAM. 5. ATOPOSAURIDAE.–The few members of this family, Atoposaurus, Alligatorium, and Alligatorellus, lived in the Upper Oolitic period of France, and were small, about one foot in length. The vertebrae are amphicoelous. The nasal groove is divided by a prolongation of the nasal bones. The head is short, and in its general shape rather like that of a lizard.

FAM. 6. GONIOPHOLIDAE, in the Purbeck and Wealden of Europe and the corresponding level of North America. The vertebrae are amphicoelous. The choanae are still elongated but are situated between the palatines and pterygoids. The premaxillaries are rather large, and each sends a broad triangular process between the nasal and maxillary. The nasals are broad and are well separated from the nasal groove. The splenials help to form the mandibular symphysis.

Goniopholis.–The general configuration of the skull is rather like that of Crocodilus vulgaris. There is a pair of deep notches in the upper jaw for the reception of the lower canine teeth. G. simus and G. crassidens in England and continental Europe, and {454}others in Colorado, were large-sized Crocodiles, some with a skull 2 feet in length. The dermal armour consisted of a pair of dorsal rows, a thoracic and an abdominal shield, composed as in the Teleosauridae of six to eight longitudinal sutured rows.

FAM. 7. CROCODILIDAE.–Beginning in the Upper Cretaceous period of Europe and North America, many forms of Crocodiles, Alligators, and Caimans existed in the Tertiary period in America, Europe, and India; persisting in Europe until the Plistocene. The vertebrae are procoelous. The choanae are completely surrounded by the pterygoids. The nasals reach the nasal groove, except in Crocodilus cataphractus. The orbits are larger than the small supratemporal fossae, and always continuous superficially with the lateral temporal fossae, the postfronto-jugal bridge not reaching the surface. The dorsal armour consists of more than one pair of longitudinal rows, while the ventral armour is much reduced in thickness or absent.

Diplocynodon.–Common in the Oligocene and Miocene of Europe, e.g. D. hastingsiae. The skull resembles that of the Alligators, but has a pair of lateral notches in the premaxilla for the reception of the third, and sometimes also of the fourth mandibular tooth. The ventral armour is still rather strong.

Crocodilus.–The fourth mandibular tooth fits, as a rule, into a notch in the upper jaw. The other teeth are more or less interlocked with those of the other jaw. The fifth upper tooth is the largest. The nasal bones form the posterior border of the nasal groove, but do not extend into it as a septum. The bony scutes of the dorsal shield are keeled, and stand closely together, being rarely united by suture; and they form from four to six principal rows.

Crocodiles have occurred since the Upper Chalk in Europe; many species existed in the Tertiary epoch in Europe and North America, decreasing in numbers in the Pliocene and disappearing with the beginning of the Plistocene. About ten recent species are known, and these have now a somewhat scattered distribution; namely, three species in Africa, one of them extending into Syria; three in tropical America and the West Indian Islands; the rest in the Malay, Indian, and North Australian countries.

C. palustris.–The "Mugger" of India. The premaxillo-maxillary suture is transverse, as in the Alligators. The adults {455}retain the five teeth in each half of the premaxilla. The mandibular symphysis is short, extending only to the level of the fourth or fifth tooth. The snout is stout, rather broad; the top of the head is rough but without any ridges. The upper and lower jaw each contain nineteen teeth on either side. The nuchal scutes, six in number, are packed closely together, the four biggest forming a square. Four smaller scutes are arranged in a curved line on the occiput. The dorsal shield is composed of four, sometimes of six rows of larger scutes, of which the central pair is the broadest. The fingers are webbed at the base; the outer toes are broadly webbed, and the outer edge of the hind-limbs is turned into a serrated fringe. The general colour of the upper parts is dark olive-brown; the young are pale, with black spots. The length of twelve feet is considered a fair average size for a large specimen.

This, the "Marsh Crocodile," has a wide distribution. It inhabits the rivers, ponds, tanks, and marshes of India and Ceylon, extending eastwards through Burma and Malacca into most of the Malay islands, westwards into Beluchistan. This species is frequently venerated by the Hindoos, and is kept in a kind of domesticated condition, attended by fakirs. One of the most famous crocodile ponds, the so-called "mugger-peer," lies in an oasis of the sandy stretches to the north-west of Karachi. A. L. Adams has described a visit to this pond.

"The greater pond is about 300 yards in circumference, and contains many little grassy islands, on which the majority of the Crocodiles were then basking; some were asleep on its slimy sides, others half submerged in the muddy water, while now and then a huge monster would raise himself upon his diminutive legs, and waddling for a few paces, fall flat on his belly. Young ones, {456}from a foot in length and upwards, ran nimbly along the margin of the pond, disappearing suddenly in the turbid waters as soon as we approached. The largest crocodile lives in a long narrow tank separated from the others. The fakirs, and natives who worship in the neighbouring temples, have painted his forehead red; they venerate the old monster, making a salaam to his majesty whenever he shows himself above water. A handsome young Beloochee, whose occupation it was to feed the animals, informed us that this specimen was upwards of 200 years old, and that by way of a 'tit-bit' he was in the habit of devouring the young crocodiles. During our visit this enormous brute was asleep on the bank of his dwelling-place, and seemed quite indifferent to our presence, although we came within a foot of him, and even attempted to arouse him by rubbing his nose with a leg of goat's flesh, which, however, a young one greedily seized. Our attendant tried in vain to excite their ferocity, but beyond a feeble attempt to snap their trenchant teeth, the animals showed no disposition to attack us.

"A pony was wading about in the pond and feeding on the grassy hillocks, but the crocodiles took no notice of him.

"The crocodiles dig deep in the sand, under the neighbouring date-trees, and there deposit their eggs. Quantities of deciduous teeth, of various sizes, were strewn along the slimy sides of the pond.

"Strangers are expected to stand treat, not only by the fakirs and natives, who gain a livelihood by hanging about the pond and showing the monsters, but even the crocodiles themselves seem to anticipate a feast, and on the arrival of a party come out in unusual numbers. Accordingly, we had a goat slaughtered, during which operation the brutes seemed to rouse themselves, as if preparing for a rush. Then our guide, taking piece after piece of the flesh, dashed it on the bank, uttering a low growling sound, at which the whole tank became in motion, and crocodiles, of whose existence we had been before ignorant, splashed through the shallow water, struggling which would seize the prize. The shore was literally covered with scaly monsters, snapping their jaws at one another."

Sir J. Emerson Tennent has had many opportunities of studying the habits of the Marsh Crocodile. According to him {457}it is essentially cowardly in its instincts, and hastens to conceal itself on the approach of man. One of these creatures, which was overtaken in the jungle by a gentleman riding on horseback, fled to a shallow pool, and thrusting its head into the mud till it covered up its eyes, remained motionless, in profound confidence of perfect concealment.

"There is a popular belief that the crocodile is exceedingly sensitive to tickling, and that it will relax its hold of a man if he can only contrive to reach and rub with his hand the softer parts of its under side. An incident of some reality in this piece of folk-lore came under my own observation. One morning ... we came suddenly upon a crocodile asleep under some bushes of the buffalo-thorn, several hundred yards from the water. The terror of the poor wretch was extreme when it awoke and found itself discovered and completely surrounded. It was a hideous creature, upwards of 10 feet long.... It started to its feet and turned round in a circle, hissing and clanking its bony jaws, with its ugly green eye intently fixed upon us. On being struck with a stick, it lay perfectly quiet and apparently dead. Presently it looked cunningly round, and made a rush towards the water, but on a second blow it lay again motionless and feigning death. We tried to rouse it, but without effect; pulled its tail, slapped its back, struck its hard scales, and teased it in every way, but all in vain; nothing would induce it to move till, accidentally, my son, then a boy of twelve years old, tickled it gently under the arm, and in an instant it drew the limb close to its side and turned to avoid a repetition of the experiment. Again it was touched under the other arm, and the same emotion was exhibited, the great monster twisting about like an infant to avoid being tickled."

In the dry season, when the tanks become exhausted, the Marsh Crocodiles have occasionally been encountered in the jungle, wandering in search of water. During a severe drought, in 1844, they deserted a tank near Kornegalle, and traversed the town during the night, on their way to another reservoir in the suburb; two or three fell into the wells; others, in their trepidation, laid eggs in the street, and some were found entangled in garden fences and killed.

Generally, however, during the extreme drought, when unable to procure their ordinary food from the drying up of the {458}watercourses, they bury themselves in the mud and remain in a state of torpor till released by the recurrence of rains.

C. porosus s. biporcatus.–The premaxillo-maxillary suture on the palate does not form a transverse line, but is W-shaped, and extends backwards as in the rest of the species of Crocodiles to be described. This Indian species is easily recognised by the prominent longitudinal ridge which extends in front of each eye, over the prefrontal bones, and by the absence of sub-occipital scutes. The nuchal scutes consist of four large ones, which form a square, and one or two smaller scutes on each side. The dorsal shield contains four to eight principal longitudinal rows. The digits, webs, and the serrated fringe of the legs are like those of C. palustris. The head and snout, however, are distinctly longer, and more slender in proportion, and the adult has only four teeth in each premaxilla. The general colour is dark olive-brown. Young specimens, as usual, are much paler and are spotted with black.

This species attains a much larger size than the Marsh Crocodile. Specimens of 15 to 20 feet in length are not uncommon, and there is a record of one monster of 33 feet. Consequently this is, both in bulk and length, undoubtedly the largest species of recent reptiles. It is essentially an inhabitant of tidal waters or estuaries, frequently entering salt water and going out to sea. Herewith corresponds its wide distribution, namely, the whole coast of the Gulf of Bengal, extending to {459}Southern China, and across the Malay Archipelago to the northern coasts of Australia. Eastwards it ranges to the Solomon Islands and even to Fiji. Curiously enough, it does not seem to occur on the west coast of India.

According to Tennent it is ready to assail man when pressed by hunger, and the same authority mentions the following serio-comic incident. A man was fishing, seated on the branch of a tree overhanging the water, and to shelter himself from the drizzling rain he covered his head and shoulders with a bag folded into a shape common with the natives. While in this attitude, a leopard sprang upon him from the jungle, but missing its aim, seized the bag and not the man, and fell with it into the river. Here a crocodile, which had been eyeing the angler in despair, seized the leopard as it fell, and sank with it to the bottom.

I have had some personal experience in the bringing up of the young of this species. Two dozen of them had come from Ceylon when quite young, only one foot long. At first they were very shy, and huddled together in their tank, but they took food greedily–strips of fish and, later on, sheep's heart. When frightened they emitted peculiar, high-pitched, half-croaking sounds. Some of them snapped at the finger when touched; others were of a more gentle disposition; the shy ones were undoubtedly the most vicious. Within one year they grew to 18 or 20 inches, and added much to their bulk. Then they were transferred to a deeper and larger tank in a greenhouse, in which they could roam about at liberty. In the daytime they dozed on the margins of their pond, mostly in such a position that, at the slightest alarm, they could plunge back into the water. The strongest specimen left the tank entirely, and took up its favourite place for basking on the stump of a tree, to reach which it had to climb up a rough wall of stones. After three years, several had grown to the length of three and a half, and even four feet, and had by this time become formidable pets. Although handled frequently, they never became tame, the only change in their behaviour being that, instead of rushing off in a fright, and hiding for half an hour at the bottom of the tank, they became more vicious and confident, making for and snapping at the hand which fed them. The nights were spent regularly in the water, either floating {460}with just the nostrils exposed, or in search of food, frogs being their favourite prey, while their main sustenance consisted of "lights," with an occasional mouse, or a piece of solid meat by way of an entrée. Small pieces were bolted. The tough "lights," namely lungs with the windpipe and blood-vessels, were causes of great quarrels. Two or three would get hold of a lump of this kind, tearing at it, and twisting and rolling over in opposite directions. The supply of warm water came through a stout pipe of red india-rubber, and this was an irresistible attraction to the crocodiles. On many a morning the tube was found twisted into a knot, one of the creatures having spent hours in chewing it and in trying to wrench it off. In order to aid digestion they swallowed pebbles. The most favourable temperature of the water was 85° F.; if below 75° F. they refused to eat, but a continued exposure to 60° F. did not hurt them. When the temperature rose above 95° F. they left the water, although means had to be taken to prevent them from lying on the hot-water pipes.

C. niloticus s. vulgaris.–The premaxillo-maxillary suture on the palate is W-shaped. The nasal bones form only a small part of the posterior border of the nasal groove. There are eighteen or nineteen upper and fifteen lower teeth on each side. In old specimens some of the anterior mandibular teeth perforate the premaxillae, as indicated in Fig. 109, and they even pierce through the integument so as to be visible from above. The nuchals are composed of four large scutes, with a smaller one on each side and sometimes one behind, and there is a row of smaller pieces across the occiput. The dorsal shield contains six to eight principal longitudinal rows. The fingers are webbed at the base; the outer toes are very broadly webbed; and there is a serrated fringe on the outer side of the leg. The general colour of the adult is dark olive-brown; the young are paler, with black spots and vermiculations. The under parts are yellowish white.

{461}The Nile Crocodile is essentially African, ranging from the Senegal to the Cape and to Egypt. It is also very common in Madagascar. Nothing is known about its occurrence in Arabia, but a few specimens of rather small size seem still to exist in Syria, in the Wadi Zerka, an eastern tributary of the Jordan.

Even in historical times the Crocodile must have been very common in lower Egypt, to judge from the number of mummies preserved by the old Egyptians. Now it is practically exterminated, and there are scarcely any left below Wadi Halfa.

Such a conspicuous and dangerous creature has naturally always enjoyed notoriety. It is well described in one of the oldest writings of the world, the Book of Job. "Canst thou draw out leviathan with an hook? or his tongue with a cord which thou lettest down?... His scales are his pride, shut up together as with a close seal. One is so near to another, that no air can come between them. They are joined one to another, they stick together, that they cannot be sundered.... Lay thine hand upon him, remember the battle, do no more." Bows and arrows, spears and clubs, are of little avail against such a {462}monster; the dragging out of a hooked, full-grown specimen requires many men and is a formidable task. Of course firearms have changed all this, and its invulnerability to bullets is nonsense. It is true that a bullet sent into the head is generally ineffective, since it is a hundred to one that the bullet does not hit the small brain, and even if it does, the creature sinks to the bottom and is lost to view until decomposition sets in and the gases developing in the body cause it to float.

Herodotus has quaint stories about these crocodiles and their worship. Amongst other stories he mentions that the bird Trochilus, supposed to be the Pluvianus aegyptius, a kind of Plover, slips into the gaping mouth to pick off the leeches which infest the reptile's gums. "In Egypt it is called Champsa, but the Ionians call them κοκοδρίλοι on account of the resemblance to the lizards which live on their garden walls." This is in fact the origin of the name crocodile, κόρδυλος being the ancient Greek for lizard and newt. With reduplication κορκόρδυλος and by metathesis ultimately κροκόδειλος. The Arabic name is ledschun.

The story about the Plover seems to be true. These birds are sometimes seen sitting upon basking crocodiles, and since the latter are in the habit of resting, perhaps half asleep, with the mouth wide open, it is possible that these agile birds do pick their teeth, and that they, being also very watchful, by their own cry of warning and by fluttering off on the approach of danger, give the alarm to the crocodiles and thus benefit them in more than one way.

But the equally old story about the Ichneumon or Mongoose is an idle invention. Mongooses are partial to eggs, but they certainly prefer those of hens and other birds to those of the crocodile, which are far too hard and strong to be broken by such a little animal. Moreover, as we shall see presently, the eggs are far too well concealed.

The best account of the habits of these crocodiles is the one given recently by Voeltzkow, who has spent a long time in Madagascar to collect material for the study of their development.

He says that C. niloticus is not only the most common reptile, but perhaps the most common vertebrate in Madagascar. {463}It occurs in every pool and river in great numbers, especially upon the sandbanks of the Betsiboka River, where one may see more than one hundred within one hour's paddling down stream. The largest specimen measured by Voeltzkow was 13 feet long; the largest in the National Collection is a little less than 15 feet.

The crocodiles are caught in various ways. The simplest apparatus consists of two pointed sticks, which are fastened cross-wise within the bait to which is attached a rope, and this is made fast on the bank of the river or lake. The animal, when it has once swallowed this spiked bait, keeps its jaws firmly closed, so that it can be dragged out of the water. Another method is more reliable. A long and strong rope is made into an easily slipping noose, with an opening of about 18 inches. The bait is attached to the upper part of the noose, while the lower portion is kept open by a springy branch, the whole thing being so balanced that it will float upright. When a crocodile seizes the bait, which it does with a side jerk of the head, the branch falls out of the noose and the latter closes around the upper or lower jaw.

These crocodiles dig long subterranean passages of 30 to 40 feet in length; the passage opens in the bank below the level of the water, and gradually ascending ends in a somewhat wider compartment, which allows the creature to turn round. Two or three air-holes are pierced through the ceiling of the burrow, in which bones and other remains of food are often found, so that the natives' belief, that the crocodiles retire into these chambers in order to devour their prey in undisturbed secrecy, appears very probable. When suddenly disturbed or frightened they take to these lairs, and since their position is clearly marked by the air-holes, the natives block the passage and then dig the animal out from above.

Eggs are laid, in Madagascar, from the end of August to the end of September; the number of one set varies from twenty to thirty. They are deposited in a nest. This is in the ground, mostly in white sand, and consists of a hollow 18 inches to 2 feet deep. The walls are rather vertical, but near the bottom they are undermined, and here the eggs are placed. The centre of the pit being somewhat higher, the eggs roll by themselves into the undermined peripheral region. The laying takes place {464}during the night, mostly a little before daybreak. After one half of the eggs has been laid, they are covered up with sand, whereupon the other half is deposited. Then the hole is completely filled up and no visible traces are left behind; but the mother sleeps upon the nest and thus leads to its discovery. The position of the nest is so chosen that it cannot be reached by moisture from below; the eggs are most susceptible to moisture, a very slight amount of which causes them to turn bad.

The shape of the eggs of one and the same clutch varies much, some being elliptical, others cylindrical with rounded off ends. Their size varies from 5.5 to 9 cm. in length, and 4 to 5 cm. in width. The shell is white and glossy, thick and hard, either roughly granular or smooth. They are hatched in about twelve weeks.

Voeltzkow feels certain that the mother returns to the nest at the proper time in order to dig the young ones out and to conduct them to the water. To test this story he had a nest surrounded with a fence; the mother returned several times and partly destroyed the fence, which was then replaced by a stronger one. One day, when the young had been hatched, the nest was found to be filled with sand, the shells and one dead little crocodile being at the bottom of the hole. The mother had dug a deep ditch below the fence, but had not succeeded in reaching the nest, although she had received and conducted her offspring away. As a rule, when the young are hatched, the sand and the shells are found to be scraped out of the nest. The mother is probably warned by the hiccough-like sound which the young emit while still within the unbroken shell. Voeltzkow heard them piping from the other end of his room, the eggs being covered with a layer of sand two feet high. The sounds were heard when he walked past the nest, or knocked against the box. Possibly the young hear the mother when she retires to the nest to sleep on it, and give her warning to remove the eggs out of the groove. However, they do not break the shell until several days later.

The hatching is not caused by the rainy season, since it took place a fortnight before the first showers. The "egg-tooth" of the newly hatched young is 0.5 to 0.75 mm. high, bicuspid, and acts like a borer or auger. It is still visible on the tip of the upper jaw, in front of the nose, when the creature is two weeks old. The {465}newly hatched crocodile is of an astonishing size, so that it is rather puzzling to understand how it was stowed away in the egg. For instance, an egg of 8 cm. length and 5 cm. width, sends forth a crocodile 28 cm. or 11 inches in length. Even at this early age they snap at the finger.

The egg is covered by a hard shell, within which is a thicker outer and a thinner inner membrane. The "white" is jelly-like, sometimes of a greenish tinge, and is so consistent that it will not flow. The yolk is round, and so large that it nearly reaches the shell-membrane in the short diameter. The yolk itself is surrounded by a very thin but strong membrane.

The embryo begins to develop long before the egg is laid. When laid the germ is about 4 mm. long and shows about twelve somites. The cephalic bend begins at the end of the second week, the tail grows longer and the embryo becomes curled up. At the end of the third week it measures 10 mm. in a straight line from brain to vent. The limbs begin to bud in the fourth week. With the sixth week the final shape begins to reveal itself, and is completed at the age of eight weeks; but a third month is necessary to ripen the embryo.

C. cataphractus is the Common Crocodile of West Africa, from the Senegal to the Congo. In opposition to C. niloticus it does not enter brackish water. It is easily recognised by the very slender snout, which rather resembles that of the Gavial; but the mandibular symphysis, although extending to the level of the eighth tooth, does not reach the splenial bones. The premaxillo-maxillary suture on the palate is not transverse, but extends backwards. In conformity with the length of the snout the maxillaries meet in the dorso-medial line behind the nasal opening, thus excluding the nasals from the latter. The nuchal scutes consist of two large pairs, almost in contact with the dorsals, six of which form the principal longitudinal rows. The gular and ventral scutes ossify in the adult, hence the specific name. The fingers and toes are slightly webbed. General colour above, dark olive-brown; yellowish below. The young are olive with large black spots.

The natives of the Lower Congo catch the crocodiles with two pointed sticks tied together cross-wise, surrounded with entrails by way of a bait. The whole is fastened to a pole or a strong rope and thrown into the river; and a narrow line, with a float {466}attached to the cross-sticks, indicates the whereabouts of the crocodile when it has taken the bait and has sunk to the bottom.

C. johnstoni, of Northern Australia and Northern Queensland, and C. intermedius, of the Orinoko, are allied to C. cataphractus, at least so far as the configuration of the bones of the slender and long snout is concerned. The former is small, scarcely reaching the length of 7 feet, while the South American species grows to 13 feet.

C. americanus s. acutus.–This species, which inhabits the West Indian Islands, being there the only representative of the order, occurs also in Florida, and extends through the warmer parts of Central America into Venezuela, Colombia, and Ecuador. Its characteristic feature is a median ridge or swelling on the snout. The length and relative width of the latter varies considerably. The maxillaries sometimes meet dorsally, or they remain separated by the narrow nasals, which in this case reach the posterior corner of the nasal groove. The nuchal scutes vary likewise; there being often a smaller pair on the side of and another behind the four principal scutes, which, as usual, form a square. A transverse row of little suboccipital scutes is also common. Largest size about 12 feet long.

Osteolaemus tetraspis s. frontatus.–The only species of this genus inhabits the rivers of the west coast of Africa, from Sierra Leone to the Ogowai. It differs from Crocodilus chiefly by the bony septum of the nasal groove, produced by forward extension of the nasal bones. The snout is rather short and stout; the upper surface very rugose and deeply pitted, but without ridges. The gular and ventral scutes are ossified, hence the generic name. Total length about 5 feet.

Alligator.–The fourth mandibular tooth fits into a pit in {467}the upper jaw, and this pit is in some adult specimens transformed into a hole, the tip of the tooth appearing on the upper surface through the perforation. Most of the other teeth of the lower jaw are overlapped by those of the upper jaw. The number of teeth on either side amounts to seventeen to twenty in the upper and eighteen to twenty in the lower jaw. The nasal bones form not only the posterior border of the nasal groove, but they divide the latter by a median bony septum. The dorsal shield is formed by six or eight longitudinal series of keeled bony scutes, which, although standing close together, do not articulate with each other. Ossification of the gular and ventral scutes is absent or very slight.

Alligators occur in the fluviatile deposits of the age of the Upper Chalk in Europe, where they did not die out until the Pliocene age; they are now restricted to two species, one in the Southern States of North America, the other in China.

A. mississippiensis.–The much-depressed and broadly rounded snout bears some resemblance to that of a pike, hence the now discarded specific name of lucius. The neck is protected by two pairs of large scutes, which form a square, interrupted in the middle line, with a pair of small scutes in front and another behind. Of the eighteen transverse dorsal rows of scutes eight are broad and prominent. The fingers are about half webbed, the outer toes about two-thirds webbed. The general colour is greenish black or dark brown above, yellowish below. Young specimens have yellowish cross-bands on a darker brown ground.

The Alligator's northern limit is the mouth of the river Neuss in North Carolina, 35° N. lat. From this point they abound near the mouths of all the creeks and rivers as far south as the Rio Grande, ascending the Mississippi to the entrance of the Red River in 33° 50' N. lat.

The habits and the embryology of the American Alligator have been described by S. F. Clarke, who gives the following vivid and minute account:–

"Usually one finds them in the waters of the smaller streams and ponds, lying with only the tip of the nose and the eyes exposed, or lying on an exposed place on the bank where the grass and other plants are beaten down, and the black, rich mud of the river bank is smoothed by the repeated movements of the {468}alligators in climbing up and down. There they bask in the sunlight until disturbed by the hunter or the desire for food. When aroused they make for the bottom, and I have never waited long enough to see one return unless he were vigorously stimulated with a long pole. They frequently dig a cave for themselves in the bottom of the pond or stream, or in the bank beneath the water. Oftentimes one can start them out of the cave by using a pole, but if very obstinate, the hunters dig them out with spades.

"As the water decreases in the streams and ponds with the summer heat, the alligators travel to the larger bodies of water. {469}During the breeding season, from the end of May to the beginning of July, the males are very active, wandering about to various ponds and rivers in search of the females. Fierce battles are said to take place during this time between the excited males; and the mutilated specimens that one sees are weighty evidence for the truth of this assertion.... It is in the breeding season also that their bellowing is mostly heard, and more in the night than during the day. I have frequently heard them, while lying in the swamps at night, when they were in ponds fully a mile distant.

"The largest specimen I saw measured 12 feet in length; and none of the many hunters and other natives of Florida I have met have seen any longer than 13 feet. All the hunters agree that it is only the males that acquire the great size; no one had ever seen a female that measured over 8 feet, and the majority are not over seven.

"The male has a heavier, more powerful head, and during the breeding season especially is more brilliantly coloured. The more brilliant colour occurs in patches and streaks on the sides of the head and body; it is generally a light yellow, or even whitish, and on one large male I saw a fairly bright red spot over each eye.

"The alligators are rapidly diminishing in numbers under the stimulus of the high prices offered to the hunters for their hides. Both Whites and Indians make increasing war upon them. Several thousand skins were brought into the little station of Fort Pierce in 1890. The pioneers and settlers always destroy the nests and eggs, because the alligators eat their pigs; and the cleaned eggs and young alligators are sold by hundreds in the curio shops farther north. As their numbers diminish in Florida it is noticed that the Moccasin snakes increase. In Louisiana also the alligators are disappearing; and there the musk-rats are at the same time increasing, and are doing much damage by burrowing in the levees along the Mississippi. While the alligator can make a very stout fight, I have never seen one offer fight if there was any chance of retreat. They never offered to molest us, even when we waded through the ponds where they were.

"The nest of the alligator is very large, and is built by the female. A great quantity of dead leaves and twigs, together with {470}much of the finely divided humus underlying them, is scraped together into a low mound about 3 feet high; this varies considerably in its other dimensions, being in some instances 8 feet in diameter at the base. The nests are built on the bank of a stream or pool, and the female digs a cave under water in the bank close to the nest. Careful examination, of the largest nest found showed a root of a neighbouring palmetto-tree, nearly an inch in diameter, running through it at about a foot above the ground; there were also roots of a grape vine growing near, which extended nearly through the nest. This furnishes strong support to the statement of many of the hunters, that the nests are used for more than one season. I could get no evidence whatever that the nests are used more than once a year.

"The eggs are laid near the top of the nest, within 8 inches of the surface, are four or five layers deep, and have no regular arrangement or uniform position of their axes in relation to the nest. The number of eggs to a nest varies from twenty to thirty, and averages twenty-eight; the maximum found was forty-seven.

The eggs are white, elliptical, and vary in length from 50 to 90 mm. or 2 to 3½ inches, and in the shorter diameter from 28 to 45 mm. Generally there is only slight variation in the eggs of one nest, but occasionally a nest is found in which most of the eggs are about the average size, while from two to five are very much smaller.

"The shell is much rougher than that of a hen's egg, and much thicker. The shell membrane consists of an outer and an inner layer, in both of which the fibres are arranged spirally about the egg, but at right angles to one another.

"The white of the egg has the consistency of a very thick jelly, is very clear and transparent, and is so firm that the whole egg, when perfectly fresh, may be turned out of the shell and shell membrane, and transferred from one hand to the other without breaking, and with but slight change of form. The white lies mostly at either end of the shell, but extends also in a thin layer between the yolk and the sides of the shell. The yolk holds a median position in the egg, is spherical, of a very light pale yellow, and so large that it almost touches the shell membrane about the midline."

According to Holbrook the young as soon as they are disengaged from the shell seek the water and shift for themselves, {471}the parents taking no care of them, though they may remain for some weeks in the same locality. In the spring and early summer months, and during the time of incubation, and especially on cloudy days or in the evening, alligators make a great noise; their croak is not unlike that of the bullfrog, but louder and less prolonged. On the approach of winter they select holes in the ground, where they remain torpid until spring. In this state of hibernation many are dug out by the negroes, who esteem the tail as an article of food.

A. sinensis.–The first intimation of the existence of a Crocodilian in the Yang-tse-kiang was made by Swinhoe in 1870, but it was not until nine years later that Fauvel described the creature as A. sinensis. The same gentleman gave also an exhaustive account of the former records of this species in Chinese literature. According to Boulenger its nearest ally is A. mississippiensis, but it approaches the Caimans by the presence of ossifications in the ventral shields, which ossifications are, however, wide apart from each other. There are three pairs of large nuchal scutes in contact in the median line, besides smaller scutes in front of the nuchals and behind the occiput. The dorsal shield contains six rows of larger scutes. The fingers are not webbed. The general colour is greenish black above, speckled with yellow; greyish below. Total length only about six feet.

Caiman.–The five species of this genus, confined to Central America or to the East Andesian parts of South America, resemble the Alligators in most features, but differ from them in the following points. The nasals, although bordering the nasal groove, do not form a bony nasal septum. The supratemporal fossae are very small; or closed up, as in C. trigonatus and C. palpebrosus of Guiana. The ventral armour is composed of overlapping bony scutes, each of which is formed of two parts united by a suture.

C. sclerops has the widest distribution, from Southern Mexico to the northern half of Argentina. The upper eyelid is rugose, although only incompletely ossified, and is often more or less produced into a small horn. C. niger has flat upper eyelids.

According to Bates, Caimans exist in myriads in the waters of the Upper Amazons. One species, C. trigonatus, the Jacaré-tinga {472}of the natives, reaches only six feet in length and has a slender muzzle and a black-banded tail. Another species, C. niger, the Jacaré-nassu or large Caiman, attains an enormous bulk and a length of 20 feet. They migrate annually, retreating to the flooded forests in the wet season and descending to the main rivers in the dry season.

{473}CHAPTER XI

PLESIOSAURIA–ICHTHYOSAURIA–PTEROSAURIA–PYTHONOMORPHA

SUB-CLASS VII.–PLESIOSAURIA.

Mesozoic aquatic reptiles, with two pairs of pentadactyle limbs, firmly fixed quadrate bones, single temporal arches, numerous alveolar teeth, and ribs which articulate only with the centra of the biconcave vertebrae.

The Plesiosauria comprise the Mesosauri, Nothosauri, and Plesiosauri in an ascending order of development, which concerns especially the changes from a semi-terrestrial to an absolutely aquatic life;–elongation of the neck with corresponding shortening of the tail, and the gradual transformation of the limbs into hyperphalangeal paddles.

The skull varies considerably in length. Seen from above it shows the nostrils, orbits, very large supratemporal foramina, and the interparietal hole. The nostrils lie rather far back, in front of the orbits, between the elongated premaxillaries, short nasals, and the usually large maxillaries. The orbits are rather small, bordered behind by the postfrontals and postorbitals, which two bones fuse together in the Plesiosauri. The temporal bridge is long, and is formed by the junction of the two bones just mentioned with the squamosal mass, which overlaps the greater portion of the quadrate, and perhaps contains the quadrato-jugal. The dorsal branch of the squamosal joins a corresponding diverging branch of the parietal, and completely shuts off the posterior region of the supratemporal foramen. The interparietal hole is small and placed far back. The palate possesses a row of teeth on the pterygoids in Lariosaurus. The choanae open separately between the vomers and maxillaries. The pterygoids are very long; posteriorly they join the quadrates, anteriorly they extend {474}right up to the vomers, separating the palatines from each other thereby. Palatal vacuities are absent in Nothosaurus; small and oval, between the palatines, pterygoids, ectopterygoids and maxillaries in Lariosaurus; still smaller in the Plesiosauri.

The vertebrae are mostly biconcave, in the Triassic genera still perforated by the chorda, while in many Plesiosauri the centra are solid, with almost plane articulating surfaces. The neural arches are usually firmly sutured, or quite fused with the centra. Intercentra are absent, except as chevrons in the tail. Although the cervical and some of the thoracic ribs of the Triassic genera have typical capitula and tubercula, they articulate exclusively upon the centra, and not upon the neural arches also. The number of cervical vertebrae amounts to nine in Mesosaurus; in Lariosaurus it is increased to about twenty; and in some Plesiosauri to between thirty and forty. The cervical ribs are very short, but they increase gradually towards the thorax, which is well protected by long and strong ribs, which decrease again very gradually, being still long in the lumbar region. There is, properly speaking, no sacrum, because the one to four sacral ribs remain quite separate. The tail is still long in Lariosaurus, consisting of about forty much shortened vertebrae; considerably shorter than the neck in most of the Plesiosauri. A sternum is absent, but the belly is protected by many strong abdominal ribs, crowded together, and consisting each of a median and two pairs of lateral pieces.

The shoulder-girdle is very strong, composed of scapulae, very strong coracoids, clavicles, and an interclavicle. The precoracoids are indicated by a process and a notch in the Triassic genera; in the later forms they are abolished. The coracoids always meet in the median line, and often produce a strong symphysis. The scapulae possess a very prominent and large acromial process, upon which rest the dorsal or lateral ends of the clavicles. In some Plesiosauri the shoulder-girdle has undergone an absolutely unique modification. The correct interpretation has been given by C. W. Andrews after the examination of exquisitely preserved specimens of Cryptoclidus from the Oxford clay of the Middle Oolite, near Peterborough. The dorsal portion or main shaft of the scapula is reduced to what now looks like a dorso-lateral process, while the broad acromial process is much elongated, and lies in Plesiosaurus upon the {475}ventral surface of the clavicle; the latter and the irregularly T-shaped interclavicle being, however, still visible from below. In Cryptoclidus the two acromial processes meet each other and form a long ventral symphysis, which meets that of the much-enlarged coracoids, the latter enclosing with the scapulae a pair of roundish foramina. The clavicles are not visible from below; they rest upon the dorsal surface of the scapular symphysis, and the interclavicle seems to be suppressed. Young Cryptoclidus (Fig. 113, B) and various species of Plesiosaurus show intermediate conditions.

This unique arrangement is correlated with the enormous development of the fore-limbs, although nothing of the kind has taken place in the Ichthyosauri, which have similar large paddles. The limbs exhibit considerable differences in the various groups of Plesiosauria, but they are all pentadactyle. In the oldest, the Mesosauri and Nothosauri, the limbs are still of the terrestrial type, although fitted for swimming; the chief bones are still slender and elongated, and none of the five fingers and toes have more than five phalanges, the usual number of which seems to be 2, 3, 4, 5, 3 for the first to fifth digits respectively. In the Plesiosauri the limbs are transformed into long hyperphalangeal paddles, unfit for progression on land, rather like those of the Ichthyosauria, with much {476}shortened radius and ulna, tibia and fibula; but the phalanges, which increase to about ten, are always longer than broad, and there is no indication of an increase of the number of fingers, or of additional, lateral, phalanx-like nodules. The pelvis is very strong; the broad pubes and ischia meet in the middle line, and they either enclose one wide undivided foramen, or the two symphysial portions meet, and there are then two obturator-foramina. The pubes are generally much larger, especially broader, than the ischia; and although partaking in the formation of the acetabulum, they do not articulate with the ilia, at least not in Plesiosauri. The ilia are always small; in Plesiosauri attached to only one or two sacral ribs; to three or four in the Triassic genera.

Ichthyosauri and Plesiosauri were combined as "Enaliosauria" by Conybeare. Owen recognised their fundamental differences, and separated them as "Ichthyopterygia" and "Sauropterygia," according to the structure of the limbs. We now know that the paddles of the Ichthyosauri bear but a superficial resemblance to the fins of fishes, and are fundamentally referable to the pentadactyle type, as are the paddles of the Plesiosauri, although the latter retain more of the typical features of reptilian limbs. It was soon recognised that the Nothosauri are allied to the Plesiosauri, but the Mesosauri (until then vaguely grouped with the Rhynchocephalia, or linked with Protorosauri as Proganosauria) have only recently received their proper place in the system as members of the Plesiosauria, which we divide into two main groups.

ORDER I. NOTHOSAURI.

The limbs are of the terrestrial type; the five digits have the usual number of phalanges, which do not exceed five. The bones of the limbs are slender; the humerus has an entepicondylar foramen.

FAM. 1. MESOSAURIDAE.–The neck contains about ten vertebrae. The vertebrae are deeply biconcave, perforated by the chorda dorsalis. Sacral vertebrae four in number. Clavicles strong; interclavicle very small. Mesosaurus, the only genus, with one species, M. tenuidens, about one foot in length, was found in {477}South Africa, probably in Triassic sandstone. Very similar specimens are known from São Paolo in Brazil.

FAM. 2. NOTHOSAURIDAE.–With sixteen to twenty-one cervical and three to five sacral vertebrae. The vertebrae are biconcave. The clavicles are strong; the interclavicle is much reduced. Coracoids with distinct acromial processes.

Nothosaurus mirabilis, of the Muschelkalk of Germany. Total length about ten feet. Length of head about one foot. The teeth are very irregular. About five slender, long teeth are implanted in each side of the premaxilla, with wide spaces between them, similar to those of the symphysial portion of the lower jaw. Those of the maxillaries are numerous and small, except two large pairs in the anterior portion, on a level between the orbits and nostrils. The upper and lower teeth overlap, or cross each other. The palate of the long and slender skull is quite bony, without anterior palatal or infra-orbital vacuities.

Lariosaurus balsami, about one foot in length, from the fresh-water deposits of the Upper Trias in Lombardy. Neck with about twenty, tail with about forty vertebrae. Head comparatively shorter; more triangular than in Nothosaurus; palate with small infra-orbital vacuities. The number of the phalanges of the fingers and toes is apparently 2, 3, 4, 4, 3 and 2, 3, 4, 5, 4.

Anarosaurus pumilio, of the Muschelkalk, near Magdeburg, and Neusticosaurus and Simosaurus of the same geological age, are allied forms.

ORDER II. PLESIOSAURI.

The limbs are transformed into hyperphalangeal paddles. The clavicles are small, and are overlapped ventrally by the strongly developed acromial processes of the scapulae. The vertebrae are slightly biconcave or plane. The neck consists of at least twenty vertebrae; those of the thoracic region have long transverse processes; the sacral vertebrae are mostly reduced to two or one. Very large, massive animals.

FAM. 1. PLIOSAURIDAE.–About twenty cervical vertebrae, with proximally bifurcated ribs. The scapulae do not meet ventrally; they enclose with the coracoids a single large foramen, and are fused with the clavicles. Pliosaurus, the principal genus, contains several species of gigantic size; for instance, P. grandis, of the Kimmeridge clay, Upper Oolite, of England, has a skull {478}nearly 5 feet long and 2 feet broad, armed with many enormous conical teeth, some of which reach one foot in length, inclusive of the long collar and root-portion. The neck is rather short, owing to the much condensed, disc-shaped centra of the vertebrae. Total length of this species about 30 feet. Other species in England and continental Europe as far as Russia.

FAM. 2. PLESIOSAURIDAE.–The neck is very long, and consists of from twenty-eight to forty vertebrae. The scapulae do not meet ventrally, but the symphysial portion of the coracoids meets the clavicles and the interclavicle, the pectoral arch thus enclosing two foramina. Chief genus Plesiosaurus, with many species. The head is comparatively small, the neck very long, the tail short, although consisting of from thirty to forty vertebrae. The third digit (Fig. 113, C) is the longest, and possesses nine or ten phalanges. The abdominal ribs are very strong, and reach from the pectoral to the pelvic girdle. Range from the Lower Trias to the Lower Oolite, chiefly European. P. dolichodirus and P. conybeari, the latter reaching a total length of more than 15 feet, from the Lower Lias, especially at Lyme Regis.

FAM. 3. ELASMOSAURIDAE.–The neck is extremely long, possessing from thirty-five to seventy-two vertebrae, with single-headed, not bifurcated, ribs. The scapulae meet ventrally, and enclose with the very broad coracoids two foramina. The tail is short. The pisiform bone articulates with the humerus. Otherwise much resembling the Plesiosauridae. Principal genus Cimoliasaurus, with many synonyms, and many species from the Middle Oolite to the Upper Chalk; cosmopolitan distribution, e.g. C. cantabrigiensis, of the Greensand and Upper Chalk; C. trochantericus, of the Kimmeridge clay; C. haasti in New Zealand; C. australis, C. chilensis; others in North America. Cryptoclidus of the Middle and Upper Oolite of Europe. Elasmosaurus, of the Upper Cretaceous formation in Kansas, with a computed total length of 45 feet, of which 22 belong to the neck, with its seventy-two vertebrae.

SUB-CLASS VIII.–ICHTHYOSAURIA.

Marine, whale-shaped reptiles, with the anterior and posterior limbs transformed into hyperphalangeal paddles. Restricted to the Mesozoic age from the Trias to the Upper Chalk.

The skull is long, owing to the elongated slender snout, which {479}is formed mainly by the premaxillary bones. The nostrils lie far back, in front of the orbits, and are bordered by the long nasals, the premaxillaries, a small part of the maxillaries, and posteriorly by the large lacrymal bones. The eyes are large, and are strengthened by a sclerotic ring composed of many closely overlapping bones. The orbits are very large, and are directed sideways so as to be scarcely visible from above. They are formed above by the long prefrontals, which join the postfrontals; behind by the long postorbitals; below by the long and slender jugals; in front by the lacrymals and prefrontals. The postorbito-temporal region of the skull is short but high, and, with the exception of the supratemporal foramen, is entirely closed in by bones, namely, the quadrato-jugals, supratemporals, and squamosals. The latter, with the parietals and large postfrontals, surround the supratemporal foramina. The parietals and the small frontals enclose the parietal foramen. The whole temporal arch consequently recalls much that of the Pareiasauri and Stegocephali, chiefly owing to the presence of conspicuous supratemporal and postorbital bones, which, together with the quadrato-jugal, close in the whole side without any indication of a lateral or infratemporal foramen. The postorbital completely separates the jugal from the quadrato-jugal, and this almost hides the quadrate. The occipital condyle is single. The lateral occipitals and the supra-occipital bones retain their sutures. The pro-otic and opisthotic bones remain separate. The latter lie between the basi- and lateral occipitals, the squamosal, quadrate, and pterygoid. The pterygoids, which posteriorly touch the quadrato-jugals, basi-occipitals, opisthotics, and basisphenoid, are very long and remain widely separated from each other; in the space between them appears the long ensiform presphenoid. Anteriorly they are connected through the ectopterygoids with the maxillae, and touch the palatines. These are likewise narrow and slender, but touch each other in the middle line, and contain the well-separated, slit-like choanae, laterally to which lie the elongated, rather narrow, palatal vacuities. The vomers are mostly not visible; when they appear on the surface they are long and narrow, and enclose the choanae between them and the palatines.

The teeth are pointed, conical and thickly covered with enamel, which in transverse sections forms vertical ridges, recalling {480}the folds of the Labyrinthodonts. The teeth have open roots, and are not implanted in separate alveoli, but lie in long grooves of the premaxillaries, maxillaries, and dentals.

The vertebrae are numerous, up to 150, two-thirds of which belong to the tail. The centra are deeply biconcave and short, not co-ossified with the neural arches, which have therefore often broken loose. The atlas much resembles the other cervical vertebrae in so far as its centrum is concave in front and scarcely ankylosed with that of the second. Its basiventrals, equivalent to the ventral half of the atlas-ring of other reptiles, thus become an unpaired intercentral wedge, between the first centrum and the basis of the cranium; the neural arches rest upon the centrum, but remain separate from each other, or at least diverge dorsally. The atlas carries no ribs. Intercentra occur also between the second and third vertebrae; they reappear in the tail as chevron-bones. All the other vertebrae carry ribs, which gradually increase in length towards the trunk and decrease again equally gradually on the tail. In the neck and trunk they have separate capitula and tubercula, which articulate upon short knobs of the centra; towards the tail these shift farther and farther towards the ventral side, and ultimately unite. Although the ribs of the trunk are so long, there is no trace of a sternum, but there are many "abdominal ribs" crowded together, each consisting of a middle and a pair of lateral pieces.

The shoulder-girdle is very complete, but the pieces remain separate, or at least do not co-ossify; it consists of a T-shaped interclavicle, clavicles, broad coracoids touching each other in the middle line, and short scapulae. The existence of small separate precoracoids is doubtful. The pelvis is much reduced; the small ilium is quite unconnected with any vertebrae; the small pubes and ischia form no symphyses. The fore- and hind-limbs are very similar to each other; the posterior are, however, much smaller. Both are transformed into highly specialised paddles. It is of the greatest importance, as an indication that the Ichthyosauri are descendants of a terrestrial stock, and have been modified into what they are owing to having taken to marine life, that in the oldest members known, the paddle-like structure of the limbs was less advanced than in the later species. In Mixosaurus of the Muschelkalk of Europe the ulna and radius are still distinctly longer than broad, and they enclose a space {481}between them. They articulate with three carpal bones, the ulnare, intermedium, and radiale, while a small pisiform bone lies on the outer side, between the ulnare and the outer distal carpal bone. In Ichthyosaurus, from the Liassic period onwards, the ulna and radius are much shortened, broader than long, and touch each other without any intervening space; the pisiform element is enlarged. Lastly, in Ophthalmosaurus of the Middle Oolite (but not in contemporary species of Ichthyosaurus) the ulna and radius are still more reduced, and the pisiform has moved up to the humerus, so that the latter articulates with three bones.

Other important features of these paddles are not only the much-increased number of phalanges (sometimes up to twenty or more), but also the increase of digits to six or more, produced apparently by a splitting of the third finger into two series, and by the development of additional rows of phalanx-like bones on the outer and inner margins of the paddle. This increase of fingers exists, for instance, in Ichthyosaurus communis, but not in I. tenuirostris. Owing to this peculiar development of paddles the constituent bones are extremely numerous, and from the radius and ulna downwards they are all closely packed, and have assumed a polygonal, often hexagonal, shape, dwindling to more or {482}less flattened nodules towards the ends of the digits. These carpal and phalangeal bones are common objects in amateurs' collections; they fit together by the short angular facets, while the two flat and broader surfaces are those of the dorsal and ventral sides.

The Ichthyosaurs lived upon fishes and cuttlefish, as is indicated by their dentition and the shape of the snout, and proved by the coprolites, most of which are full of fragments of bones and ganoid scales of fishes, and of the beaks and shells of cuttlefish; the larger of these true coprolites (literally "petrified dung"), in coprolite-beds, contain also an abundance of other fossils, such as Ammonites, Terebratulae, molluscs and fish-remains; they are several inches long, and many of them show on the outside ring-like impressions, undoubtedly caused by a spiral valve of the intestinal canal. In conformity with their absolutely aquatic life the Ichthyosaurs were viviparous. Several well-preserved adult specimens have been found, which contain the skeletons of one or more rather large young within the body, in exactly the position in which such foetal creatures would lie, namely, with the head in the pelvic region of the mother, while the rest of the body stretches along the vertebral column towards the chest. The suggestion that these young Ichthyosaurs have been swallowed by their cannibal elders is too idle to require serious refutation.

Until within a few years Ichthyosaurs were always restored with a smooth and even back, but several well-preserved specimens have come to light in Würtemberg which show the complete contour of the animals, with a long, somewhat jagged fin on the middle of the back. Since then not a few specimens in various collections have on closer examination revealed the same feature, except, of course, those in which the outlines of the fin had been chiselled away in order to "improve" the look of the slab. The fins were undoubtedly of the "adipose" kind;–raised folds of the skin. The latter is now known to have been covered, at least at the bases of the dorsal fins, with hard little scales, probably osteoderms.

Many specimens are beautifully preserved, others present a very peculiar appearance. They look, namely, like long rolls of clay, and nobody but an expert would suspect an Ichthyosaurus within such a log. The explanation is simple. The dead {483}creature was rolled about by the waves of the surf on the Liassic muddy beach until it was wrapped in a mantle of clay and then imbedded on the shore.

The distribution of Ichthyosaurs in time and space is wide. The earliest are found in the Middle Trias; in the Lias they are very common, fairly frequent in the Oolites, dying out with the Cretaceous epoch. They have left no descendants, being far too specialised, and their origin is quite unknown. Mixosaurus, the oldest genus, occurred in Europe, and has also been found in the Triassic strata of Spitsbergen. Ichthyosaurus, the chief genus, is known from the Liassic, Oolite, and Cretaceous strata of Europe, a famous place being Lyme Regis; and also from the Cretaceous strata of Queensland and New Zealand. The Jurassic of Wyoming has yielded Baptanodon.

ORDER ICHTHYOSAURI.

The few genera are easily recognised.

Mixosaurus, Triassic, with radius and ulna still elongated, a longitudinal space occurring between them. Both jaws with numerous uniform teeth.

Ichthyosaurus, with much shortened radius and ulna; both jaws with uniform series of teeth. Many species are known, some with four to five, others with several additional and incomplete rows of fingers and toes. I. trigonodon of the Lias in Würtemberg seems to have reached the size of 30 feet, the vertebrae showing a diameter of 9 inches, while the skull is 6 feet long. I. communis and I. tenuirostris are common in the English Lias. The long-snouted I. campylodon, with large, spaced teeth, occurs in the Gault of Cambridge, Dover, and France; and {484}there are many others. Ophthalmosaurus, of the Upper Oolitic and Cretaceous formations of England, had very small vestigial teeth.

Baptanodon, of the Upper Jurassic epoch of Wyoming, was toothless, and was one of the six-toed forms.

SUB-CLASS IX.–PTEROSAURIA.

Mesozoic reptiles with fixed quadrate bones and with the anterior limbs transformed into wings, the enormously elongated ulnar finger carrying a patagium.

The skull bears a superficial resemblance to that of Birds. It articulates with the neck by a single condyle, at nearly a right angle. The interparietal foramen is absent, but there are five pairs of foramina on the surface of the skull, namely, the nostrils, orbits, supra- and infra-temporal and pre-orbital foramina. Most of the constituent bones of the cranium fuse with each other, and the composition of the various arches is therefore difficult to make out with certainty. The premaxillaries are fused together, and extend dorsally backwards between the nasals, which themselves diverge towards the prefrontals. The nostrils are bordered chiefly by the maxillaries, nasals, and prefrontals. The orbits are very large, mostly shut off in front from the pre-orbital foramina by a bridge, which is formed by descending processes of the prefrontals and ascending processes of the jugal. Above and behind, the orbits are bordered by the frontals, postfrontals, and possibly the quadrato-jugals. The whole temporal region is shortened from before backwards, but heightened dorso-ventrally, and the whole temporal fossa is divided into a supra- and infra-temporal portion by the junction of the postfrontal with the squamosal, the latter joining the parietal, thus closing the supratemporal fossa behind. This is conspicuous only in the older forms, e.g. Dimorphodon, but is very small in Pterodactylus, and quite abolished in Pteranodon. The infratemporal fossa is a narrow slit, slanting obliquely upwards and backwards, between the quadrate and the quadrato-jugal. A foramen of this kind occurs elsewhere only in the Rhynchocephalia. The quadrate is long, firmly fixed, and slants so far forwards that the mandibular joint lies on a level below the middle of the orbit. The pterygoids articulate with strong and long processes of the basisphenoid, touch the quadrate posteriorly, enclose an interpterygoid vacuity, {485}and extend forwards as slender bones to the vomer, separating the palatines. The choanae are enclosed by the vomer, palatines, and maxillaries, and they lie in dorsal recesses above the level of the roof of the mouth. The teeth are alveolar, pointed, of variable size, and restricted to the jaws; in the Pteranodonts they are absent.

The brain is known from the natural cast of Scaphognathus, and shows some remarkably bird-like features, especially the width of the hemispheres, which touch the well-developed cerebellum, while the optic lobes lie on the sides of the cerebellum, with a pair of appendices, the so-called flocculi, elsewhere known in birds only.

The caudal vertebrae are still amphicoelous, while the presacral vertebrae are procoelous. Abdominal ribs are few in number and are very thin. The true ribs possess capitula and tubercula; those of the neck are very short and directed backwards; in the thoracic region they are long, and some are attached to a broad sternum with a keel and a median anterior process, on the sides of which latter articulate the coracoids. Precoracoids and clavicles are absent. The scapulae are long, sabre-shaped, and turned back as in birds; in Pteranodon they show the unique modification of articulating with special processes of the neural arches of several ankylosed thoracic vertebrae.

The hand possesses only four fingers; the four phalanges of the ulnar finger are very much elongated for the support of the patagium; the other fingers remain short and are provided with little claws. The ilia are expanded horizontally, and are firmly attached to from three to six vertebrae, which mostly fuse together into a sacrum. The ventral half of the pelvis consists of a pair of broad bones, which contain a small obturator-foramen; they form a ventral symphysis, and are usually fused with the ilium. These bones represent the conjoint ischia and pubes, while the so-called pubes, a pair of flat and club-shaped bones, are excluded {486}from the acetabulum. The whole arrangement resembles that of the Crocodilian pelvis. The hind-limbs are bird-like in so far as the fibulae are reduced to splints, and attached to the proximal halves of the long and slender tibiae. The feet contain five separate toes with rather long metatarsals and short claws. Many of the bones are hollow.

The Pterosauria have no relationship with the birds, in spite of the number of apparently striking resemblances (e.g. choanae, pre-orbital foramina, brain, scapula, fibula, cervical vertebrae), which are, however, coincidences, cases of convergence, in conformity with the aerial life. The totally different plan of the wings is sufficient to show this. On the other hand, the real affinities of this group of flying reptiles are unknown. They turn up "fully fledged" in the Lower Lias, and they reach their highest specialisation in the Upper Cretaceous epoch, with which they have died out. In fact we do not know any forms through which to connect them with other extinct reptiles. The skull shows some Rhynchocephalian features; the pelvis, Crocodilian features; and this combination points back a long way.

ORDER PTEROSAURI.

SUB-ORDER 1. PTERODACTYLI, with alveolar teeth in the upper and lower jaws. Imperfect remains, impressions of phalanges of the long patagial finger, are known from the Rhaetic of Würtemberg. The oldest well-known genus is Dimorphodon, Lower Lias of Lyme Regis. D. macronyx.–Total length between 3 and 4 feet, of which the large light skull takes up about 9 inches, and the long thin tail about 2 feet. The patagial finger is about 20 inches, the whole wing about 28 inches long. Rhamphorhynchus longicaudatus of the Upper Oolite of Germany is remarkable for the long slender teeth, which are directed forwards and separated by wide spaces from each other. The nine or ten cervical vertebrae are elongated. R. phyllurus of the same geological age has left impressions of the flying membranes. They extend from the whole length of the wing and the sides of the trunk to the thigh as far as the knee, and from the inside of the hind-limbs to the tail. The end of the tail carries a spatulate membrane. Allied is Ornithocheirus, with many species in the English Wealden and Greensand. {487}Pterodactylus, with many species from the Upper Oolite, chiefly of Germany.–The tail is very short, consisting of a few vertebrae only. The seven neck-vertebrae are so much elongated that the neck is as long as the trunk with the tail. P. longirostris measures about 1 foot in total length, while P. spectabilis is one of the smallest, only of the size of a lark. The wings, however, measure 10 inches from tip to tip. The largest is P. giganteus, with a "spread" of more than 5 feet.

SUB-ORDER 2. PTERANODONTES.–The beak is long, pointed, toothless, and laterally compressed; mandibular symphysis very long. Pteranodon longiceps.–The skull has a long parieto-supraoccipital crest, which extends far back. The supratemporal foramina are abolished. The pre-orbital and orbital foramina are confluent. The scapulae are attached to several thoracic vertebrae. The skull of this gigantic species has a length of two feet and a half, and the spread of the wings measures nearly 20 feet. This, and several much smaller species, are from the Middle Cretaceous formation of Kansas.

SUB-CLASS X.–PYTHONOMORPHA.

Very long-necked and long-bodied marine Cretaceous reptiles, with movable quadrates, single lateral temporal arches and procoelous vertebrae; with paddle-shaped, pentadactyle limbs; and with the teeth ankylosed to the jaws.

The skull possesses many of the essential features of the typical lizards. The premaxillaries, frontals, and parietals are fused into unpaired bones. There is an interparietal foramen. {488}The nostrils are dorsal, bordered by the premaxillae, nasals, prefrontals, and maxillaries. The quadrato-jugal arch is incomplete, and the orbit is posteriorly confluent with the infratemporal fossa, but a supratemporal space is shut off by the single arch, which is composed of the postfrontal, squamosal, and supratemporal. The latter is interposed between, and connects the squamosal and quadrate with the latero-posterior branch of the parietal. There is a space between this parieto-squamosal arcade and the epi-otic, which is fused with the lateral wing of the lateral occipital bone. The foramen magnum is bordered by the two supra-occipital, lateral occipital, and the unpaired basioccipital bones; the condyle is triple. The quadrate is movable, articulating with the squamosal and laterally expanded epi-otic. There is no bony connexion of the quadrate with the jugal, which is restricted to its anterior half, and attached to the maxillary and lacrymal. The quadrato-jugal is absent as a separate bone; it is probably fused with the anterior surface of the quadrate, as indicated by a perforation of the quadrate, resembling in this respect the Rhynchocephalia. The vomers are long, and separate the elongated choanae from each other. The palatines separate the vomers from the pterygoids, which enclose a long median vacuity and are not connected with the quadrates. The teeth are conical, and stand near the inner margin of the jaws upon little prominences, with which they fuse. Some genera have teeth upon the pterygoids also.

The vertebrae are very numerous and are mostly procoelous. They are noteworthy for the possession of an additional anterior and a posterior pair of articulating processes on the neural arches, homologous with the zygosphenes and zygantra of Snakes and Iguanidae (see p. 582). Intercentra are absent, except in the tail. The ribs have no tubercula, and articulate with the centra of the vertebrae to which they belong.

The pectoral arch is strong. The scapulae are short and broad; the coracoids, fused with the precoracoids, except for a notch, are flat and broad, and meet ventrally; posteriorly they articulate upon the anterior margin of the flat sternum, to the lateral margin of which are attached several ribs. Clavicles and interclavicle seem to be absent. Abdominal ribs are likewise absent. The pelvic girdle is feeble; the ilia, ischia, and pubes are loosely connected with each other, the pairs of ventral elements {489}meeting also in the middle line. The ilia are loosely attached to two vertebrae in the Dolichosauri; in the Mosasauri they have lost this connexion. Both anterior and posterior limbs are transformed into pentadactyle paddles, with much shortened and broadened bones of the arms and legs. The digits are to a certain extent hyperphalangeal, since several of them possess five phalanges.

The Pythonomorpha are undoubtedly allied to the Sauria, but they are certainly not their ancestors, since typical Autosauri occur in the Lower Chalk; nor are the Snakes their descendants, in spite of many convergent resemblances. We consider them to be the marine collateral branch of the Sauria, which rapidly developed highly specialised, often very large forms, restricted to the Cretaceous epoch, with a wide, cosmopolitan distribution.

ORDER I. DOLICHOSAURI.

This older group is characterised by the sutural symphysial connexion of the two mandibles and by the possession of two sacral vertebrae. The body is snake-like. Pleurodont. Dolichosaurus longicollis of the Lower Chalk of Kent and Sussex; total length about 3 feet, with about seventeen cervical vertebrae and pleurodont teeth. Acteosaurus of Istria; anterior extremities distinctly shorter than the posterior pair; tail long. Vertebrae, like those of Dolichosaurus, with zygosphenes. Plioplatecarpus of the Upper Chalk of Holland has a slender interclavicle; the vertebrae are without zygosphenes, but those of the cervical region possess a downwardly directed long hypapophysial process with a separately ossified epiphysis.

ORDER II. MOSASAURI.

The two halves of the lower jaw are connected by ligament and are therefore movable as in Snakes. There are no sacral vertebrae, the pelvis having lost its connexion with the vertebral column. The formation of the limbs into paddles is more pronounced than in the Dolichosauri.

Mosasaurus, the chief genus, so called from Mosa, the Latin name of the river Maas, with several species from the Upper Cretaceous strata of the Netherlands, England, and North {490}America. M. camperi, from Belgium, with a skull about 4 feet in length, armed with many large, curved, acrodont teeth. The vertebral column consists of about one hundred caudal and thirty-four precaudal vertebrae, of which seven are cervical, without zygosphenes. The total length of the type-specimen is estimated at 25 feet.

Platecarpus of North America and New Zealand, and various other North American genera, also contained species of large size.

Liodon.–Premaxilla without teeth, the others nearly smooth instead of being ridged. With a very wide distribution in the Chalk of Europe, North America, and New Zealand. L. haumuriensis of New Zealand seems to have been the giant amongst these monstrous marine creatures; its total length has been computed from imperfect fragments at 100 feet.

Clidastes, of the Upper Cretaceous of North America and Europe, although not so massive, comprises the most elongated forms. The cervical vertebrae possess long median hypapophyses with separate epiphyses; most of the vertebrae are much elongated and have well-developed zygosphenes. C. tortor had a skull nearly two feet and a half long.

{491}CHAPTER XII

SAURIA–AUTOSAURI OR LACERTILIA–LIZARDS

SUB-CLASS XI.–SAURIA.

Reptiles with movable quadrate bones, with a transverse, external, cloacal opening, near the posterior lateral corners of which open the eversible, paired (right and left) copulatory organs.

The Sauria, which comprise the AUTOSAURI or Lacertilia in the wider sense and the OPHIDIA or Snakes, are the most recently developed groups of Reptiles. No fossils are known from strata earlier than those of the Cretaceous epoch. Their origin has probably to be looked for among the Prosauria, of which Sphenodon, cf. p. 294, is the only surviving member. The Sauria have attained their great development within the Tertiary period. They, both Autosauri and Ophidia, are now the two dominant Reptilian groups, and they have, so to speak, a future before them, being apparently still on the increase in numbers and species, but certainly not in size.

ORDER I. AUTOSAURI OR LACERTILIA–LIZARDS.

Saurians which have the right and left halves of the mandibles connected by a sutural symphysis.

The overwhelming majority possess well-developed limbs, movable eyelids and cutaneous scales, covered by the mostly thin and horny epidermis. But there are many kinds of Autosauri, especially those belonging to the degraded, burrowing families, which have lost not only one or both pairs of limbs, but even the limb-girdles, while the eyes have become concealed beneath the skin, and in some cases the scales have been lost, or reduced {492}to mere vestiges. Moreover in some of these burrowing and limbless forms the quadrate bones have become more or less immovable.

We divide the Autosauri into three sub-orders:–I. GECKONES, p. 502; II. LACERTAE, p. 513; III. CHAMAELEONTES, p. 567, with about 270, 1500, and 50 species respectively.

The Autosauri are of great interest, since they exhibit a great, almost endless variety in shape, size, and structure in direct adaptation to their surroundings. Most of these modifications are restricted to the external organs, or rather to those which come into direct contact with the outer world, namely the skin, the limbs, the tail, or the tongue. The majority of the Autosauri are terrestrial, but there are also semi-aquatic forms. There are climbing, swiftly running, and even flying forms, while others lead a subterranean life like earthworms. Most of them live on animal food, varying from tiny insects and worms to Birds and Mammals, while others live upon vegetable diet. According to this diet, the teeth and the whole digestive tract are modified. The intestine is relatively short in the carnivorous, long in the herbivorous species. But swiftness, the apparatus necessary for climbing, running, and digging, the mechanism of the tongue, the armament and the muscles of the jaws (hence modifications of the cranial arches, etc.), stand also in correlation with the kind of food and with the way in which it has to be procured.

A very interesting study of the influence of the climate and the nature of the country upon Reptiles has been made by Boettger with especial reference to the Transcaspian desert-region. The winter is there short, but very severe, and there is a considerable amount of snowfall, while the summer is intolerably hot. The spring arrives suddenly. Lilies and tulips, which have been asleep for nine or ten months, sprout towards the end of February, and a carpet of flowers covers the ground for a short time. Then everything shrivels up during the rainless and fierce heat of the summer, and the autumnal storms of dust and sand kill off the last remnants of vegetation. There are no trees, and even prickly shrubs are rare. Instead of broad leaves the plants have grass-like blades or needles. The little shrubs do not form coherent patches, but they are scattered {493}about, and around the roots of each shrub the wind accumulates little mounds of sand and dust, a place of retreat for rodents, lizards, snakes, and even for the female tortoises. G. Kadde's "law of the steppe" is in full force;–there is little change of forms in a wide district, but all these forms are peculiar, and they congregate socially in great numbers. Most characteristic are those kinds of Geckos which, like Teratoscincus, cf. p. 507, have become inhabitants of sand instead of climbers of rocks and trees; various kinds of Phrynocephalus, cf. p. 521, and Varanus griseus; the four desert-species of Lacertidae are brownish-grey or sandy yellow, with conspicuous stripes or spots. Of snakes are to be mentioned Eryx jaculus, digging in the sand, and about ten other non-poisonous snakes. Tropidonotus is, of course, restricted to permanently watery places, where they can get frogs and fishes. Of poisonous snakes there is the Cobra and Echis arenicola. Of Amphibia only Bufo viridis and Rana esculenta var. ridibunda exist in suitable places, but there are neither Tree-frogs nor Newts.

Characteristic features of these inhabitants of the desert are the following:–

1. Velocity. The Lizards are slender. The Sand-snake, Tephrometopon, is whip-like; even the Cobra has a relatively narrower and longer tail than the Indian specimens, although the number of the vertebrae and of the scales is the same. All the desert-snakes are remarkable for the great number of their ventral shields, two hundred and more.

2. Hard, scaly covering, for instance in Agama, Echis, Gymnodactylus, Teratoscincus; the latter with its fish-like scales is exceptional among Geckos, resembling the likewise deserticolous Geckolepis and Homopholis of Africa.

3. Capacity for digging in the sand in order to escape great cold, or burning heat. All the Lizards and the Tortoise, Testudo horsfieldi, have strong claws. The snakes Typhlops and Eryx dig with their specially modified snouts, and their tails are very short and blunt. The Sand-viper, Echis, has the scales of the back arranged in very oblique rows, so that it can heap sand upon its body by wriggling, shaking, and up-and-down motions of the body. The Agamoid Phrynocephalus does this by means of lateral folds of the skin.

4. Arrangements for running on sand. The lizard Eremias {494}has very large crural shields; Scapteira has the digits broadened out into shovels; others, e.g. Phrynocephalus and Teratoscincus, have long lateral fringes on the digits, a very rare arrangement among Geckos, occurring elsewhere among them only in Ptenopus and Stenodactylus, which are likewise inhabitants of the desert.

5. Protection against the everlasting, ubiquitous sand. In the digging species the nostrils are directed upwards instead of forwards; in most of the snakes they are protected by complicated valves, or they are reduced to small pin-holes. The eyes of Typhlops are overhung by the head-shields. In Agama and Phrynocephalus the margins of the lids are broadened into plates and are furnished with peculiar scales. In Teratoscincus the upper lid is enlarged. The lizard Mabuia has the lower lid much enlarged, with a transparent window in it, so that the eye can be closed without impeding sight, an arrangement carried to the extreme in Ablepharus, cf. p. 560. The ear-opening is either small, or protected by fringes of scales, or it is abolished, e.g. in Phrynocephalus.

6. Coloration. Pure green is quite absent, even in Bufo viridis and in Rana esculenta, since there is no green in that country, at least not of long duration. White, with grey and black spots, occurs only in the nocturnal Geckos. Yellow, brownish, reddish colours are common, in adaptation to the sand. The advantages of the carmine-red, and of the blue spots of Phrynocephalus, and the yellow or bright red under surface of its tail, are unknown. Striation is of frequent occurrence among the lizards and snakes, probably in adaptation to the dry grass heaped up around the scattered shrubs.

Concerning the various organic systems of the Autosauri only some of the more important features may here be mentioned.

SKELETON.–The vertebrae are procoelous, with the exception of most of the Geckones, in which they are amphicoelous. So-called intercentra, in the shape of unpaired nodules or wedges, persist between most of the cervical vertebrae. In the tail these wedges, the remnants of the basiventralia, are generally present, frequently in the shape of chevron-bones. Sometimes they fuse with the centra of the vertebrae; occasionally the axial or central portion of these basiventrals persists as a sort of fibrous disc, which may calcify separately, and is interposed between the caudal end of the centrum and the articulating {495}knob. The caudal vertebrae of the Geckones and of most Lacertae are liable to break across, like those of Sphenodon. They are enabled to do this owing to a transverse split, which makes its appearance with the ossification of the vertebral bodies and extends later into and across the neural arch and the various lateral processes. The split is ultimately referable to a transverse septum of cartilage, wrongly called chordal cartilage, which develops in the shell of the body of the vertebra, destroys the chorda, and extends peripherally. The cells of this septum retain throughout life their juvenile quasi-embryonic character. When the tail is broken off–and this always happens at such a septum–the cells of the remaining half reproduce a new tail. The latter is, however, in reality a sham tail, since neither new centra nor arches, but only a non-segmented rod or tube of fibro-cartilage is produced by this process of regeneration. Reproduction of centra is precluded by the previous normal reduction of the chorda, around which alone proper bony centra could be formed. The regenerated tail is, however, invested with new muscles, and with skin, but the scales often differ considerably from those of the normal organ. Boulenger has found that the new or aberrant scaling is in some cases a reversion to an ancestral form. This is, for instance, the case in Pseudopus, and in the Tejoid genus Gymnophthalmus; to a certain extent also in Geckos and Skinks. On the other hand, Lacertidae, Gerrhosauridae, and also Anguidae reproduce a caudal scaling true to their type. Injured or broken-off tails are often reproduced double, or even trifid; sometimes an additional little tail grows out from an injured spot, anywhere on the side of the old remaining but mended tail.

The ribs of the trunk articulate by their capitula only, while the reduced tubercula are attached to their vertebrae by ligaments. In the tail the capitular portion is much reduced, while the tuberculum is much stronger and lies behind, no longer above, the capitulum, fusing sometimes directly with the centrum. The ribs of the poststernal region of Geckos and Chameleons are very long, and meet each other in the middle line, forming thin cartilaginous hoops.

The limbs are of the typical pentadactyloid type. The distal tarsalia are often fused with the metatarsals, so that the chief {496}bending of the foot is effected by truly intertarsal joints. The greatest modification occurs in the foot of the Chameleons, in which the proximal tarsalia are reduced in number, and form a globe for the articulation with the tibia and fibula.

The shoulder-girdle and sternum much resemble that of Sphenodon in their completeness. The coracoids articulate with the sternum; the precoracoids and the basal parts of the scapulae often send out several processes towards those of the other side, so that several fenestrae are formed. The clavicles are complete, but are absent in the Chameleons. The interclavicle is mostly T-shaped. A presternum is absent, but the sternum proper is well developed, often forming a rhomboid plate, usually cartilaginous, often diverging backwards into xiphisternal processes.

The pelvis is attached to two vertebrae by means of several ribs. The ischium and pubis form symphyses. The pubis carries a well-developed lateral process, and the obturator-nerve pierces the shaft of the pubis. Epipubic and hypo-ischial cartilages are of frequent occurrence.

The hyoid apparatus consists of a median, styliform rod, which extends forwards into the tongue; it is often bifid behind. The unpaired piece carries two pairs of horns. The posterior of these, the first pair of branchial arches, extends backwards along the gullet, and is very long if the tongue is very slender and protractile. The anterior pair, the hyoid arches, consists of two pieces on either side, one short and directed forwards, the other long, connected with the former at a sharp angle and continued upwards to the sides of the skull, often in direct continuity with the columellar chain of the ear.

The modifications of the skull concern chiefly the composition of the temporal arches, see Figs. 55, M, N, O, p. 281. The quadrate bone is movable, but it has become fixed in various degraded families, where the skull shows a great reduction and concentration; the postorbital and temporal arches, the interorbital septum, and with it the columellae cranii are lost. The columella cranii of the Chameleons, which is generally stated to be absent, is really present, although in a much reduced state, and is partly imbedded in the interorbital septum. The occipital condyle has become bifid in Amphisbaenidae.

Burrowing and living in sand are often correlated with partial or complete reduction or loss of the limbs and their {497}girdles. This loss of limbs is as a rule correlated with an elongation of the trunk, not always at the expense of the tail, which in such cases is much shortened. The vestiges of the hind-limbs come to lie as near the vent as possible. This reduction of the limbs occurred in several families which are not directly related to each other. Moreover, it does not occur in all the members of the family, not always in those of the same genus, and there is a considerable amount of individual variation. In most cases of reduction the fore-limbs disappear before, or are smaller than, the hind-limbs. In the Amphisbaenidae (cf. Chirotes, p. 566), and in the Tejidae the reverse takes place. In extreme cases the reduction is so complete that even the pectoral girdle has disappeared, leaving scarcely any trace, e.g. in Dibamus, p. 564.

The SKIN is normally covered with scales, which are formed by the cutis and have a horny epidermal coating. The latter, thin and transparent, is shed periodically, peeling off in flakes, except in Anguis and perhaps other snake-shaped creatures, which shed the skin in one piece. In the Amphisbaenidae the scales have practically disappeared. When well developed the scales are prominent, and imbricate or overlap with their free posterior edges; but in many cases the scales are not "scale-like" at all, only like little tubercles, which give the skin a granular appearance. Frequently, for instance in the Scincidae and Anguidae, all the scales contain "osteoderms," or ossified portions of the cutis, and encase the whole body and tail. In other families, e.g. Lacertidae, such osteoderms are restricted to the scales or shields on the head, where they come into contact and fuse with the underlying cranial bones, and moreover roof in the supratemporal fossa.

The skin of the Autosauri is entirely devoid of glands. The femoral and pre-anal pores of many families, occurring especially in the males, are probably not glands. They are arranged in rows on the under surface of the thighs and in front of the anal opening. Each of these organs perforates a scale and leads into a tubular invagination, which is lined with epidermal cells, the proliferation of which produces a horny yellowish débris, and this fills the tube and appears above the surface in the shape of a little cone. The use of this "excretion" is unknown; it is possibly hedonic.

{498}Most Autosauri are capable of changing colour. In most of them this faculty is restricted to the assumption of paler or darker tints owing to the shifting of the colouring matter contained in the chromatophores. In others new, often vivid colours are the result. The mechanism is described in detail in the Chameleon on pp. 570 and 574.

Pigment is deposited either directly in the upper strata of the cutis, just below the Malpighian layer, or it is contained in chromatophores. The latter are imbedded in the deeper layers of the cutis, and send out movable contractile processes, in which their pigmented protoplasm is conveyed towards or away from the surface. The only colours available are black, red, yellow, and white, with their combinations of grey and brown. The white pigment consists of guanin-salts. Blue and green are structural colours, not due to pigment. The same can no longer be said of the Ophidia, since Boulenger has observed accidentally that green Tree-snakes (e.g. Dryophis) give the alcohol in which they are kept the colour of green Chartreuse.

DIGESTIVE ORGANS.–The tongue is very variably developed, and affords good taxonomic characters. It is always furnished with many tactile, or with gustatory, corpuscles. When the tongue is very long and narrow it is generally forked, and in these cases, for instance in the Varanidae, is almost entirely used as a sensory organ. In others, especially where it is broad, it assists in catching the food, and in the Chameleons it has attained a most elaborate development (see p. 569).

Salivary glands are restricted to labial glands. In Heloderma those of the lower jaw are transformed into poison-glands, an analogy to what prevails in the poisonous snakes. The intestinal canal is longest in the herbivorous forms; the rectum sometimes possesses a short blind sac or caecum.

The CLOACA of the Sauria is somewhat modified; instead of the Coprodaeum, Urodaeum, and Proctodaeum forming three successive chambers, the urodaeum is practically reduced to its dorsal half, forming a dorsal recess between the two other chambers. The Coprodaeum is constricted into several successive chambers, and is always well shut off from the urodaeum by a strong sphincter. The urodaeum receives the urinary excretions, which are mostly chalky white and are rather consistent instead of being fluid. The right and left oviducts also open into it. The vasa {499}deferentia open into the dorso-lateral portions of the walls of the urodaeum, but the sperma is conducted by folds of the lining of this chamber towards the bases of the copulatory organs, which, although arising from the lateral and posterior corners of the cloaca, where uro- and procto-daeum meet, are stowed away outside the cloaca. These organs are always paired. The proctodaeum or outermost cloacal chamber is shallow. Its inner opening is round and is furnished with a sphincter, but it is surrounded and covered by lips of the outer skin, which form a transverse slit. This is due to the peculiar arrangement of the copulatory organs.

Each organ consists of a tube of erectile tissue, and can be everted like the finger of a glove. To the apex of the tube is attached a long retractor muscle, which arises from the ventro-lateral surfaces of the caudal vertebrae and extends a considerable distance back. When at rest and withdrawn the organs form slight conical, longitudinal swellings on either side of the root of the tail, an external feature by which male specimens can generally be distinguished. Only one organ is inserted at one time.

The majority of Autosauri lay EGGS, surrounded by a white or yellowish shell, which is either hard, for instance in Geckos, or parchment-like, e.g. in Chameleons, in Lacerta viridis and L. agilis, and in L. vivipara. Eggs with a thin and soft shell sometimes exhibit the paradoxical feature of increasing in size after they have been laid. This is explained by the growth of the embryo, which stretches the shell and does not merely live upon the white and yellow contents of the egg itself, but also takes in air and moisture. Many Lizards do not lay their eggs until they contain ripe embryos, which burst the shell shortly after deposition. Some, for instance Lacerta vivipara, Anguis fragilis, and Chamaeleo pumilus, are practically viviparous. The embryos, especially those which are enclosed in hard-shelled eggs, are provided with a sharp, calcareous "egg-tooth" on the top of the snout.

The LUNGS are thin-walled sacs, sometimes provided with lateral ex-sacculations, and these reach their greatest development in the Chameleons. The breathing is effected by the motion of the ribs. Inflatable sacs on the throat, or on the sides of the neck, for ornamental or sexual purposes, occur in various families. The lungs of much-elongated, snake-shaped Lizards are generally {500}asymmetrical; the right being reduced in Amphisbaenidae; the left in other cases.

Several Autosauri, for instance the Geckos, Psammodromus, and various other Lacertidae have a weak voice.

The FAT-BODIES are mysterious organs which are situated beneath the skin, and extend from the inguinal region forwards along the ventral sides of the belly. They are often of considerable dimensions; largest in the spring, in both sexes, at the time of propagation. Their colour is greyish-white or yellow, owing to the great accumulation of fat in the meshes of the connective tissue which composes the frame-work of these organs. An artery enters them, breaks up into capillaries, and these combine to form an efferent vein. After the time of propagation these organs are reduced to grey or reddish flaps, consisting mainly of very vascular connective tissue. G. W. Butler has written a long paper on their morphology. The same author has investigated the "sub-divisions of the body-cavity in Lizards, Crocodiles, and Birds," with reference to peritoneal diaphragmatic structures.

The GEOGRAPHICAL DISTRIBUTION OF THE AUTOSAURI teaches few, but important lessons. We have to restrict ourselves to the principal families, leaving out those which are small and have a limited distribution; also those which, like the few Anelytropidae in Africa and in Mexico, are not natural groups.

The Geckones, which are probably the oldest of modern Autosauri, are practically cosmopolitan, being absent only in the cold and in the cooler temperate regions. They are common even in Oceanic Islands, for instance in New Zealand and in the Sandwich Islands. Although not at all aquatic, they are particularly fit to be transported accidentally on or in the trunks of floating trees, to which they cling firmly, and they can exist without food for months. I once received a little South American Gecko in perfect health from a grocer, who found it in a well-closed wooden box containing canned meat, two months after delivery of the box in Cambridge.

The Scincidae, likewise an old family, are equally cosmopolitan, but although many exist in the islands of the Pacific a few only occur in New Zealand. Many of the genera have a very wide distribution; for instance, Lygosoma, with its one hundred and sixty or more species, occurs in the Australian and {501}Palaeotropical regions, and also in North and Central America, not extending, however, into South America. Mabuia, with more than sixty species, occurs in the Palaeotropical and the Neotropical regions. Whether these and other widely-distributed genera are all natural is another question.

The Agamidae, Varanidae, Lacertidae, and the Chamaeleontes are restricted to the Old World. The Agamidae and Varanidae have the widest distribution, occurring in the whole of the Old World with the notable exception of Madagascar and New Zealand. The Lacertidae are Palaearctic and Palaeotropical, being however absent in Madagascar, and, broadly speaking, not extending eastwards beyond Wallace's line. It is a most suggestive fact that most of those families of Reptiles, and even of other Vertebrates which have a wide distribution and are apparently debarred from transgressing Wallace's line, are also absent from Madagascar.

The Chameleons are essentially African, with their centre of greatest abundance and development in Madagascar, only one or two species occurring in Socotra, Southern Arabia, and in Ceylon and Southern India. Since they also exist, Ch. sechellensis, on various islands in the Indian Ocean, for instance in Mauritius and the Seychelles, the Chameleons are perhaps an indication of the former existence of a direct land-connexion between Southern India and Southern Africa.

The Iguanidae are essentially American, with the remarkable exceptions of Chalarodon and Hoplurus in Madagascar, and Brachylophus in the Fiji and Friendly Islands. This peculiar distribution finds some analogies in that of Dendrobatinae (p. 272), certain Boinae (p. 601), and Centetes and Solenodon among Insectivora. An Iguana (I. europaea) has, however, been described from the Eocene of France and England. The supposed relationship of the Iguanidae with the Agamidae makes the problem only more puzzling, since Agamidae are absent in Madagascar. If we have recourse to the Zonuridae, which are confined to Africa and Madagascar, and are supposed to be intermediate between Anguidae and Iguanidae, then we may have ultimately to conclude that the Malagasy Iguanoid genera and the American Iguanidae are a case of convergent evolution.

The Amphisbaenidae are distributed over America, including the West Indies, Africa exclusive of Madagascar, and the {502}Mediterranean countries. This is very puzzling, considering that these subterranean, helpless creatures positively cannot travel. Boulenger regards them "as a degraded type of the Tejidae, with which they are to some extent connected by Chalcides and its allies," i.e. genera with reduced limbs, cf. p. 562.

However, this supposed relationship with a strictly American family does not explain the occurrence of Amphisbaenidae in Africa. Either they are not a natural group, or they had, as already degraded, limbless creatures, a much wider range; and this would imply their being a very old family, perhaps as old as we suppose the Coecilians to be.

Anguidae occur in North and South America, in Europe and the Mediterranean parts of North Africa, and in Trans-Gangetic India. Their older relations, the Zonuridae, inhabit Africa and Madagascar.

Madagascar is consequently devoid of Agamidae, Varanidae, Lacertidae, Anguidae, and Amphisbaenidae, while it possesses, besides the cosmopolitan Scincidae and Geckones, only Chameleons, Gerrhosauridae, and Zonuridae,–all three essentially African families,–and a few Iguanidae. This means that the Autosaurian fauna of Madagascar is intimately related to that of Africa, and that it possesses only old families so far as Sauria are concerned. But since this great island was separated from its continent not earlier than in Mid-Tertiary times, it follows that most of these "old" families are comparatively recent.

Australia possesses only Agamidae and Varanidae besides the ubiquitous Geckos and Skinks. Besides the latter two families it has nothing in common either with Madagascar (an analogy with the Anura) or with America. The Autosauri consequently do not support the idea of a Notogaea, cf. p. 74. This again indicates the comparatively recent age of Autosaurian families. The marked difference which exists between the Old and the New World points to the same conclusion. On the other hand, the Autosauri support the idea that the Palaeotropical region is but the tropical and therefore richer continuation of the now impoverished Palaearctic sub-region.

SUB-ORDER 1. GECKONES.–The typical Geckos are characterised as follows. Four-footed Autosauri with amphicoelous vertebrae; skull without bony temporal arches; clavicles dilated and with a perforation near the ventral end; parietal bones {503}separate; eyes (with few exceptions) without movable lids; pleurodont; tongue fleshy and broad, slightly nicked anteriorly, and capable of protrusion.

This definition does not apply to a few forms. In the Eublepharinae the vertebrae have advanced to the procoelous condition, and the parietals are fused together, while the eyes are provided with typical, movable lids. In the Uroplatinae the clavicles are not dilated, and the nasals are fused into one bone. The Geckos seem to be not only a very independent but also a very old branch of Saurians. Although fossil representatives are unknown, the resemblance of their vertebrae to those of the Palaeozoic Microsauri is at least remarkable. They are now practically cosmopolitan within the warmer zones, being found in abundance in all intertropical countries and islands, even in New Zealand. About two hundred and seventy species are known, which have been subdivided into about fifty genera. The generic differences are trivial with few exceptions, and refer mostly to the structure of the digits.

The more important features of the vertebral column are the absence of axial joints and the persistence and life-long growth of the chorda dorsalis. Each vertebral centrum consists of a cartilaginous tube, more or less calcified or ossified, with a narrow waist and a cartilaginous septum in the middle. In the tail this septum, which is only slightly invaded by ossification, coincides exactly with the line of transverse division of the vertebrae into an anterior and a posterior half. This is the level where the tail breaks off and whence it is renewed. Between every two successive centra lies an intercentrum, broadest ventrally, crescent- {504}or wedge-shaped. Dorsally it is continued as fibro-cartilage, and the whole ring acts as an articular pad instead of the joint. Chevron-bones are common in the tail.

The ribs are bifurcated, but the tubercular portion is frequently reduced. The post-thoracic ribs are usually very slender, and so long that they meet each other in the middle line, in this case bearing an extraordinary resemblance to the so-called "abdominal ribs" of other reptiles.

The bony frame of the skull is slender. There is a complete absence of bony arches spanning over the temporal fossae, or bordering the orbit, which is open posteriorly. The upper jaw, owing to the slender and flexible nature of the respective bones, is movable upon the rest of the skull; in this respect not unlike the upper jaw of a duck. The dentition is pleurodont and the teeth are minute. The eyes of the typical Geckos are peculiar. They are covered with an absolutely transparent skin, shaped like a watch-glass, beneath which the eye moves freely, while the true upper and lower lids are reduced to tiny folds. The covering "watch-glass" is probably a modification of the nictitating membrane. In the Eublepharinae, however, and in the few species of the Geckonine genera Aelurosaurus of Borneo and Australia, and Ptenopus of South Africa, the upper and lower lids are present and movable. The pupil contracts mostly into a vertical slit, except in the few diurnal kinds, e.g. Phelsuma, of the islands in the Indian Ocean, and the African Lygodactylus.

Another peculiarity of at least many Geckos is the extraordinary development of the endo-lymphatic sacs of the ear, which, being filled with the chalk-like otoconia or otolithic crystals, perforate the skull, and are stowed away in the shape of a pair of large bags behind the ears, or on the sides of the neck.

The skin exhibits considerable variety. It is mostly soft above, with little granular tubercles, sometimes containing small dermal ossifications or calcifications. The latter are most developed on the head, where they occasionally fuse with the underlying bones. A few species of Tarentola possess supra-orbital bones, independent remnants of such osteoderms. The ventral surface is generally covered with small imbricating scales, but in some genera, e.g. Homopholis, such scales occur also on the dorsal surface, reaching their highest development in Teratoscincus (p. 507). In a few forms, notably in Ptychozoon {505}(p. 512), the skin of the sides of the body and tail is produced into a series of lobes and flaps, the object of which seems to assist adhesion. Many, perhaps the majority of Geckos, have adhesive digits, by means of which some kinds are enabled to climb absolutely smooth and vertical surfaces, for instance a window-pane; or, what is more startling, they run along the smooth, white-washed ceiling, back downwards. The apparatus is complicated in its minute detail, but is very simple in principle. The adhesion is effected neither by sticky matter, nor in the way described in the Anura (p. 187), but by small and numerous vacua. The under surface of each digit is furnished with many transverse lamellae. The pressing down of the foot upon a smooth surface causes the lamellae to spread asunder and to drive out the air; partial retraction lets them return to their original position by virtue of their elasticity; and little vacua are produced. Each lamella is further beset with tiny hair-like excrescences, which secure adpression to even the slightest irregularity of surface and at the same time enhance the elasticity of the pads. The arrangement of the lamellae and pads differs much in the various genera. For instance, the lamellae are either broad and entire, or they are divided into two parallel rows, with or without lateral hairy fringes; or the under surface of the digits is granular, but strongly fringed; or the lamellae are restricted to the dilated tips of the digits, etc. The fingers and toes are mostly furnished with sharp, curved claws, and these are in many cases retractile between some of the lamellae, or into a special sheath. Those Geckos which live on sandy, barren ground are as a rule devoid of adhesive pads, the digits being narrow. The typically padded, adhesive digits cause a peculiar sensation when a Gecko hangs on to one's finger, and this feeling has perhaps given rise to the erroneous notion of stickiness.

The tail exhibits many kinds of shape and size. Mostly {506}cylindrical and tapering to a point, it is leaf-like in Gymnodactylus platurus of Australia; provided with many lobes, and used as a parachute in the Malay Ptychozoon. In Nephrurus asper of Eastern Australia the tail is quite short, much shorter than the limbs, much swollen at the base, and very thin towards the end, which carries a round knob. The tail of all Geckos is very brittle and can be quickly regenerated, except the long rat-like tail of the Persian Agamura. In many other desert-forms the tail is long, slender, and laterally compressed, acting in such cases like that of desert-forms among the Lizards.

Many Geckos have a voice, mostly rather feeble, and sounding like a soft "click" or "chick" produced by our tongue. Repetition of this sound resembles in some species the word "gecko." They lay eggs, rather globular, or but slightly oval, hard-shelled, and white, mostly two in number. Naultinus elegans of New Zealand is said to be viviparous. The males are generally larger than the females, and they are further distinguished by the possession of femoral or pre-anal pores.

All Geckos feed upon animals, chiefly upon insects, but the larger forms take anything they can master. With few exceptions they are nocturnal, which, however, does not prevent them from occasionally baking themselves in the sun. They are capable of changing colour, but since their ground-colour is almost universally grey, yellow, or brown, the range of the colour-changes is restricted to the adoption of darker or lighter hues. The skin is shed in flakes and eaten.

Geckos are absolutely harmless; they cannot even inflict painful bites. However, in many countries they are feared as much or even more than the most poisonous snakes. In the south of Spain and Portugal, for instance, where Geckos are plentiful in and outside the houses, and are consequently objects of daily observation, the "osga" is considered a dreadfully poisonous creature. They become very tame, or rather confiding in their regular habits, provided they are not molested. If caught–and they have many enemies among other lizards and snakes–the only safety of these defenceless and mostly small creatures lies in their tail, which, being extremely brittle, is left in the claws or jaws of the pursuer. The remaining stump soon produces a new tail, in shape and size like the old one, but with a different and simpler scaling. I knew of several specimens of {507}the Portuguese Platydactylus facetanus, which, having lost their tails in the act of being caught, were kept in a box for six weeks without food. On their arrival in England they had each grown a new stump nearly half an inch long!

FAM. GECKONIDAE. SUB-FAM. 1. GECKONINAE.–Vertebrae amphicoelous; parietal bones separate; clavicles dilated and perforated. Hereto belong the overwhelming majority of Geckos, only a few of which can be mentioned.

Teratoscincus scincus.–This most peculiar creature, about six inches in length, inhabits the steppes of Turkestan and neighbouring desert-regions of Persia. It is a thorough desert-form. The digits are devoid of adhesive lamellae, but are granular inferiorly and strongly fringed laterally, an arrangement which is rare among Geckos, practically restricted to it with Ptenopus and Stenodactylus, which are likewise deserticolous. This is a beautiful illustration of adaptation to the surroundings. A Gecko, instead of climbing rocks and trees, has lost the climbing apparatus, or has transformed parts of it for running upon loose sand. The body is covered with imbricating, rather large and smooth scales. The tail is round at the base, compressed in its posterior half, covered below and on the sides with scales like those of the body, but on the upper side with a series of large, transverse, nail-like plates. By rubbing these plates upon each other, this Gecko produces a shrill, cricket-like noise, sitting at night in front of his house, perhaps in order to attract grasshoppers. The noise is made by both sexes.

Ptenopus, a Gecko of Damara Land, likewise adapted to desert-life, produces a similar chirping noise by its throat.

Phyllodactylus is a genus of world-wide distribution, occurring in tropical America, Africa, Madagascar, and Australia, extending to the Norfolk Islands and to Lord Howe's Island. One species, Ph. europaeus, occurs on the islands in the Western Mediterranean. The digits are furnished with transverse lamellae, the greater number of which are broken up into small scales forming three longitudinal series. The ends of the digits are dilated, with two large plates inferiorly, separated by a longitudinal groove into which the claw is retracted. The upper parts of the body are covered with juxtaposed scales intermixed with larger tubercles. The abdominal scales are small and imbricating. The cylindrical, tapering tail is slightly prehensile, covered with {508}small scales arranged in verticils. This species is devoid of femoral or anal pores. General colour above grey-brown, with darker and lighter markings; a dark streak on the side of the head, passing through the eye. Under parts whitish. Total length up to 3 inches. The eggs are almost round, measuring 8.7 by 7 mm.

Hemidactylus, likewise a widely distributed genus, with many species. The digits are dilated, inferiorly with two rows of lamellae; the clawed joints are slender, bent at an angle, and rising from within the extremity of the dilated portion. H. turcicus, between 3 and 4 inches long.–The upper parts of the body are covered with minute granules, mixed with larger tubercles. The abdominal scales are small and slightly imbricating. The male has several pre-anal pores. The tail is covered above with minute scales and tubercles, below with a series of large transversely dilated plates. The general colour is white below, brown above, with darker spots, and with white specks on many of the tubercles. This species extends from {509}Southern Portugal and Spain to Karachi. Like Phyllodactylus and various other kinds of Geckos, the body is semi-transparent; so much so indeed that the white eggs shimmer through the body in certain lights.

Tarentola mauritanica s. Platydactylus facetanus.–The digits are strongly dilated, with undivided lamellae below, and a flat, nail-like scute on their upper surface near the tip. Only the third and fourth digits are clawed. Femoral or pre-anal pores are absent. The upper parts are covered with scales and granules, and bear several longitudinal rows of strongly keeled, large tubercles; the under parts have hexagonal scales. General colour above greyish-brown, with darker or lighter markings; with a dark streak through the eye. Total length of large males about 6 inches. This species is one of the commonest Geckos in the Southern Mediterranean countries. In Portugal it extends northwards to the Douro. It has been introduced by ships into the ports of Cette, Toulon, and Marseilles. It is easily kept in captivity, like most Geckos indeed, provided they are supplied with a variety of insect-food, water in the shape of drops, and suitable places to hide in. A female, which I had received from Algiers in a little tin box, with a lump of meat (presumably its food!), laid two eggs six weeks after its arrival. This was towards the end of April. Towards the end of June in the same year it again laid two eggs, measuring 13 × 10 mm. Another specimen laid in June in two successive years. These and other Geckos live very well in a greenhouse, or in a large glass cage. They change colour most adaptively. They hunt preferably at night for insects, which are stalked and then suddenly rushed at. Drops of water are taken by a lapping motion of the tongue. For sleeping-places they selected bits of hollow bamboo, but these had to be vacated when some tree-frogs crept into them for the daytime, and the Geckos took to some curved pieces of bark, on the under side of which they slept, with their backs downwards. This is, by the way, a favourite position of rest of most Geckos. But Stenodactylus guttatus of Egypt lies flat on its belly, tucks the fore-feet under and inwards like a cat, rests the head upon them, and stretches the hind-limbs out backwards. The little Geckos are rather intelligent. They take no notice of a finger put against the other side of the glass to which they happen to cling; but {510}when the hand is put inside their cage and approaches them too near, they dart off suddenly. When driven into a corner they wriggle and wag their tails, or even raise the latter, perhaps as an invitation to grasp it, in which case it would of course break off. When caught, they emit feeble sounds, and attempt to bite with the mouth widely open. During the moulting, which takes place at least twice a year, in the spring and in the autumn, the skin peels off in flakes; if, as happens sometimes, the skin upon the lamellae is not stripped off neatly, these refuse to act, and the creature cannot climb until all the old skin has been rubbed off.

In their native haunts they are very regular in their habits. Favourite resorts of theirs are old olive trees or oak trees, the rough and cracked bark of which affords excellent places for hiding in. Hollow trees are of course preferred. Not a single specimen is seen during the early hours of the morning or in the forenoon; but when the sun has become broiling hot, and our own shadow passes over the stem of a tree, we become aware of flitting little shadows which jerk over its surface. These are Geckos which had been basking, motionless; very dark grey, almost blackish, just like the colour of the grey bark upon which the last wet season's moss has been scorched to a black cinder. It is difficult to espy a Gecko whilst it is glued on to such a tree. Only the little beady eyes betray it, watching you carefully. Nothing appears more easy than to catch that motionless thing. You put out your hand and it is gone; like a flash it has moved a foot higher up, or down, to the right or to the left, just where you least expected it to go, and there it clings on motionless as before. It does not seem to run; it glides along, dodging over to the other side of the stem and back again. There is system in its motions, since, taking a last leisurely look around, it gently disappears in a rent or hole. Towards the evening, or when the shadows become longer, the Geckos become lively. One after another appears on the surface, upon the tree, or at the entrance of the cave, and they all move about in their peculiar rushing jerks. Spiders, flies, mosquitoes, moths, form the principal diet, and the hunting goes on well into the night. Where a gecko has been seen once it is sure to reappear the next day at the same hour. Those which take up their abode inside a house become almost domesticated. They are strange sights when hunting for flies, {511}running up and down the papered walls; but we fairly gasp when they come to the upper corner, calmly bend over, and with the next jerk slide along the white-washed ceiling. We are accustomed to flies performing such feats, but at animals five inches long, supple and fat, we are inclined to draw the line. However, that is the way of Geckos, and–be it confessed–the more we ponder over the mechanism of their fingers and toes, the less we comprehend how such little vacua can support or suspend such heavy creatures from a dry and often porous surface.

Gecko.–The digits are strongly dilated with undivided lamellae. All, except the pollex and hallux, have a very short compressed terminal phalanx with a retractile claw. Males with femoral or pre-anal pores. This Eastern genus includes some of the largest of all Geckos.

G. stentor of the Malay countries reaches a length of 15 inches. G. verticillatus s. verus s. guttatus ranges from Eastern Bengal to China and through the Indian archipelago. It grows to about one foot in length. The head is large; the back is covered with small granules and about a dozen rows of large tubercles. The tail, when intact, and the belly are covered with scales, those of the tail being arranged in transverse rows, several of which make up distinct rings. The upper parts of the body are grey or yellowish with red spots and vermiculations. According to Theobald it lays about eight hard-shelled white eggs as big as a musket-ball, cementing them to trees, rocks, or secluded buildings. The cry is "touk-tay," several times repeated, and ending in a long-drawn out, diminuendo, guttural rumble. This animal does not confine itself to insects, but eats young rats also. Dr. Mason has seen it devour smaller species of house-lizards, and Theobald has seen it seize a bat flying round the room, and devour it.

Tennent tells the following story about one of these creatures: "In an officer's quarter in the fort of Colombo, a Gecko had been taught to come daily to the dinner-table, and always made its appearance along with the dessert. The family were absent for some months, during which the house underwent extensive repairs, the roof having been raised, the walls stuccoed, and the {512}ceilings whitened. It was naturally surmised that so long a suspension of its accustomed habits would have led to the disappearance of the little lizard; but on the return of its old friends, it made its entrance as usual at their first dinner the instant the cloth was removed."

Ptychozoon.–The digits have the same structure as described in the genus Gecko, but they are entirely webbed. The extraordinary feature of Ptychozoon is the membranous expansions on the sides of the head, body, limbs, and tail, which are said to act as parachutes. P. homalocephalum, the only species, inhabits the Malay Islands and the Malay Peninsula. It reaches a length of 8 inches. A specimen obtained by F. H. Bauer in Java, in the month of November, laid two eggs a few days after its capture. One young was hatched in the middle of the following May, and two days later another came out of the second egg. The characteristic folds of the skin were already clearly discernible.

SUB-FAM. 2. EUBLEPHARINAE.–Differing from the true Geckos by their procoelous vertebrae and the fusion of the two parietal bones into one. The eyelids are not reduced, but remain functional. This sub-family is undoubtedly a heterogeneous assembly, as indicated by the very scattered distribution of its few species (about seven), in India, West Africa, and Central America.

SUB-FAM. 3. UROPLATINAE, composed of a few species of the genus Uroplates in Madagascar. The distinctive characters of {513}these otherwise typical Geckos are the fusion of the nasal bones into one, the small size of the interclavicle, and the non-dilated shape of the clavicles.

Neither the Eublepharinae nor the Uroplatinae are more nearly related to other Autosauri than are the other Geckos. They are modifications within the sub-order of the Geckones.

SUB-ORDER 2. LACERTAE.–Autosauri with procoelous, solid vertebrae, and with the ventral portions of the clavicles not dilated.

Cope, discarding outer appearances as deceptive in the classification of the Lacertae, laid stress upon internal characters, notably the presence or absence of osteoderms, the formation of the skull, and the structure of the tongue. Boulenger has followed and improved upon Cope's arrangement, and has elaborated the classification, which, being used by himself in the three volumes of the Catalogue of Lizards in the British Museum, has also been followed in the present work, with slight alterations in the order of treatment of the families. For our present purpose we diagnose the families as follows, giving preference to such characters as are most easily ascertained:–

SYNOPSIS OF THE FAMILIES OF LACERTAE.

Fam. 1. Agamidae. Acrodont. Tongue broad and thick. No osteoderms. Old World, p. 515.

Fam. 2. Iguanidae. Pleurodont. Tongue short and thick. No osteoderms. America, Madagascar, Fiji Islands, p. 528.

Fam. 3. Xenosauridae. Pleurodont, solid teeth. Anterior part of tongue retractile. No osteoderms on the body. Mexico, p. 536.

Fam. 4. Zonuridae. Pleurodont. Tongue short, not retractile. With osteoderms at least upon the skull, where they roof in the supratemporal fossae. African sub-region, p. 536.

Fam. 5. Anguidae. Pleurodont, solid teeth. Anterior part of tongue emarginate, retractile into the posterior portion. Osteoderms on body and head, roofing over the supratemporal fossae. Limbs mostly reduced. America, Europe, India, p. 537.

Fam. 6. Helodermatidae. Pleurodont, lower teeth grooved, with poison- glands. Tongue bifid. Osteoderms tiny. Postfronto-squamosal arch absent, p. 540.

Fam. 7. Lanthanotidae. Pleurodont. Tongue short and bifid. {514} Postfronto-squamosal arch absent. No osteoderms. Borneo, p. 541.

Fam. 8. Varanidae. Pleurodont. Tongue very long, bifid, smooth, very protractile. No osteoderms. Postorbital and temporal arches incomplete. Old World, p. 542.

Fam. 9. Xantusiidae. Pleurodont. Tongue very short and scaly. No osteoderms. Supratemporal fossa roofed over by the cranial bones. No movable eyelids. Central America and Cuba, p. 547.

Fam. 10. Tejidae. Teeth solid, almost acrodont. Tongue long, deeply bifid, with papillae. No osteoderms. Limbs sometimes reduced. America, p. 547.

Fam. 11. Lacertidae. Pleurodont. Tongue long, bifid, with papillae or folds. With osteoderms on the head. Supratemporal fossae roofed over by the cranial bones. Old World, p. 549.

Fam. 12. Gerrhosauridae. Pleurodont. Tongue long, with papillae, but feebly nicked. With osteoderms on the head and body, roofing over the supratemporal fossae. African sub-region, p. 559.

Fam. 13. Scincidae. Pleurodont. Tongue scaly, feebly nicked. Osteoderms on the head and body. Limbs often reduced. Cosmopolitan, p. 559.

The following five "families" are much degraded in conformity with their usually subterranean life, see p. 496:–

Fam. 14. Anelytropidae. Without limbs. Body covered with scales. Mexico and Africa, p. 564.

Fam. 15. Dibamidae. Vermiform, limbless body covered with scales, without osteoderms. Australasia and Nicobar Islands, p. 564.

Fam. 16. Aniellidae. Without limbs; body covered with scales, without osteoderms. California, p. 564.

Fam. 17. Amphisbaenidae. The body is covered with soft skin, forming numerous rings with mere vestiges of scales. Without limbs, except Chirotes with four- clawed fore-limbs, p. 565.

Fam. 18. Pygopodidae. Snake-shaped, with scales. Fore-limbs absent, hind-limbs appearing as a pair of scaly flaps. Australia, p. 567.

These eighteen "families" of the Lacertae fall into four main groups. We naturally assume that the presence of osteoderms and of complete cranial arches indicate more archaic conditions than their absence, just as we conclude that limbless forms have been evolved from creatures with fully developed limbs. We arrange the four groups with their families as follows:–

{515}Group I. Zonuridae and Anguidae assume a central position, with Iguanidae and Agamidae as two parallel families of highest development. Aniellidae as the most degraded forms. Helodermatidae and Lanthanotidae as rather primitive and solitary survivals.

Agamidae Iguanidae | | | Xenosauridae | | Zonuridae–Anguidae–Helodermatidae. | V Aniellidae.

Group II. Xantusiidae–Tejidae–Amphisbaenidae.

Group III. Scincidae–Gerrhosauridae–Lacertidae.–Here also Anelytropidae and perhaps also Dibamidae as degraded Scincoids.

Group IV. Varanidae, which are in many respects the most highly developed of all.

Pygopodidae are of obscure relationship.

FAM. 1. AGAMIDAE.–Acrodont, Old-World Lizards, with a broad and short tongue. The teeth are usually differentiated into incisors, canines, and molars. The orbit is closed posteriorly; the temporal fossa is bridged over by an arch which is formed chiefly by the squamosal and the well-developed jugal; the postorbital mostly remaining small, and the postfrontal and supratemporal bones being either absent or not present as separate elements. The limbs are well developed. The eye, provided with complete eyelids, is distinctly small and has a round pupil. The skin is devoid of osteoderms, although large and numerous spines are often present, especially on the head and on the tail. The Agamidae, of which about two hundred species, arranged {516}in about thirty genera, are known, exhibit a great diversity of mostly flat-bodied, terrestrial and more laterally compressed, arboreal forms. The majority are insectivorous, a few Agamas have a mixed diet, while Uromastix and some others are chiefly, if not entirely, frugivorous and herbivorous. They are an exclusively Old-World family, avoiding the cooler parts of the Palaearctic sub-region, and also, a very curious fact, Madagascar. The majority live in Australia and in the Indian and Malay countries, comparatively few in Africa, chiefly the genus Agama.

Draco ("Flying Dragon").–The body is much depressed and the sides extend as a pair of large wing-like membranes, which are supported by five or six of the much-elongated posterior ribs, and can be folded up like a fan. On the throat are three pointed appendages, a short one on either side and a long one in the middle. The tail is very long and slender, but not brittle. About twenty species of this extraordinary genus inhabit the various Indo-Malayan countries; one, D. dussumieri, occurs in Madras. D. volans of the Malay Peninsula, Sumatra, Java, and Borneo is about 10 inches long, 5 of which are taken up by the tail. The {517}male has a small nuchal crest. The upper parts of this pretty creature have a metallic sheen, with small dark spots and undulating cross-bands upon the rich brown ground-colour. The wings are orange with black markings. The gular sac of the male is orange, that of the female is blue.

The "Flying Dragons" use their wings as parachutes, but their sailing powers are said to be very moderate. Certainly they do not fly by moving the wings, but when at rest upon a branch, amidst the luxurious vegetation and in the immediate neighbourhood of gorgeously coloured flowers, which partly conceal them by their likeness, they greatly resemble butterflies, especially since they have the habit of opening and folding their pretty wings.

Ceratophora.–This exclusively Ceylonese genus is remarkable for a flexible, erect, and pointed appendage which arises from the top of the snout; it is best developed in the males, vestigial or absent in the females. Gular appendages are absent. The trunk is crestless, slightly compressed, and covered with partly keeled scales. The tail is slender and very long, about two-thirds of the total length of the animal. The general colour is olive-brown, with irregular darker markings and with light streaks on the head and thighs. C. stoddarti and C. tennenti are about 10 inches long, the former without, the latter with, little scales upon the rostral appendage.

Lyriocephalus, with L. scutatus (Fig. 124) of Ceylon as the only species, is remarkable for its Chameleon-like appearance. A splendid case of convergent evolution, but most improbably of mimicry. The tympanum is quite hidden. The head is raised into a pair of sharp bony edges. On the top of the nose is a thick globular lump, recalling the genus Ceratophora, and also various Malagasy Chameleons. The back and sides are covered with very small granular scales, intermixed with several rows of enlarged scales as in Chameleo pumilus, and there is a serrated crest along the back from neck to tail. The under parts are covered with large keeled scales with sharp points directed backwards, especially on the tail. The whole body is laterally compressed. The pollex and the fifth toe are strongly opposed to the other digits. The general colour is greenish above, whitish below. Total length about one foot.

Calotes, with many species in India and in the Malay Islands, is distinguished by a crest on the neck and back. Many of the males have a gular sac. The tail is extremely long. These lizards are remarkable for their changes of colour.

{518}[Illustration: FIG. 124.–Lyriocephalus scutatus. × ⅔.]

C. versicolor ranges from Afghanistan through the whole of India to Southern China, and attains a length of 14 inches, 11 of which are taken up by the tail. It possesses no gular sac, but has a well-developed crest. The whole body and tail are covered with strongly keeled scales. When the lizard is irritated, or swallowing its food, the head and neck become brilliant red, whilst the usually brownish tint of the body is converted into pale yellow. Mr. Annandale has favoured me with the following observations on C. emma:–"In the Malay Peninsula the Europeans misname this lizard Chameleon. The colour-changes appear to be brought about by emotions, although the lizard is often darker towards {519}evening than it is at mid-day. The males are very pugnacious, and change colour as they fight. At the time of courtship a curious performance is gone through by the male, the female remaining concealed in the foliage hard by. He chooses some convenient station, such as a banana leaf or the top of a fence, and advances slowly towards the female. His colour is then pale yellowish flesh-colour, with a conspicuous dark spot on each of the gular pouches, which are extended to their utmost. He stands upright, raising the fore part of the body as high as possible, and nodding his head solemnly up and down. As he does so, the mouth is rapidly and repeatedly opened and shut, but no sound is emitted. When he is driven away, caught or killed, the dark spot disappears entirely from the neck. If one male is captured, another takes his place within a few hours."

C. ophiomachus of Southern India and Ceylon reaches 2 feet in length, has a fold of skin in front of each shoulder, and is generally known as the "blood-sucker" on account of the red colour displayed during excitement on the head and neck.

C. mystaceus, chiefly in Burma and Siam, but also in the Nicobar Islands and in Ceylon, has a small gular sac and an oblique fold in front of each shoulder. The specific name seems to refer to the yellowish lips. Mason gives the following vivid account of it:–

"This is a very common species in gardens in Toung-ngoo. A pair made their home in the mango trees near my study window. The female blundered into the house a few days ago, but I found her a very unattractive animal of a uniform earth-brown colour. The male, however, is sometimes a beauty. He may be often seen jerking his head up and down, with the head, pouch, and whole front of the body a glowing ultramarine blue, contrasting beautifully with the reddish-brown of the hinder part of the body and tail. From the nose to the shoulders, below the eye, is a broad white band, which is interrupted by three reddish-brown patches, in line with the white band, before reaching the uniform reddish brown of the hinder part of the body. Occasionally the white band below the eye assumes a brownish colour, and the animal appears to have a brown band down each side. He does not always, however, appear in this gay dress. While I am writing, I see him coming down the trunk of one of the trees {520}in a very faded garment. His skin suggests a bright calico after it has been washed, whose colours succumb to soap. The blue is there, but it is no longer the bright blue of yesterday. It has changed to a dull light indigo colour. He runs across the grass to the foot of another tree, and stops on the bare ground at its base, where for a minute or more he bites with great energy at a struggling grasshopper, and while thus exercising himself the blue fades out from his body altogether, and his whole body takes the colour of the brown earth on which he stands. After tarrying a minute or two he ran up the other tree, and the dull light blue colour seemed to return to him."

Agama with many species in Africa and Asia; some in South-Eastern Europe. The body is somewhat depressed. There is a fold across the throat and a pit on either side; the presence of a gular sac is variable. A dorsal crest is absent or but feebly developed. The males have pre-anal pores.

A. sanguinolenta.–The body is covered with strongly keeled and pointed scales. On the sides of the head are a few spine-like scales. The ear-opening is partly concealed by a fringe of spinous scales. The males have a gular pouch. This is a typical inhabitant of the deserts and steppes of Turkestan. Zander has observed the habits and many changes of colour of this lizard. The usual garb is earthy brown above, with somewhat darker and rather indistinct markings. The under parts are whitish. Sometimes the creature changes to dirty white, at other times into blackish or grey brown. Bluish-red stripes may appear on the sides of the body; blue lines begin to show on the throat, and ultimately the whole belly, originally white, may become ultramarine blue. When the general tone happens to be sulphurous yellow, blue often appears on the tail and limbs. Brick red appears on four longitudinal rows of patches on the sides of the body. Sometimes the whole animal assumes a vinous tinge, or it is at first greenish before turning into blue. The change begins on the tail and limbs, extends over the head, and at length reaches the back. Red appears in both sexes, more frequently in the female; blue almost entirely in the male. Sunlight and warmth only intensify the colours. Adaptive coloration, besides the usual sandy garb, has not been observed. The lizards live on soil which is baked as hard as bricks, or in {521}cavities of old walls, provided there is vegetation. They require vegetable food, besides insects, grazing on grass, and having a fondness also for Mesembryanthemum cardiforme. Very large males reach a total length of one foot. They are pugnacious, especially during the time of breeding. The male inflates its gular sac into the size of a walnut, stands up upon its four limbs, with its head slightly lowered and turned to one side. Then it darts upon the foe which it has been eyeing for some time.

A. stellio is the commonest Agama in Egypt, Asia Minor, and in some of the Grecian Islands, where the Greeks still call it korkordilos, just as they did in the time of old Herodotus. The Arabic name is hardun. This lizard is easily recognised by the irregular folds on the neck, which are beset with spinous horny scales. It grows to a length of 15 inches. The general colour is brown, with dark patches on the back. When basking they become almost black; in the breeding season the male assumes red tints on the head and neck.

Phrynocephalus.–This is a typical Agamoid of the steppes and deserts of Asia. The head is short and thick, the ear is {522}hidden. The body is depressed, devoid of a dorsal crest; on the throat is a transverse fold but no sac.

A. Zander has made interesting observations upon the habits of several species.

Ph. helioscopus lives on hard stretches of soil, which are absolutely bare of vegetation, the soil being baked as hard as a paved road. The lizards live on any insects they can get hold of, chiefly, however, upon mining ants. When chased they run with short jerks, carrying the tail high or rolled up.

Ph. interscapularis occurs, in Transcaspia, on the shifting, loose sand. It runs so fast that one scarcely sees anything but its shadow. The tail is rolled upwards. With short jerks it suddenly changes its direction, stops behind a few blades of grass, or in the open, makes a few shaking, wavy movements, and covers itself lightly with sand. Shortly after that the top of the head appears, the grains of sand rolling off between the strong supraciliary ridges, and the little creature, only about 3 inches long, peeps out of its temporary hiding-place.

Ph. mystaceus, which inhabits Transcaspia and parts of Southern Russia, often faces its aggressor, raising itself upon its fore-limbs, curling and uncurling its tail in its excitement, and holding its mouth widely open. The creature, which attains a length of 9 inches, inclusive of the long tail, then assumes a markedly changed aspect. The flaps of skin at the corners of the mouth swell up into a half-moon-shaped transverse plate, the hinder surface of which is covered by the outer skin, while the front is a continuation of the rosy lining of the mouth, which thereby appears hugely enlarged. When biting it hangs firmly on to the finger. This frightening attitude is interesting, since it occurs in a much more developed condition in the following genus.

Chlamydosaurus kingi.–This peculiar Agamoid, which inhabits Queensland and Northern and North-Western Australia, is easily recognised by the large frill-shaped dermal expansion on either side of the neck. The two halves are confluent on the throat. The whole frill can be erected, and is worked by the much-elongated arches or horns of the hyoid apparatus, which extend into the flaps of skin, somewhat like the ribs of an umbrella. The specially modified hyoidean muscles spread out {523}and fold the frill. When this curious creature is pursued it folds the frill and runs in a semi-erect position upon its hind-limbs, with its fore-limbs hanging down. However, it cannot keep up this peculiar gait for long, and it then suddenly turns to bay, frequently at the root of a tree, which it can climb with ease. When standing at bay it spreads out the shield to its full extent, in the middle of which appears the widely opened mouth, which is red inside and armed with powerful teeth. Altogether this lizard presents a formidable aspect, and is an enemy not to be despised, considering that it is strongly built and grows to nearly 3 feet in length. For a further account of the habits and of the mechanism of the frill see De Vis.

Physignathus.–This is a water-loving genus, inhabiting well-watered districts with luxuriant vegetation in Australia, Papuasia, Siam, and Cochin China. The body and the very long tail are laterally compressed and furnished with a low, serrated crest. Ph. lesueuri of Queensland reaches a length of about 18 inches. The general colour is dark olive above, with darker and lighter {524}cross-bands, and with a broad black band reaching from the eye to the shoulder. The under parts are pale olive, with small black dots. The throat, although devoid of a special sac, is frequently bulged out by the hyoid apparatus, as shown in Fig. 127, taken from a specimen in the Zoological Gardens in London.

Uromastix is a typical desert-form, inhabiting the dry and sandy tracts of North Africa, Arabia, Syria, Persia, and North-Western India. The genus is easily recognised by the short and thick tail, which is covered with whorls of large spinous scales, while the much-depressed body and head are almost smooth, being covered with very small scales. The tympanum of the ear is quite exposed. The incisors are large, uniting in the adult into one or two pairs of large cutting teeth, separated from the molars by a toothless space. There is a transverse fold on the throat. Pre-anal and femoral pores are well developed.

These "Spiny-tailed Lizards" live chiefly upon vegetable food, leaves, grass and fruit, but they vary this diet with insects, at least in captivity, where they become rather partial to meal-worms. They are absolutely terrestrial and diurnal, preferring sandy places, where they bask or rather roast themselves in the sun; for the night, at the approach of rain, or on dull and chilly days, they retire into their burrows, which they dig in {525}the sand or in the hard ground, unless they hide in the cracks of rocks. They have a regular mania for digging with their strong limbs and short, curved claws. Although they love a great amount of heat, and become stiff when cooled down to about 16° C. = 60 F., they can stand several degrees of dry frost without injury. During the cold season they hibernate. The spiny tail is used for defence. The lizard lies as a rule in such a position in its hole that the tail blocks the narrow passage; when touched with the hand it deals out jerky side-blows with the tail. The bite is deliberate and very painful.

U. hardwicki is a native of North-Western India and Beluchistan, occurring especially in Sindh and Rajputana, for instance near Delhi and Agra. This species is of a delicate sandy colour, with dark dots or vermiculations, interspersed, occasionally, with pale blue specks. The under parts are whitish on the tail with a greenish hue. A distinctive and obvious mark is a large blackish patch on the anterior side of the thigh. Total length up to one foot.

I have several times received consignments of the Indian Spiny-tailed Lizard through the kindness of friends, but I must confess that they are far less easily kept than one is led to believe from certain exaggerated accounts. They are lovely, most interesting, and surprisingly tame creatures. I received one lot in the month of June. They made burrows in the dry soil, basked in the sun and on the grassy sods of their roomy cage, and showed great curiosity. When approached, they at first scrambled off or sank down flat, shut their eyes and feigned death. They then opened their tiny yellow eyes a little, while others peeped out of their retreats to see if all was safe, or attracted by some noise. Soon they became so tame that they crawled over my hand. But the difficulty consisted in feeding them. They greedily lapped up drops of water. Their dung consisted of the indigestible parts of some species of Equisetum or Mare's tail, mixed with fragments of beetles and ants. Lettuce, cabbage, cauliflower, grass, the flowers of red and white clover, Mare's tail, wheat, rice, and Indian corn were offered, but they only took a few blades of grass and the hard Indian corn, besides meal-worms. This is all the more astonishing since other specimens are known to partake freely of herbaceous food. None of them survived the late autumn, and most of them succumbed to a disease {526}known as intussusception of the gut. They certainly could not complain of the want of heat, since the bottom of their cage was kept permanently warm by a lamp, and in the autumn they invariably slept in the warmest part of the soil, avoiding the cool regions which would have given them a chance of hibernating.

Another consignment arrived in the month of February. None of them ate anything or survived the early summer.

U. acanthinurus and U. spinipes are common in Algeria, Tunis, and Egypt, where they prefer sandy and rocky localities. Their Arabic name is Dab. In Algeria they are sometimes called "lézards des palmiers," perhaps because they eat dates, besides berries, grass, and various flowers. Very large specimens attain a length of 18 inches. Like the other species of Uromastix they have no voice. The African species can change colour to a great extent. At a low temperature they are mostly grey or brownish black above, dirty white below. When it is warmer they change to lighter shades of brown or even to orange yellow and to green, with black or brown specks and vermiculations. {527}A young specimen of U. acanthinurus has been observed to grow within twelve months from 90 to 150 mm. in length.

Moloch.–The mouth of this peculiar-looking creature is very small; the lateral teeth of the upper-jaw are implanted horizontally and directed inwards. The body is much depressed, and, like the short tail and head, is covered with small scales or tubercles intermixed with large spines. M. horridus, the only species, inhabits the sandy districts of Western and Southern Australia. Nothing is known about its habits except that it seems to live upon ants. Its extremely rough skin is, according to an accidental observation by Dr. Willey, highly hygroscopic. He happened to put a live specimen into a shallow dish with water, when, to his surprise, the water was sucked up as by blotting-paper.

Liolepis.–The body is depressed, without a crest, and is covered with minute granular scales. The tail is long, and has small keeled scales. There is a strong transverse gular fold, and a fold along the side of the body. The tympanum is distinct. Femoral, but no pre-anal, pores are present.

L. belli, the only species, about 18 inches long when full grown, is a native of South-Eastern Asia. The general colour is brownish, with pale black-edged spots along the back; the sides are marked with black and orange vertical bars; the under parts are orange, variegated with blue. Annandale remarks that this is perhaps the commonest lizard on the barren stretches of sand in Lower Siam, especially near the coast. It is exceedingly active and timid. Though its colour is brilliant, the green and {528}grey eye-like spots which ornament its back, and the orange and purple stripes on its sides, are not conspicuous amidst the natural surroundings, the former harmonising with the shadows cast upon the sand by the scanty vegetation which it supports, and the latter being more or less concealed by the folds into which the skin that covers the ribs naturally falls. When the male is roughly handled and is unable to use its powerful jaws, it flattens its body in such a way that the stripes become most conspicuous. The female is unable to do this with such effect, as her ribs do not seem to be so mobile and her colours are less bright. Liolepis lives in holes in the ground, which often go down vertically for more than 2 feet before there is a bend in their course. Each burrow generally contains a pair of these lizards, which, according to the natives, are strictly monogamous.

FAM. 2. IGUANIDAE.–Pleurodont lizards with a short and thick, non-protractile tongue; almost entirely American, with the remarkable exception of two genera, Hoplurus and Chalarodon in Madagascar, and one, Brachylophus, in the Fiji Islands. Most of the Iguanidae are insectivorous, but some of the most striking forms are herbivorous, e.g. Iguana, Amblyrhynchus, and Basiliscus. In their general structure the Iguanidae closely resemble the Agamidae, from which they differ chiefly by the pleurodont dentition. The orbit is surrounded by bone, and the temporal fossa is bridged over by an arch which is formed by the junction of the squamosal chiefly with the postorbital, the jugal taking as a rule less share in the arch. Dermal ossifications are absent on the body.

There are about three hundred different species, which have been grouped into about fifty genera, representing arboreal, terrestrial, burrowing, semi-aquatic forms, and even one semi-marine species. Their external appearance varies consequently within wide limits.

Anolis is distinguished by the partial dilatation on the middle phalanges, which carry a series of transverse adhesive lamellae. In its general shape Anolis resembles slenderly built and long-tailed Lacertidae, which it may be said to represent in tropical and sub-tropical America, inclusive of the West Indian Islands. The males have a large gular appendage, which can be distended by the hyoid bones. Anolis is an expert climber, living in trees, or rushing about on fences or walls of houses in search of insects; {529}most species can change colour to a great extent. More than a hundred species are known, of which we mention only one, very common in the Southern United States.

A. carolinensis of the South-Eastern United States and of Cuba is beautiful golden green on the whole upper surface; the gular sac becomes vermilion when stretched; when flaccid, it is white with occasional red lines and spots. The under parts are white. In cold weather and in confinement this little lizard, which is scarcely 6 inches in length, appears dark brown, sometimes with a white line along the back. The changes of colour are very sudden. They are thoroughly arboreal, leaping from leaf to leaf like Tree-frogs.

In Anolis, Polychrus, Hoplurus, Chalarodon, Liosaurus, and a few others, the posterior ribs are much elongated and imbedded in the abdominal muscles, often reaching the medioventral line, a feature elsewhere known in the Geckos only.

Polychrus.–The body is laterally compressed, covered with small scales, but devoid of crests. The digits are likewise compressed, with keeled lamellae on the under surface and with four large scales at the base of each claw. Both sexes have femoral pores. The male possesses a small gular sac. A few species in Tropical America.

P. marmoratus in South America, where it is often called the Chameleon on account of its power of changing colour. The tail is nearly three times as long as the head and body, and is covered with keeled scales. The general colour of this arboreal creature, {530}which reaches a length of 18 inches, is green, but the hues are very variable, and within a short time the creature can change into dull brown, with or without blackish spots and bands, or with whitish spots and black lines on the head and other parts of the body.

Basiliscus is remarkable for the high and erectile crests which are developed on the back and tail of the males. The toes are bordered on the outer side with small lobes. The limbs are long, the hind-limbs when stretched forwards reaching the tip of the snout. Several species in Central America and the adjoining countries to the south.

B. americanus reaches the considerable length of nearly 3 feet. The male has a crest on the top of the head, and this is produced backwards into a leathery lobe. The back is adorned with a very high crest; the folds and dark-coloured marks in which give, in the accompanying illustration, the impression that the crest is supported by spines. The long tail carries a similar crest. The general colour of the "Basilisc" is green and brown with dark cross-bars on the back. The crest of the male is said to be red. These creatures are very common amidst the {531}luxuriant vegetation on the banks of the rivers of the Tierra Caliente of Mexico and in Guatemala. They lie upon the branches of trees, preferring those which overhang the water, into which they plunge at the slightest alarm. The high crests, being restricted to the male sex, are not essential to their swimming; they propel themselves by rapid strokes of the fore-limbs, letting the long rudder-like tail drag behind. The eggs, measuring 20 by 13 mm., are laid in April or May, and are hidden in a hole at the base of a tree. About one dozen make a set, and they are said to be hatched within a very short time. Owing to their being strictly herbivorous, these pretty and striking-looking creatures do not endure captivity in Europe, unless indeed their particular food can be procured.

Iguana.–The body and tail are laterally compressed and are covered with very small scales, while those on the top of the head are large. The neck and back carry a high crest, which is composed of separate, laterally compressed, soft spines. A similar but lower crest borders the anterior edge of the large gular sac, which is not dilatable. The lateral teeth are remarkable for their finely serrated or denticulated anterior and posterior edges. Both sexes have long rows of femoral pores. Only two species in Tropical America, absolutely herbivorous. Their delicate flesh is much esteemed as food.

I. tuberculata (Fig. 132), of South and Central America and the West Indies, reaches a length of 5 to 6 feet. The general colour of the upper parts is a mixture of green and blackish, frequently speckled with white or yellow, and there is usually a pale band in front of each arm. The flanks are marked with dark, light-edged bars. The under parts are pale greenish or whitish. The Iguanas live in the trees, and when there is danger they jump into the water whatever the height of the tree, coming down with violence. In going up some of the narrow, unfrequented creeks in the Mosquito country, according to Napier Bell, the voyager often encounters quite a shower of falling Iguanas, and runs some risk of getting his neck broken. Large specimens, 6 feet long, weigh perhaps 30 lbs. They burrow deep horizontal holes in the sloping side of a bank. About two dozen eggs, nearly 2 inches long, are laid in a hole, where they are hatched in the month of May.

{532}Iguanas are often brought to the markets, either lashed lengthwise to a branch of the tree on which the specimen happened to be surprised, or tied up with the long tendons of their own toes.

Metopoceros cornutus of Hayti is closely allied to Iguana, but the male has three conical horn-like scales on its head. The general colour of the whole animal, which grows to more than one yard in length, is dull black.

The following two genera, each containing one species only, are restricted to the Galapagos Islands. Darwin gives a long and vividly written account of their habits.

Conolophus subcristatus.–Fully grown specimens are a yard long. Their shape is stout, the head and fore part of the body appearing especially heavy. The head is covered, or rather paved, with large cobble-stone-like scales. On the neck is a low crest of recurved spines, while the median line of the back appears simply serrated. All the teeth are trilobate. A gular sac is absent. The coloration is striking. The head is lemon-yellow; {533}the back is red, merging into dark brown on the flanks. The belly is dark yellow with a tinge of reddish brown.

This lizard was found by Darwin on some of the Galapagos Islands. On James' Island it was so common that the party found it difficult to pitch their tent, on account of the ground being undermined by the many burrows of the reptiles. They feed during the daytime upon the succulent cactus and the leaves of various trees. The perfectly harmless creatures are, or were, eaten by the inhabitants.

Amblyrhynchus cristatus is closely allied to Conolophus, of which it may be said to be an aquatic modification. The top of the blunt head is covered with low, conical, broad-based scales. Over the neck, back, and tail extends a continuous crest of low, recurved, spiny scales. All the teeth are trilobate. The body and even more so the tail are laterally compressed. The general colour is dark brown above, paler and inclining to whitish below. Younger specimens have pale grey spots and blackish cross-bands on the back and sides. Total length up to 4 feet. The remarkable feature of this Iguanoid is its semi-marine life. It inhabits the rocky and sandy strips of coast of most of the Galapagos Islands, feeding upon certain kinds of algae, which it has to dive for, since these plants grow below tide-marks.

Phrynosoma ("Horned Toads").–The body of these little creatures is much flattened and broadened, devoid of a dorsal crest, but covered with larger and smaller, strongly keeled scales. The head is bordered posteriorly by conspicuous osseous spines. The under parts are covered with small, very regular scales. Both sexes have a long row of pores on the under surface of the thighs. The general colour of the upper parts is a mixture of yellow, grey, brown, and black, the larger spiny scales causing the animal to look as if it were sprinkled with the dried husks of seeds, for instance those of Buckwheat. The object is concealment, by close adaptation to the arid, sandy localities which are the home of "Horned Toads." About one dozen species inhabit the western half of the United States and Central America. All the species are viviparous, almost the only instance among Iguanidae.

Ph. cornutum has five spikes on each side of the head: one postorbital, three temporal, and one occipital, the latter being by far the largest. The sides of the lower jaw project in the shape {534}of prominent ledges, and are protected by a series of small spines. The ventral scales are keeled. The under parts are yellowish, frequently with a few brown spots. This species, which grows to a length of 5 inches, ranges from Illinois through Kansas and Texas to Northern Mexico.

Ph. coronatum, an inhabitant of California, has an additional smaller spine between the two large occipitals. The scales of the belly are quite smooth.

These peculiar-looking and interesting creatures recall some of the extinct Dinosaurs in the curious configuration of their head: small miniatures indeed. In order to be kept in good health, and to be observed properly, they require, above all, warmth, sunshine to bask in, sand to burrow in, and proper food. The latter consists of all kinds of small insects, the necessary variety of which is best procured by making sweepings with a butterfly-net in a meadow. They take green-flies, house-flies, ants, smooth caterpillars, small moths, meal-worms, wood-lice, etc. The food is snapped up very quickly by a flash of the tongue, which can be turned out, almost like that of a frog, but only to the extent of half an inch. Water in the shape of dew, or drops, is absolutely necessary. When in good condition, they defaecate regularly every alternate day.

{535}[Illustration: FIG. 134.–Phrynosoma coronatum ("Horned Toad"). × 1.]

They love to bask in the broiling sun, heating themselves well through; and in the afternoon, long before sunset, when the sand is warmed up to 40° C., or fever-heat, they prepare to go to bed. For this they select a dry and soft spot, and within a few minutes manage to dig themselves in flat, literally sinking into the sand by pushing themselves forwards, and by shovelling the sand upon their backs with peculiar motions of the fringed sides of their flat bodies. Sometimes the spines of the head remain sticking out, looking like dry thorns scattered over the sand. To prevent the latter from getting into the nostrils, these are provided with closely-fitting valves. Thus they remain concealed during the night, and not until the sun is well up do they leave their hiding-place, first peeping out, and then raising their head and neck, letting the sand roll off between the spines. Still half concealed, the back covered with little pebbles, seeds, or bits of dry leaves, they wait for a long time before they feel lively enough to sally forth. Although mostly slow and deliberate in their movements, stalking about with arched back, and raised upon the fore-limbs, they can run fast enough for a few yards before they stop again and nod in a ridiculous way. When they see themselves observed, they shut their eyes and slowly sink {536}down. On cool and dull days they do not appear at all, and during part of the cooler season they require artificial heat until they are ready to hibernate. Unless they are allowed to hibernate, they will keep on feeding through the winter, but in that case are sure to die in the following spring.

FAM. 3. XENOSAURIDAE, with Xenosaurus grandis in Southern Mexico as the sole species, seems to connect the Iguanidae with the Anguidae. According to Boulenger, its affinity to the former is shown by the T-shaped interclavicle, the absence of symmetrical bony shields on the head and of osteodermal plates on the body. Affinity to the Anguidae is indicated first by the short tongue, which has a narrow, feebly incised, retractile anterior part, covered with flat papillae; secondly, by the teeth, which, instead of being hollow at the base, are solid; lastly, by the palatine bones, which are widely separated.

X. grandis, scarcely one foot in length. The body is depressed, covered above with minute granules and tubercles, below with smooth scales. A distinct fold of skin extends from the axilla to the groin, recalling the more strongly developed lateral fold of some of the Anguidae.

FAM. 4. ZONURIDAE.–This family, comprising four genera with about one dozen species in South and Tropical Africa, and in Madagascar, likewise seems to connect Iguanidae and Anguidae. It is distinguished from the former by dermal ossifications, which roof over the supratemporal fossa; from the latter by the tongue, the hollow teeth, and, in Zonurus at least, by the occurrence of dermal ossifications on the trunk and tail. The tongue is short, villose, scarcely protractile, entire, or but feebly nicked at the tip. The Zonuridae may therefore be defined as pleurodont African lizards with a short tongue, and with a bony roof to the supratemporal fossae.

Zonurus.–The whole head, back, and tail are covered with bony scales, the horny covering of which forms very sharp spikes, especially on the tail. The body is depressed. The ear-opening is large. South Africa, in dry and rocky localities; one species, Z. tropidosternum, in Madagascar.

Z. giganteus s. derbianus, with strong spikes on the occiput, neck, and tail. General colour yellowish brown. Total length about 15 inches.

Chamaesaura of South Africa closely approaches the {537}Anguidae by its snake-shaped body, extremely long tail, and vestigial limbs. In Ch. aenea both pairs of limbs are still present and pentadactyle, but are very small; in Ch. anguina the limbs are reduced to little styliform stumps; and in Ch. macrolepis they are altogether absent. The scales of the body and tail are strongly keeled and imbricating, but are devoid of dermal ossifications. Total length up to 2 feet.

FAM. 5. ANGUIDAE.–Pleurodont lizards with osteoderms, and with the tongue composed of two distinct portions, of which the anterior is thin, emarginate, extensible, and retractile into the posterior thicker portion. The supratemporal fossa is roofed in by dermal bones. The whole body is protected by bony plates underlying the imbricating scales. The teeth vary much in shape, but they are always solid, the new teeth not growing into the base of the old ones, but between them. The limbs are in a very unstable condition, there being in the family a general tendency to reduce and lose the limbs. The shoulder- and pelvic-girdle however remain, although sometimes merely vestigial. The tail is long, very brittle, and easily reproduced. All the Anguidae are strictly terrestrial, and live on animal diet. {538}Some Anguis, at least, are viviparous. The distribution of the seven genera, with some forty species, is very scattered. The majority, chiefly Gerrhonotus, inhabit Central America, a few occur farther north and south–two, Anguis fragilis and Pseudopus pallasi, in Europe, and one in the Himalayas and in Burmah.

Gerrhonotus has a pair of deep longitudinal folds, each of which extends from the region of the neck along the side of the body towards the tail. The four limbs are well developed and pentadactyle. The teeth are conical. Many species, mostly in Central America. G. coeruleus has the widest range, extending from Costa Rica to Vancouver. It is also one of the largest species, reaching a length of more than one foot. The tail is nearly twice as long as the rest of the body. General colour above brown with blackish bars and spots, especially on the more yellowish flanks; under parts whitish with a greenish tinge, often with brown spots arranged in longitudinal rows.

Ophisaurus s. Pseudopus is closely allied to the previous genus, being possessed of the same kind of deep lateral folds; the limbs are, however, reduced to a pair of tiny spikes, half concealed at the sides of the anal cleft. The teeth are conical, and in the adult have somewhat flattened crowns. The body and tail are very long and snake-like, but the head is that of a typical Lizard.

O. apus s. Pseudopus pallasi, the Glass-Snake of the Balkan Peninsula, South Russia, Asia Minor, and Morocco, grows to more than one yard in length, of which about two-thirds belong to the tail. The general colour is brown above, paler below. Young specimens are olive-grey with dark brown cross-bands on the back. O. gracilis inhabits the Eastern Himalayas and Burmah, the others live in North America.

The "Glass-Snake" inhabits bushy localities, where it can hide under the fallen leaves and in the sand; it cannot climb, and avoids the water. Its movements resemble those of a snake, but are far less graceful, owing to the stiff armour in which the whole body is encased. The food consists chiefly of snails, the shells of which are crushed, and of mice, but nothing comes amiss which can be mastered, namely insects, worms, small lizards, young birds, and vipers. The prey, when caught, is rapidly twisted round and round, or shaken until it is giddy or stunned, whereupon the Glass-Snake proceeds to chew it with its powerful jaws, and then to swallow it in pieces. {539}Although it can bite so well, it never does so when caught, but resorts to the much more disagreeable defence of twisting itself around one's hand and arm, and besmearing them with its disgustingly stinking excrements. Those who have observed Glass-snakes praise their tameness, and the intelligent way in which they hunt about in search of their food. They lay eggs under moss and leaves, and the young seem to require many years to grow up.

Anguis, with only one species, A. fragilis, the "Slow-worm" or "Blind-worm," is devoid of a lateral fold. Limbs are entirely absent. The whole body is covered with smooth roundish scales, with a substratum of dermal ossifications. The teeth are curved backwards, fang-shaped, and have a very faint longitudinal groove on their anterior surface. The ear-opening is very minute, more or less hidden by surrounding scales. The eyes are perfectly well developed, provided with movable lids, and it does not speak well for the power of observation of most people that this creature should generally be known as the "Blind-worm." The whole skin is shiny, metallic, quite smooth, brown above, blackish below. But the coloration is subject to much individual variation. Old specimens are sometimes adorned with blue specks. The very young are exquisitely beautiful, the upper surface being silvery white, with a median and two more lateral lines of deep black; the under parts are black. The iris is yellowish red. Very large specimens measure more than one {540}foot in length, more than half of which belongs to the tail. One in the British Museum is 425 mm. = 17 inches long.

The Slow-worm is viviparous, i.e. the young are fully developed, and burst the transparent, soft, yellowish eggs immediately after these are laid. This takes place in the months of August or September, about one dozen making a litter. The little creatures are at first about one inch and a half long, and as thin as an ordinary match. They eat the smallest of spiders and delicate insects; later on earth-worms, which they bite into and then suck out before devouring them. When six weeks old and well fed they are about 3 inches long, but it is at least four or five years before they are mature. The little ones carefully avoid the hot sunshine, and the adults are likewise rather partial to the shade, although strictly diurnal. Their chief food consists of earth-worms and slugs. For the night they retire under moss, leaves, stones, or into the ground. In the autumn the Slow-worms dig passages or burrows, which often serve as the winter-quarters of many specimens, as if there were no other place available, or rather as if the spot selected were by far the best with regard to safety, dryness, and warmth.

FAM. 6. HELODERMATIDAE.–Pleurodont, poisonous lizards of North America. The teeth are fang-like, recurved, with slightly swollen bases, rather loosely attached to the inner edge of the jaws. Each tooth has a groove on its anterior and posterior surface, and a series of labial glands which secrete the poison open near the bases of the teeth of the lower jaw. The skull has strong postorbital but no postfronto-squamosal arches. The pre- and post-frontals are in contact, separating the frontal from the orbit; the premaxillaries are fused into one; the nasals and frontals remain separate. The limbs are short, but strong and well developed. The tongue is villose, with an anterior smooth portion, which is bifid and protractile, resembling the tongue of the Anguidae and of Aniella. The skin of the upper surface is granular, with many irregular bony tubercles, which give it an ugly warty look. The under parts are covered with flat scales.

Heloderma, the only genus, with H. horridum in Mexico and H. suspectum in New Mexico and Arizona, reaches about 2 feet {541}in length. The animal, stout, depressed, thick-tailed, looks rather repulsive when it squats down in its usual lethargic way. The whole skin is blackish brown and yellow or orange, these two "warning" colours being distributed unevenly, except on the thick, peculiarly-shaped tail, where they are arranged in alternate rings. The specific differences are rather imaginary. The New Mexican form is supposed to be more orange and yellow than black, with a somewhat smoother skin and with shorter toes and tail.

The "Gila Monster" inhabits dry localities, spends most of the daytime in concealment between the roots of trees, and crawls about in the evening in search of worms, centipedes, frogs, and the eggs of large lizards. Frogs are probably paralysed or killed by the bite which, although not so dangerous as that of poisonous snakes, is effective enough to produce severe symptoms even on man, and a few cases of death of people who had been bitten are on record. In captivity they are very partial to eggs, which they break and then lap up. During the dry and hot season they aestivate.

FAM. 7. LANTHANOTIDAE.–Lanthanotus borneensis, of which only two specimens are known, one in the Vienna Museum, the {542}other in the Sarawak Museum, was described by Steindachner as the type of a distinct family, near the Helodermatidae. Boulenger, after examination of the Sarawak specimen by means of a sciagraph, has come to the conclusion "that the affinity of Lanthanotus to the Helodermatidae is fully confirmed." The teeth of Lanthanotus show, however, no traces of grooves; poison-glands are probably absent, and there are no osteoderms. The skin is covered with wart-like tubercles, each with a horny, peeled scale. The eyes are very small, the ears are concealed. The general colour is reddish brown above, yellowish, with brownish bands, below. Total length about one foot, a little more than half of which belongs to the roundish tail.

FAM. 8. VARANIDAE.–Pleurodont Old-World Lizards, with a long, deeply bifid and protractile smooth tongue. They reach a large size, and the neck is relatively much longer than that of other lizards. The limbs are well developed. The skin is {543}covered with very small juxtaposed scales and tubercles above, while the ventral scales are squarish and arranged in transverse rows. Osteoderms are entirely absent. The tail is very long, often laterally compressed. The teeth are large and pointed, dilated at the base. The premaxilla is unpaired and dorsally extends backwards to the likewise unpaired nasal. There is a pair of small supra-orbital bones, easily lost during maceration. The orbit is open behind, the jugal being short and not meeting the postfrontal; the postorbital forms a slender arch with the supratemporal. The vomers are long and diverge posteriorly. The palatines, pterygoids, and ectopterygoids enclose on either side an oval infra-orbital foramen. The Varanidae contain only one genus, Varanus, with nearly thirty species in Africa, Southern Asia, and Australia, but not in Madagascar.

Varanus.–The name of "Monitor" bestowed upon these creatures has a curious origin, owing to a ridiculous etymological mistake. The Arabic term for Lizard is "Ouaran"; this has been wrongly taken to mean warning lizard, hence the Latin Monitor, one of the many synonyms of this genus, e.g. Hydrosaurus and Psammosaurus. Many of the "Monitors" are semi-aquatic, others inhabit dry, sandy districts, while others are at home in well-wooded localities. They are all rapacious, taking whatever animals they can master according to their size, which in some species amounts to 6 or 7 feet.

V. niloticus inhabits the whole of Africa, except the north-western part. It reaches a length of more than 5 feet. The colour of the adult is brownish or greenish grey above, with darker reticulations and yellowish ocellated spots on the back and limbs. The under parts are yellowish with blackish cross-bands. The ground-colour of the young is black above with yellow lines on the head and neck, and with yellow spots on the back and limbs; the tail has black and yellow bars.

V. salvator ranges from Nepal to Ceylon, Cape York, and {544}Southern China, inclusive of the Malay Islands and the Philippines. This is the largest species, specimens of 7 feet in length being on record. The general colour is dark brown or blackish above, with yellow spots or ocelli. The snout and chin have transverse black lines on a lighter ground. A black band, bordered with yellow, extends from the eye along the side of the neck. The under parts are yellow.

Mr. Annandale has favoured me with the following observations:–"Varanus salvator is common in Lower Siam, where it is equally at home on land, in water, and among the branches of trees. The eggs are laid in hollow tree-trunks. When in the water the lizard swims beneath the surface, the legs being closely applied to the sides, and the tail functioning both as oar and as rudder. Their food is very varied. In the states of Patalung and Singora, in which the Siamese practise a form of tree-burial, these great lizards are accused, probably with justice, of eating the flesh of the corpses in the aërial coffins. I have disturbed a large Monitor devouring the body of one of its own species, which had evidently been dead for some days. Another, which was chased by some men, dropped from its mouth a small flying squirrel (Sciuropterus); a third, which I dissected, had lately swallowed a small tortoise, the hard shell of which had been broken into innumerable fragments. The stomachs of several others contained nothing but dung-beetles, for which Varanus may often be seen hunting, turning over the dung of elephants and buffaloes with its fore-feet. The Malay name of these lizards is Biawak."

According to Mason and Theobald all the Varanidae and their eggs are highly esteemed for food, and are sought for in hollow trees with the aid of dogs. If not wanted at once, the wretched creature has its fore-feet bent over its back, a few of its toes are broken and the sinews drawn out and tied into a knot, rendering the animal helpless. The Karens, who are extravagantly fond of the flesh, steal up the tree with a noose at the end of a bamboo, and often noose them while leaping for the water, or catch them in a boat which is brought under the tree. The head, the natives say, is venomous, and they discard it altogether, but the flesh of the other parts, which smells most odiously, is deemed preferable to that of fowls.

{545}Sir J. G. Tennent gives the following account of V. salvator:–

"The 'Kabara-goya' of the Singhalese is partial to marshy ground, and when disturbed upon land will take refuge in the nearest water. From the somewhat eruptive appearance of the yellow blotches on its scales, a closely allied species, similarly spotted, obtained the name of Monitor exanthematicus, and it is curious that the native appellation of this one, Kabara, is suggestive of the same idea. The Singhalese, on a strictly homoeopathic principle, believe that its fat, externally applied, is a cure for cutaneous disorders, but that taken inwardly it is poisonous. The skilfulness of the Singhalese in their preparation of poisons and their addiction to using them are unfortunately notorious traits in the character of the rural population. Amongst these preparations the one which above all others excites the utmost dread, from the number of murders attributed to its agency, is the potent kabara-tel, a term which Europeans sometimes corrupt into cobra-tel, implying that the venom is obtained from the hooded-snake; whereas it professes to be extracted from the Kabara-goya.

"In the preparation of this mysterious compound, the unfortunate Kabara-goya is forced to take a painfully prominent part. The receipt, as written down by a Kandyan, was sent to me from Kornegalle by Mr. Morris, the civil officer of that district; and in dramatic arrangement it far outdoes the cauldron of Macbeth's witches. The ingredients are extracted from venomous snakes by making incisions in the head of these reptiles and suspending them over a basin to collect the poison as it flows. To this, arsenic and other drugs are added, and the whole is boiled in a human skull, with the aid of three Kabara-goyas, which are tied on three sides of the fire, with their heads directed towards it, and tormented by whips to make them hiss so that the fire may blaze. The froth from their lips is then added to the boiling mixture, and so soon as an oily scum rises to the surface, the kabara-tel is complete. Before commencing the operation of preparing the poison, a cock has to be sacrificed to the demons.

"This ugly lizard is itself regarded with such aversion by the Singhalese that if one enter a house or walk over the roof, it is regarded as an omen of ill-fortune, sickness, or death; and in {546}order to avert the evil, a priest is employed to go through a rhythmical incantation."

Captain Robinson, renowned as a hunter of tigers on foot in the old days of muzzle-loading rifles, has told me the following unique use to which these large lizards are put by ingenious thieves in India. In order to be able to get over a wall too high for climbing without assistance, the thief provides himself with a strong lizard, ties a rope round its waist and lets the animal go, when it at once scales the mud wall by its strong and sharp claws, and jumps down on the other side. The weight of the lizard, which, moreover, holds vigorously on to the ground, and the friction of the rope on the top of the wall, are sufficient to help the man over!

It is a sight, never failing in its attraction to the visitors of the Zoological Gardens in London, to see one of the big Monitors fed with an egg. The lizard knows the treat well that is in store for it. It raises itself up high in expectation, then examines the egg with the long tongue, takes it up gingerly and swallows it entire, crushing it by the contraction of the muscles of its gullet. On one occasion it was given a rotten egg which burst in its mouth, and the lizard refused for a long time to take another.

V. gouldi is common in Australia and in New Guinea. It reaches a length of about 4 feet. Its colour is brown above {547}with yellow spots on the back and limbs, and with yellow rings on the tail. Two yellow streaks separated by a black band extend from the temples along the side of the neck. The under parts are yellowish, sometimes with black spots.

FAM. 9. XANTUSIIDAE.–Three Californian, or West-Indian genera, with less than half-a-dozen species. Pleurodont with a short tongue and with the supratemporal fossa roofed over by bone. The tongue is scarcely extensible, with oblique overlapping folds which converge towards the median line, and with scale-like imbricate papillae towards the tip. The skull possesses complete postorbital and postfronto-squamosal arches, the latter meeting the parietals and roofing over the supratemporal fossa. The palatines are in contact with each other, and there are no infra-orbital fossae. There are no osteoderms; the body is covered above with small granular scales, below with larger scales. The eyes are devoid of movable lids. The tympanum is exposed. Femoral pores are present. Limbs and tail well developed. Xantusia and Lepidophyma.

FAM. 10. TEJIDAE.–American Lizards with a long and bifid tongue. The greater portion of the tongue is covered with scale-like papillae; the anterior forked and pointed ends are smooth. The teeth are solid and implanted almost upon the edge of the jaw, being therefore intermediate between the acrodont and pleurodont condition. The shape of the posterior teeth shows several modifications; they are conical or tricuspid, or molar-like in the adult Tejus; in Dracaena they are transformed into large, oval crushers. The palatines are in contact anteriorly. The infra-orbital fossae are surrounded by the palatine, pterygoid, and ectopterygoid bones, the maxillary being excluded from the fossa, as in Varanus (see Fig. 138, p. 542). The skull has no supra-temporal arch. Osteoderms are absent; the body is covered with small scales, or the skin is simply granular above; the under surface is covered with larger scales, generally arranged in transverse rows.

This large family, which comprises nearly forty genera with more than a hundred species, exhibits great diversity of form. Some are inhabitants of forests and are arboreal, while others are strictly terrestrial, preferring hot and sandy plains, or they dwell below the surface and are transformed into almost limbless and blind-worm-shaped creatures. The range of the family extends over the whole of the South American continent, over the West {548}Indian Islands, and through Central America into the warmer parts of the United States.

Tupinambis ("Teju").–The skin of the back is smooth, covered with small scales; with large scales on the top of the head. The skin on the neck is generally thrown into two irregular transverse folds. The long and narrow tongue is capable of being telescoped into a sheath at its base. The lateral teeth are compressed and tricuspid in the young, but the later generations of teeth have obtuse crowns in the adult. T. teguixin is the largest member of the whole family; it reaches a length of a yard, most of which, however, belongs to the tail. The general colour is bluish black, with pale or whitish-yellow spots on the back, flanks, and tail, combining into more or less transversely arranged bands. The limbs are black, with many and tiny yellow dots. The ground-colour of the under parts is reddish yellow, with irregular black bars. This species inhabits the greater part of South America, east of the Andes, from Uruguay to the West Indies. T. nigropunctatus is confined to the Continent, and lacks the dark cross-bands on the belly, which is uniformly yellowish or speckled with black.

{549}The "Tejus" frequent forests and plantations, and are carnivorous. Their strength and swiftness enable them to catch all kinds of animals, from insects and worms to frogs, snakes, mice, and birds. As they take chickens and eggs from the farms they are considered noxious, and they are frequently hunted down with dogs for the sake of their flesh, which is regarded as good to eat. They defend themselves with lashing strokes of their long tail and with their powerful jaws. They retire into burrows, and they deposit their hard-shelled eggs in the ground. In captivity they can easily be kept on meat.

Dracaena guianensis of the Guianas and the basin of the Amazon has the lateral teeth transformed into regular large molars, with broad and rounded crowns. The tail is strongly compressed, with a double, denticulated keel. It seems to be semi-aquatic, and, to judge from the teeth, herbivorous.

Ameiva and Cnemidophorus, with many species chiefly in tropical America, have laterally compressed bi- or tri-cuspid teeth. The skin forms a double fold on the neck, and is covered on the upper surface of the body with very small scales; those on the ventral surface are large, and arranged in regular rows. Most of the species are small, under one foot in length, and are extremely pretty, very active, timid, and mainly insectivorous.

C. sexlineatus is one of the few species of Cnemidophorus which inhabits the southern half of North America. Like all its relations it has the appearance of an ordinary lizard (Lacerta). The head is dark brown. A purple or brownish band extends over the back and tail, bordered on either side with three golden-yellow longitudinal lines. The flanks are brown, the under parts bluish white. The iris is golden, and the inner margins of the lids are bordered with a narrow band of bright yellow. This species is a very fast runner, and frequents dry and sandy places. Its total length amounts to about 10 inches.

FAM. 11. LACERTIDAE.–Pleurodont Old-World Lizards, without osteoderms on the body, and with the supratemporal regions roofed over by osteoderms.

The limbs are always well developed, and have five fingers and five toes, always provided with sharp claws. The skin covering the head forms large shields, mixed with small scales; most of which, especially the shields, contain dermal ossifications. These frequently fuse with the underlying bones of the top of the skull.

{550}[Illustration: FIG. 142.–Skull and lower jaw of Lacerta viridis. A, Dorsal view; B, ventral view; C, from the left side; D, right half of the lower jaw, from the inner side, with some of the pleurodont teeth. E.P, Ectopterygoid; F, Fr, frontal; jug, jugal; Lac, lacrymal; Max, maxillary; N, Na, nasal; N{1}, in B, inner narial opening; Pal, palatine; Par, parietal; Pmx, premaxillary; Pr.f, prefrontal; Pt.f, postorbital; Pt.f{2}, postfrontal; Ptg, pterygoid; Q, quadrate; S.ang, supra-angular; Sq, squamosal; Vo, vomer.]

The latter is always well marked off from the neck. The postorbital arch is complete. The temporal region is completely roofed over by bones dorsally, chiefly owing to the size of the postfrontal (Fig. 142, pt.f{2}) which fills the space between the parietal and the squamoso-postorbital bridge, thus abolishing the supra-temporal fossa. The squamosal is very small, placed {551}between the postfrontal (pt.f{2}), the lateral occipital and the supratemporal. The large jugal and the quadrate are not connected with each other. The columella cranii is well developed. The infra-orbital fossae are surrounded by the palatines, pterygoids, ectopterygoids, and maxillaries. The palatines and pterygoids remain separated in the middle line. The pterygoids frequently carry little teeth. The other teeth are typically pleurodont, hollow, slightly curved, and bi- or tri-cuspid.

The skin covering the body, the legs, and the tail is devoid of osteoderms. The scales on the dorsal surface vary much in size, from large, strongly keeled scales to tiny granulations. Those of the ventral surface are large, broader than long, and are frequently arranged in regular transverse and longitudinal rows. The tail, generally long and pointed, is very brittle. All the sense-organs are well developed. The tympanum is exposed. The tongue is deeply bifurcated, narrow, flat, and covered with scale-like papillae.

Various Lacertidae, especially some of those genera which live and dig in the sand, have a transparent disc in the middle of the lower eyelid, so that they can see while the eye itself is protected. This is for instance the case in some specimens of the Indian and African Eremias. In the Indian genus Cabrita the transparent disc is very large, and in Ophiops, which inhabits sandy stretches from North Africa to India, the lower eyelid is fused with the rim of the much-reduced upper lid, and forms a large transparent window.

The Lacertidae or True Lizards comprise nearly twenty genera, with about one hundred species, and are typical of the Old World, being found in Europe, Asia, and Africa, but not in Madagascar nor in the Australian region. They are most abundant in Africa. Their northern limit coincides fairly closely with the limit of the permanently frozen under-ground. This is indicated in the map (Fig. 143) by the dotted line. All the Lacertidae live upon animal food, chiefly insects, and after them worms and snails; but the larger lizards take what they can master, frequently other lizards, and even younger members of their own kind. Many of them love sugar, which they lick, and all require water. They are all terrestrial, preferring, according to their kind, such localities as yield them their particular food.

{552}[Illustration: FIG. 143.–Map showing the distribution of the Lacertidae.]

Sunshine and warmth make a marvellous change in the same individual, which on dull, rainy, or cold days lies in its hole, or shows only sluggish movements. Their sense of locality is great, or rather each individual inhabits one place, of which it knows every nook and corner, cranny, tree, and bush. It has its favourite hole to sleep in, a stone, the branch of a tree, or a wall to bask upon, and when disturbed or chased it makes with unerring swiftness for a safe spot to retire into. The same lizard, when once driven away from its own locality, seems to lose all its presence of mind, flounders about, and is comparatively easily caught. Most lizards are extremely curious, although shy, and this state of their mind can be made use of by those who want to catch them without injury, and above all without getting the animal minus the brittle tail. This safe way of catching lizards consists in taking a thin rod with a running noose of thread at the end, in drawing the latter over the lizard's head, and then raising it. The little creature does not mind the rod in the least; on the contrary, it watches it carefully, and often makes for the thread. The boys in Southern Italy have improved upon and simplified this mode of catching lizards by bending the end of a wisp of grass into a noose, and covering the latter over with a thin film of saliva. The shiny film, like a soap-bubble, is sure to excite the curiosity of the creature. The late Professor Eimer refers to this practice {553}as carried out by the children of two thousand years ago, and he sagaciously explains that the beautiful statue of the so-called Apollo Sauroctonos represents a boy who is in the act of noosing the little lizard on the tree.

Lacerta.–A row of enlarged scales forms a distinct collar across the ventral half of the neck, in front of the chest. The scales on the back are much smaller than those on the tail, which is long, round, and pointed. The digits have smooth, tubercular lamellae on the under surface. Femoral pores are well marked. This genus, with about twenty species, ranges through Europe, Northern and Western Asia, and Africa north of the Equator.

L. vivipara, the Common English Lizard, has a very wide range, through Northern and Central Europe and Siberia to the Amoor country and the Island of Saghalien. It occurs throughout Great Britain, even in Ireland, where it is the only species of reptile, occurring, for instance, in the County of Meath and in the south-eastern counties, e.g. Waterford. It does not occur south of the Pyrenees or south of the Alps. The supra-ocular and the supraciliary scales are in contact with each other, not being separated by a series of little granules. Normally there is a single postnasal and a single anterior loreal shield. The ventral scales are arranged in six or eight longitudinal series, of which the second series on each side from the median ventral line is the largest. The coloration of this species is subject to much variation. The general colour of the adult is brown or reddish above, with small darker and lighter spots; many specimens have a blackish vertebral streak and a dark lateral band edged with yellow. The under parts are orange to red in the male, with conspicuous black spots; yellow or pale orange in the female, either without or with scanty black spots. The newly-born specimens are almost black. The males are slightly smaller than the females; males of a total length of 6 inches, and females 7 inches long, may be considered rather large specimens.

This lizard is, as the specific name implies, viviparous, i.e. the six to twelve young burst the eggs immediately after they have been laid; sometimes the mother has to retard the laying, in which case the young are born free. The female does not make a nest, but simply deposits her offspring on the ground and leaves the young to their fate. For the first few days the little ones, which scarcely measure three-quarters of an inch in {554}length, remain almost motionless between leaves or in cracks of the ground, and they do not take any food. They grow, however, quickly, living upon the remains of the yolk which has slipped into their body. Their first food consists of Aphides and similar tiny insects.

The Common Lizard prefers moist localities and is very hardy. It extends northwards to Archangel, and in the Alps it ascends to nearly 10,000 feet above the level of the sea. However, on the approach of the cold season, in the month of October, it withdraws into its winter quarters, frequently in company with many of its own kind.

L. agilis, the Sand-Lizard, has nearly the same wide range as L. vivipara, except that it does not go so far north and does not extend eastwards beyond Central Siberia. It is absent in Ireland and Scotland, while in England it is restricted to the southern half.

The characters which distinguish the Sand-Lizard from L. vivipara are few, although the majority of the specimens of either kind are very distinct in their coloration, and L. agilis is strictly oviparous, depositing its eggs in the ground, under leaves, in heaps of weeds and similar places. The Sand-Lizard has usually a single postnasal and two superposed anterior loreals, the three shields forming a triangle. The temples are covered with flat scales, two or three of which are enlarged and in contact with the parietals, but there is no tympanic scale.

The coloration is subject to much variation, local as well as individual. As a rule the Sand-Lizard gives the impression of being striped longitudinally, the striation being caused by rows of dark and white spots and patches along the sides of the back, flanks, and tail. In the male a more or less pronounced green, in the female brown and grey are the prevailing ground-colours. A typically coloured male during the breeding season is grass-green on the sides and suffused with green on the yellow under parts; the sides are dotted with black, with whitish eye-spots. The under parts are spotted with black. The adult female is brown or grey above, with large dark brown, white-centred spots, which are arranged in three rows on each side. The under parts are cream-coloured, with or without black specks. The young are grey-brown above with white, black-edged spots; the under parts are whitish. Total length of the adult up to 8 inches. {555}The male is a little smaller than the female but has a relatively longer tail, a little less than half the total length.

The Sand-Lizard is easily kept in captivity, and lives for years if allowed a variety of food and proper places to hibernate in. It pairs in the spring, in England in May or June; the white, parchment-like eggs, numbering five to eight, are hatched in the following July or August.

L. viridis, the Green Lizard, inhabits Southern and Middle Europe and South-Western Asia. The general colour of this beautiful lizard is emerald-green above, changing into greenish yellow on the flanks and into yellow on the belly. The throat, especially in the males during the breeding season, is blue. The upper parts are frequently speckled with black. The young are brown or green above with one or two yellowish lateral stripes, which persist in some adult females. There are usually two superposed postnasal shields. The semilunar collar on the neck is well pronounced, and there is usually a distinct gular fold. The tail is often very long, especially in the males, sometimes nearly three-quarters of the total length, which in very large males reaches 16 or 17 inches. The females do not quite reach this length.

The Green or Emerald-Lizard prefers rocky localities, from the sea-level, as for instance in Jersey, up to a height of several thousand feet. It is extremely swift and can climb trees, which it sometimes resorts to when chased. When hard pressed it takes tremendous leaps down to the ground, marvellously enough without injury to body or tail, which latter is otherwise very brittle. They pair in the spring or early summer after much fighting between the males; the eggs, to the number of about ten, are whitish and are deposited a month later. The young are hatched after another four weeks.

This beautiful lizard does not keep well in captivity, although it becomes very tame; it eats meal-worms, snails, earth-worms, and insects, especially butterflies, but it sickens after the first winter even if it has been allowed to hibernate.

In Portugal and Spain L. viridis is represented by a slightly different kind, L. schreiberi, the chief interest of which lies in the fact that it approaches L. ocellata in several respects. The occipital shield is large and is usually broader than the interparietal. The dorsal scales are smaller, and there are eight {556}well-developed rows of ventral scales. Instead of being uniformly green, the upper parts are usually spotted and vermiculated with black; sometimes, especially in the females, the black spots have a white ocellus in the centre. The under parts are yellowish, with or without black spots. The throat is blue. The young look very different. They are olive-brown above with large yellow, or bluish-white, black-edged ocelli on the side of the head and body.

Other forms, perhaps of sub-specific rank, approaching L. ocellata, occur in the Balkan Peninsula, where, for instance in Dalmatia, the typical L. viridis attains its most beautiful development.

L. ocellata, the Eyed Lizard, inhabits Spain and Portugal, extending northwards into the South of France and into the Riviera, southwards into Morocco and Algeria; these southern forms (L. pater and L. tangitana) approach L. viridis. The Eyed Lizard is green or dark olive above, with black or yellowish dots, which are sometimes combined into a kind of network pattern. The under parts are uniformly greenish yellow. The sides of the body are adorned with about two dozen blue, black-edged spots or "eyes." The intensity of the blue and the depth of the green ground-colour vary much according to sex, time of the year, and state of health. Males during the breeding season are most beautiful and brilliant. The occipital shield is broad; there are two superposed nasal but no tympanic shields. The supraoculars are separated from the supraciliaries by a series of granules. The collar is well marked, but not the gular fold. {557}The dorsal scales are minute and granular; the ventral shields are arranged in eight or ten longitudinal rows.

The "Eyed Lizard" reaches a considerable size, especially the males, which develop a very strong and thick head, and are much more robust and powerful than the more slender females. Old males reach a length of 2 feet, two-thirds of which length belong to the tail; but the latter varies much, even if it has never been broken and renewed.

The Eyed Lizard keeps extremely well in captivity, and in this respect is unlike the Green Lizard. A case has been recorded of its living thirteen years. This species is very intelligent. Although at first ferociously wild and biting furiously, these lizards soon become tame and take food regularly. One of my own, a half-grown male from Northern Spain, about one foot in length, made its home in a little niche of the greenhouse-wall, whence it emerged regularly to take the offered food from my hand. It soon knew the whole place thoroughly, making use of the creepers whilst scaling up to its retreat, jumping over certain gaps, descending to the ground at certain spots, basking on certain stones, invariably in the same methodical way. In the month of October it retires into the ground on the coolest side of the greenhouse, and although the latter is well warmed, the lizard remains invisible until the next February or March, when on some fine day it is rediscovered basking upon exactly the same stone where it had been seen five months before. The only drawback in connexion with keeping this kind of lizard in company with other creatures is their voraciousness; since large, fully adult specimens attack and eat any other small lizard, slow-worm, or snake they can find. They also take mice. The eggs are often deposited in hollow trees.

L. muralis, the Wall-Lizard, is very common in Southern Europe, Asia Minor, and Northern Africa. Northward it extends into Belgium and into South Germany. In the Iberian Peninsula it ascends up to 5000 or 6000 feet above the level of the sea. This graceful little creature, with an average length of 6 to 8 inches, is easily recognised by the series of granules between the supraocular and supraciliary scales and usually by having only six rows of ventral scales. The great variety in coloration has given rise to the establishment of many races, varieties, and sub-species. In the typical forms the upper parts are brown or {558}greyish, with blackish spots or streaks, sometimes with a bronzy greenish sheen. The under parts are white, yellow, pink, or red, either uniform or, especially in the males, with large black spots. The lateral rows of ventral shields are frequently blue. The colour-varieties are almost endless. One of the most noteworthy is that described as var. coerulea by Eimer; this, confined to the Faraglione Rocks near Cápri, is blackish above, like the rock, and sapphire-blue below. Similarly coloured specimens, var. lilfordi, occur on some of the rocky islets of the Balearic Isles.

The Wall-Lizard deserves its name, since in the Mediterranean countries there is scarcely a wall on which these active lizards do not bask or run up and down, often head downwards, in search of insects. They are oviparous. The hibernation is short and not very deep, since these lizards can sometimes be seen basking on sunny winter days before their regular appearance in the early spring.

Psammodromus, with a few species in South-Western Europe, notably in the Iberian Peninsula and in North-Western Africa, has no distinct semilunar collar, but has a short fold in front of each arm. The back is covered with large, rhombic, strongly keeled and imbricating scales. The lateral scales pass gradually into the ventrals, which are smooth and arranged in six longitudinal rows.

P. hispanicus is bronzy brown above, with small black and white specks, and with one or two longitudinal streaks on each side. The under parts are white. Total length about 5 inches. Although also found inland, this species prefers sandy dunes, studded with prickly and scanty vegetation. It runs very fast and digs itself rapidly into the sand when pursued. When caught it either utters a faint cry like "tsi-tsi," or it feigns death. The pairing takes place in June; half-a-dozen eggs are laid about eighteen days later, deeply imbedded in the warm sand, and they are hatched in eight weeks. The eggs are said to grow after they have been laid from 13 by 7 mm. to 17-20 by 10-11 mm. The newly hatched little creatures measure about 2 inches in length, more than half of which belongs to the tail.

P. (Tropidosaura) algirus has the same range as P. hispanicus, but grows to 10 inches in length, and is much more {559}beautifully coloured. The upper parts are bronzy brown with one or two golden, dark-edged, lateral streaks; the under parts are whitish; the male has one or more blue-eyed spots above each shoulder.

Acanthodactylus is distinguished by the laterally fringed digits. This genus ranges throughout Northern Africa to the Punjab. One species, A. vulgaris, extends into Spain and Portugal. The dorsal scales are small and almost smooth, but those on the tail are strongly keeled; the ventrals are much broader than long, and are arranged in eight to ten rows. The fringes on the digits are but feebly developed in the shape of lateral denticulations. The adults are grey-brown with faint longitudinal stripes, and with more conspicuous black and pale spots; in the breeding season larger blue-eyed spots appear on the sides near the limbs. The tail is often pink, especially on the under surface. Total length about 7 inches.

FAM. 12. GERRHOSAURIDAE.–Pleurodont African Lacertidae with osteoderms on the head and body.

This family is intermediate between the Lacertidae and the Scincidae. The tongue is constructed like that of the Lacertidae, but is only feebly nicked anteriorly. Dermal ossifications roof over the temporal region, and femoral pores are present. On the other hand, the osteoderms, which cover the whole body, are in their structure and arrangement typically Scincoid. The tail is long and fragile. A lateral fold is usually present. The limbs are sometimes reduced to useless stumps. The few genera and species of this family are strictly confined to the African sub-region, being found in the whole of Africa south of the Sahara, and in Madagascar.

Gerrhosaurus, with a strongly developed lateral fold and complete limbs, occurs in Africa. G. flavigularis, of South Africa, has a total length about one foot.

Tetradactylus, of South Africa, has also a strong lateral fold, but the limbs are either very short and pentadactyle (T. seps), or tetradactyle, or they are minute pointed stumps, as in T. africanus.

FAM. 13. SCINCIDAE.–Pleurodont lizards with strongly developed osteoderms on head and body, with very feebly nicked, scaly tongue, with complete cranial arches, and with separated premaxillaries.

{560}The temporal region is covered over, as in the Lacertidae, with strongly developed, bony, dermal ossifications. Similar osteoderms underlie the scales which cover the body and tail. The tongue is relatively short, not forked behind, and but very feebly nicked at the tip; it is covered with scale-like papillae. Femoral pores are absent.

All the Skinks prefer dry, sandy ground, in which they not only burrow, but move quickly about, either for protection or in search of their animal food. In connexion with this sand-loving and at least temporary subterranean life stands the frequent reduction of the limbs. Every stage from the fully developed and functional pentadactyle limb to complete absence of limbs is represented. There are species within the same genus with five, four, three, or two fingers or toes. There are Skinks without fore-limbs, but with vestigial hind-limbs, and vice versa. The interesting point is that these reductions do not indicate relationship within the family, but have happened independently. They are impressive illustrations of convergent retrogressive evolution.

Ablepharus, widely distributed in the Old World, has the lower eyelid transformed into a transparent cover, which is fused with the rim of the reduced upper lid, exactly as in the Lacertine genus Ophiops.

All the Scincidae seem to be viviparous, some of them, e.g. Trachysaurus, in the strict sense of the word, since the hard or parchment-like egg-shell has been dispensed with.

The family contains about four hundred species, which have been arranged in nearly thirty genera, many of them on fanciful grounds. The family is cosmopolitan, but reaches its greatest diversity in numbers and forms in the tropical parts of the Old World, especially in the Australian region, inclusive of the islands of the Pacific. America, notably South America, has the smallest number.

Trachysaurus, with one species, T. rugosus, inhabits the whole of the Australian continent. It is easily recognised by the large and rough scales, and the short and broad stump-like tail. It is dark brown above with yellowish irregular markings; the under parts are yellowish, marked with brown. Embryos of this species have yellow transverse bands on the back, but these often fade away before birth. The creature is strictly {561}viviparous, the egg-membrane being very thin, and the two or three embryos are ripened in uterus-like dilatations of the oviducts. The period of gestation is about three months, and the birth takes place, in South Australia, about April. According to Fischer this species, which is often in the market, is easily kept. It requires warmth, sand and stones for basking, and water, in which it soaks itself preparatory to the shedding of the skin, which takes place half-a-dozen times in the year, and is a slow process, requiring eight to ten days. The food consists chiefly of worms, lizards, and snakes, but meat, cabbage, and lettuce are also taken. The total length is about one foot.

Cyclodus s. Tiliqua, of Australia, Tasmania, and the Malay Islands, has stout lateral teeth with spherical crowns. The imbricating, cycloid scales of the body and the rather short but pointed tail are quite smooth and shiny. C. gigas, of New Guinea and the Moluccas, reaches a length of nearly 2 feet. The general colour is brownish yellow, with broad, dark bands across the body and tail.

Scincus, of North Africa, Arabia, Persia, and Sindh, has pentadactyle limbs, with laterally serrated digits. The eyelids are well developed, but the ear is hidden under scaly flaps. S. officinalis, of the Sahara and of Egypt, grows to about 8 inches in length. The snout is peculiarly shaped, cuneiform. The eyes are very small. The scales of the body are perfectly smooth; the sides of the belly are somewhat angular. The {562}whole shape of the creature, the scales, and the digits are adapted to burrowing and moving quickly through the loose sand. The general colour is yellowish or brownish above, each scale with small brown and whitish spots; the under parts are uniform whitish. The young are quite beautiful, being uniform pale salmon-coloured above, silvery white below. When a little older, yellow spots appear on the flanks and grey bands across the back. These Skinks live in the absolutely dry reddish-yellow sand of the desert, in which they may almost be said to swim about, so swift and easy are their movements. They live on insects, while in their turn they are eaten by snakes, and above all by the Varanus lizards.

Of Mabuia with about forty species, in the whole of Africa, Southern Asia, and in Tropical America, we mention only M. (Euprepes) vittata, on account of its partly semi-aquatic life, a very rare condition among Scincidae. This creature, about 7 inches long when full grown, frequents damp localities in Tunis and Algeria, where the French call it "Poisson de sable." It often sits on the floating leaves of Nymphaea alba, and dives into the water in order to escape. Its proper element is, however, the sand, and for the night it retires under stones. The general colour is olive brown with a lighter vertebral band and two narrow whitish lines on each side, sometimes edged with black. The under parts are yellowish or greenish white.

Chalcides s. Seps s. Gongylus, of the Mediterranean countries {563}also occurs in South-Western Asia. The lower eyelid has a transparent disc. The body is much elongated, and is covered with smooth shiny scales. The limbs are very short, or reduced to mere vestiges.

Ch. ocellatus, of the Southern Mediterranean countries, occurring also in Malta and Sardinia, reaches about 10 inches in length. The snout is conical, the ear-opening a small slit or hole. The limbs have five fingers and toes. The under parts are uniform silvery white, but the colour of the upper parts is very variable, mostly olive brown with black spots and irregular cross-bars, or with dark and light spots; sometimes uniform bronzy brown with a light upper and a black lateral band. This Skink seems to have no fixed abode, but digs itself into the sand wherever it wants to hide. The skin is not shed in flakes, but, as in most Skinks, it peels off by a process of gradual desquamation. Fischer's specimens paired towards the end of December. The gestation lasted 56 days, when nine young were born, which measured about 75 mm. or 3 inches; when three weeks old they had increased to nearly double this length.

Ch. lineatus, of Spain and Portugal, and of the South of France, like Ch. tridactylus of Italy and North-West Africa, has only three fingers and toes. The fore-limbs are only about one quarter of an inch in length in large specimens of 10 inches total length; the hind-limbs are a little longer. The general colour is bronzy olive or brown above, in the former species with nine or eleven darker longitudinal streaks; uniform, and with an even number of streaks in the latter species. Ch. bedriagae, of Spain and Portugal, has mostly five fingers and toes, and the limbs are relatively longer in this smaller species; but it is a question if these and other species of this genus are not to a great extent simply individual variations, since the reduction of the limbs and toes seems to be a very recent feature. Ch. guentheri, of Palestine, otherwise in every respect like Ch. tridactylus, but reaching a length of more than 14 inches, has the limbs reduced to tiny conical stumps without a trace of separate digits.

I have caught Seps accidentally under stones or pieces of bark in sandy districts. On the western coast of Galicia and Portugal, close to the sea, they frequent the gorse-bushes, on which they can be seen basking, provided they are approached {564}stealthily. They disappear on the slightest alarm, almost swimming, as it were, with great agility through the prickly cover, and then hiding and wriggling through the loose sand between the roots.

The following five "families" are composed of degraded forms of various descent. Most of them lead a burrowing, subterranean life, in adaptation to which the body has become snake-shaped or worm-like. The fore-limbs are entirely absent, except in Chirotes; the hind-limbs are absent, or reduced to small flaps; the girdles are reduced correspondingly. The skull is devoid of postorbital, postfronto-squamosal, supratemporal, and jugal arches. The quadrate bone is mostly immovable. The eyes and ears are concealed, except in the Pygopodidae.

FAM. 14. ANELYTROPIDAE.–An artificial assembly of a few degraded Scincoids. The worm-shaped, limbless body is devoid of osteoderms. The tongue is short, slightly nicked anteriorly, and covered with imbricating papillae. Columellae cranii are present. Anelytropsis papillosus in Mexico. Typhlosaurus and Feylinia in South and West Africa.

FAM. 15. DIBAMIDAE, consisting of the genus Dibamus, with D. novae-guineae, in New Guinea, the Moluccas, Celebes, and the Nicobar Islands. The tongue is arrow-shaped, undivided in front, covered with curved papillae. Columellae cranii are absent. The vermiform body is covered with cycloid imbricating scales without osteoderms. The limbs and even their arches are absent, but in the males the hind-limbs are represented by a pair of flaps. Total length of the animal about 6 inches.

FAM. 16. ANIELLIDAE.–The genus Aniella comprises a few small worm- or snake-shaped species in California, which seem to be degraded forms of Anguidae. The eyes and ears are concealed, limbs are entirely absent, the body and tail are covered with soft, imbricating, more or less hexagonal scales. The tongue is villose, smooth, and bifid anteriorly. The teeth are relatively large, few in numbers, recurved, with short swollen bases. The skull, by reduction, approaches the Ophidian type; there is no columella cranii, the postorbital arch is ligamentous, the premaxillary is single, the nasals and frontals remain separate, the pre- and post-orbitals are in contact with each other, excluding the frontal from the orbit.

A. pulchra.–Silvery, the scales edged with brown; back and {565}tail with a narrow, brown, median line. Total length, 7 to 8 inches.

FAM. 17. AMPHISBAENIDAE.–Worm-shaped lizards with the soft skin forming numerous rings, each of which is divided into many little squares, the vestiges of scales which are otherwise restricted to the head. The eyes and ears are concealed. Limbs are absent except in Chirotes, which has short four-clawed fore-limbs. The pectoral arch, and still more so the pelvic arch, are reduced to minute vestiges. The tail is very short. The skull is small, compact, and strongly ossified, in adaptation to the burrowing life, and is devoid of postorbital and postfronto-squamosal arches and of columellae. The teeth are either acrodont or pleurodont. The tongue is slightly elongated, covered with scale-like papillae, and bifurcates into two long and narrow smooth points.

The Amphisbaenas lead an entirely subterranean, burrowing life, like earth-worms. They are frequently found in ants' nests or in manure-heaps. Their progression is very worm-like, their annulated soft skin enabling them to make almost peristaltic motions and to move backwards as well as forwards. They crawl in a straight line, with slight vertical waves, not, like other limbless lizards or snakes, by lateral undulations. The food consists of worms and small insects. About one dozen genera with more than sixty species are known, most of which inhabit the warmer parts of America, the West Indies, and Africa. Four inhabit Mediterranean countries.

{566}If the tongue and the dentition be taken as indications of relationship, the Amphisbaenidae may perhaps be considered as degraded descendants of Iguanidae, a family which contains various limbless, burrowing, worm-shaped forms. But it is also possible that the Amphisbaenidae are not a natural group. This consideration applies with most force to the genera Amphisbaena and Anops, the various species of which occur in America and in Africa.

Chirotes canaliculatus, the only species of the genus, is the only Amphisbaenid which still possesses fore-limbs. These are short, stout, placed close behind the head, and are provided with four-clawed digits. This species occurs in Mexico and California, is brownish or flesh-coloured, and reaches a length of about 8 inches.

Amphisbaena, with nearly thirty species, in Tropical America and Africa. On account of the short rounded-off head and the almost equally blunt tail these creatures are called by the natives "cobras de dous cabezas," i.e. snakes with two heads, or they are known as "maes das formigas," i.e. mothers of ants, because of their predilection for taking up their quarters in the nests of ants or termites. The scientific name refers of course to their capability of moving forwards and backwards (ἀμφίς, at both ends, and βαίνω, walk).

A. fuliginosa, one of the commonest species in South America and in the West Indies, is chequered black and white. The skin of the body has about two hundred rings, the tail about thirty. Total length between one and two feet. A more or less distinct fold extends along each side of the body from the neck to the tail, at the level where the dorsal scales originally joined the ventral scales.

Blanus is the only genus of the Mediterranean province. B. cinereus, of Portugal, Spain south of the Cantabrian range, Morocco, and Algeria, reaches a length of 10 inches, but such large specimens are rather rare. The general colour of the living animal is pink with a brownish tinge and with minute grey specks. The lateral lines or folds are well marked, and a stronger transverse fold is placed behind the head. The body shows from one hundred and ten to one hundred and twenty-five rings, the tail from twenty to twenty-two; each body-ring contains about thirty little squares or remnants of scales. There are a few pre-anal pores.

{567}I have sometimes found this species in Portugal whilst digging for earth-worms in manure-heaps and similar moist places, where they lead the same life as the worms except that they live upon them and upon insects. When kept dry they become very thin and shrunken, but when put back into moist soil they again become turgid and supple within a short time. Those which I have kept in glass jars filled with rich mould throve very well, living upon the tiny insects and worms which infest such compost soil; they dug long tortuous channels, in which they moved forwards and sometimes backwards, but they never came to the surface.

FAM. 18. PYGOPODIDAE.–Pleurodont, snake-shaped lizards, without fore-limbs, but with the hind-limbs appearing as a pair of scaly flaps.

The shoulder-girdle is much reduced. The hind-limbs, although very small and hidden within the scaly, almost fin-like flaps, still possess five toes. The ischium appears externally as a small spur on either side of the anal cleft. The eyes are devoid of movable lids, remaining open and unprotected; the pupil is vertical. The ear is either concealed or exposed. The tongue is fleshy, slightly forked and extensible. The body is covered with roundish imbricating scales. The tail is very long and brittle. The few genera of this undoubtedly natural family of unknown relationship contain in all about ten species, restricted entirely to Australia, Tasmania, and perhaps New Guinea. Next to nothing is known about their habits, except that some of them eat other lizards.

Pygopus lepidopus is distributed over the whole of Australia. It reaches a total length of about 2 feet, 16 inches of which belong to the tail. General colour coppery grey above, sometimes with several longitudinal series of dark spots.

Lialis burtoni of nearly the same size and equally wide distribution has the hind-limbs reduced to extremely small, scarcely visible, narrow appendages.

SUB-ORDER 3. CHAMAELEONTES.–Acrodont Old-World Saurians with a laterally compressed body, prehensile tail, and well-developed limbs with the digits arranged in opposing, grasping, bundles of two and three respectively.

The Chameleons are an essentially African family. About half of the fifty species known inhabit Madagascar, the others {568}the African continent. One, the common Chameleon, is North African, extending into Andalucia; two others occur in South Arabia and Socotra, and only one in Southern India and Ceylon.

This sub-order is well distinguished from all other Saurians by several, mostly unique, characters. The tongue is club-shaped and extremely projectile, to a length equal to that of the body. The head is usually described as forming a casque, with prominent crests and tubercles. There is no tympanum and no tympanic cavity. The parietal bones, united into one, extend backwards far beyond the occiput, and the tip of this projection is met by a much-elongated supratemporal bone, which, partly fused with the squamosal, helps to enclose a huge supratemporal fossa. The latter is widely open behind. The postfronto-squamosal arch and the postorbital arch are strong. The jugal is widely separated from the quadrate; the latter stands vertically and is not reached by the pterygoid. There is no columella cranii. The pre- and post-frontals often join to form a supra-orbital roof. The nasals are very small and are excluded from the nares, which are bordered entirely by the enlarged prefrontals and by the maxillaries. The premaxillaries are small and carry no teeth. The latter are acrodont, compressed and tricuspid, and are restricted to the maxillaries and mandibles.

The limbs are peculiar. Not only are they relatively long and very slender, but two digits are permanently opposed to the other three. On the hand the first three fingers form an inner bundle opposed to the outer, or fourth and fifth fingers. On the foot the inner bundle is formed by the first and second, the outer by the other toes. The shoulder-girdle is of the ordinary Saurian type, but there are no clavicles and no interclavicle. The costal sternum is well developed; the ribs posterior to those which meet the sternum are very thin and elongated: they meet and fuse with their fellows in the medio-ventral line. These hoops are not connected with their neighbours in front or behind. The tail is prehensile by being rolled downwards; it is not brittle and is incapable of being renewed. The skin is not covered with scales, but with {569}granules. The eyes are very remarkable. The eyeballs themselves are large, but the eyelids are united into one fold with a small central opening. However, when the Chameleon is asleep the margins of this opening sometimes become more slit-like. The right and left eye can be, and are incessantly, moved separately from each other, and the creature squints terribly. Each eyeball, together with the pin-hole eyelid, is rolled up and down, backwards and forwards, independently of the other eye. This is a unique feature, but it also occurs in people who squint badly. The question "What, and how, do these creatures see?" is therefore quite idle, especially since in reptiles binocular vision does not exist at all and, consequently, cannot be disturbed by squinting.

The tongue has attained an extraordinary development. The tongue proper (Fig. 152) is club-shaped, and is covered with a sticky secretion. The base or root of the tongue is very narrow, composed of extremely elastic fibres, and is supported by a much-elongated copular piece of the hyoid. The elastic part of the tongue is, so to speak, telescoped over the style-shaped copula, and the whole apparatus is kept in a contracted state like a spring in a tube.

A pair of wide, very elastic blood-vessels and special elastic bands extend from the base into the thick end of the tongue. {570}By rapidly filling the apparatus with blood, and by the action of certain hyoid muscles, the spring is, so to speak, released, and the momentum gained by the thick and heavy club-shaped tongue proper projects it far out of the mouth. The sticky end of the club shapes itself into an upper and a lower flap, which partly envelop the prey, and the elastic bands of the far-stretched stalk withdraw the whole. The detailed working of this ingenious shooting apparatus is not easy to follow. An ordinary full-grown Chameleon can shoot a fly at the distance of 7 or 8 inches. The whole performance is very quick, lasting less than one second. When the desired object is very near, only 2 or 3 inches off, the Chameleon has a certain difficulty in shooting its prey. The tongue is at first put out slowly, tentatively, the following jerk is feeble, and it seems as if the apparatus refuses to work unless it is allowed to shoot out with full force.

Another remarkable and quite proverbial feature of Chameleons is their changing of colour. This is by no means restricted to Chameleons, which indeed are rivalled in this respect by various other lizards, for instance by the Indian Agamoid Calotes and by the American Ameiva.

The microscopical structure and mechanism of the colour-changing apparatus is, in Chamaeleon vulgaris, as follows:–

The epidermis is colourless, and the Malpighian layer is not particularly modified except that in it are imbedded some iridescent cells, with very minute wavy striation on their surface. The cutis contains in its leathery tissue a great number of small and closely packed cells, filled with strongly refractive granules, chiefly guanine-crystals. These cause the white colour by diffuse reflection of direct light. The cells nearer the surface are charged with oil-drops and appear yellow. Large chromatophores are imbedded in the white granular mass, most of them with blackish-brown, others with reddish pigment, the granules of which are shifted up and down, towards and away from the surface of the cutis, in ramified branches of the chromatophores. When these branches are contracted the pigment is conveyed back into the bulbous basal portion of the chromatophores and the skin appears yellow or white. When all the pigment is shifted towards the surface of the cutis, the animal looks dark, sometimes black. In intermediate conditions the light is changed into green by diffraction through the yellowish upper strata and by the finely {571}striated iridescent cells of the Malpighian layer. Those parts into which the chromatophores do not send pigment appear as yellow spots. The chromatophores are to a great extent under control of the will of the Chameleon, but external stimuli, as heat and cold and other reflex actions, also play a great part in their movements.

For further information on this subject see Brücke, P. Bert, Pouchet, Thilenius, and lastly Keller, who has written a very long but rather confused account.

The process of moulting is curious. When the Chameleon is in good health the whole process is accomplished within a few hours. The skin to be cast off becomes loose and assumes a blistered appearance. Sometimes the creature looks as if it were wrapped up in white, semi-transparent tissue paper. By rubbing against stones, or between the twigs of trees, the skin comes off in large flakes, first on the lips, then on the contorted body, and last on the under surface of the hands and feet. During a rapid and successful moult the changes of colour go on as usual in the new skin. Sometimes large flakes of the old skin remain adherent for days, especially on the top of the head. The moulting takes place several times in one year. One of my Ch. vulgaris moulted in January and September, and then not until June of the next following year. A Ch. pumilus moulted in the months of May, October, and March.

When they know themselves to be discovered, Chameleons make themselves as thin as possible by compressing the body or rather the belly. This is done by means of the peculiarly elongated abdominal ribs described above. The whole body is then put into such a position that, by presenting only its narrow edge to the enemy, it has become as little visible as {572}possible. At the same time the Chameleon turns round upon its twig, so that the latter comes to stand between the observer and its own body, which may thereby be completely hidden. When angry, the creature either presents its broadest surface, swaying to the right and left, or it blows itself up and hisses. The lungs are very capacious, and, instead of being bag-shaped, end in several narrow blind sacs which extend far down into the body-cavity, so that not only the chest but the whole body can be blown up.

The usual mode of propagation is by means of eggs, but a few species allied to Ch. pumilus are viviparous. The time of incubation and of gestation is long. For instance, the pairing of Ch. vulgaris takes place in the month of August. The eggs are laid in the last week of October, about fifty to sixty days later. Sometimes, however, the eggs are retained much longer, since I have received specimens with ripening eggs in July which did not lay until the end of October. The eggs are deposited in the ground and are not hatched until the following February or March, i.e. about 130 days later. The new-born little creatures are snowy white, and cannot change or rather assume colour until after the second week.

All Chameleons are insectivorous and require enormous quantities of food, which must be alive to be taken. Most of them prefer Orthoptera, e.g. Locusts and Grasshoppers, and Lepidoptera. They also eat flies, meal-worms, and cockroaches, but their tastes differ not only individually but also temporarily. They require change of diet. One individual will take cockroaches greedily, whilst another of the same kind will rather starve itself than touch one. The same applies to meal-worms. It is a great but common mistake to suppose that Chameleons do not require water. On the contrary they drink regularly and often, generally by licking up drops of water or by scooping them up with their lips, shoving the snout along the edges of wet leaves. It is not too much to say that most Chameleons are short-lived in captivity on account of the want of water. Those which are sold by the dealers are generally in a parched condition. Sprinkling the twigs or leaves of their cage with water works a wonderful change in them; the dull, apathetic-looking creatures drink and drink, revive, assume brighter colours, and will soon take food, which they have until then refused {573}obstinately. Once I have even seen a Chameleon, when put into the greenhouse, make straight for a tank and actually drink in gulps.

After they have fattened themselves in the autumn, Chameleons, at least those of North Africa, withdraw to hibernate in the ground. But nothing is known about how, when, and where they do this, nor is it known if tropical species aestivate during the dry season.

Chameleons are notoriously difficult to keep successfully, whereby we do not mean the keeping for three to six months. This is easy enough, since it takes them several months to die of starvation. The difficulty is to keep them through the winter. To enable them to do this, it is absolutely necessary to fatten them up during the summer and autumn. Otherwise, although kept in a warm place, they are liable to lose their appetite in the autumn, when they become restless, probably with the desire to hibernate. Those few individuals which get over this critical period, say during the month of October, and do not refuse food, are probably safe. But those are doomed which refuse to eat meal-worms or cockroaches or such food as can be procured easily during the winter.

The origin of the Chameleons is unknown. They form only one family, CHAMAELEONTIDAE, with between fifty and sixty species, which, with a few exceptions, belong to the genus Chamaeleon.

Ch. vulgaris is the Common Chameleon of North Africa, Syria, and Asia Minor. It occurs also in a few parts of Southern Andalucia, for instance near Jerez, and near Nerja, to the east of Malaga, where it has possibly been introduced. A series of conical, slightly enlarged granules forms a little crest on the median line of the throat. A whitish line, which does not change colour, extends from the chin to the vent. The rest of the skin, with the exception of a median dorsal series of slightly enlarged tubercles on part of the back, is composed of small granules. A small but distinct lobe of leathery skin extends along either side of the occiput towards the posterior end of the median parietal crest. Dead or spirit-specimens are usually pale yellow; living ones are greenish, usually with differently coloured patches on the sides. Exceptionally large males reach a total length of about 9 inches, females reach the length of perhaps a foot, but about half of the total length belongs to the tail.

{574}It is impossible to say what is the colour of this Chameleon, since the same specimen may within a few days appear in half-a-dozen different garbs, not counting minor combinations of colour. After it has been watched for several months, when all its possibilities seem to be exhausted, it will probably surprise us by a totally new combination. Not every specimen changes alike: some keep the same appearance for a long time, others change often; some are partial to specks, others to large patches. In the group of Chameleons shown in Fig. 152 several of the more usual arrangements of colour have been indicated by stippling and various kinds of cross-hatching.

A represents the usual coloration at night. The whole animal, which has just been stirred up from its sleep in the dark, is cream-coloured, with irregular patches of yellow on the head, the back, the sides of the body, the legs, and the tail.

B has the usual coloration: grey-green, with innumerable small darker specks, with two series of pale brown patches on the sides of the body, and with one patch on the region of the ear.

{575}[Illustration: FIG. 152.–Showing changes of colour in Chameleons. A to D, Chamaeleon vulgaris (see p. 574). Chamaeleon pumilus in the right upper corner.]

{576}C is the same specimen in an excited frame of mind; it is represented in the act of shooting a fly. The light brown patches have changed to maroon brown; and many round golden yellow spots have appeared on the green parts.

D shows a specimen, coloured like C, within a few seconds after it has been put into an angry mood, in the present case by having its tail squeezed. The whole body is blown out, the thick tongue causes the throat to bulge out, and all the yellow spots have become blackish green.

Many small spots scattered over the body are usually a sign of anger. One of the specimens described above was, when fast asleep in a dark room, dirty white, with about two dozen large and small round spots of a rich yellow on each side of its body. Then a lighted lamp was brought into the room without in any way disturbing the animal. Within sixteen minutes the yellow spots had vanished completely; the whole body and tail had become suffused with greenish yellow, which gradually turned to pale yellowish green, and those parts which in Fig. B are pale brown, were just distinguishable as pale yellowish-white regions. The Chameleon was found to be fast asleep, and it kept this coloration during the rest of the evening. Other specimens behaved on similar occasions in the same way, but the greatest interest is attached to the fact that frequently only that side of the body "greened up" which happened to be exposed to the light, whilst the opposite side remained whitish. These changes are not absolutely unconscious; they are, after all, under the control of the creature. In order to test the possibility of direct action of the light, I have taken the precaution of throwing the light of a candle only upon the body, whilst the head was kept in darkness. No changes of colour took place whilst the animal was asleep, but when a little light was allowed to sweep across the closed eye, this soon began to twitch, and although the creature did not open the eye, the usual changes of colour began to take place. When the light was removed, the animal soon re-assumed its whitish appearance. Artificially coloured light, for instance green, red, or blue glass or paper, has apparently no influence upon the changes of colour. The Chameleons behave as they would behave under ordinary conditions. Direct and hot sunshine however causes them to darken, sometimes to turn uniform dull black, except for the white median ventral {577}line. Occasionally I found one of the specimens described above deep maroon brown, with dozens of round orange spots. Blue and red do not seem to be within the range of Ch. vulgaris, but the combinations of green, yellow, brown, black, and white, with their various shades, are almost endless. Sometimes the Chameleons do not turn pale during the night, but remain more or less dull green, with or without brownish patches. Adaptation to their immediate surroundings takes place to a very moderate degree only, but as a rule they are brightest, especially in their green tints, when they are allowed to sit amongst green foliage. The introduction of a branch with fresh leaves generally has a brightening effect upon those which have previously been confined in a cage with dry twigs only. Cold does not necessarily make them pale, but they appear duller, and the changes take place more slowly. After all, Linnaeus has summed up the little we really know about the causes of these changes, in the following terse sentence: "Vivus varios colores assumit secundum animi passiones, calorem et frigus."

Chameleons are not very amiable. When taken up they blow themselves out or they bite painfully, and it is a long time before they are tame enough not to go through various antics of anger when one approaches them. When taken in the hand they produce a peculiar faint grunting noise, which, however, can be better felt than heard. They quarrel much amongst each other; and the males, during the pairing season, are particularly ill-tempered. Each individual selects its own particular branch to sleep on, if possible a horizontal one, upon which it crouches down lengthwise, with the head and belly resting upon the branch. The tail generally makes a turn round another branch, and the four legs, grasping some supporting branch, are put into any, sometimes into an almost incredibly, awkward position. Although they climb about a good deal during the daytime, they generally resort to their accustomed sleeping branch, and they defend this vigorously against would-be intruders.

Chameleons are most deliberate in their movements, sometimes provokingly slow. Each arm and foot leaves the firmly grasped branch with great hesitation, and makes with equal deliberation for some other foothold. It does not matter if the thigh appears almost twisted out of its joint. The creature will {578}remain in the most uncomfortable position, forgetting, one might think, to put one or more of its limbs down, but keeping them instead in the air.

It is most interesting to watch them stalking their prey. Suppose we have introduced some butterflies into their roomy cage, which is furnished with living plants and with plenty of twigs. The Chameleons, hitherto quite motionless, perhaps basking with flattened-out bodies so as to catch as many of the sun's rays as possible, become at once lively. One of them makes for a butterfly which has settled in the farther upper corner of the cage. With unusually fast motions the Chameleon stilts along and across the branches and all seems to go well, until he discovers that the end of the branch is still 8 inches from the prey, and he knows perfectly well that 7 inches are the utmost limit to a shot with his tongue. He pauses to think, perhaps with two limbs in the air, but stability is secured by a judicious turn of the tail. After he has solved the puzzle, he retraces his steps to the base of the branch, climbs up the main stem, creeps along the next branch above, and when arrived at the 7 inch distance, he shoots the butterfly with unerring aim. The capacity of the mouth and throat is astonishing. A full-grown Chameleon will catch, chew, and swallow the largest moth, for instance a Sphinx ligustri. When large, the prey is chewed, but the wings and legs are swallowed with the rest. Occasionally these parts are bitten off, especially the prickly long legs of large locusts.

In water Chameleons are quite helpless. Sometimes they inflate themselves, but they always topple over on to the side, and the movements of their limbs are absolutely without any definite purpose.

When the eggs are ripe, and this happens with the Common Chameleon about the end of October, the female refuses to take food, and becomes restless. One of my specimens searched about probing the ground for about a week before she dug a hole in some more solid soil. This took two days. In the evening I found her sitting in the hole to the middle of her body. On the following morning she was still there, but busy filling the hole with soil and covering it with dry leaves. A few eggs were lying about outside, two of which at least I saw her taking up by the hand and putting them on the {579}nest, which was found to contain some thirty soft-shelled eggs closely packed upon each other. During the whole process she was very snappy, and hissed much when approached. After that she crept into the twigs as usual, but refused to eat, vomited at once the artificially introduced food, became restless on the sixth day, crawling about at the bottom of the cage, and died on the following day. This is the usual fate, almost without exception, of females after they have deposited their eggs in captivity. The great number of eggs and their deposition naturally exhausts them, and they probably want to hibernate at once. The eggs, which are yellowish, long-oval, about half an inch long and covered with a parchment-like shell, are very difficult to rear, chiefly on account of the difficulty of regulating the moisture. They shrink up when too dry, and they are very liable to become mouldy. According to Fischer the eggs can be hatched in a large flower-pot with a layer of horse-droppings at the bottom, then a layer of 6 inches of slightly moist soil, then the eggs, then another 6 inches of loose soil, with a glass plate covering the top, securing at the same time ventilation. In this way he succeeded in hatching several sets of eggs after 125 and 133 days respectively.

Ch. calcaratus, the Indian Chameleon, is found in the southern half of the Peninsula and in Ceylon, but it is far from common. It much resembles Ch. vulgaris, but the male is distinguished by a tarsal process or "spur," covered with skin, on the inner side of the foot.

Ch. pumilus, the Dwarf Chameleon of South Africa, reaches a total length of 5 to 6 inches. It has a well-marked, serrated gular crest, which extends from the chin to the end of the neck. The chest and belly are without a toothed line, but a strongly serrated series extends from the occiput over the back and tail (see the right upper corner of Fig. 152 on p. 575). A row of enlarged tubercles or scales extends along the sides of the body. The general colour is green, with a large and long patch of brick-red on the sides; small dots and spots of intense red are scattered over various parts of the body. The changes of colour are rather limited. At night the Dwarf Chameleon does not turn pale, but generally keeps its colour. When they are very well the green is quite saturated, and the large red patch on the side is {580}interrupted by several blue spots. When they are angry or unhappy the red turns into dirty brown, and the green becomes quite dull. Sometimes the whole animal turns dull black.

This pretty little species is relatively hardy, being, as a native of South Africa, accustomed to cold nights. It does well in an ordinary temperate greenhouse, where it will live for several years, provided it has an ample supply of flies and meal-worms. It is viviparous, the young being probably born in the month of March or April.

Ch. bifidus, of Madagascar, shows an extraordinary difference between the sexes. The male reaches the great length of 16 inches, and develops two long rostral processes, which extend forwards beyond the snout; these processes are formed of dense connective tissue, which ossifies in the adult, and they are covered with scaly skin.

Ch. parsoni, likewise of Madagascar, is the giant amongst Chameleons, reaching a total length of 2 feet. The male has two large rostral processes which diverge upwards and outwards.

Brookesia, with several species in Madagascar, may be mentioned on account of its stunted appearance. The tail is much shorter than the body and scarcely prehensile; the scales on the soles are spinous. Total length only about 3 inches.

Rhampholeon, of tropical continental Africa, with several species, is likewise remarkable for the stunted and dwarfed appearance, and for the peculiar claws, each of which is furnished with a second cusp which is directed downwards. The tail is much shorter than the body. The total length of Rh. spectrum of the Camaroons is about 3 inches.

{581}CHAPTER XIII

SAURIA, continued–OPHIDIA–SNAKES

ORDER II. OPHIDIA–SNAKES.

Saurians which have the right and left halves of the lower jaw connected by an elastic band.

The Snakes are the most highly specialised branch of the Sauria, from which they do not differ in any fundamental characters. The chief modifications consist in the absence of the limbs and limb-girdles (a feature intimately correlated with the much-elongated body), and in the swallowing apparatus. The reduction of the limbs and the elongation of the body also occurs in many Lacertilia; in several of the older families of Snakes (e.g. Typhlopidae and Boidae) vestiges of the hind-limbs and even of the pelvis are still in existence. Even the peculiar suspensorial apparatus of the lower jaw approaches that of the Lacertilia in the burrowing Ilysiidae and in Xenopeltis.

In the majority of the Snakes the quadrate is very loosely suspended from the squamosal (by some authorities homologised with the supratemporal bone of other reptiles), and this again is loosely attached to the lateral parietal region of the skull, placed horizontally, and elongated so far backwards that the vertically placed quadrate lies in a plane behind the skull. In most Snakes the elongated pterygoids are loosely attached to the inner side of the distal end of the quadrates, and they also often touch the mandibles. The whole palatal apparatus is movably attached to the skull, except in some burrowing families. The right and left pterygoids and palatines are widely separated from each other. The pterygoids and maxillaries, connected by the ectopterygoids, are absent, owing to reduction, in the {582}Typhlopidae and Glauconiidae only. The premaxilla is unpaired and small, and is rarely furnished with teeth. The latter are always sharp and recurved, and are lodged in sockets upon the edge of the supporting bone, with which they become firmly ankylosed. There is a perpetual succession of teeth. In the majority of Snakes teeth are carried by the maxillaries, palatines, pterygoids, and dentaries, rarely by the premaxillaries. The palatal teeth are restricted to the palatines in Oligodon, Dasypeltis, and Atractaspis only.

Peculiar modifications prevail in the poisonous Snakes. Those maxillary teeth which are at their base in connexion with the openings of poison-glands (modified upper labial glands), either have a furrow on the anterior side (Proteroglypha if the anterior teeth are grooved, e.g. the Cobras; Opisthoglypha if some of the posterior teeth are grooved), or the groove is converted into a canal, as in the Solenoglypha or Viperidae. The special modification of the maxillaries of the vipers with their long poison-fangs is described on pp. 587 and 637.

The orbit is generally closed behind by the postfrontal. Quadrato-jugal, postfronto-squamosal, and other arches are absent, so that the temporal fossa is quite open (see Fig. 156, p. 597, and Fig. 155, p. 596). The occipital condyle is distinctly triple. The mandibles are composed of several bones, but the coronoid is absent in the Xenopeltidae, Colubridae, Amblycephalidae, and Viperidae; it is large in the Boidae, reduced to a nodule in the Ilysiidae.

The parietals are always fused into a large unpaired bone, which generally forms a sharp crest and partly overlaps the occipitals; there is no interparietal or pineal foramen.

The vertebral column consists of many, often nearly three hundred vertebrae, and these skeletal segments correspond in number with those of the ventral and transverse scales of the skin. The vertebrae are procoelous; in addition to the anterior and posterior zygapophyses they have a pair of accessory articulations on the neural arches, dorsally to the zygapophyses;–the "zygantrum" carried by the posterior end of the neural arches, its articular surfaces looking upwards; and the "zygosphene" carried by the anterior end and looking downwards. Such accessory articulations occur also in a few Lizards, e.g. Iguanidae. The vertebrae of many Snakes have unpaired vertical, blade-like {583}haemapophyses on their centra for the more effective attachment of the muscles. All the vertebrae, except the atlas, carry ribs. These articulate by their capitular portions only, and are very movable in a head- and tail-ward direction. The ribs being long, and fitting with their ventral ends into the connective tissue of the sides of the ventral transverse scales, are the principal agents in pushing the body forwards, the posterior edges of these scales being sharp and imbricating.

The skin is covered with scales, absolutely devoid of osteoderms. When the scales are enlarged they are called shields. The keel, a common feature, is caused by a slight ridge of the cutaneous part of the scale. The whole skin is covered with a thin layer of horny epidermis, which is shed frequently, at least several times in one year; the shedding begins at the lips, and the whole outer skin is turned inside out from head to tail, retaining every minute detail of the cutaneous scales; even the watch-glass-like covering of the eyes is preserved.

The eyes are peculiar in so far as they possess no lids. The latter are still present in a vestigial condition in the embryo, but their place is taken by what is probably a modification of the nictitating membrane, which is drawn over the eye and covered with a single transparent scale of the horny skin, like a watch-glass. The eyes themselves are quite movable. The "tears," which of course cannot appear on the outside, are drained off into the nasal cavities by the naso-lacrymal ducts.

The ear is likewise peculiar. There is a long columellar rod with a fibrous or cartilaginous pad at the outer end, which plays against the middle of the shaft of the quadrate, an arrangement which, we must assume, produces a thundering noise in the internal ear, since every motion of the quadrate during the act of swallowing conveys the vibrations directly to the fenestra ovalis. The tympanic cavity, the Eustachian tubes, and the tympanum are abolished, and no external traces of the ear are visible. However, in spite of all this, Snakes can hear very well.

The nose is well developed, and many Snakes, for instance the Grass-Snake, are guided to their prey as much by the sense of smell as by the eyes and ears. The tongue is slender, very protractile and bifid, always moist, and furnished with many sensory corpuscles. It acts entirely as an additional sense-organ, hence the incessant play of the tongue of a snake which wants {584}to investigate anything. In spite of the protractility of the tongue, the hyoid apparatus is very small; the hyoid arches themselves are reduced to mere vestiges near the base of the first and only branchial arches, which are thread-like and extend backwards down the throat.

The trachea is very long, and opens far forwards in the mouth; it can be slightly protruded between the two halves of the lower jaw so as not to be blocked during the act of swallowing. This is a laborious process. The snake, having got hold of its prey with its teeth, generally shifts it into the most convenient position, in order to swallow the head first. One half of the mandible is then pushed forwards, then the other half; the recurved teeth afford the necessary hold, and the snake, little by little, draws its mouth-cavity, and later on itself, over the prey. In fact, it literally gets outside it. Sometimes with a large victim this process may last for hours; the whole mouth and head become painfully distended and the veins swollen almost to bursting. The snake pushes the prey against a stone or other obstacle, rests awhile quite exhausted, and begins afresh. At last the bulk of the prey has passed the mouth, the skin of the neck is stretched to the utmost, the scales being separated by wide interstices, the ribs work spasmodically, the victim is pressed into the shape of a sausage, and the deed is done. In order to assist deglutition there is a great amount of salivation, but the often-heard story that Snakes cover their prey with saliva before they swallow it, is a fable, or based upon faulty observation, snakes sometimes being forced to disgorge the half-swallowed prey, which, in such a case, is covered with slime. One of my tame snakes had swallowed a frog on my table when a friend entered the room. The snake was frightened, jumped on to the ground, striking it with its full belly, and thereby hurting the frog, which squeaked loudly, whereupon the snake reversed its mechanism and the frog hopped away, none the worse for its terrible experience.

In correlation with the elongated narrow space of the body-cavity the lungs are not equally developed, the right being much smaller than the left. The latter is a very thin-walled, hollow bag, and the posterior half or third scarcely contains any of the honey-comb-like respiratory "cells," but acts merely as a reservoir of air.

{585}The cloacal arrangement is essentially the same as that of the Lacertilia, but Snakes possess no urinary bladder. The copulatory organs are stowed away beneath the skin in recesses of the posterior lateral corners of the shallow cloacal vestibulum. Each organ is generally bifurcated at the free end, and furnished with little spike-shaped, but scarcely horny, excrescences. On each side of the outer cloacal chamber, in both sexes, lies a roundish gland with an offensive, strongly-scented secretion; that of various Boas smells disagreeably sweet and musky. The majority of Snakes lay eggs, but most of the Viperidae and the thoroughly aquatic kinds, besides a few terrestrial forms, are viviparous. The egg-shells are like parchment, with very little or no calcareous deposit, so that they are always soft; many embryos are, however, provided with a little "egg-tooth" on the tip of the snout.

Snakes are intelligent creatures; some become quite affectionate in captivity, but most of them are of a morose disposition, and do not care for company.

The GEOGRAPHICAL DISTRIBUTION of Snakes has been dealt with in detail in connexion with the various families. Unfortunately very few fossils are known. One of the oldest is Palaeophis, of the London clay (Lower Eocene). Remains of Elapine and of innocuous Colubrine snakes have been found in the Lower Miocene of Germany; Crotaline forms are known from the Miocene of Turkey and North America. All the Plistocene {586}remains belong to recent genera. There are indications that the Ophidia are a relatively young branch of Reptilia, essentially of Tertiary date, but the foundations of the distribution of most of the older families were laid in Miocene times. The older families, notably those which still possess vestiges of hind-limbs or of the pelvis, are circumtropical, e.g. Typhlopidae, Boidae. The few survivors of the Glauconiidae are likewise circumtropical, with the exception of Australia. The Ilysiidae occur in South-Eastern Asia and in tropical South America; their offshoot the Uropeltidae are restricted to India and Ceylon. The Colubridae and even many of their sub-families are cosmopolitan. It is quite possible that the Opisthoglypha and Proteroglypha are not natural groups, but that their respective conditions have been developed on various occasions and in different countries. The same applies more strongly to the Viperidae, a further development of the Opisthoglyphous type. To judge from their distribution, the Crotaline snakes were possibly developed in the Palaearctic sub-region; they spread all over America, but they were debarred from entering either Australia or Africa. The Viperidae, on the other hand, are restricted entirely to the Palaeotropical region and to the Palaearctic sub-region. The fact that no separating belt of water existed for them between Europe and Africa, indicates their being the most recently developed of poisonous snakes. Madagascar is the only large country which, besides snakeless New Zealand, enjoys a total absence of poisonous snakes of any kind, while the Oriental is the only sub-region which suffers from the presence of numerous species of every sub-family of poisonous Elapine, Crotaline, and Viperine snakes.

Snake-Poison.–Many Snakes, belonging to different families, are poisonous, and unfortunately there is no external character, easily ascertained, by which every poisonous snake can be distinguished from a harmless kind. If the head is very broad, this is probably due to the pair of poison-glands on the sides of the head; but many harmless snakes can flatten and broaden their heads in a suspicious way, and, what is much worse, many of the most poisonous snakes, for instance the Cobras, have a head as smooth and as sleek-looking as the Grass- or Ring-Snake, the most harmless of species. It so happens that, with a few exceptions, for instance among the Crotalines and Vipers, no {587}badly poisonous snake has loreal shields, i.e. a pair of shields intercalated between the nasals and the preoculars, but this character is obviously no good for any practical purposes. Therefore, unless you know a snake well enough when you see it, leave it alone, because a mistake may be fatal.

The poison is secreted in modified upper labial glands, or in a pair of large glands which are the homologues of the parotid salivary glands of other animals. A duct passes from the gland forwards along the side of the upper jaw. Just in front of the fang it doubles on itself, so as to open by a small papilla on the anterior wall of the sheath of mucous membrane which embraces the base of the tooth like a pocket. As mentioned before (p. 582), the poison is conveyed either along a furrow on the anterior side of the tooth, or the growing substance of the tooth partly converts the furrow into a canal which opens only near the end of the tooth. This is a perfectly devilish contrivance, ensuring the conveyance of the poison into the very deepest part of the wound. The Elapinae have relatively short fangs, while those of the Vipers, and especially those of the Crotaline snakes, are much longer, sometimes measuring nearly an inch in length. The most formidable apparatus is that of the Viperidae, since in them the maxillaries, each provided with only one acting fang, and without any other teeth behind, can be erected. The mechanism is explained in Fig. 154 and Fig. 179 (p. 647). The apparatus of the upper jaw is so constructed that the pushing forwards of the horizontal pterygoid bar will, by acting on the ectopterygoid, rotate and erect the short maxillary. The pulling forwards is effected by contraction of the spheno-pterygoid muscle, which arises far forwards from the basal orbito-sphenoid region, and is inserted on to the inner dorsal surface of the pterygoid. The principal closing muscles of the mouth are the temporo-masseteric muscles (Fig. 179, T.a. and T.p.) and the inner and outer pterygoid muscles, which latter arise from the outer surface of the pterygoid bone, or from the maxillary, and are inserted on to the articular region of the mandible.

A strong ligament arises from the squamoso-quadrate junction, and spreads fan-shaped upon the connective tissue {588}wall of the poison-gland; the anterior and posterior ends of the gland are held by another strong band, which stretches from the maxilla to the mandibular joint. The whole is so arranged that the acts of opening the jaws (by the digastric muscles) and the erection of the fang-bearing maxillaries are enough to mechanically squeeze the contents out of the poison-gland. A portion of the anterior temporal muscle is attached to the capsule of the poison-gland.

An excellent account of the nature and of the effect of the venom of Snakes has been written by Charles J. Martin. The following condensed account has been abstracted from it:–

"The poison is a clear, pale yellow, or straw-coloured fluid, {589}which reacts acid, and contains about 30 per cent of solids, but this varies much according to the state of concentration. Most venoms are tasteless, but Cobra poison is said to be disagreeably bitter. Dried venom keeps indefinitely, and dissolves readily in water. It keeps also in glycerine. It contains albuminous bodies in solution. The venom is, in fact, a pure solution of two or more poisonous proteids, which are the active agents, with a small quantity of an organic acid or colouring matter. The venom is destroyed by reagents which precipitate proteids in an insoluble form, or which destroy them, e.g. silver nitrate or permanganate of potash. Hypochlorites have the same effect. Carbolic acid and caustic potash destroy it only after a day or two.

"The venom is generally introduced into the subcutaneous tissue, whence it reaches the general circulation by absorption through the lymph and blood-vessels. When introduced directly into a vein, the effects are instantaneous. It is absorbed by the conjunctiva, but, excepting Cobra poison, not by the mouth or alimentary canal, provided there be no hollow teeth or no abrasions. The venom of the various kinds of Snakes acts differently.

"The symptoms of Cobra poison. Burning pain, followed by sleepiness, and weakness in the legs after half an hour. Then profuse salivation, paralysis of the tongue and larynx, and inability to speak. Vomiting. Incapability of movement. The patient seems to be conscious, but is unable to express himself. The breathing becomes difficult. The heart's action is quickened. The pupil remains contracted and reacts to light. At length breathing ceases, with or without convulsions, and the heart slowly stops. Should the patient survive, he returns rapidly to complete health.

"The symptoms of Rattle-snake poison. The painful wound is speedily discoloured and swollen. Constitutional symptoms appear as a rule in less than fifteen minutes: prostration, staggering, cold sweats, vomiting, feeble and quick pulse, dilatation of the pupil, and slight mental disturbance. In this state the patient may die in about twelve hours. If he recovers from the depression, the local symptoms begin to play a much more important part than in Cobra poisoning: great swelling and discoloration extending up the limb and trunk, rise of {590}temperature and repeated syncope, and laboured respiration. Death may occur in this stage. The local haemorrhagic extravasation frequently suppurates, or becomes gangrenous, and from this the patient may die even weeks afterwards. Recovery is sudden, and within a few hours the patient becomes bright and intelligent.

"Symptoms of bite from the European Viper. Local burning pain; the bitten limb soon swells and is discoloured. Great prostration, vomiting, and cold, clammy perspiration follow within one to three hours. The pulse is very feeble, with slight difficulty in breathing, and restlessness. In severe cases the pulse may become imperceptible, the extremities may become cold, and the patient may pass into coma. In from twelve to twenty-four hours these severe constitutional symptoms usually pass off, but in the meantime the swelling and discoloration have spread enormously. Within a few days recovery usually occurs somewhat suddenly, but death may occur from the severe depression, or from the secondary effects of suppuration.

"Symptoms of bite from the Daboia or Vipera russelli. These resemble the effects of Rattle-snake poison, but sanious discharges from the rectum, etc., are an additional and prominent feature. The recovering patient suffers from haemorrhagic extravasations in various organs, besides from the lungs, nose, mouth, and bowels. Kidney haemorrhage and albuminuria is a constant symptom. The pupil is always dilated and insensitive to light.

"Symptoms of bite of Australian Elapine snakes. Pain and local swelling. The first constitutional symptoms appear in fifteen minutes to two hours. First faintness, and an irresistible desire to sleep. Then alarming prostration and vomiting. The pulse is extremely feeble and thread-like, and uncountable. The limbs are cold, and the skin is blanched. Respiration becomes shallow with the increasing coma. Sensation is blunted. The pupil is widely dilated, and insensible to light. There is sometimes passing of blood. If the patient survives the coma, recovery is complete and as a rule rapid, without secondary symptoms. The Australian venom and that of all viperine snakes, perhaps also that of the Cobra, if introduced rapidly into the circulation, occasions extensive intravascular clotting. If the venom is slowly absorbed, the blood loses its coagulability, {591}owing to the breaking down of the red blood-corpuscles, most so with vipers, less with Australian snakes, least so with the Cobra. The Cobra venom is supposed to extinguish the functions of the various nerve-centres of the cerebro-spinal system, the paralysation extending from below upwards, and it has a special affinity for the respiratory centre. The toxicity or relative strength of the Cobra venom has been calculated to be sixteen times that of the European Viper. Snakes can poison each other, even those of the same kind.

"Treatment.–Apply a ligature above, not on the top of the situation of the bite; twist the string tightly with a stick. Then make a free incision into the wound. Sucking out is dangerous! Then bandage the limb downwards, progressing towards the wound; repeat this several times. Direct application into the widened wound of calcium hypochlorite, i.e. bleaching powder, is very good, or of a 1 per cent solution of permanganate of potash, or Condy's fluid. Amputation of the finger is the best remedy of all if a large snake has bitten it. Do not keep the ligature longer than half an hour. Then let the circulation return, and apply the ligature again. In any case, do not keep the ligature on for more than one hour for fear of gangrene.

"Internal remedies.–The administration of enormous doses of alcohol is to be condemned strongly; small stimulating doses are good, but stimulation can be more effectively produced by ammonia or strychnia. Hypodermic injection of strychnine, in some cases as much as one to two grains (but not into a vein!) has in some cases had good results; but injection of ammonia, instead of doing any good, has disastrous sloughing results. There is only one fairly reliable treatment, that by serum therapeutics, the injection of considerable quantities of serum of animals which have been partially immunised by repeated doses of snake-venom. Unfortunately this treatment will not often be available."

Several well-known Mammals and Birds are immune by nature against snake-venom, but most of them avoid being bitten. Some birds induce the snake to strike and bite frequently into their spread-out wings. Such more or less immune creatures are the Mongoose, the Hedgehog, and the Pig, the Secretary bird, the Honey Buzzard, the Stork and probably other snake-eaters.

{592}CLASSIFICATION OF OPHIDIA.–Duméril and Bibron divided Snakes according to their teeth into Opotérodonts, Aglyphodonts, Solenoglypha, Proteroglypha, and Opisthoglypha.

J. E. Gray divided Snakes into two sub-orders: Viperina and Colubrinia. Günther distinguished between Ophidii colubriformes, O. colubriformes venenosi (Elapidae and Hydrophidae) and O. viperiformes. Cope laid stress upon the modifications of the squamosal, ectopterygoid, and ectopterygoid bones, and also upon the condition of the vestigial limbs. He divided the snakes into Scolecophidia (Typhlopidae), Catodonta, Tortricina, Asinea (the harmless snakes without limb-vestiges), Proteroglypha, and Solenoglypha.

Boulenger has accepted Cope's principles, and, mainly by combining the Asinea with the Proteroglypha as Colubridae, has produced a logically conceived system, by far the best hitherto proposed. It has been followed in the present work. Boulenger's phylogenetic system stands as follows:–

9 Viperidae 5 Uropeltidae | 8 Amblycephalidae | 7a C. Opisthoglypha 7b C. Proteroglypha | | | | | | +––––––––––––––––––––+––––––––––––+ | | 4 Ilysiidae 7 Colubridae Aglypha | 6 Xenopeltidae | | | | +––––––––––––––––––+–––––––––-–––––––––––––+ | 1 Typhlopidae 3 Boidae 2 Glauconiidae

I. No ectopterygoid; pterygoid not extending to quadrate or to mandible; no supratemporal (squamosal); prefrontal forming a suture with nasal; coronoid present; vestiges of pelvis.

Maxillary vertical, loosely attached, toothed; mandible edentulous; a single pelvic bone. .......... Typhlopidae, p. 593.

Maxillary bordering mouth, forming a suture with premaxillary, prefrontal, and frontal, toothless; lower jaw toothed; pubis and ischium present, latter forming a symphysis. .......... Glauconiidae, p. 594.

II. Ectopterygoid present; both jaws toothed.

A. Coronoid present; prefrontal in contact with nasal.

1. Vestiges of hind-limbs; supratemporal (squamosal) present.

Squamosal large, suspending quadrate. .......... Boidae, p. 596.

Squamosal small, intercalated in the cranial wall. .......... Ilysiidae, p. 594.

2. No vestiges of limbs; squamosal absent. .......... Uropeltidae, p. 595.

{593}B. Coronoid absent; squamosal present.

1. Maxillary horizontal; pterygoid reaching quadrate or mandible.

Prefrontal bone in contact with nasal. .......... Xenopeltidae, p. 605.

Prefrontal not in contact with nasal. .......... Colubridae, p. 606.

2. Maxillary horizontal; pterygoid not reaching quadrate or mandible. .......... Amblycephalidae, p. 637.

3. Maxillary vertically erectile, perpendicularly to ectopterygoid; pterygoid reaching quadrate or mandible. .......... Viperidae, p. 637.

For ordinary practical purposes this synopsis is useless, being based entirely upon anatomical characters, not all easily ascertained. The following characterisation of families may therefore be preferred:–

Eyes vestigial; no teeth in the lower jaw; without enlarged ventral scales. .......... Typhlopidae.

Eyes vestigial; teeth restricted to the lower jaw; without enlarged ventral scales. .......... Glauconiidae.

Eyes very small; head not distinct; ventral scales scarcely enlarged; tail extremely short, ending obtusely and covered with peculiar scales. .......... Uropeltidae.

With vestiges of the hind-limbs appearing as claw-like spurs on each side of the vent; ventral scales transversely enlarged; eyes functional, free.

Ventral scales scarcely enlarged. .......... Ilysiidae.

Ventral scales transversely enlarged. .......... Boidae.

With a pair of poison-fangs in the front part of the mouth, carried by the otherwise toothless, much shortened, and vertically erectile maxillaries; ventral scales transversely enlarged; eyes free. .......... Viperidae.

All the remaining Snakes combine the following characters: the maxillaries are typical, not separately movable, horizontal, with a series of teeth. The mandible is toothed but has no coronoid bone. There are no vestiges of limbs or of their girdles. The eyes are free.

Dentary movably attached to the tip of the articular bone of the mandible; skin beautifully iridescent. .......... Xenopeltidae.

Without a mental groove; the ends of the pterygoids are free, not reaching the quadrates. .......... Amblycephalidae.

With a median longitudinal groove between the shields of the chin; the squamosal is horizontally elongated, movable; the pterygoid reaches the quadrate. .......... Colubridae.

FAM. 1. TYPHLOPIDAE.–Burrowing snakes which have the whole body covered with uniform cycloid scales, and with the teeth restricted to the small and transversely placed maxillary bones. The pterygoids do not extend backwards to the quadrates, and there are no endopterygoids. The quadrates slant obliquely forwards, and are attached directly to the pro-otics, {594}owing to the absence of squamosal bones. The prefrontals are in lateral contact with the nasals. There are vestiges of the pelvis, reduced to a single bone on each side. The eyes are hidden by shields of the skin.

The Typhlopidae, mainly composed of the genus Typhlops, with about one hundred species, are undoubtedly the last living descendants of formerly cosmopolitan, rather archaic, snakes, which in adaptation to their burrowing life and insectivorous diet have undergone degradation. They are still widely distributed in all tropical and sub-tropical countries, some on the solitary Christmas Island, but not in New Zealand. One species, T. vermicularis, inhabits the Balkan Peninsula and South-West Asia. It is brown above, yellowish below, and reaches a length of about 10 inches. The tail is extremely short and ends in a horny spine. T. braminus is widely distributed in Southern Asia, the Malay Islands, the islands in the Indian Ocean and in Southern Africa.

FAM. 2. GLAUCONIIDAE.–In most respects resembling the Typhlopidae, but the maxillaries retain their normal position and are toothless, teeth being restricted to the lower jaw, which is stout and short. The pelvic girdle and the hind-limbs show the least reduction found in any recent Snakes; in the pelvis the ilia, pubes, and ischia can still be distinguished, the last even retaining their symphysis; there are also vestiges of femurs. About thirty species, nearly all belonging to the genus Glauconia, are found in South-Western Asia, Africa, and the warmer parts of America, including the West Indies.

FAM. 3. ILYSIIDAE.–The scales of the cylindrical body are smooth and small, those on the ventral side are scarcely larger. The tail is extremely short and blunt. The head is very small, not distinct from the neck. The gape of the mouth is very narrow. Teeth are carried by the mandibles, the pterygoids, palatines, maxillaries, and one or two or more by the premaxillae. The endopterygoids are short. An important cranial feature is the short quadrates, which stand rather vertically and are connected with the cranium by the squamosals; these are very small and are firmly wedged in between the upper ends of the quadrates and the pro-otic, lateral, and supra-occipital bones; now forming part of the cranial wall. Vestiges of the pelvis and hind-limbs are very incomplete, and terminate in claw-like spurs, {595}protruding between the scales on either side of the vent. The eyes are very small, and are either free or covered by transparent shields. The few, scarcely half-a-dozen, species are found in South America (Ilysia) and in Ceylon, the Malay Islands, and Indo-China.

Ilysia (Tortrix) scytale, the Coral-Snake of Tropical South America, is a beautiful coral-red with black rings. On account of its beauty, perfectly harmless nature, and for "cooling purposes," this snake, which grows to nearly a yard in length, is sometimes worn as a necklace by native ladies. All the Ilysiidae lead a partly burrowing life, live chiefly upon worms, insects, and little Typhlopidae, and are viviparous.

FAM. 4. UROPELTIDAE.–Burrowing snakes of Ceylon and Southern India, with a short and rigid cylindrical body and a very short tail, which ends in a large peculiar shield, often obliquely truncated. The scales of the body are smooth, and are little larger on the belly; the coloration is mostly very beautiful. The eyes are very small.

The Uropeltidae are somewhat intermediate between the Ilysiidae, Glauconiidae, and Boidae. The pterygoids do not reach the quadrates; but ectopterygoids are present; the quadrates are very small and directly attached to the skull, squamosals being absent. Teeth are carried by the mandibles and by the maxillaries, which are normal in their position. There are no vestiges of hind-limbs or of the pelvis. The Uropeltidae, of which about forty species are known, are viviparous, burrow in the ground, and frequent damp localities, preferring mountain-forests. The use of the characteristic tail-shield is not clear; perhaps it assists these rather rigid creatures in digging, by being pressed against the ground.

Uropeltis.–The tail is obliquely truncated, ending in a roundish, flat shield.

U. grandis s. philippinus.–The latter name seems to have misled W. Marshall into including the Philippine Islands in the range of the family, a mistake which is sure to be propagated. The species, the only one of the genus, is confined to Ceylon; it is blackish above, yellow below, frequently with small yellow spots above and brown spots on the under surface. It grows to about 18 inches in length.

{596}Rhinophis.–The tail-shield is convex and the snout is pointed. Rh. sanguineus of Southern India is black above with a bluish gloss, sometimes with small pale specks; the belly and several of the lateral series of scales are bright red, spotted with black. The tail-shield is black and red.

FAM. 5. BOIDAE.–Typical Snakes, usually large, and with vestiges of pelvis and hind-limbs, appearing externally as claw-like spurs on each side of the vent. The scales of the upper surface are usually small and smooth, while those of the ventral surface form one broad series on the belly, and one or two rows on the tail. The quadrate is carried by the horizontally elongated squamosal, which rests loosely upon the lateral occipital region. The prefrontal is in contact with the nasal. Teeth are carried by the mandibles, the pterygoids, palatines, maxillaries, and, in the Pythoninae, by the premaxillaries also. For further details see Figs. 155, 156.

{597}[Illustration: FIG. 156.–A, Ventral, B, dorsal, view of the skull of Eunectes murinus. Lettering as in Fig. 155. × 1.]

The Boidae comprise between sixty and seventy species, which have been grouped into many genera, on unimportant characters, referring to the scales and shields of the head. It is doubtful if they are natural groups, a consideration which detracts much from their value in the study of geographical distribution. Even the two sub-families are not free from this reproach. The range of the family is world-wide, Boidae occurring in all tropical and sub-tropical countries, including islands, except New Zealand. A few species live in South-Eastern Europe (Eryx) and in North-Western America. They mostly prefer wooded districts, especially forests; climbing trees, assisted by the short and partly prehensile tail. Others are semi-aquatic, and a few live in sandy localities. They are all rapacious, and by preference feed on warm-blooded creatures, which they constrict by coils of the body in order to hold, kill, and crush the victim before swallowing it. Exaggerated notions are entertained about their swallowing capacity. It is obvious that a large snake, 20 feet long, half a foot thick, and weighing several hundred pounds, can crush a tiger, a stag, or even a {598}cow; but common sense tells us where to draw the line when it comes to the swallowing of the prey. Small game, although of a bulk apparently far too big for the snake, is so crushed and mangled that it is turned into the shape of a sausage preparatory to the long process of swallowing. The Boidae lay eggs, and some species incubate them, or rather the female coils herself round them for the sake of protection. No appreciable amount of extra warmth is developed. Unfortunately the observations of one of the best cases on record were conducted so imperfectly that they are of little value.

SUB-FAM. 1. PYTHONINAE.–With a pair of supra-orbital bones, intercalated between the prefrontal, frontal, and postfrontal bones. The sub-caudal scales are mostly in two rows. The premaxilla often carries a few small teeth.

The Pythoninae, comprising about twenty species, are restricted to the Palaeotropical and Australian regions, with the sole exception of Loxocemus bicolor in Southern Mexico.

Python, the principal genus, has teeth on the premaxilla. The rostral, each of the anterior upper labials, and some of the lower labial shields, contain a deep, probably sensory, pit. The maxillary and mandibular teeth are long, but decrease from before backwards. The head is distinct from the neck, and is covered with symmetrical shields or with small scales. The scales of the body are small and smooth. The tail is short and prehensile; below with two rows of scales. The pupil of the eye is vertical. The range of the genus extends over the whole of the Palaeotropical and Australian regions, excepting Madagascar and New Zealand.

P. spilotes, the "Carpet Snake" of Australia and New Guinea, is mostly beautifully marked, but is subject to much variation in colour. The more typical specimens are black above, each scale with a yellowish dot, with yellow spots or combinations of dots, more or less arranged in rows. The under parts are yellow. It reaches a length of about two yards, and spends a great part of its time in trees.

P. reticulatus is the commonest species in Indo-China and in the Malay Islands. Four upper labial shields of each side are pitted. The specific name refers to the bold, dark, lozenge-shaped markings upon the lighter yellowish or brown ground. A black {599}line extends over the head from the nose to the neck, and another on each side from the eye to the angle of the mouth. The under parts are mostly yellowish, with small brown spots on the sides.

This is one of the largest species of Python, some specimens being known which measured about 30 feet in length.

As a sample of folk-lore connected with this monstrous snake the following Burmese fable has been recorded by Mason:–

"According to a Karen legend all the poisonous serpents derive their virulence from the Python, which, though innocuous now, was originally the only one that was venomous. In those days he was perfectly white, but having seduced away a man's wife, Aunt Eu (Eve), he made her, while she was in his den, weave figures on his skin in the forms which are now seen. At that time, if he bit the footstep of a man in the road, such was the virulence of his poison that the man died, how far soever that man might have passed from the bitten track. The Python had not, however, an ocular demonstration of the fact, so he said to the Crow: 'Crow, go and see whether people die or not when I bite the foot-track.' The Crow went to the neighbourhood of a Karen cabin, and found the people, as is their custom at funerals, laughing, singing, dancing, jumping, and beating drums. He therefore returned to the Python, and told him that so far from {600}his efforts producing death, on the contrary they produced joy. The Python was so angry when he heard this that he ascended a tree and spit up all his venom, but other creeping things came and swallowed it, and people die of their malignancy to this day. The tree, therefore, from which the Python spat up his venom became deadly, and its juice is used to this day for the purpose of poisoning arrows. The Python made the other creatures promise not to bite without provocation. The Cobra said: 'If there be transgression so as to dazzle my eyes, to make my tears fall seven times in one day, I will bite.' So said the Tiger (whose bite the Karens esteem as virulent as a serpent's) and others, and they were allowed to retain their poison. But the Water Snake and Frog said they would bite with or without cause as they liked; so the Python drove them into the water, where their poison melted away and their bite became harmless."

P. molurus is the species of India and Ceylon, ranging, however, also into Indo-China. Boulenger quotes W. Elliot {601}as the authority for the statement that this species grows to the length of 30 feet. Only two pairs of upper labials are pitted. The general colour above is greyish or yellowish brown with a dorsal series of large reddish-brown, black-edged patches, and on the sides of the body with a series of smaller spots with light centres. On the head is a lance-shaped marking; a brown stripe passes from the eye backwards. The under parts are yellowish.

P. sebae and P. regius are African species. The former has two pairs of upper labials pitted, the latter four pairs. P. sebae is generally pale brown above with dark brown, black-edged cross-bars, which are usually connected by a sinuous dark stripe along each side of the back. The upper surface of the tail has a light stripe between two black stripes. The belly is spotted and dotted with dark brown. P. sebae ranges over the whole of Tropical and Southern Africa, perhaps with the exception of Eastern Africa. P. regius of West Africa is beautifully marked, and may be recognised by the dark brown, black-edged band along the back, sending down triangular or Y-shaped processes on the sides, which are pale brown. This dorsal band encloses a light streak on the neck and another on the tail. The belly is yellowish.

These African Pythons grow to a length of about 15 feet, but specimens so large as this are not often met with. The negroes of certain parts of the coast of Guinea are said to worship them and to keep them in special temples, where they are regularly attended to. Their food consists chiefly of small Mammals, notably rats, and of Birds. A couple of these snakes paired in the Zoological Gardens of London in the month of June. The female laid nearly one hundred eggs in the following January, and incubated them until April, when the embryos were found to be still unripe.

SUB-FAM. 2. BOINAE.–Without supra-orbital bones. The premaxilla is toothless. The subcaudal scales form mostly a single row.

The Boinae comprise between forty and fifty species. Most of them are American, but the genus Eryx inhabits North Africa, Greece, and South-Western Asia; the genus Enygrus inhabits New Guinea and many of the Pacific Islands, for instance New Britain (Neu Pommern), the Solomon, Loyalty and Fiji Islands, {602}and the New Hebrides. Casarea dussumieri is found on Round Island near Mauritius; and two species of Boa and one of Corallus represent the Boidae in Madagascar, while all the others live in Central and South America.

Boa.–The maxillary and mandibular teeth gradually decrease in size. The scales of the upper parts of the body and tail are smooth and very small. The rostral shield is enlarged. The nostrils are placed between two or three nasals, and these are separated from those of the other side by small scales. The tail is short and prehensile. The pupil is vertical.

B. constrictor, of South America, has the head covered with small scales, one of the pre-oculars being enlarged. The eye is separated from the labials by several series of tiny scales. The general colour is a delicate "pale brown above, with fifteen to twenty dark brown cross-bars widening on each side, and, if connected by a dark dorso-lateral streak, enclosing large elongate oval spots.... On each side is a series of large dark brown spots with light centres, most of which alternate with the cross-bars. On the tail the markings become much larger, brick-red, edged with black, and separated by narrow, yellowish interspaces." Under parts yellowish with black dots. Boa constrictor, a name applied in popular parlance to many species, reaches a length of more than 10 feet; the largest specimen in the British Museum measures exactly 11 feet. A few other species inhabit Central America and the West Indies. B. dumerili and B. madagascariensis, both of Madagascar, cannot be separated from the genus Boa.

A. D. Bartlett has described the following incident:–

"In the evening of 5th October 1892 two pigeons were put into the cage in which two fine specimens of Boa constrictor had been living on friendly terms since the beginning of the year. The larger snake seized one of the pigeons and the keeper left the house. The next morning only one of the snakes, the larger specimen, was visible, and from its enormously extended body it was evident that it had swallowed its companion, which was about 9 feet in length. It had no longer the power of curling itself round, but remained extended nearly to its full length in a straight line, and appeared to be at least three times its normal circumference. It was almost painful to see the distended skin, {603}which had separated the scales all over the middle of the body. By 2nd November, twenty-eight days later, the snake had not only digested its companion but had regained its appetite as well as its normal size, and it immediately swallowed a pigeon put into its den."

This peculiar case is not one of ordinary cannibalism. It is rather an unintentional accident. When two snakes happen to get hold of the same animal (in the present case a pigeon) and begin to swallow it, the action of swallowing becomes almost mechanical, the snakes continuing to push their jaws over the prey–which in the case of a bird or mammal they cannot taste, nor can they see it–so long as they feel something in the mouth. After the original prey has been mastered, it is the turn of the opposite snake's head, and if the weaker snake does not give way it is swallowed by its stronger mate. Grass-Snakes will swallow several frogs if these are tied together in a string, and other snakes do the same with mice. There are instances on record in which a Python swallowed its blanket, which, being absolutely indigestible, caused its death.

Casarea, the "Round-Island Snake," differs from Boa chiefly by the rough and strongly keeled scales, and by the relatively much longer tail.

Eunectes murinus, the "Anaconda," is an aquatic Boa. It differs from this genus mainly by the inner of the three nasal shields being in contact with that of the other side (see Fig. 159), and by the absence of the little scales between the eye and the labials; the snout is, moreover, covered with shields instead of small scales. The pupil of the eye is normally vertical, but it had contracted into a round pinhole in the dead but still fresh {604}specimen from which the figure was drawn. The general colour is dark olive-brown, with large oval black spots arranged in two more or less alternating rows along the back, and with smaller black, white-eyed spots along the sides. The under parts are whitish, spotted with black. The upper parts of this and of many other dark-coloured species of Boidae are often shiny, with an iridescent lustre.

The Anaconda combines an arboreal with an aquatic life, a kind of existence eminently in harmony with the well-watered, dense forests of Tropical South America, which are the home of this, the largest of all modern Snakes. It is said to attain a length of as much as 33 feet. There is no inherent impossibility in such statements, but the giant specimens seem to have a knack of keeping out of the naturalist's way.

The Anaconda feeds chiefly upon Birds and Mammals, which it catches either on land, mostly during the night-time, or in the water. For the latter purpose it lies submerged in the rivers or floats about leisurely, only the head being above the surface, and anything suitable is attacked. In other localities the snake, if so inclined, establishes itself upon the branches of a tree which overhangs the water, or the track of the game. These aquatic Snakes seem to be viviparous.

Eryx has the head not distinct from the neck and covered entirely with small scales. Those of the body are likewise small, and are either smooth or keeled. The tail is very short. The anterior maxillary and mandibular teeth are longer than the posterior teeth. These snakes, most of which are less than 3 feet in length, inhabit the sandy districts of North Africa, Arabia, and South-Western Asia, extending into Central Asia. One species, E. jaculus, extends into Greece and the Ionian Islands. Like the other species it is an ugly creature, pale grey or yellowish above, with darker patches and spots. The under parts are whitish. The scales are smooth on the front half of the body, becoming keeled further back and on the tail. Total length under 2 feet. The pupil is vertical.

According to Zander and Werner this snake lives in sandy localities, digging itself into the sand, or covering the body lightly with sand and leaving only the eyes and nostrils free. The whole body is very flabby, and presses itself into any irregularity of the {605}ground over which the snake creeps. Some specimens live on lizards, others prefer mice. The prey is caught by the head, and further secured by several turns of the body of the captor, whose tail is then turned forwards, round the head of the victim, so as to form a kind of knot.

Not less striking than their agility is their jealousy, which is so strong that a snake will occasionally leave the mouse which it has just strangled in order to seize another snake's mouse. Sometimes several snakes fight for the same mouse, coiled together into one inextricable lump so that the mouse itself is quite invisible. The snakes poke their heads about in search of the hidden prey, and every attempt of one of the snakes to free itself, causes the others to squeeze it firmer and firmer, thinking apparently that the motion was caused by the lost prey.

Occasionally one of Werner's captives caught several mice in succession. With these it crawled into a corner, dropped the mice, and then proceeded quietly to swallow one after another. After a fortnight the whole repast was digested, and the snake was ready for more.

FAM. 6. XENOPELTIDAE.–The single species, Xenopeltis unicolor, of South-Eastern Asia, including the Malay Islands, has been raised to the dignity of family-rank on account of the following combination of characters. The prefrontal bones are still in contact with the nasals as in the previous families, but the coronoid bones of the mandibles are absent as in the remaining families. The whole suspensorial apparatus and the lower jaw itself are peculiar. The dentary bone is movably attached to the end of the much-elongated articular bone, the movability being enhanced by the absence of the coronoid element. The quadrate is short and thick, and is carried by the short and broad squamosal, which lies flat against the skull, resembling in this respect that of some of the Ilysiidae. Boulenger rightly considers Xenopeltis to be in various ways intermediate between this family, the Boidae and the Colubridae. The head is small and not distinct from the neck. The eyes are small and have a vertical pupil. The body is cylindrical, covered above with {606}smooth black or brown and highly iridescent scales, hence the generic name. The ventral scales are white and transversely enlarged as in the majority of snakes. The tail is short, but not stunted, measuring about 4 inches in full-grown specimens of a total length of 3 feet.

FAM. 7. COLUBRIDAE.–This family comprises those snakes (about nine-tenths of all recent species) which combine the following characters:–ectopterygoids are present: the squamosals are loosely attached to the skull, and carry the quadrates, which are not reached by the pterygoids: the prefrontals are not in contact with the nasals: the maxillaries are horizontal and form the greater portion of the upper jaws: the mandibles lack the coronoid process or element: both jaws are toothed.

The best arrangement of this enormous cosmopolitan family with terrestrial, arboreal, and aquatic forms, is that by Boulenger, who, adopting Duméril's terms, has divided them into three parallel series.

A. Aglypha.–All the teeth are solid and not grooved.

B. Opisthoglypha.–One or more of the posterior maxillary teeth are grooved.

C. Proteroglypha.–The anterior maxillary teeth are grooved or "perforated."

The Aglypha are harmless, non-poisonous. Most of the Opisthoglypha are poisonous, although few of them are dangerously so. The Proteroglypha, which comprise the "Cobras" and their allies, are deadly poisonous.

SERIES A. AGLYPHA.

SUB-FAM. 1. ACROCHORDINAE.–The postfrontal bones, besides bordering the orbits posteriorly, are extended forwards so as to form the upper border of the orbits, separating the latter from the frontals. The few genera and species of this sub-family are mostly aquatic, inhabiting rivers, or estuaries with brackish water, and they have been known to swim far out into the sea. The body is covered with small, frequently granular scales; in the typically aquatic forms the body is slightly compressed laterally, and the ventral scales are scarcely larger than the others. Most of these ugly snakes inhabit the rivers of coasts of South-Eastern Asia and Papuasia; one, Stoliczkaia, is found in the Khasia Hills {607}of North-Eastern India; another, Nothopsis, lives far from its supposed allies, on the Isthmus of Darien, Central America.

Acrochordus javanicus has no ventral shields. The head is flat, covered with small granules, with the eyes and nostrils on the upper surface. The general colour is dull olive-brown, lighter and spotted beneath. The food consists of fishes. Total length up to 4 feet.

Chersydrus granulatus ranges from the coast of Madras to New Guinea. The body and tail are compressed, and form a ventral fold, covered with tiny scales like the rest of the body. General colour grey above, yellow below.

SUB-FAM. 2. COLUBRINAE.–The postfrontal bones are restricted to the posterior border of the orbits. The maxillary and dentary bones carry teeth on their whole length. The scales are usually imbricating. This sub-family contains the overwhelming majority of snakes, about 1000 species, all of them harmless so far as poison is concerned. None of them reach a great size, species of 6 or 7 feet in length being rare, e.g. Zamenis mucosus, but a few species of the Indian genus Zaocys s. Coryphodon grow to 10 feet. Most of the Colubrine snakes are oviparous, but some, e.g. Coronella, are viviparous. Some are aquatic, or semi-aquatic, others are absolutely arboreal, others again prefer dry, sandy, or rocky localities, according to their food. The distribution of the sub-family is cosmopolitan, finding its natural limits only in the permanently frozen under-ground, a condition which makes hibernation impossible. Most of them love warmth and like to bask, although many are not fond of the broiling sun. In the temperate regions they hibernate. As a rule they are intelligent and some of them become even affectionate.

Tropidonotus.–The teeth form closely set series on the whole length of the maxillaries, palatines, pterygoids, and the greater portion of the dentaries. The premaxilla is toothless. The teeth of the maxillaries gradually increase in length, the posterior teeth being the longest. The pupil is round. There is a pair of internasal shields. The scales covering the body have each an apical, sensory pit, are mostly keeled, and are arranged in longitudinal series. The ventral shields are broad; the sub-caudals form two rows. This genus, with more than seventy species, has a wide range, practically over the whole world with the exception of New Zealand and the southern half of Australia.

{608}T. natrix, the common Grass-Snake, has a divided, or double, anal shield. The strongly keeled scales of the body form nineteen rows. There are normally seven upper labials, the third and fourth of which border the eye. The usual colour of the Grass-Snake is olive-grey or brown above, with black spots and narrow cross-bands. The labials are white or yellowish, with black sutures. The belly is checkered black and white, more or less suffused with grey. There are several colour-varieties. The typical or northern form has a white, yellow, or orange collar, bordered behind by a black collar; the pale collar is sometimes faint or absent. The second variety, rather common in Spain and Portugal, although not the only form in the Peninsula, has no collar whatever, and these specimens are sometimes almost uniformly grey-green above. The third variety, common in South-Eastern Europe and in Asia Minor, has a well-marked collar and a yellowish streak along each side of the back. But there are also almost black specimens.

The usual length of an adult female Grass-Snake is about 3 feet, but very exceptional cases of more than 6 feet are on record; the males are smaller and more slenderly built. The range extends over the whole of Middle Europe, Algeria, West and Central Asia. It does not, however, occur in Ireland or Scotland. Its northern limit is the southern part of Sweden.

The Grass-Snake prefers moist, grassy localities, with the neighbourhood of water, chiefly on account of the food, which consists entirely of fishes and Amphibia, notably of frogs; tree-frogs are preferred to anything else; toads are occasionally eaten, but mice are never taken.

The Grass-Snake can climb trees or rather shrubs and is an accomplished swimmer, often spending much of its time in water for fishing purposes. The fish is caught by the belly and then generally swallowed on land. The Grass-Snakes appear in the spring and disappear in the autumn to hibernate in the ground. They pair, in England, in the month of May or June, usually on warm and sunny mornings. The eggs are laid from July to the end of August, mostly in rich vegetable soil, in heaps of weeds or in manure-heaps. Young snakes lay fewer eggs than old specimens, which sometimes produce more than three dozen at a time. The eggs are soft, whitish yellow, about one inch long, and soon stick together, so that the whole clump {609}can be taken up at once. As a rule the new-laid eggs do not contain any visible sign of the embryo, but it often happens that the snake has to delay oviposition, and then the embryos are more or less advanced. This is especially the case with recently caught specimens. The young are hatched in the late summer or in the autumn, and seem to live at first upon soft insects and worms. Curiously enough they are easily drowned when they fall into the water, even in a shallow tank. My tame snakes have often laid eggs between the stones in the greenhouse; the young throve well upon unknown food, but most of them met their fate in the water. When they are a few weeks old they are strong enough to take baby-frogs.

The Grass-Snake becomes very tame, learns to distinguish between different people, allows itself to be handled without hissing or without voiding the obnoxiously smelling contents of its cloaca and anal glands, will in time take the offered food from the hand, and will even crawl up the arm or sleeve and coil itself up contentedly. One of the finest specimens, quite green, without a trace of a collar, and with brownish-red eyes, I caught in the Guadiana, where it had been fishing in midstream. It swam towards the bank, dived, and hid itself at the bottom between rocks. This snake, a female, became very tame. It never hibernated, shed its skin regularly every few months, and grew within nine years from 35 inches to 42 inches in length.

The Grass-Snake is perfectly harmless: although hissing, and striking out furiously with its head, it never bites, not even when it is severely handled. Its only defence consists of the awful contents of the cloaca and the anal glands, the secretion of which smells of concentrated essence of garlic mixed with other indescribable odours. The wildest specimens I have ever met with inhabited a swamp with a little stream to the north of Oporto close to the coast. To my utter surprise some of them actually made for me, swimming along rapidly with the head erect, about 6 inches above the water, and darting forwards with widely opened jaws, but they did not bite. These and other kinds of allied snakes require to drink much and often. Occasionally they drink milk when this is offered them, but that they suck the udders of cows or the breasts of women is an idle fable.

{610}T. viperinus.–The scales are strongly keeled and form twenty-one to twenty-three longitudinal rows. The third and fourth labials border the eye. The anal shield is divided. The eyes and nostrils are directed upwards instead of sidewards, in adaptation to the essentially aquatic habits of this species, which lives upon fishes and Amphibia. The general colour is grey to reddish brown, with a black zigzag band along the back and a lateral series of black, yellow-eyed spots. The belly is yellow or red, checkered with black.

The Viperine Snake bears a general resemblance to the common viper. It inhabits France, Italy, Spain and Portugal, and Morocco. Very large specimens attain a length of nearly 3 feet, but the ordinary size of adults is 2 feet. This snake spends most of its time in the water, but it is often found on land, basking on the top of a low wall or on a low shrub. It is exceedingly common in Spain and Portugal, where it inhabits almost every ditch, any standing water or slow river. In the Alemtejo, when during the rainless and hot summer the small {611}rivers have nearly dried up, these snakes collect in great quantities in the remaining stagnant and muddy pools, and as the stock of suitable fish gets exhausted, are often reduced to a deplorably emaciated condition. By the month of August they have become so thoroughly aquatic that they cannot be kept alive in dry surroundings for twenty-four hours. Those which I collected generally died, apparently from some kind of cutaneous suffocation, during the night following their capture. Taken under other conditions they are very easily kept and tamed.

I once caught a Viperine Snake in a ditch whilst it was swallowing an eel of nearly its own length. Both were separated, and then put into a small bag together with other creatures, and no more attention was paid to them for several hours. When I opened the bag again, the snake, undisturbed by my incessant walking about, was again busily engaged in trying to get outside that same eel!

T. sirtalis (Fig. 160) is one of the almost endless varieties of what is now known by the name T. ordinatus, of North and Central America.

T. tesselatus is closely allied to T. viperinus, which it represents in South Germany, Italy, South-Eastern Europe, and Asia; but the scales form only nineteen rows, and the fourth, or fourth and fifth labials, border the eye. The usual colour is olive-grey with dark little spots, and with a dark chevron-shaped band behind the occiput. The lower parts are yellow or red checkered with black, hence the specific name.

Zamenis.–The maxillary teeth are not closely packed; they increase slightly in size backwards, and the last two are often a little larger and separated from the rest by a diastema. The mandibular teeth rather decrease in size from before backwards, inversely with the upper teeth. The scales are smooth with apical pits; the sub-caudals form two rows. The eye is large, and has a round pupil. The range of this genus, with about thirty species, extends over the whole of the Periarctic region.

Z. (Ptyas) mucosus (Fig. 161), the Rat Snake of India, extending from Transcaspia to Java, is a very common species, often seen in menageries. Its general colour is brown above, often with black cross-bands on the hinder part of the body and tail. The under parts are yellowish. The fourth and fifth labials border the eye. {612}The scales on the body form only seventeen rows. Another feature of this species is the prominent ridge of the back-bone, not only in half-starved but in well-conditioned specimens. The Rat Snake grows to a length of more than 7 feet, and is as ill-tempered as most species of this genus.

Z. gemonensis s. viridiflavus inhabits France, Italy, the Balkan Peninsula, and Asia Minor. Its coloration is very variable. In general it is either green above and yellow below, hence the appropriate name viridiflavus, or the ground-colour of the back is greyish or olive-yellow with brownish spots, which form more or less longitudinal rows on the trunk, but gradually pass into blackish continuous lines on the tail; the under parts are yellow or greenish white, often with many very small, dark specks. The scales form seventeen or nineteen rows; the anal shield is divided. There are two small postocular scales and one subocular; of the eight labials, the fourth and fifth border the eye. This species is very lively, attacks {613}and bites furiously, climbs well, and when suspended from branches can protrude half of its length in a horizontal direction. It eats any kind of Reptile, Bird, or Mammal it can master; small animals are swallowed directly, rats and moles are first killed by constrictions. Large specimens reach perhaps 6 feet in length.

Z. hippocrepis is the representative species in the Iberian Peninsula and in North-Western Africa. It is rarely more than 4 feet long, and is very pretty, the ground-colour being reddish or olive-yellow with a row of large, dark brown, yellow-edged spots along the back. Two rows of smaller spots adorn the sides; where the dark spots are large, the pale ground-colour is restricted to forming rings around the spots, producing a pretty appearance. The under parts are yellow or orange, with black spots. On the head is a dark, pale-edged patch in the shape of a horse-shoe, a feature alluded to by the specific name. Structural characters are the possession of a row of little subocular scales, which completely separate the eye from the labials, the double anal shield, and the small and smooth scales on the body, which form generally as many as twenty-seven rows.

Z. constrictor.–The American Black Snake. The scales are smooth, and arranged in seventeen rows; the anal shield is divided. The general colour above is uniform bluish-black; below slaty, tinged with blue; the chin and throat are silvery white, sometimes with a black spot. Large specimens attain a total length of 6 feet.

Holbrook gives the following exhaustive account of this species, about which many sensational stories are current even in would-be scientific periodicals:–

The "Black Snake" is one of the commonest of North American species. It is extremely active, climbing with facility, and running with great rapidity, whence it is not uncommonly called the "Racer." It frequents shady places, covered with thick shrubs, on the margins of water. It feeds on mice, toads, or small birds; and, as it is an excellent climber, is frequently seen on trees in search of birds' nests. It is a bold and daring serpent, enters barns and out-houses without fear, and has been known to destroy young chickens. Its specific name constrictor would imply that it suffocates or crushes its prey, but this according to Holbrook is at least doubtful. In the {614}breeding season it is extremely irascible, and will frequently attack persons passing at a distance of several steps; the tail then quivers with rage, making a quick vibrating motion, which in forests and among dead leaves sounds not unlike the Rattle-Snake; it now elevates the head one or two feet from the ground, and darts upon its adversary; luckily its bite is harmless, and not more painful than the scratch of a pin.

"It will even descend from trees to attack its enemy if teazed, yet it does not twine itself around the legs, as is commonly supposed.

"The same power of charming its prey has been attributed to the Black as to the Rattle-Snake, and with still less appearance of reason; for this is a nimble animal, and can pursue its prey, while the Rattle-Snake must lie in wait for his. It is remarkable that the birds most commonly found 'charmed' are the Cat-bird (Turdus carolinensis) or red-winged Black-bird (Icterus phoeniceus). These birds choose thick and shady places on the margins of streams for their residence, and generally build their nests on such shrubs as the alder; the latter bird not unfrequently takes the precaution to select such bushes as are on small islands, or such as have their roots surrounded by water, and thus their home is more secure. Now the Black Snake chooses precisely the same localities, knowing probably the haunts of its prey. The serpent begins the war by besieging the nest; the old bird, aware of its intention, attacks it with fluttering and uncertain motions, accompanied by a plaintive cry of distress, and is then said to be 'charmed.' The snake is at last either driven off, or it captures the young and not unfrequently the old bird too.

"Sometimes the old bird, by her cries, calls in the assistance of her neighbours to drive away the aggressor. I have seen more than a dozen birds thus engaged with a large Black Snake that had probably just committed some depredation, but was now quietly stretched on a rock, basking in the sun; and it was not a little singular that birds of very different genera, and those seldom seen together, all united in this warfare against a common enemy, and finally compelled him to seek shelter among some low, thick shrubs, by the violence of their assault."

Zaocys, with about half-a-dozen species in South-Eastern Asia, is closely allied to Zamenis. Z. carinatus, of the Malay {615}Islands, grows to 10 feet in length; it is consequently one of the largest harmless Colubrine snakes. The scales form only sixteen to eighteen rows. The sub-caudals are double. The general colour above is dark olive, passing into greenish brown farther back. The under parts are yellowish; black and yellow posteriorly. The fifth and sixth labials border the eye.

Coluber.–The maxillary teeth are of equal size, but the anterior mandibular teeth are the longest. The head is distinct from the neck. The nasals are distinct; not fused with the loreals. The eye is rather large, with a round pupil. The scales, smooth or keeled, have apical pits; the ventrals are rounded or angulate laterally; the sub-caudals are double. They all lay eggs and constrict their food. Nearly fifty species in the Periarctic region.

C. (Elaphis) quatuorlineatus s. quaterradiatus inhabits Italy and South-Eastern Europe. It occurs also in the Southern Tyrol. The scales of this large snake, which grows to nearly 6 feet in length, are arranged in twenty-five rows, and are feebly {616}keeled. The anal is divided. Adult specimens have a yellowish-brown ground-colour with a pair of black streaks on each side of the back. A black line extends from the eye to the angle of the mouth; the under parts are yellow, mostly closely spotted with brown. This snake is good-tempered, and keeps well in captivity. They live on sparrows, mice, lizards, etc., and are very fond of eggs. Large specimens can swallow several fowls' eggs in succession; the crushed remains of the shells are later disgorged. This handsome snake climbs extremely well in search of birds and their eggs, and it is not afraid of the water. The prey is caught either with the teeth or by a rapid twist of the tail; in any case, the prey is always strangulated by the constriction of coils thrown round it. A sparrow thus secured is literally passed through the moving coils along the snake's body into a position convenient for swallowing. Hungry snakes catch and secure several birds or mice before eating them. My own specimens became almost affectionately tame, never attempted to bite, and took food from the hand.

C. leopardinus is smaller, but is one of the handsomest snakes of Southern Italy, South-Eastern Europe, and Asia Minor. It is closely allied to the previously described species. The ground-colour is pale brown with a dorsal series of dark brown or reddish, black-edged, transverse spots, and a lateral alternating series of smaller black spots, or with two dark brown, black-edged stripes bordering a yellowish vertebral stripe; usually with a forked black mark on the occiput and nape. The under parts are white, checkered with black, sometimes with the latter colour prevailing.

C. flavescens s. aesculapii is the Aesculap-Snake, for which the almost unknown name of longissimus has now been unearthed in deference to the fetish of priority. This snake is of an extremely graceful and slender build, with a very long tail. Its home is the South of France, Italy, and South-Eastern Europe. It occurs sporadically in the Tyrol, for instance near Bozen, in Austria, at Baden near Vienna, in Germany only in the Taunus, especially at Schlangenbad, which has received its name from the frequent occurrence of this snake. This sporadic distribution favours the idea that these snakes were introduced by the Romans as inmates of the temples erected to Aesculapius at such watering-places. Specific characters are the smooth and shiny scales, {617}which are arranged in twenty-one to twenty-three rows, the distinctly angulate ventrals and the double anal and sub-caudals; the fourth and fifth of the upper labials border the eye, which has a round pupil. The coloration is very variable, as a rule olive-brown above with a dark streak behind the eye; the upper lips and a triangular patch on the temples are yellow; the under parts are uniform pale yellow. Some specimens are pale golden brown; others are very dark, almost black; while some have four darker stripes along the body, and lastly whitish specks occur on the upper surface. Large Aesculap snakes grow to a length of 5 feet. Their food consists chiefly of mice. They become very tame, although many of them at first bite furiously. Their climbing capacities are astonishing, the snakes being able to scale high and vertical walls provided there is the slightest "foothold." Some of my specimens escaped in the room and were at last found near the ceiling, resting on the rods of the curtains, up the folds of which they had managed to wriggle. Boulenger kept one for many years in a glass cage, where the snake entwined himself round the branches of a stick and allowed us to take him with the stick out of its socket and to inspect him. Being kept in an inhabited room, the snake did not exactly hibernate, creeping into the moss at the bottom of the cage; but it refused to feed, and remained in a rather drowsy condition coiled up on its favourite stand. During the pairing season they frequently resort to the water, at Schlangenbad at least; the few eggs are deposited under dry moss or in dry, decayed wood, and are hatched in about six weeks.

C. (Rhinechis) scalaris has the smooth scales disposed in twenty-seven rows. The snout is strongly projecting, and has a V-shaped dark mark on the top; a black streak runs through the eye, and another black spot lies below the eye. Young specimens are pale brown with a series of dark H-shaped marks on the back, suggesting a ladder, hence the specific name. In the adult these marks are replaced by a pair of brown stripes running along the back; the under parts are always uniform yellow. Total length about 3 feet. This snake is restricted to the Iberian Peninsula and to the South of France. Most specimens are very ill-tempered. The young live upon locusts and small lizards, the old eat mice and small birds. In captivity they also take dead animals–a rare habit with snakes.

{618}Dendrophis with about ten species inhabits South-Eastern Asia and Australia. They are typical Tree-Snakes. The scales are keeled, and form only thirteen or fifteen rows; those of the vertebral row are enlarged; the ventrals have a pair of suture-like lateral keels and a notch on each side, arrangements which are of great assistance in climbing, these snakes being able to slide up the branches of trees in almost straight lines instead of having to twist and undulate their way up.

D. punctulatus, of Northern and Eastern Australia, is olive-brown above, uniform or with black edges and yellow outer borders to the scales. The upper lips, the throat and anterior ventrals, are yellowish. Total length up to 6 feet.

Leptophis is a Neotropical genus of Tree-Snakes. The body and the extremely long, whip-like tail are very slender. The head is very distinct from the neck; the eye is large, with a round pupil. The scales form thirteen or fifteen rows; the ventrals are sometimes angulate laterally; the sub-caudals are double. L. (Ahaetulla) liocerus is a beautiful snake, green above {619}with a golden lustre, while the under parts are yellow or white. The total length of this species amounts to 6 feet, the tail then being nearly 2 feet long. These graceful Tree-Snakes live upon small reptiles and birds and their eggs. When shaken out of a tree or frightened off they let themselves fall down from considerable heights, coiling body and tail like a watch-spring, and alighting on the ground upon the spiral, which breaks the fall.

Coronella.–The teeth are nearly all of equal size and form continuous series. The scales are smooth and have apical pits; the sub-caudals are double. The head is scarcely distinct from the neck. The pupil is round. This genus, with nearly twenty species, is widely distributed except in the Australian region, the northern half of Asia, and South America. We can mention only the two European species, one of which occurs in England.

{620}[Illustration: FIG. 165.–Coronella laevis, Smooth Snake (left), and two Vipera berus, Common Viper (right). × ½.]

{621}C. austriaca s. laevis, the Smooth Snake. The scales are arranged in nineteen rows. Mostly the third and fourth labials border the eye. The anal shield is divided. The general colour is brown or reddish above, often with one or two lighter stripes, with small dark brown or red spots; two dark brown or red stripes on the nape, usually confluent with a large dark patch on the occiput; a dark streak extends from the nostril through the eye to the angle of the mouth. The under parts are red, orange, brown, grey or blackish, either uniform or speckled with black and white. The coloration is, however, subject to much variation, and some specimens strikingly resemble some of the Common Viper, which is also very variable in its coloration. The resemblance is enhanced when the Smooth Snake broadens its head by widening the jaws, as it is in the habit of doing. Two such similarly coloured specimens are represented in Fig. 165. On closer inspection the differences are great enough, the harmless snake having smooth scales, and the top of the head being covered with large shields; while the Viper has keeled scales, the top of the head being covered mostly with scales, a vertical (not round) pupil, and, moreover, when attacked, usually coils itself into a spiral disc with the head standing out in the middle, ready to strike. However, these two species are sometimes mistaken for each other.–The Smooth Snake prefers lizards as food to anything else, but it also takes mice. The prey is hunted chiefly in the late afternoon and in the evening, and is constricted by the coils of the snake. When caught or even when handled after months of captivity, the Smooth Snake bites deliberately and firmly, selecting a suitable spot, for instance a finger, opens the mouth widely and almost chews the spot. The bite is of course quite harmless, and scarcely draws blood, few of these snakes attaining a length of more than 2 feet. They are viviparous, bringing forth about half-a-dozen young at a time. The range of the Smooth Snake extends over the greater part of temperate Europe, from England and the Iberian Peninsula to Berlin, and south-eastwards to Asia Minor. In England it occurs in a few counties only, for instance in Hampshire and in Dorsetshire.

C. girondica, of the South of France, Italy, the Iberian Peninsula and North-Western Africa, much resembles the English Smooth Snake, from which it differs in a few points only. The scales are arranged in twenty-one, rarely in nineteen, rows; usually the fourth and fifth labials border the eye; and the rostral {622}shield, covering the end of the snout, is much broader than high. The coloration is variable, but there is always a pair of elongated blackish spots or a U-shaped mark on the nape.

SUB-FAM. 3. RHACHIODONTINAE.–With only a few teeth on the posterior part of the maxillaries, on the palatines and dentaries. Some of the vertebrae in the region of the lower neck have strongly developed hypapophyses, which are directed forwards and pierce the oesophagus. They are used for filing through or breaking the birds' eggs which seem to be the chief food of these snakes.

Dasypeltis scabra, the only species, inhabits Tropical and South Africa; although it reaches scarcely more than two feet and a half in length, such a specimen is able to swallow an ordinary fowl's egg. Pigeons' eggs are swallowed by snakes little more than one foot in length, which seems at first sight quite impossible. The swallowed egg distends the skin to its utmost capacity; it then slides down further, the snake makes some slight contortions and the swelling collapses; after a while the broken and sucked-out shell is vomited out as a crumpled up {623}mass. Miss Durham has illustrated this curious process in a series of drawings.

SERIES B. OPISTHOGLYPHA.

One, or a few, of the posterior maxillary teeth have a groove or furrow in front, which conducts the secretion of the enlarged upper labial glands. Apparently all these snakes are more or less poisonous, paralysing their prey before or during the act of deglutition. So far as man is concerned they are rather harmless, since the poison is not very strong, not available in large quantities, and above all because the small poison-teeth stand so far back that the snakes cannot easily inflict wounds with them.

The Opisthoglypha are of considerable morphological interest, since they connect the Colubridae with the Viperidae, the characteristic poisonous apparatus of which seems to have been derived from that of the Opisthoglypha by the reduction or shortening of the anterior portion of the maxillaries and the harmless teeth, so that the posterior or poison-fangs come to the front.

The Opisthoglypha comprise about three hundred species and are cosmopolitan, including Madagascar but excepting New Zealand. They contain truly terrestrial, arboreal, and thoroughly aquatic forms.

SUB-FAM. 1. DIPSADOMORPHINAE.–The nostrils are lateral and the dentition is well developed. Long-tailed, terrestrial, and arboreal forms. Most of the arboreal species are green above, often with white or yellow longitudinal bands, while the under parts are white or yellow. They feed chiefly upon lizards, birds and their eggs.

Dipsadomorphus s. Dipsas (part).–Typical, very long-bodied and long-tailed Tree-Snakes, with a vertical pupil. The median or vertebral row of smooth scales is enlarged; the broad ventral scales are bent at an obtuse angle on the sides, the resulting ridge assisting in climbing. The sub-caudals are arranged in two rows. Ten to fourteen maxillary teeth are followed by two or three enlarged, grooved fangs.

D. trigonatus, of India, grows to one yard in length. Yellowish olive or pale grey above, with a white, black-edged {624}zigzag band along the back, or with a series of white, black-edged spots.

D. cyaneus, of Northern India, Assam, etc., is a beautiful Tree-Snake, green above, with the skin between the scales black, uniform greenish yellow below. Total length up to 4 or 5 feet.

Dipsas e.g. D. bucephala.–Maxillaries with eleven or more teeth. Pterygoids toothless. Body strongly compressed, with thirteen rows of smooth scales; the vertebral row enlarged; sub-caudals double; tail very long. Tropical South America.

Leptognathus with many species in Central and South America, like Dipsas, but with teeth on the pterygoids.

Coelopeltis.–Terrestrial and diurnal, with a round pupil. The row of small maxillary teeth is followed by one or two much larger, grooved fangs situated at a level below the posterior border of the eye. The first half-a-dozen mandibular teeth are much larger than the rest. The scales of the adult are more or less distinctly grooved longitudinally, hence the generic name, and are arranged in seventeen or nineteen rows. The sub-caudals form two rows; the ventrals are rounded off laterally. Two species in the Mediterranean countries and in South-Western Asia.

C. monspessulana s. lacertina is one of the largest snakes in Europe, reaching a length of 6 feet, of which the tail takes up 18 inches. Olive-brown or yellowish or reddish above, frequently with small, dark, light-edged spots. The sides are often blackish, with whitish specks. The under parts are yellowish white, with or without brownish markings. Some specimens are very green, with a dull blackish neck. One of the specific names of this terrestrial snake is the latinised form of Montpellier; the other refers to the shape of the head, which is not unlike that of a lizard, partly owing to the concave forehead. This species inhabits rather dry localities studded with shrubs, where it hunts for lizards, birds, and mice. It is sure to attract notice by its loud hissing when it is disturbed. When driven into a corner it strikes out furiously, but does not, as a rule, bite. I have caught some which after a few days became quite gentle. Small animals become torpid a few minutes after they have been bitten.

Macroprotodon cucullatus occurs in Andalucia, the Balearic Islands, and in North Africa. The dentition is peculiar. The {625}fourth and fifth maxillary teeth are enlarged, followed by an interspace, then follow several small teeth, and lastly the two enlarged, grooved teeth. The sixth mandibular tooth is very long, separated by a space from the much smaller posterior teeth. The general colour of this sand-loving snake is pale brown or grey above with small spots or streaks on the trunk, and with a large black patch behind the head extending over the sides of the neck, hence the specific name. The under parts are bright red or yellowish, sometimes spotted with black. Total length under 2 feet.

SUB-FAM. 2. ELACHISTODONTINAE.–With only a few teeth on the posterior part of the maxillary and dentary bones, and on the palatines and pterygoids. Some of the vertebrae in the thoracic region have much-developed unpaired hypapophyses, which are directed forwards and pierce the dorsal wall of the gullet. In this respect Elachistodon westermanni, of Bengal, the only species, bears a striking resemblance to the South African Aglyphodont Dasypeltis (see p. 622), and it is probable that this apparently very rare Indian snake also swallows eggs. It is brown above, with a yellowish vertebral stripe; yellowish below.

SUB-FAM. 3. HOMALOPSINAE.–The nostrils of these absolutely aquatic and viviparous snakes are valvular, and are situated on the upper surface of the snout. The eyes are small with vertical pupils. The two dozen species, mostly very ugly, inhabit the rivers and estuaries of the East Indies from Bengal to North Australia. Some species have very small and narrow ventral scales, recalling the Hydrophinae, or the burrowing snakes, none of which use their ventral scales for locomotory purposes.

Homalopsis buccata, Cerberus rhynchops and Hypsirhina, e.g. H. plumbea, have well-developed ventral scales; the other scales of the first two genera are keeled, those of the third are smooth. In Hipistes the whole head is covered with very small scales; all the scales of the body are smooth except the very narrow ventrals, which have double keels. H. hydrinus, of Siam and the Malay Peninsula, has a compressed body, and in its general appearance much resembles the Hydrophinae. It lives, like its allies, upon fishes, and it swims far out into the sea.

SERIES C. PROTEROGLYPHA.

The anterior maxillary teeth are deeply grooved, or so folded {626}as to appear hollow or perforated. Behind these enlarged poison-fangs the maxilla carries a series of smaller, solid teeth; hence the term "proteroglyphous," which means that the anterior teeth are grooved, in opposition to "opisthoglyphous." Both series have been developed independently.

The Proteroglypha are all extremely poisonous, mostly viviparous, and widely distributed over the whole of the Australian, Palaeotropical and Neotropical regions, with the exception of Madagascar and New Zealand; they extend northwards into the warmer parts of North America, and they also range over a great portion of the Palaearctic sub-region, being found in North Africa and South-Western Asia. They form two natural sub-families: Elapinae, with cylindrical tails, and Hydrophinae or Sea-Snakes, with laterally compressed tails.

SUB-FAM. 1. ELAPINAE.–The tail is cylindrical. The Elapinae comprise nearly 150 species, which have been grouped into a great number of, mostly somewhat imaginary, genera. In Australia they constitute the great majority of Snakes, there being besides the deadly Elapinae only a few Pythons and Typhlopidae, and very few Colubrinae.

Naja.–The pair of large and grooved poison-fangs are separated by an interspace from one to three small, faintly grooved teeth near the posterior end of the maxillaries. The scales are smooth and without pits, and are arranged in fifteen to twenty-five oblique rows on the trunk, although more occur in the region of the neck; the vertebral row is not enlarged. The head is but slightly distinct from the neck. Each nostril lies between two nasals and the internasal. The sub-caudals form two rows. The pupil is round. The neck-region can be expanded {627}into a hood by the spreading and moving headwards of the ribs. Several species in Southern Asia and in Africa.

N. tripudians (the "Cobra").–The coloration varies much. The typical form is yellowish to dark brown with a black and white spectacle-mark on the dorsal side of the hood, and with a large black and white spot on each side of the corresponding under surface. Other specimens are uniform pale brown to blackish grey, without any markings on the hood. The Cobra is widely distributed, from Transcaspia to China and to the Malay Islands; in the Himalayas it ascends to about 8000 feet above the level of the sea. Very large specimens are said to attain more than 6 feet in length, but a cobra of 5 feet, inclusive of the tail of 9 inches, is considered large. The Cobra prefers places which afford it a convenient hole to retire into; for instance, deserted hills of termites, ruins, heaps of stones and stacks of wood, and it has the disagreeable habit, like the harmless Rat-snake, Zamenis mucosus, of making itself at home in inhabited houses, probably attracted by the rats. Its chief food consists of small Vertebrates;–frogs, lizards, rats, occasionally fishes and {628}small birds. It drinks much, and hunts chiefly in the late afternoon and in the evening, although it possesses a round pupil. It avoids hot sunshine. Many observations show that the cobras live in pairs, otherwise they do not take much notice of each other or of other kinds of snakes. The female lays about a dozen soft-shelled eggs as large as those of pigeons.

This cobra is used by Indian conjurers. The "dance" is the habit of these snakes of erecting themselves, when agitated, upon the hinder third or quarter of their length, whilst they spread out the hood and sway the head and neck to the right and left, always in an attitude ready for striking. They are docile and by nature not vicious. Most of the performing cobras have their teeth drawn, and they then know well that they cannot bite. They only strike at the hand, just as uninjured specimens soon avoid biting into the iron rod with which they are lifted up in menageries. The drawing of the teeth is an operation which has to be repeated, since reserve-teeth soon take the place of the lost pair.

I cannot refrain from relating an abstract of a ridiculous episode which happened in the Munich Aquarium in the year 1882. One of six specimens of the African species Naja haje was missing. The police closed the establishment, which during the following eight days was turned inside out without any other effect than that two other, harmless, snakes were discovered. Twice the building was fumigated with sulphur, until the Cobra was at last found suffocated, fifteen days after the beginning of the search. This snake caused the owner of the Aquarium a loss of nearly £1500. But the cruel joke was, that during the commotion the man who had collected and sold the six snakes declared upon oath that their teeth had been so well drawn and the germs of possible reserve-teeth had been so thoroughly destroyed that the snakes were rendered absolutely harmless. But he was not believed, in spite of a commission of professors and doctors appointed, who experimented upon the remaining five Cobras with sulphur and did not find any poison-fangs, "although the mouth was probed and poked into as far down as the larynx."

Cobras have quite a number of enemies. Peafowl and Jungle-cocks are said to be partial to young snakes; pigs eat them greedily, and are to a certain extent immune against {629}their bite. The same applies, according to the most recent observations, to the famous Mongoos. Sir E. Tennent, in his Natural History of Ceylon, quoted several times in the present book, makes the following remarks about the immunity of this little creature:–

"I have found universally that the natives of Ceylon attach no credit to the European story of the Mongoos (Herpestes griseus) resorting to some plant, which no one has yet succeeded in identifying, as an antidote against the bite of the venomous serpents on which it preys. There is no doubt that, in its conflicts with the cobra and other poisonous snakes, which it attacks with as little hesitation as the harmless ones, it may be seen occasionally to retreat, and even to retire into the jungle, and, it is added, to eat some vegetable.... A number of plants, such as the Ophioxylon serpentinum and Ophiorhiza mungos, the Aristolochia indica, the Mimosa octandria, and others, have each been asserted to be the Ichneumon's specific.... If the Ichneumon were inspired by that courage which would result from the consciousness of security, it would be so indifferent to the bite of the serpent, that we might conclude that, both in its approaches and its assault, it would be utterly careless as to the precise mode of attack. Such, however, is far from being the case; and next to its audacity, nothing can be more surprising than the adroitness with which it escapes the spring of the snake under a due sense of danger, and the cunning with which it makes its arrangements to leap upon the back and fasten its teeth in the head of the cobra. It is this display of instinctive ingenuity that Lucan celebrates where he paints the Ichneumon diverting the attention of the Asp by the motion of his bushy tail, and then seizing it in the midst of its confusion. See Pharsalia, lib. iv. verses 729-734."

There is a widespread belief in the efficacy of "Snake-stones," which are generally pieces of charred bone, well polished, occasionally pieces of chalk or some similar porous substance, which, if pressed upon the bleeding wound, are supposed to absorb the poison. Snake-charmers profess to prepare such "stones," and to preserve the composition as a secret. The manufacture is a lucrative trade. The Boers bought them, imported from India, at high prices. Mr. Selous saw one, or heard of one, that was kept as an heirloom. Snake-stones are {630}also made, and used, in Mexico, of charred hartshorn; they are called "piedras ponsonas."

The use of the Snake-stone, called "Pamboo-Kaloo," has probably been communicated to the Singhalese by the itinerant snake-charmers who resort to the island from the coast of Coromandel.

Although Sir E. Tennent describes several instances of the successful application of snake-stones as well authenticated, he has never himself been an eye-witness. Although two cases have been fully described, they do not at all exclude the possibility, nay the probability, that the Tamils imposed upon the Europeans in order to sell the snake-stones.

"No doubt the snake-stones, owing to their porous nature, adhered to the bleeding wound, became saturated with blood, and then fell off. Very likely, in case of a poisonous bite, some of the venom would be sucked up too, but we do not know if those snakes were still in the possession of their poison-fangs. Properly conducted experiments with snake-stones have proved as little efficacious as the application of dry cup.

"Theoretically snake-stones as quick absorbent agents of the blood with the poison are good; they will certainly prevent some of the poison from entering the system, but that would, at best, be a partial cure only.

"In March 1854 a friend of mine was riding, with some other civil officers of the Government, along a jungle path in the vicinity of Bintenne, when he saw one of two Tamils, who were approaching the party, suddenly dart into the forest and return, holding in both hands a Cobra de capello, which he had seized by the head and tail. He called to his companion for assistance to place it in their covered basket, but in doing this, he handled it so inexpertly that it seized him by the finger, and retained its hold for a few seconds, as if unable to retract its fangs. The blood flowed, and intense pain appeared to follow almost immediately; but with all expedition the friend of the sufferer undid his waist-cloth, and took from it two snake-stones, each of the size of a small almond, intensely black and highly polished, though of an extremely light substance. These he applied, one to each wound inflicted by the teeth of the serpent, to which they attached themselves closely; the blood that oozed from the bites being rapidly imbibed by the porous texture of {631}the article applied. The stones adhered tenaciously for three or four minutes, the wounded man's companion in the meanwhile rubbing his arm downwards from the shoulders towards the fingers. At length the snake-stones dropped off of their own accord; the suffering of the man appeared to subside; he twisted his fingers till the joints cracked, and went on his way without concern. Whilst this had been going on, another Indian of the party, who had come up, took from his bag a small piece of white wood, which resembled a root, and passed it gently near the head of the cobra, which the latter immediately inclined close to the ground; he then lifted the snake without hesitation, and coiled it into a circle at the bottom of his basket. The root by which he professed to be enabled to perform this operation with safety he called the "Naya-thalic kalanga" (the root of the snake-plant), protected by which he professed his ability to approach any reptile with impunity."

The following narrative, communicated to Sir E. Tennent by H. E. Reyne, of the Department of Public Works, Colombo, seems to exclude the possibility of deception:–

"A snake-charmer came to my bungalow in 1854, requesting me to allow him to show me his snakes dancing. As I had frequently seen them, I told him I would give him a rupee if he would accompany me to the jungle and catch a cobra that I knew frequented the place. He was willing, and as I was anxious to test the truth of the charm, I counted his tame snakes, and put a watch over them until I returned with him. Before going I examined the man, and satisfied myself he had no snake about his person. When we arrived at the spot, he played on a small pipe, and after persevering for some time, out came a large cobra from an ant-hill, which I knew it occupied. On seeing the man it tried to escape, but he caught it by the tail and kept swinging it round until we reached the bungalow. He then made it dance, but before long it bit him above the knee. He immediately bandaged the leg above the bite, and applied a snake-stone to the wound to extract the poison. He was in great pain for a few minutes, but after that it gradually went away, the stone falling off just before he was relieved. When he recovered he held a cloth up, which the snake flew at, and caught its fangs in it; while in that position, the man passed his hand up its back, and having seized it by the throat, {632}he extracted the fangs in my presence and gave them to me. He then squeezed out the poison on to a leaf. It was a clear oily substance, and when rubbed on the hand produced a fine lather. I carefully watched the whole operation, which was also witnessed by my clerk and two or three other persons."

N. haje is the common hooded cobra of Africa, the "Aspis," so called on account of its shield or hood–the "Spy-Slange" of the Boers. As a rule the spectacle-marks on the neck are absent or indistinct, the general colour varies much, either brown above, yellowish beneath, with or without brown spots; or dark brown above with yellowish spots, dark brown beneath; or blackish above and beneath. The name Spy-Slange, meaning Spitting Snake, refers to the habit which this and other African Cobras have of letting the poison drop from the mouth like saliva when they are excited. This is not a particularly economical habit, nor is it of the slightest use to the snake.

N. (Ophiophagus s. Hamadryas) bungarus s. elaps is the "Hamadryad" or "Snake-eating Cobra" or "King Cobra." It has a well dilatable hood; the very variable coloration is yellowish to black, with or without an olive gloss. Many specimens have more or less distinct dark cross-bands or rings around the body, while others are olive above with black-edged scales, and others again are very dark above and beneath. The distinctive, specific character is the small number of scales, these forming only fifteen rows on the middle of the body, nineteen or twenty-one on the dilatable neck. There is a pair of large occipital shields behind the parietals.

This snake reaches the length, enormous for a poisonous snake, of 12 feet or more. Its size and very poisonous nature make it the curse of the jungle. It ranges from India to South China, and to the Philippines. The food seems to consist entirely of other snakes.

Sepedon haemachates is another hooded snake in South Africa, where it is known as the "Ringhals," i.e. banded neck. It differs from Naja by the absence of small teeth on the maxillaries behind the fangs, and by the strongly keeled scales, which form nineteen rows. The general colour is black above variegated with yellow or pale brown; the under parts are also black, often with one or two whitish bands across the lower portion of the neck.

{633}The Rev. G. Fisk mentions the case of two young "Ringhals," of 10 and 9 inches in length, having been attacked and partly devoured by a mouse, supposed to be Dendromys melanotis, which was put with the snakes in a band-box. On the habits of the Ringhals see Symonds.

Bungarus.–The scales are smooth, and form thirteen to seventeen rows. The spine is very prominent, and the median row of scales which covers the ridge is much enlarged. There is no dilatable hood. In other respects Bungarus is closely allied to Naja; about half-a-dozen species, in South-Eastern Asia.

B. fasciatus reaches a length of 5 feet. The general colour is bright yellow, alternating with blackish rings.

B. coeruleus s. candidus is the dreaded "Krait," occurring in the whole of the Indian sub-region. It is dark brown or bluish black with narrow cross-bars or white specks, or it is alternately barred brown and yellow; the under parts are uniform white. Total length rarely 4 feet.

The "Krait" seems to cause more deaths in India than any other snake, since it is very common, especially in Bengal and in {634}Southern India, and often creeps into the houses. It lives chiefly on rats, lizards, and snakes.

Callophis.–With only thirteen rows of smooth scales. The head is small, not distinct from the neck. The small eye has a round pupil. The short tail has two ventral rows of scales. The whole body is cylindrical. Several small species, one or two feet in length, in South-Eastern Asia. C. macclellandi in India and Indo-China is reddish brown above, yellow below, with regular, equidistant, black, light-edged cross-bands or rings. Total length up to 2 feet.

Doliophis differs from Callophis mainly by the enormously developed poison-glands which, instead of being restricted to the head, extend along the anterior third of the body, gradually thickening, and terminating in front of the heart with club-shaped ends. Owing to the extension of these glands, which can be felt through the skin as thickenings at the end of the first third of the body, the heart has been shifted farther back than in any other snake. Several species in Indo-China and in the Malay Islands, D. intestinalis with many colour-variations.

Australia suffers from an abundance of Elapine snakes, of which we will mention only the three commonest.

Pseudechis e.g. Ps. porphyriaceus, the "Black Snake" of Australia, has seventeen rows of smooth scales on the body, a few more on the neck, which however is not, or is only slightly, dilated. A few of the sub-caudal scales are undivided, the rest are paired. The head is distinct from the neck; the pupil is round. Total length up to 5 or 6 feet. The general colour above is black, with the outer row of scales red at the base; the ventral scales are red with black edges. The females are generally more brown than black, and are therefore sometimes known as "Brown Adders." They live on small mammals, birds, lizards and other snakes.

Notechis scutatus s. Hoplocephalus curtus, the "Tiger Snake," has rather small eyes with round pupils. The head is distinct from the cylindrical body, which is covered with fifteen to nineteen rows of smooth scales. The sub-caudals are single. The head of this variably coloured snake is mostly black, the body olive brown with dark cross-bands; towards the tail the coloration becomes more uniformly blackish. The under parts are pale {635}yellow. The range of this very common snake extends over Tasmania and Australia.

Acanthophis antarcticus, the "Death Adder," is easily recognised by the peculiar tail, the end of which is laterally compressed, beset with a few rows of enlarged imbricating scales, and terminates in a thin horny spine. The head is distinct from the neck, and flat; the eye has a vertical pupil. The short and thick body is covered with twenty-one or twenty-three rows of keeled scales. The anterior caudals are single, the posterior double. The colours of the upper parts are a mixture of brown, reddish and yellow, with dark cross-bands. The belly is pale yellow, often spotted with brown or black. The end of the tail is yellow, reddish brown or black. The total length of this stout and ugly viviparous creature remains under 3 feet. It is widely distributed from South Australia to the Moluccas. The use of the peculiar tail very probably consists in attracting or fixing the attention of small animals; the snake, lying coiled up on a dry and sandy spot, slightly raising and vibrating the tip of the tail.

Elaps is an entirely American genus, with many species, most of which are extremely prettily coloured, red and black in alternate rings being a favourite pattern. The maxillaries carry no teeth behind the poison-fangs. The scales of the body are smooth and form fifteen rows. The tail is short. The small eye has mostly a vertical pupil. The head is very small, not distinct from the neck. The squamosal and quadrate bones are short, and the gape of the mouth is so limited that these beautiful snakes, although possessing strong poison, are practically harmless to man. One of the prettiest is E. corallinus of the forests of Tropical South America and the Lesser Antilles. The whole body, above and below, is adorned with about twenty deep black rings, which are edged with yellow and again separated by red rings equalling in width the black ones. Sometimes the red rings are dotted with black, and the black dots may form additional rings between the red and the yellow. Total length under 3 feet.

SUB-FAM. 2. HYDROPHINAE (Sea-Snakes).–The tail is strongly compressed, sometimes the body also. All the scales are small, and there are often no enlarged ventrals. The eyes are small, with round pupils. All these snakes are very poisonous and live in the sea, often at considerable distances from the land, {636}with the exception of one species of Distira, D. semperi, which is confined to the land-locked freshwater Lake Taal at Luzon in the Philippines. They live on fish, and range from the Persian Gulf to Central America. In conformity with their absolutely aquatic life they are viviparous, and they die when kept out of the water for any length of time. About fifty species are known.

Enhydrina valakadien s. bengalensis has scales with a small tubercle or keel, which is stronger in the males; the ventrals are very small, forming a scarcely enlarged series. The maxillaries carry two or more small grooved teeth in addition to the poison-fangs. The back is olive or dark grey, with black transverse bands, which are most distinct in the young. The under parts are white. This species ranges from Persia to the Malay Islands.

Hydrophis e.g. H. obscura.–The body is long; the head and neck are very slender, the body becoming much thicker farther back. The small teeth behind the poison-fangs are not grooved. The ventral scales are very small, the others are keeled, strongly so {637}in the males. The general coloration of this Sea-Snake, which reaches about one yard in length, is dark olive-green above with yellowish cross-bars, which form complete rings round the slender part of the body. Other specimens are pale olive, with dark cross-bands. This species occurs in the Bay of Bengal and the Malay Archipelago.

As a rule Sea-Snakes are not found in mid-ocean. After leaving Ceylon, the steamer meets them again in the Straits of Malacca. Those which occur near the south coast of Japan, e.g. Distira cyanocincta, are found there only in the summer, and are probably carried there by the south-west monsoon.

According to Semper the gravid female visits the shores of low islands, there to give birth to its young between the rocks, and she remains with her offspring for some time. Semper once found a large female, probably Platurus fasciatus s. colubrinus, coiled up amongst rocks, and between the folds were at least twenty young, each already about 2 feet long.

Boulenger has written an interesting popular account of Sea-Snakes.

FAM. 8. AMBLYCEPHALIDAE.–Some thirty species of Neotropical and Oriental Snakes have been separated from the Colubridae on account of the pterygoids, which are widely separated from the quadrates, the posterior ends of the pterygoids not reaching beyond the level of the occipital condyle. This condition can be ascertained when the mouth is opened widely. The prefrontals are not in contact with the nasals. The squamosals are reduced to pad-like vestiges. Externally the Amblycephalidae are easily distinguished from the Colubridae by the absence of a longitudinal median mental groove. The head is thick, very distinct from the neck, and gives these harmless snakes a "poisonous" appearance. The pupil is vertical.

Amblycephalus, e.g. A. monticola.–Maxillaries short, with only five or six teeth. Sub-caudals in two rows. Body compressed, covered with fifteen rows of scales. South-Eastern Asia.

FAM. 9. VIPERIDAE.–The maxillaries are very short, movably attached to the prefrontals and ectopterygoids, so that they can be erected together with the large poison-fangs, which (besides reserve-teeth) are the only maxillary teeth. The prefrontals are not in contact with the nasals. The squamosals are very loosely {638}attached. For further details see Fig. 180. The poison-fangs are perforated, having a wide hole on the anterior side at the base, in connexion with the large poison-gland; the hole leads into a canal, which opens gradually as a semi-canal on the anterior surface of the distal third or quarter of the tooth. As usual in poisonous snakes, several reserve-teeth are stowed away behind the acting fang. When the latter is broken off or has served its time it is cast off at the base, and the next reserve tooth takes its place. The supply of reserve-teeth is indefinite, half-finished teeth down to mere germs constantly growing.

All the Viperidae are very poisonous, and all, except the African Atractaspis, are viviparous. They include terrestrial, arboreal, semi-aquatic, and burrowing types. The family is cosmopolitan, excepting Madagascar and the whole of the Australian region; it is divided into Vipers and Pit-Vipers.

SUB-FAM. 1. VIPERINAE (Vipers).–There is no sensory external pit between the eye and the nose, and the maxillary is not hollowed out above. The Vipers are absolutely restricted to the Old World, ranging over the whole of Europe, Africa, and Asia, with the exception of Madagascar; their northern extension is limited only by the permanently frozen condition of the underground. Nine genera with about forty species are known.

Causus with a few species in Africa and Azemiops feae in Upper Burmah are the only vipers which have the head covered {639}with large symmetrical shields, while in the other genera the head-shields are broken up into scales or small shields. Causus rhombeatus is very common in Africa, from the Gambia to the Cape. It reaches a length of a little more than 2 feet. Pale olive-brown above, usually with a dorsal series of large rhombic or V-shaped dark brown, sometimes white-edged spots, and with a dark arrow-shaped mark on the occiput; under parts yellowish white or grey.

Bitis s. Echidna.–Very much like Vipera, but the nasal shields are separated from the rostral by small scales, and the postfrontal bone is very large. Several species in Africa.

The head is very distinct from the neck, chiefly owing to the large poison-glands and to its being, like the body, much depressed. The small eye has a vertical pupil, and is separated from the labials by a series of small scales. The scales are keeled, and form many, from twenty-nine to forty-one, rows; the tail is very short, with two rows of scales below.

In B. arietans, the "Puff Adder," the nostrils are directed upwards. This ugly brute is yellowish to orange brown above with regular, chevron-shaped dark bars or other markings, helping {640}to conceal the creature when it is lying on sandy and stony ground; the under parts are yellowish white. The Puff Adder reaches a length of 4, or very rarely 5 feet, ranging all over Africa, except the north coast, and extending into Southern Arabia. It is very slow, and trusts to not being discovered when lying in the dry grass; when approached it inflates the body and hisses loudly with a puffing sound, watches the enemy with raised and characteristically bent head and neck; but it bites only when actually touched or attacked. The effect of the bite is very dangerous. Its prey consists chiefly of small mammals, which are hunted during the night.

B. (Echidna) nasicornis, of Tropical West Africa, has two or three enlarged scales above the supranasals; they stand upon erectile tissue so as to form horn-like elevations. This "Nose-horned Viper" grows to a length of 4 feet, and is rather prettily marked; the ground-colour is purplish or reddish brown, with a vertebral series of large, pale, dark-edged spots and oblique crosses. The young are at birth as much as one foot in length, and are very tastefully coloured.

Cerastes and Echis prefer to burrow in sand. The lateral scales are smaller than the dorsals, and arranged obliquely with serrated keels, so that the snakes can cover themselves with sand by lateral shovelling motions of the sides of the body.

Cerastes cornutus, the "Horned Viper" of North-Eastern Africa, from Algeria to Arabia, extending also into Palestine, has the sides of the ventral scales bent angularly, with an obtuse keel on either side. Above each eye stands a large horny, spiky scale. The upper parts are pale yellowish brown, mostly with dark spots arranged in several longitudinal rows. The under parts are white. This, or perhaps C. vipera, which has no horns, is supposed to be the species which has become famous through the suicide of Cleopatra.

About twenty years ago a number of "Horned Vipers" were brought to the Zoological Gardens of London, and attracted attention by their unusually long horns. It was found that some wily Egyptian snake-catcher had tried to manufacture a new species by taking specimens of the hornless C. vipera and inserting a pair of hedgehog's spines, pushing them upwards through the mouth.

The "Horned Viper" attains a length of two feet and a half. {641}In the daytime it is invisible, being buried in the sand with only the eyes, nostrils, and the "horns" appearing above the surface.

Vipera.–The head is distinct from the neck, and is covered with small scales and a few larger shields. The eye is separated from the labials by scales; the nasals are in contact with the rostral shield or separated by one naso-rostral shield. The scales on the body are strongly keeled; they are in two rows on the short tail. This genus with about ten species ranges over Europe, Asia, and the greater part of Africa.

V. berus, the Common European Viper (see Fig. 165, p. 620). The snout is not turned up at the end; between the small head-scales there is generally a pair of well-developed parietal and frontal shields. The scales of the trunk form twenty-one rows. The coloration is very variable, there being grey, brown, red, or black specimens in the same country, and the much-spoken-of black zigzag line along the back is so often indistinct that it is a character not to be relied upon. Usually the grey, yellowish, olive, brown or red ground-colour is set off by a dark zigzag band along the spine, and by a series of lateral spots; an oblique or St. Andrew's cross or two diverging bold streaks of dark brown or black are usually present on the back of the head, and there is a dark streak behind the eye. The under parts are grey, brown, or black, uniform or speckled; the end of the tail is usually yellow or red.

{642}[Illustration: FIG. 174.–Skin of Viper. × 1. (From White's History of Selborne.)]

According to Boulenger, who is making a special study of the individual variations of Vipers (concerning colour, scaling, number of vertebrae, etc.), some specimens are entirely black in the males through extension of the black markings, in the females through darkening of the ground-colour. Males are usually distinguishable from females by darker, deep black markings and lighter ground-colour. The females are mostly larger than the males. The largest specimen in the British Museum measures 700 mm. = 28 inches, but a viper 2 feet long may be considered a very large specimen. The Common Viper has a wide range, from Wales to Saghalien Island, and from Caithness to the north of Spain. It ascends the Alps to a considerable altitude, up to 6000 feet. J. Blum has published an elaborate statistical account of the Viper in Germany, unfortunately confining himself strictly to the political frontiers. According to the map attached to his work, the Viper is common all over Germany with the exception of South-Western and parts of Middle Germany. It is absent in Alsace, the Bavarian Palatinate, Rhenish Prussia, Hesse, the northern half of Baden, Würtemberg, and Franconia, countries which, speaking broadly, have a warm subsoil, composed of Red Sandstone and Basaltic formation. As a rule the Viper prefers heaths, moors, and mixed woods with sunny slopes. Brambles, clumps of nettles, hedges, the edges of little copses, heaps of stones, are favourite places of retreat, affording shelter, holes, and the vicinity of mice, which form its chief sustenance. At harvest-time it is often found in cornfields, and it frequently hides in the sheaves. Vipers are fond of basking on certain spots, on the top of a stone, the stump of a tree, or a patch of sand: a shower of rain or even passing clouds drive them back into their holes. They are eminently nocturnal, when they regularly "beat" their district, biting and paralysing their prey before swallowing it. A fire kindled at night is sure to draw vipers near; the same applies to other vipers, for instance Cerastes, which appears in perplexing {643}numbers at the camp-fire. They cannot climb, and they avoid going into water. The pairing takes place as a rule from March to May, a number of individuals, mostly males, collecting around the females, and forming entangled lumps of snakes; parturition takes place in the following July and August. In exceptionally warm winters they have been known to pair in December, having left their winter-quarters. They hibernate for about six months, more or less according to the climate, congregating in great numbers, sometimes in dozens. With very rare exceptions Vipers do not take food in captivity, but prefer starving themselves to death. The bite is as a rule not fatal. The seriousness of the case depends of course upon many circumstances, as for instance the state of concentration of the venom, the position and depth of the bite, and last but not least upon the general condition of health of the victim. General depression aggravated by nervousness, weakness of the bitten limb, occasional breaking out of the wound, are of frequent and protracted occurrence. (See also p. 590.)

V. aspis is a more southern and western European Viper, occurring from France to the Tyrol, and in Italy. The snout is slightly turned up at the end, and still more so in V. latastei of Spain and Portugal. In V. ammodytes, of South-Eastern Europe, the raised portion is produced into a soft, scaly appendage (see the lower figure on p. 641). Vipers are sometimes unpleasantly common in certain localities. This was for instance the case at the drill-ground near Metz, and the military authorities paid a price for each viper delivered to them. The supply of the latter increased to an alarming extent until the German authorities discovered that a regular trade had been established across the frontier, and that the French Lorrainers were importing vipers briskly.

V. russelli, the "Daboia" or Russell's Viper, is one of the scourges of India, Ceylon, Burma, and Siam. The scales form about thirty rows on the body. The upper surface of the head is covered with small, imbricating, usually keeled scales. The general colour is pale brown above with three longitudinal series of black, light-edged rings, which sometimes encircle reddish spots. The under parts are yellowish white, uniform, or with small crescentic black spots. Total length up to about 5 feet. The poisoning symptoms are described on p. 590.

{644}SUB-FAM. 2. CROTALINAE ("Pit-Vipers").–With a deep cavity or pit between the eye and the nose, lodged in the hollowed-out maxillary bone. This pit is lined with a modified continuation of the epidermis, and is amply supplied with branches from the trigeminal nerve. It is undoubtedly sensory, but we do not know its function. A good anatomical account of this organ has been given by West. Some of the Pit-Vipers have a rattle at the end of the tail; these are the Rattle-Snakes. The rattle is composed of a number of horny bells which fit into each other. The oldest or terminal bell is in reality the horny covering of the tip of the tail, and with each moult or shedding of the skin the youngest bell becomes loose, but is held by the new covering which has been developed in the meantime. There is thus produced an ever-increasing number of loosely-jointed bells, but now and then most or all the bells break off, probably when they are worn out, and a new set is gradually developed. Rattles with a dozen bells are, for instance, very rare. They naturally increase in bulk with the age of the snake, but the number of joints is no indication of the snake's age.

Pit-Vipers have a very wide distribution. They are divided into four genera with about sixty species. Rattle-Snakes are {645}restricted to America, but other Pit-Vipers occur in North and South America and in the southern half of Asia.

Ancistrodon.–Without a rattle. The upper surface of the head is covered with nine large shields, but the internasals and prefrontals are sometimes broken up into scales. The scales of the body have apical, sensory pits. About ten species, some in Central and North America, others in the Caspian district (A. halys), in the Himalayas (A. himalayanus), in Ceylon, Java, etc.

A. piscivorus s. Trigonocephalus cenchris (part), the "Water-Viper," inhabits North America from Carolina and Indiana to Florida and Texas. The general colour is reddish to dark brown, with darker cross-bands or with C-shaped markings; a dark, light-edged band extends from the eye to the angle of the mouth. The under parts are yellowish, spotted with black, or the latter is the prevailing colour. Total length up to 5 feet. The Water-Viper is semi-aquatic and lives chiefly on fishes, but it also eats other snakes and various Amphibia, Birds, and Mammals. This snake is very good-humoured in captivity, and becomes {646}easily tame. A gentleman in Berlin, rather too much addicted to making pets of poisonous snakes, had a pair which propagated regularly. When I was a boy he invited me to feed the young Water-Vipers with fishes cut into strips, and I enjoyed this immensely until he warned me not to touch the mother, which might bite strangers.

A. contortrix s. Trigonocephalus cenchris (part), the "Moccasin-Snake" or "Copper-head," is one of the few poisonous snakes which possess a loreal shield, i.e. a shield intercalated between the pre-oculars and the nasals; below it lies the pit. The general colour is yellowish to pink or pale brown, with dark brown or red cross-bars or triangular marks. The under surface is yellowish or reddish, speckled with grey or brown, and with a lateral series of large blackish spots. Total length of full-grown specimens about one yard. The Moccasin-Snake ranges from Massachusetts and Kansas to Northern Florida and Texas. It prefers swampy localities or meadows with high grass, where it hunts for small Mammals and Birds.

Lachesis.–Without a rattle. The upper surface of the head is covered with very small shields or with scales. About forty {647}species in South-Eastern Asia and in Central and South America.

L. (Bothrops s. Craspedocephalus) lanceolatus inhabits nearly the whole of South America, extending into Mexico and the Lower Antilles, e.g. Martinique, Guadaloupe, and Santa Lucia, where it is known as the "Fer-de-Lance," and is the curse of the sugar-plantations on account of its being so very common and so deadly poisonous. The Mongoose was introduced as a possible antagonist, but the little Indian Mammal wisely left the dangerous reptile alone, and has in some places established himself as another pest–as a destroyer of poultry. The Fer-de-Lance grows to a length of 6 feet, establishes itself everywhere–in swamps, plantations, forests, in the plains and in the hills–and is very prolific, producing, according to its size, dozens of young which are 10 inches long, very active and snappy.

L. (Trimeresurus) gramineus s. viridis, to mention one Asiatic species, grows to less than 3 feet in length, is bright green above, sometimes with faint blackish bars; green, yellow, or whitish below, and with a light streak along the outer row of scales. The end of the tail is usually bright red. This beautiful snake has a prehensile tail and is arboreal. Its range extends over the whole of India, to Hong-Kong and to Timor, and even into the Andaman and Nicobar Islands.

Sistrurus.–With a rattle. The upper surface of the head is covered with nine large shields. A few species in North America east of the Rocky Mountains, e.g. S. miliarius.

{648}Crotalus.–With a rattle. The upper surface of the head is covered with small scales. Range from Southern Canada and British Columbia to Northern Argentina, but not in the West Indian Islands. About ten, mostly closely-allied species.

{649}The effect of the poison of Rattle-Snakes has been discussed on p. 589.

C. horridus is the common Rattle-Snake of the United States; C. confluentus is the species in Western and C. durissus the common species in South-Eastern North America. Very large Rattle-Snakes, C. durissus, attain a length of 8 feet, others not often more than five. They prey chiefly upon small Mammals, hunting for them at night. In the daytime they are also about, mainly in order to bask. Although they occasionally take to the water in pursuit of their prey, they dislike being wetted by rain, withdrawing then into their holes, appropriating as a rule those of ground-squirrels, rats, and Prairie-dogs. The often-repeated story about Rattle-Snakes living in neighbourly friendship in the holes of Prairie-dogs, together with the little Prairie-owls, is an exaggeration. We do not know how many of the original inmates are eaten. Pairing takes place in the spring. During the cold months they hibernate under ground, often in considerable numbers.

Rattle-Snakes have few enemies besides man and pigs. The latter kill and eat them wherever they can. The rattle is decidedly useful to the snake as an instrument of warning off any approaching possible enemy, since no snake likes to bite unless in self-defence or in order to kill its prey. The noise of the rattle is very loud in dry weather, much duller on clammy days; it is a shrill sound like that of a rattling alarm-clock, and a well-conditioned snake in a room can make conversation well-nigh impossible, and can keep on rattling for half an hour or longer. The rattle is kept in such rapid lateral vibrations that it shows only a blurred image, the rattle standing with its broader sides vertically, not horizontally. They endure captivity for many years, and become tame enough not to hiss and to rattle whenever they are approached.

C. horridus is grey-brown above, usually with a rusty vertebral stripe and with V- or M-shaped blackish cross-bands; the under surface is yellowish; the end of the tail is blackish. The supra-ocular shields are smooth and much narrower than the scaly space between them, and there is only one pair of internasals.

C. durissus s. adamanteus differs from the previous species chiefly by possessing two pairs of internasals; and the dark {650}markings on the body form a handsome pattern of rhombs with lighter centres and yellowish edges. This is the largest species of Rattle-Snake, reaching a length of 8 feet.

C. confluentus has broader, transversely striated, supra-ocular shields. The specific name refers to the continuous series of large brown or red rhomboidal spots on the back.

C. terrificus ranges from Arizona to Argentina, and is the only species of Rattle-Snake in South America. It differs from the others by having a pair of prefrontal shields behind the pair of internasals.

{651}INDEX

Every reference is to the page: words in italics are names of genera or species; figures in italics indicate that the reference relates to systematic position; figures in thick type refer to an illustration; f. = and in following page or pages; n. = note.

Abdominal armour, of Cricotus, 287; of Microsauri, 289; of Prosauri, 290 Abdominal ribs, of Rhynchocephali, 292, 298; of Dinosauria, 414; of Megalosaurus, 421 Aberrant scaling of Lacertilia, 495 Ablepharus, 560; eyelids, 494 Acanthodactylus vulgaris, 559 Acanthophis antarcticus, 635 Acentrous vertebrae, i.e. those without a centrum or body, 4 Acris, 186, 189; A. gryllus, 207 f. Acrochordinae, 606 Acrochordus javanicus, 607 Acteosaurus, 489 Actinodon, 83, 287, 288 Adams, visit to the Mugger-peer, 455 f. Adaptive characters of Anura, 142 Adhesive apparatus, of tadpoles, 57, 57; of Tree-frogs, 187; of Thoropa, 209; of finger-discs of Raninae, 239; of Geckos, 505, 505 Aelurosaurus, 307 Aestivation, of Crocodiles, 457; of Tortoises, 357, 365, 404 Aetosaurus, 432; Ae. ferratus, 433, 448 Agalychnis, 189, 206 Agama, 520; A. sanguinolenta, 520; A. stellio, 521, 521 Agamidae, 513, 515 f. Agamura, tail, 506 Agassiz, on habits of Alligator Turtle, 341; of Trionyx, 407 Age of Chelonia, how to estimate, 326; great age attained by Tortoises, 369, 376, 377; see also Growth, rate of Aglossa, 139, 140, 143 f.; distribution, 143 Aglypha, 592, 606 f. Ahaetulla s. Leptophis, 618, 619 Aistopodes, 81 Aldabra, gigantic tortoises of, 373 f., 375 Algae, destructive to shell of tortoises, 357 Allantois, an embryonic outgrowth from the posterior part of the gut, acting as a respiratory organ, 278 Alligator, 450, 466 f.; A. mississippiensis, 467 f.; skull, 468; nesting, 469; A. sinensis, 471 Alligator Turtle, 340 Allopleuron hofmanni, 380 Allosaurus, 422 Alpine, Newt, 126; Salamander, 119 Altitude, high, in which Anura have been found, 181 Alytes, 157 f.; A. cisternasi, 160; A. obstetricans, 158; urino-genital organs, 49 Amblycephalidae, 592, 593, 637 Amblycephalus monticola, 637 Amblyrhynchus, 528; A. cristatus, 533 Amblystoma, skull, 17, 94, 96, 109, 110 f., 112; A. jeffersonianum, 111; A. mavortium, 115; A. opacum, 110; A. persimile, 111; A. punctatum, 110; A. talpoideum, 110; A. tigrinum, 111 f.; metamorphosis of, 112 f. Amblystomatinae, 102, 109 Ameiva, 549 Amnion, a membrane round the embryo, 278 Amphibia, 3 f.; definition, 5; systematic position, 5; numbers of species, 4 Amphicondylous, i.e. the occipital part of the skull articulates with the neck by a right and a left knob, 4 Amphignathodon, 185; A. guentheri, 188 Amphignathodontinae, 139, 188 Amphisbaena, 566; A. fuliginosa, 566 Amphisbaenidae, 514, 565 f. Amphiuma, 88, 96; A. means s. tridactyla, 100, 101 Amphiumidae, 94, 97 {652} Amphodus, 210; A. wucheri, 211 Anaconda, 603, 603 Anaides = Autodax (q.v.), 107 Anal sacs of Chelonia, used as additional respiratory organs, 330 Anarosaurus pumilio, 477 Anchisaurus, 415, 417, 421; skull of A. coelurus, 421 Ancistrodon, 645; A. contortrix, 646, 646; A. halys, 645; A. himalayanus, 645; A. piscivorus, 645, 645 Anderson, on nest of Gavialis, 452 Andrews, on Amblystoma, 110 Andrias scheuchzeri, 84 Anelytropidae, 514, 564 Anelytropsis papillosus, 564 Anguidae, 513, 537 f.; distribution, 501, 529 Anguis fragilis, 539, 539 Aniella pulchra, 564 Aniellidae, 514, 564 Annandale, on habits of Calotes, 518; of Liolepis, 527; of Rhacophorus, 247; of Varanus salvator, 544 Anodonta, as food of Trionyx, 407 Anodontohyla, 236 Anolis, 528; A. carolinensis, 529 Anomodontia, 309 Anura, 7; characters, 138; classification, 139 f., 141; phylogenetic tree of, 142 Anus, asymmetrical position of, 60 Apoda, 84 f.; affinities, 88; distribution, 89; eyes, 86; skin, 87; skull, 84, 85; spermatozoa, 87; tentacular apparatus, 88; vertebrae, 86; visceral arches, 86 Archaeopteryx, 417 Archegosaurus, vertebrae, 13, 82, 287 Arcifera, of Cope, 140; of Boulenger, 140 Arciferous, type of shoulder-girdle, 24, 25 Arion, slug, eaten by tortoises, 363 Arrau-turtle (Podocnemis), 391 f. Arteria cutanea magna, 144; A. sacralis of Anura, 144 Arthroleptis, 241, 242; A. seychellensis, 243, 243 Ascaphus, 153 Asterophrys, 161 Athecae, 333; definition of name, 337 Atlantosaurus, 415, 419; A. immanis, 419, 420 Atlas and Axis, i.e. first and second cervical vertebrae; of Cryptobranchus, 13; of Crocodilia, 283; of Chelonia, 283, 316; of Sphenodon, 283, 294; atlas fused with axis, 307 Atoposauridae, 453 Atractaspis, 638; dentition, 593 n. Atria, the thin-walled receptive parts (auricles) of the heart Auditory columellar apparatus, of Amphibia, 24; of Anura, 29 Australian, Anura, spawning time and habits of, 201; Lacertilia, 502 Autodax, 96, 104, 107; A. lugubris, 107; A. iecanus, 107 Autosauri, 491 f. Axis; see Atlas Axolotl, 65, 112 f., 112; Neoteny of, 65, 112 Azemiops feae, 638

Balancers of Amphibia, 45 Baptanodon, 483, 484 Barfurth, on absorption of Tadpole's tail, 61 Bartlett, on Boa constrictor, 602; on Pipa, 152 Basiliscus, 528, 530; B. americanus, 530, 530 Bates, on habits of Podocnemis, 392 f. Batrachomyia, fly infesting Bufonidae, 177 Batrachophrynus, 224; B. macrostomus, 225; B. brachydactylus, 224 Batrachopsis, 161 Batrachoseps, 96, 104 Batrachylodes, 241 Batrachyperus, 96; B. sinensis, 109 Baur, on Sphargis, 336 Bdellophis, 90 Bedriaga, on Axolotl, 114; synopsis of Urodelous Larvae, 59 n. Bell, J., on classification, 8 Bell, Napier, on habits of Iguana, 531 Belodon, 305, 434, 448 Bemmelen, on Sphargis, 336 Berg, on Spelerpes fuscus, 106 Bert, quoted, 571 n. Bidder's organ, 49, 52 Biedermann, on change of colour in Hyla, 35 Birds not related to Dinosaurs, 416 f. Bitis arietans, 639, 639; B. nasicornis, 640 Black Snake, of Australia, 634; of North America, 613 Blainville, de, on classification, 7 Blanus cinereus, 566 Blood, shape of red corpuscles, 4; temperature, 67 f. Blood-sucker = Calotes ophiomachus, 519 Blum, quoted, 642 n. Boa, 602; B. constrictor, 602; B. dumerili, 602; B. madagascariensis, 602 Boettger, on influence of climate and country upon reptiles, 492 f. Boidae, 592, 596 f.; skull, 596, 597 Boinae, 601 f. Bombinator, 154 f., 155; habits, 156 f.; tadpoles, 157; abnormal vertebrae, 22; shoulder-girdle, 25; urino-genital organs, 49; B. igneus, 154, 155; B. pachypus, 155 Bothrops, 647 Boulenger, classification of Amphibia Caudata, 9; {653} on vertebrae of Pelobates, 20; on vertebrae of Bombinator, 22; number of phalanges in Anura, 27; on poison of Amphibia, 36; on vocal sacs, 48; on modes of fecundation and nursing habits, 54, 56; synopsis of Tadpoles, 59 n.; on tadpoles of Rana opisthodon, 260; on classification of Anura, 140, 141; on Pipa, 152; on Scaphiopus solitarius, 165; on Alligator sinensis, 471; on Lanthanotus, 542; on aberrant scaling, 495; on Heloderma, 540 n.; on classification of Snakes, 592; on Sea-Snakes, 637; on Sphargis, 336 Boulengerula, 90 Box-Tortoises, 362, 364, 365 Brachial plexus, of Anura, 39 Brachycephalus, 226, 227; B. ephippium, 231 Brachylophus, distribution, 501, 528 Brain, of Scaphognathus, 485; small size of, in Dinosaurs, 425 Branchial arches, of Urodela, 16; of Anura, 42 Branchiosauri, 80 Branchiosaurus, skull, 80; B. salamandroides, 80 Brauer, on development of Apoda, 92; on nursing habits of Arthroleptis, 243 Breeding of Axolotl, 113 Breviceps, shoulder-girdle, 26, 225, 226, 227, 232; B. mossambicus, 232 Brithopus, 308 Brongniart, on classification, 7 Brontosaurus, 415, 418; B. excelsus, 418 Brontozoum, 415, 417; B. giganteum, 420 Brood-pouches, of Anura, 151, 248; of Hyla goeldii, 198; of Nototrema, 202; of Rhinoderma, 228 Brookesia, 580 Brown Adder, 634 Brown Frog, Common, 251 f., 255 Brücke, quoted, 571 Buchholz, on Chiromantis, 244 f. Budgett, on breeding habits of Phyllomedusa, 204; on Paludicola, 220; on Lepidobatrachus, 218; quick development of Phryniscus, 231; on Bufo marinus, 179 Bufo, sacral vertebra, 22; shoulder-girdle, 26; urine-genital organs, 49; development of adhesive apparatus, 57; B. agua, 178; B. americanus, 178; B. calamita, 181 f.; B. ceratophrys, 179; B. empusus and B. peltocephalus, dermal ossifications, 179; B. jerboa, 166; B. lentiginosus, 178, 179; map of distribution, 167, 168, 169 f.; B. marinus, 178; B. mauritanica s. pantherina, 184; B. melanostictus, 177, 179; B. quercinus, 178; B. variabilis = viridis, 180; B. viridis, 180 f., 493; B. vulgaris, 170 f., 172; large-sized specimens, 171; immured in buildings, 174; diseases, 176; distribution, 177 Bufonidae, 139, 166 f.; distribution, 167; affinities, 166 Bufoniformes, 139 Bullfrog, of America, Rana catesbiana, 261; of India, Callula pulchra, 234; Rana tigrina, 261 Bungarus coeruleus s. candidus, 633; B. fasciatus, 633 Butler, on fat-bodies, 500

Cabrita, 551 Cacopus, shoulder-girdle, 25, 225, 226, 228 Cacosternum, 225, 227 Caiman, 450, 471; vomer, 435; C. niger, 471, 472; O. palpebrosus, 471; C. sclerops, 471; C. trigonatus, 471, 472 Calcareous deposits in the skin of Amphibia, 31, 34 Calliphora silvatica, fly infesting Bufo, 176 Callophis macclellandi, 634 Calluella, 235, 236 Callula, 226, 228, 234; C. pulchra, habits of, 234 f. Callulops, 225, 228 Calophrynus, 225, 227 Calotes, 517; C. emma, 518; C. mystaceus, 519; C. ophiomachus, 519; C. versicolor, 518 Calyptocephalus, 179, 212, 215 Camptosaurus, 426 Capitosaurus, 83 Carapace, 321 f., 319, 320, 322, 323; posterior portion movable in Cinyxis, 364, 365; carapace of tortoises, evolution of, 337; composition of, 324 f.; reduction of component elements, 325; reduction in thickness, 373; correlative changes, 328; of Sphargis, 335 f.; of Chelone, 379; of Testudo, 322; of Pleurodira, 389; reduction in Trionychidae, 325; fenestration, 325; with hinge in Cinyxis, 364, 365 Cardioglossa, 274 Carettochelydidae, 313, 314 Carettochelys, 337, 389, 390; C. insculpta, 404; absence of horny shields, 325 Carpet Snake, 598, 599 Carpus (see also Limbs), of Eryops, 286; of Sphenodon, 294; of Chelonia, 320, 320; of Eusuchia, 440 Casarea, 603 Case, on Sphargis, 336 Cassina, 240 Causus, 638; C. rhombeatus, 639 Centrolene geckoideum, 211 Cerastes cornutus, 640, 641 Ceratobatrachidae, 141 {654} Ceratobatrachinae, 139, 237 f. Ceratobatrachus guentheri, 237 Ceratohyla, 211 Ceratophora, 517; C. stoddarti, 517; C. tennenti, 517 Ceratophrys, 212, 215 f.; C. cornuta, 216; C. dorsata, 215; C. ornata, 216, 217 Ceratopsia, 430 Ceratosaurus, 413, 416, 417; C. nasicornis, 422, 422 Cerberus rhynchops, 625 Cetiosaurus, 419 Chalarodon, 528; geographical distribution of; 501 Chalcides, 562; Ch. bedriagae, 563; Ch. guentheri, 563; Ch. lineatus, 563; Ch. ocellatus, 563; Ch. tridactylus, 563 Chamaeleon, 573; Ch. bifidus, 580; Ch. calcaratus, 579; Ch. parsoni, 580; Ch. pumilus, 579, 575; Ch. vulgaris, 573, 574, 575 Chamaeleontes, 567 f.; distribution, 568; skull, 568, 569; tongue, 569 f.; colour-changing mechanism, 570, 571, 573 f.; eggs, 572 Chamaeleontidae, 573 f. Chamaerops humilis, dates of, eaten by Testudo, 367 Chameleon, misnamed Calotes, 518; misnamed Polychrus, 529 Chauvin, Marie von, on Axolotl, 113; on Salamandra atra, 120 Chelodina, suppression of neural plates, 324; intergular shields, 389, 315; skull, 399; Ch. longicollis, 402 f., 403 Chelone, skull, 317; skeleton, 320; plastron, 321; shields, 327; intergular shields, 325; Ch. mydas, 381 f.; various modes of fishing, etc., 382, 383; Ch. imbricata, 384, 385 Chelonemydidae, 380 Chelonia, 312; number of species, 312; affinities of, 312; classification, 313; key to living families, 314; plastron, names of the horny shields, 315; 321, 325; vertebrae, 314 f., 316; skull, 280, 317, 356, 364, 379, 400, 405; skeleton of Testudo, 319; of Chelone, 320; pectoral arch, 318; pelvis, 319; plastron, bones of, 321; limbs, 320; bony shell, 321 f., 322, 323; evolution of, 337; evolution of the horny shields, 326 f., 327; regeneration, 329; sense-organs, 329; digestive apparatus, 330; respiration, 331; growth of Chrysemys, 349 Chelonidae, 313, 314, 378 f.; affinities of, 380 Chelydidae, 313, 314, 399; distribution, 332, 333 Chelydosaurus, 82, 287 Chelydra, 328; Ch. serpentina, 338 Chelydridae, 313, 314, 338; distribution of, 332 Chelydropsis, nuchal plates, 324 Chelys fimbriata, 400; skull, 400, 401; intergular shields, 325 Chersydrus granulatus, 607 Chioglossa, 96, 115; Ch. lusitanica, 121 Chirixalus, 241 Chiroleptes, 209, 213, 221; Ch. platycephalus, 221 Chiromantis, 238, 241, 244; Ch. petersi, 244; Ch. xerampelina, 244 Chirotes, 564; Ch. canaliculatus, 566 Chirotherium, 83 Chlamydosaurus kingi, 522, 523 Choanae, or inner nasal openings, 47 Chorda dorsalis, the axial rod between the gut and the spinal cord, around which the vertebrae are formed, 12 Chorophilus, 186, 189; Ch. ornatus, 208 Chromatophores, 35 Chrysemys, costal plates of, 325; green colour of, 328, 346 f.; colour of iris, 329; Ch. concinna, 346, 349, 350; Ch. elegans, 346; Ch. picta, 346, 347, 348; Ch. rubriventris, 346 Chthonerpeton, 87, 90 Cimoliasaurus, 478; C. australis, 478; C. cantabrigiensis, 478; C. chilensis, 478; C. haasti, 478 Cinosternidae, 313, 314, 342; distribution, 332 Cinosternum, 342 f.; arrangement of neural plates, 324; C. leucostomum, 342, 344; C. odoratum, 342, 343; C. pennsylvanicum, 342, 344 Cinyxis belliana, 365; C. erosa, 364, 365; C. homeana, 364 Cistecephalus, 310 Cistudo, arrangement of neural plates, 324; C. Carolina, 361 f., 364; colour of iris, 329 Claosaurus, 429 Clarke, on habits and development of Alligator, 467 Classification of Amphibia, historical account, 7 f. Clawed Toad (Xenopus), 146 f. Claws or nails of Amphibia, 32 Cleithra = the pair of additional clavicles; of Stegocephali, 79; of Pareiasaurus, 304, 305 Clemmys, 356 f.; C. caspica, 358; C. insculpta, 359; C. leprosa, 356 f., 353; skull, 356 Clepsydrops, 308 Clidastes tortor, 490 Cloaca, of Chelonia, 330; of Crocodiles, 445; of Lacertilia, 498 Cnemidophorus, 549; C. sexlineatus, 549 Cobra, 627, 627 Coccyx, s. Os coccygeum, of Anura, 20, 21, 22 {655} Coecilia, 89 Coeciliidae, 89 f.; distribution of, 89 Coelopeltis, 624; C. monspessulana s. lacertina, 624 Coelurus, 415; C. gracilis, 423 Colombo, gigantic tortoise of, 377 Coloration, warning colours of Amphibia, 38, 156; protective, of Amphibia, 191, 238, 252; of deserticolous reptiles, 494 Colosthetus, 238, 242 Colour, changes of, in Anura, 35; in Calotes, 518, 519, 520; in Geckos, 509; in Lacertilia, 498; mechanism of changing, in Chameleons, 570, 571 Coluber, 615 f.; C. aesculapii = flavescens = longissimus, 616 f.; C. leopardinus, 616; C. (Rhinechis) scalaris, 617 Colubridae, 593, 606 f. Colubrinae, 607 f. Columella cranii, 496, 550, 551 Columellar auditory chain, of Amphibia, 4; of Anura, 29; of Crocodiles, 446; of Lizards, 496 Comoro Islands, Tortoises of, 373 Compsognathus, 415, 416, 417; C. longipes, 423, 425 Condyle, occipital, of Theromorpha, 302; exaggerated importance of its character, 285 Conolophus subcristatus, 532 Conus arteriosus, continuation of the heart beyond the ventricles so far as it contains valves, 6 Cope, on classification of Amphibia, 9; of Anura, 140, 141; on Siren, 136; on hand-skeleton of Eryops, 286; on Sphargis, 336; classification of Lacertae, 513; classification of Snakes, 592 Cophophryne, 167, 168 Cophyla, 236 Copper-head, 646, 646 Copulatory organs, of Lacertilia, 499; absent in Sphenodon, 294; of Chelonia, 330; of Snakes, 585 Coqui, 214 Coronella, 619; C. austriaca s. laevis, 619, 620; C. girondica, 621 Cornufer, 241, 243; C. corrugatus, 244; C. johnstoni, 243; C. solomonis, 244; C. unicolor, 244 Corythomantis, 189, 207; C. greeningi, 207 Costal plates of Chelonia, 324 f., 322, 323 Craspedocephalus, 647 Crested Newt, 125, 125 Cricotus, 285, 285; C. heteroclitus, 287 Crinia, 213; spawning, 223 Crocodilia, 431 f.; skeleton, 434 f.; skull, 280, 434 f.; atlas and axis, 283, 431, 439; affinities, 432; teeth, 437; skin, 442; dermal armour, 442; skin glands, 443; tongue, 443; respiratory organs, 444; "diaphragm," 444; digestive organs, 444; cloaca, 445; heart, 445; ear, 445; eye, 446; geographical distribution, 446, 446; voice, 447; habits, 447; propagation, 447; classification, 448 Crocodilidae, 454 Crocodilus, 450, 454 f.; teeth, 437; skin glands, 443; C. acutus, 446, 449; C. americanus, 466; skull, 466; C. biporcatus = porosus, 458; rate of growth, 459; C. cataphractus, 465; C. intermedius, 466; C. johnstoni, 466; C. niloticus = vulgaris, 460 f., 449, 461; habits, 462 f.; C. palustris, 449, 454; skull, 455; C. porosus, 458; skull, 458; C. vulgaris, 449, 460 f. Crotalinae, 644 Crotalus, 648; rattle of, 644; C. adamanteus, 649, 650; C. confluentus, 649, 650; C. durissus, 648, 649, 650; C. horridus, 649; C. terrificus, 650 Cryptobranchus, 84, 96, 99; fossil, 84; C. alleghaniensis, 97; C. japonicus, 98, 99 Cryptoclidus, shoulder-girdle, 474, 475, 478 Cryptodira, 313, 338 Cryptopsophis, 89; C. multiplicatus, 92 Cryptotis, 213 Cutis, of Amphibia, 33 f. Cyamodus, 311 Cyclanorbis, 411; nuchal plate, 324 Cycloderma, 411 Cyclodus s. Tiliqua, 561; C. gigas, 561, 562 Cyclorhamphus, 212 Cynognathus, 301, 302, 303; C. berryi, 307; C. crateronotus, 306; C. platyceps, 307 Cystignathidae, 139, 209 f.; distribution, 161 Cystignathinae, 139, 211 f. Cystignathus = Leptodactylus, 210, 218

Dab = Uromastix, 526, 526 Daboia, 643 Dactylethra; see Xenopus, 146 f. Darwin, on Conolophus, 532 n.; on tortoises of Galapagos Islands, 377 Dasypeltis scabra, 622, 622; dentition, 593 n. Davison, on breeding of Amphiuma, 101 Dawsonia, 289 Death Adder, 635 Denburgh, van, on Autodax, 107 Dendrobates, 272; D. braccatus, 273; D. tinctorius, 272, 273; D. trivittatus, 273; D. typographus, 273; various uses of its poison, 38 Dendrobatinae, 139, 237, 272 f.; {656} distribution, 239 Dendrophis, 618; D. punctulatus, 618, 618 Dendrophryniscinae, 139, 224 Dendrophryniscus brevipollicatus, 224 Dentition, of snakes, 582, 592, 593; see also Teeth Dermal armour, of Cricotus, 287; of Microsauri, 289; of Prosauri, 290; of Theromorpha, 302; of Chelonia, 321 f., 337; of Dinosauria, 415; of Pseudosuchia, 433; of Parasuchia, 434; of Crocodiles, 442 Dermal ossification in Anura, 179, 190, 210 Dermatemydidae, 313, 314, 341; distribution of, 332 Dermatemys mawi, 341, 342 Dermatochelys coriacea, 333 f., 334 Dermophis, 89, 93; D. thomensis, 93 Deserticolous reptiles, 493 f. Desmognathinae, 102 Desmognathus, 96, 102; D. fuscus, 102, 103 Deuterosaurus, 308 Development, of Anura, 56 f., 57; of horny teeth, 58; of Apoda, 92; of Crocodilus, 465; of Alligator, 467 Diadectes, 308 Diademodon, 309 Diaglena, 185, 189; D. jordani, 207; D. petasata, 207 Diaphragm, of Anura, 144; of crocodiles, 444 Diapophyses (the lateral or "transverse" processes of the neural arches) of Anura, 138, 141 Dibamidae, 514, 564 Dibamus novae-guineae, 564 Dicamptodon, 96; D. ensatus, 109 Diclonius = Hadrosaurus, 429 Dicynodon, 301, 302, 303, 310; skull, 280; D. leoniceps, 310; D. orientalis, 310; D. tigriceps, 310 Digestive apparatus, of Chelonia, 330; of crocodiles, 444; of Lacertilia, 498 Digits = Fingers and Toes. Number of digits in Urodela, 15, 16; in Anura, 26; terminal phalanges, 26; number of joints, 27; adhesive discs, 27; variability in numbers, 563; digits of Eryops, 286; of Crocodiles, 441; of Plesiosauri, 475; of Geckos, 505 Dimetrodon, 308 Dimorphodon macronyx, 486 Dinosauria, 412; affinities of, 415; analogies with Birds, 416 Diplocynodon, 448; D. hastingsiae, 454 Diplodocus longus, 419 f.; skull, 419 Diplovertebron, 287, 288 Dipsadomorphinae, 623 f. Dipsadomorphus, 623; D. cyaneus, 624; D. trigonatus, 623 Dipsas bucephala, 624 Discoglossidae, 139, 152 f. Discoglossus, urino-genital organs, 49, 153; D. pictus, 153 f. Dissorophus multicinctus, 82 Distira cyanocincta, 637; D. semperi, 636 Distribution, geographical; see Maps Dolichosauri, 489 Dolichosaurus longicollis, 489 Dolichosoma longissimum, 81 Doliophis intestinalis, 634 Dollo, on Sphargis, 336 Dracaena, 547; D. guianensis, 549 Draco, 516; D. dussumieri, 516; D. volans, 516, 516 Duméril, 7, 139; and Bibron, on classification of Snakes, 592 Dwarf Chameleon, 579 Dyscophinae, 139, 235 f. Dyscophus, 236; D. antongili, 236

Ear, of Chelonia, 330; of Crocodiles, 445 f.; of Snakes, 583 Ear-opening of deserticolous reptiles, 494 Echeneis remora, used for turtle fishing, 382 Echidna s. Bitis, 639, 639 Echis, 640; E. arenicola, deserticolous, 493 Edalorhina, 212 Eggs of Amphibia, 53; mode of deposition in Amphibia, 54-56; of Ichthyophis, 91; and spermatophore of Triton viridescens, 128; nursing and taking care of, 55; by Pipa, 151; by Alytes, 159; by Rhacophorus reticulatus, 248; by Nototrema, 188, 202; by Amphignathodon, 188; by Hyla goeldii, 198, 198; by Leptodactylus mystacinus, 219; by Rhinoderma, 228; by Rhacophorus, 248; by Desmognathus fuscus, 103, 103; number of: in Bufo vulgaris, 175; in Bufo viridis, 181; in Hyla arborea, 193; in Rana esculenta, 270 Eggs of Reptilia: Sphenodon, 299; Chelonia, 331; Testudo graeca, 369; T. ibera, 369; T. elegans, 371; T. polyphemus, 372; Emys orbicularis, 355; Clemmys leprosa, 358; Chelone mydas, 382; Thalassochelys caretta, 387; Podocnemis expansa, 393 f., 398; Trionyx, 408; mode of laying by Emys, 355; by Podocnemis, 393; used commercially, 394 f.; enormous destruction of, 395, 399; Crocodilus, 463, 464 f.; Alligator, 470; eggs and nest of Gavialis, 452; Lacertilia, 499; increasing in size after deposition, 499; Geckos, 506, 508, 509, 511; Tarentola, 509; Lacerta viridis, 555; Chameleons, 572 Egg-sac, of Salamandrella, 110 {657} Egg-tooth, of Lacertilia, 499 Eimer, on habits of Lacerta, 552; on L. coerulea, 558 Elachistodon westermanni, 625 Elachistodontinae, 625 Elaphis s. Coluber, 615 f. Elapinae, 626 Elaps corallinus, 635 Elasmosauridae, 478 Elasmosaurus, 478 Elginia, 301, 304; E. mirabilis, skull, 280, 305 Elosia, 212 Elseya, 389, 399 Emerald Lizard, 555 Emery, on hand-skeleton of Eryops, 286 Empedias molaris, 308 Emyda, 411 Emydura, 389, 399 Emys, 350 f.; E. blandingi, 355; E. europaea = orbicularis, 351 f., 353 Enaliosauri, 476 Endothiodon, 307 Engystoma, 227, 231; E. carolinense, 232 Engystomatidae, 139, 225 f. Engystomatinae, 139, 225 f. Engystomops, 166, 168 Enhydrina valakadien s. bengalensis, 636, 636 Enygrus, 601 Eosphargis, 336, 337 Epichordal type of vertebrae, 20, 145 Epidermis, of Amphibia, 31 f.; sense-organs in, 33 Equisetum, eaten by Uromastix, 525 Eremias, 551; deserticolous, 493 Erpetosuchus, 433 Eryops, 285, 286; trunk-vertebrae, 286, 288, 304; E. megacephalus, 286 Eryx, 604; E. jaculus, 604; deserticolous, 493 Escuerzo = Ceratophrys, 216 Espada, on Rhinoderma, 228 Eublepharinae, 512 Euchirosaurus, 83, 287 Eunectes murinus, 603, 603 Euprepes vittata, 562 Euproctus = Triton, 130 Eurysternum, 380 Eustachian tubes, of Anura, 29; of Pelobatidae, 161; of Aglossa, 143 Eusuchia, 434 Eye, of Apoda, 86; of Chelonia, 329; of deserticolous reptiles, 494; of Chameleons, 569; of Snakes, 583 Eyed Lizard, 556, 556 Eyelid, of Geckos, 504, 512; transparent in Chelodina, 329; lower, transparent in Lacertidae, 551; in Scincidae, 560

Fasting, of Chrysemys, 347 Fat-bodies, of Amphibia, 49, 52; of Lacertilia, 500 Fecundation, various modes of, in Amphibia, 54; in Apoda, 87 Fer-de-Lance, 647 Ferreiro = Hyla faber, 196 f. Feylinia, 564 Fingers, number of, in Urodela, 15; number of joints in Anura, 26, 27; terminal modifications of, in Anura, 26; mechanism of adhesive discs in Hylidae, 187 Fire Salamander, 115 Firmisternal shoulder-girdle, 24, 25 Firmisternia, 140 Fischer-Sigwart, on growth of Alytes, 159 f.; on growth of Bufo, 175; on gestation of Chalcides, 563 Fletcher, on spawning of Australian frogs, 201, 223 Flower, S. S., on habits of Rhacophorus, 249; Phrynella pollicaris, 233; Callula pulchra, 234 Flying Dragon, 516 Flying Frog, Rhacophorus, 245 f., 246 Foot, tridactyle, in Hallopus, 423; bird-like in Compsognathus, 423 Fore-limb, of Urodela, 15; of Anura, 26; of Proreptilia, 286; of Microsauri, 289; of Prosauri, 290, 298; of Theromorpha, 302; of Chelonia, 320; of Dinosauria, 414, 423, 425, 427; of Crocodilia, 440; of Plesiosauria, 475; of Ichthyosauria, 481; of Pterosauria, 485; of Pythonomorpha, 489; of Lacertilia, 497 Frog, see Rana. Grassfrog, 251; Water-frog, 263, 268, 269

Gage, on Triton viridescens, 129 Galapagos Islands, tortoises of, 372, 377 f. Galesaurus, 307 Gampsosteonyx, 271; G. batesi, 238, 240 Gasco, on spawning of newts, 124 Gastrechmia, 140, 141, 232 Gastrocentrous vertebrae, defined, 282 Gaupp, on frogs' respiration, 47 n. Gavialidae, 451 f. Gavialis, 435, 436, 451; G. gangeticus, 452; skull, 449, 452 Gavialosuchus, 453 Gecko, 511; G. stentor, 511; G. verus = guttatus = verticillatus, 511 Geckolepis, deserticolous, 493 Geckones, 502 f.; distribution, 500, 503; adhesive apparatus, 505, 505; voice, 506; reproduction of tail, 506; eyelids, 504, 512 Geckonidae, 507 f. Geckoninae, 507 f. Gegenbaur, on classification, 9 Gegenophis, 87, 90 Geikia, 310 {658} Genital organs, of Amphibia, 48 f., 49 Genyophryne, 236; G. thomsoni, 236 Genyophrynidae, 141 Genyophryninae, 139, 236 Geographical distribution, principles of, 69 f.; regions and sub-regions, 74 f. (for details see also Maps); of Apoda, 89; of Urodela, 95, 96; of Anura, 143, 161, 167, 185, 239; of Chelonia, 331 f., 332, 333; of Crocodilia, 446; of Lacertilia, 500 f., 515, 529, 543, 552, 565, 568; of Snakes, 585 Geomolge, 96 Geosaurus, 451 Geotriton, 97 Geotrypetes, 89 Gerrhonotus, 538; G. coeruleus, 538 Gerrhosauridae, 514, 559 Gerrhosaurus flavigularis, 559 Gharial, 452; see also Gavialis Gigantic Tortoises, 372 f. Gila Monster, 541 Gills, definition, 40; development of, 41, 43; retention of, 40; external and internal, 43 f.; operculum of, 44; of Nototrema, 203 Gill-clefts, 42; of Urodela, 42; of Anura, 42 Girtanner, on musical appreciation of tortoises, 368 Glass-Snake, 538 Glauconia, 594 Glauconiidae, 592, 594 Glyphoglossus, 225, 226, 228, 233; G. molossus, 233 Goeldi, on Hyla faber, 197; on habits of Podocnemis expansa, 397 f. Gomphognathus, 308, 309 Gondwanosaurus, 83 Gongylus, 562 Goniopholidae, 453 Goniopholis, 448, 453; G. crassidens, 453; G. simus, 453 Gordonia, 301, 303, 310; skull, 280 Grass-Frog, 251 f., 255 Grass-Snake, 608 f. Greek Tortoise, 365 f. Green Lizard, 555 Green Toad, 180 Green, or Edible, Turtle, 381 f. Groenberg, on Pipa, 149 Growth, rate of, in Testudo ibera, 370; Chrysemys picta, 349; Emys orbicularis, 351, 355 Gular shields of Chelonia, 315 Gundlach, on Leptodactylus, 219 Günther, 140; on gigantic Tortoises, 374; on classification of Snakes, 592 Gutzeit, on horny teeth of Tadpoles, 58 Gymnodactylus, tail, 506, 512, 512; deserticolous, 493 Gymnophiona, 84 f. Gymnophis, 90 Gymnophthalmus, aberrant scaling, 495

Haast, on habits of Sphenodon, 299 Hadrosaurus mirabilis, 429 Haeckel, on classification, 9 Hallopus victor, 423 Hamadryad, 632 Hand-skeleton, excalation of second finger in Eryops, 286 Haptoglossa, 96 Hardun = Agama stellio, 521 Hatteria–see Sphenodon, 293 f. Hawksbill-Turtle, 384 f. Hay, on Sphargis, 337 Hearing of Chelonia, 330 Heart, modification of, in lungless Amphibia, 47 Hedonic glands (ἡδονή, lust), 443 Heleioporus, 213, 222; H. albopunctatus, 222; H. pictus, 222 Helix virgata, eaten by Hyla coerulea, 200 Heloderma horridum, 540; H. suspectum, 540, 541 Helodermatidae, 513, 540 f. Hemidactylus turcicus, 508, 508 Hemiphractinae, 139, 210 f. Hemiphractus, 210 Hemisus, 225, 226, 228, 232; shoulder-girdle, 25; H. guttatum, 232; H. sudanense, 232 Hensel, on Bufo marinus, 179; on tadpoles of Thoropa, 209; on nest-building of Leptodactylus, 219 Herodotus, on Crocodiles, 462 Herpele, 90 Herpestes griseus (Mongoos), 629 Hibernation, temperature of blood during, 68; of Tortoises, 347, 349, 354, 358, 360, 363, 365, 369, 376; of Crocodiles, 447 Hinckley, on tadpoles of Hyla versicolor, 195 Hind-limbs, of Urodela, 15; of Anura, 27; of Prosauria, 289; of Theromorpha, 302, 305; of Chelonia, 321; of Dinosauria, 414, 423, 425, 427, 429; of Crocodilia, 440; of Plesiosauria, 476; of Ichthyosauria, 480; of Pterosauria, 486; of Lacertilia, 497; of Ophidia, 593, 594, 596 Hipistes hydrinus, 625 Holbrook, on the Black Snake, 613; on habits of Alligator, 470 f. Holoblastic eggs; the whole mass of the egg undergoes the process of cleavage, 53 Homalopsinae, 625 Homalopsis buccata, 625 Homing of turtles, instances of, 386 Homoeosaurus pulchellus, 292 {659} Homopholis, deserticolous, 493 Homothermous, defined, 68 Hoplocephalus curtus, 634 Hoplurus, 528; geographical distribution, 501 Horned Toad = Ceratophrys, 215 f., 216, 217 Horned Viper, 640, 641 Horny nail, on tail of Chelonia, 328 Horny scales, of Chelonia, 328 Horny shields, of Chelonia, 314, 315, 322, 323, 326 f., 327; their growth, 326 Horny teeth, of Anura, 58 Hose, on reproduction of tortoise-shell, 386 Howes, on development of Sphenodon, 298 Humerus of Sphenodon, 294 Hutton, on Starred Tortoise, 370 f. Huxley, on classification, 9 Hydraspis, 389; skull, 399 Hydromedusa, 389, 404; H. tectifera, 404 Hydrophinae, 635 Hydrophis obscura, 636, 636 Hydrosaurus, 543 Hyla, 189 f.; H. arborea, 190 f., 190; var. meridionalis, 191; var. savignyi = japonica, 191; H. aurea, 201 f.; spawning, 201; H. carolinensis s. lateralis, 194; H. coerulea, 198 f., 199; spawning, 223; H. dasynotus and H. nigromaculata, dermal ossifications of, 190; H. ewingi, 201; spawning, 223; H. faber, peculiar nursing habits, 196 f.; H. femoralis, 194; H. goeldii, 198, 198; female with eggs, 198; H. maxima, 196; H. nebulosa s. luteola, 197; nest-building, 198; H. polytaenia, 198; H. squirella, 194; H. vasta, 195; H. versicolor, 194 f. Hylaeformes, 139 Hylaeobatrachus croyi, 83 Hylaeosaurus, 425 Hylambates, 238, 240 Hylella, 186, 189, 203 Hylidae, 139, 185 f.; distribution, 185, 186; mechanism of climbing, 187; map of distribution, 185; distribution, 186 Hylinae, 139, 189 f. Hylixalus, 238, 242 Hylodes, 212; H. martinicensis, 214 f., 214; H. abbreviatus = Thoropa miliaris, 209 Hylonomus, 288, 289 Hyloplesion longicostatum, 289 Hylopsis, 212; H. platycephalus, 224 Hylorhina, 212 Hymenochirus, 143, 144, 149 Hynobius, 96, 109 Hyoid apparatus, of Urodela, 16; of Anura, 31; of Chelonia, 318; of Chelys, 400; of Lacertilia, 496 Hyperodapedon gordoni, 292 Hyperolia, 213; spawning, 223 Hyperphalangeal limbs, of Eusuchia, 441; of Ichthyosauri, 480 Hypogeophis, 87, 89, 92; H. alternans, 92; H. rostratus, 92 Hypopachus, 226, 227, 235 Hypsilophodon foxi, 427 Hypsirhina plumbea, 625

Iberian Water-tortoise, 357 f. Ichthyodea, distribution of, 95 Ichthyophis, skull, 85, 88, 89 f., 91; I. glutinosa, 90, 91; I. monochrous, 90 Ichthyopsida, 5, 277 Ichthyopterygia, 476 Ichthyosauri, 483 f. Ichthyosauria, 478 f.; skull, 281, 479; vertebrae, 480; limbs, 481; shoulder-girdle, 481 Ichthyosaurus, 483; I. communis, 483; I. campylodon, 483; I. quadriscissus, 483; I. tenuirostris, 483; I. trigonodon, 483 Idiochelys, 380 Iguana, 306, 528, 531; I. tuberculata, 531 Iguanidae, 513, 528 f.; distribution, 501, 529 Iguanodon, 416, 417, 427; I. bernissartensis, 428, 428; I. mantelli, 427 Ihering, on breeding habits of Phyllomedusa, 205 f., 206 Ikeda, on nursing habits of Rhacophorus, 248 Ilysia, 595 Ilysiidae, 592, 594 Inframarginal shields, 326, 315 Intergular shields of Chelonia, 325, 315 Iris, colour of, in Chelonia, 329 Ixalus, 238, 241

Jaw, lower, of Salamandra, 17; of Urodela, 18; of Anura, 30

Keller, quoted, 571 n. Keraterpeton, 81, 288; K. crassum, 81 Kidneys of Amphibia, 48 f., 49 Klinckowstroem, on Pipa, 149 Kollmann, on Neoteny, 64 Krait, 633

Labial glands of Heloderma, 498 Labyrinthodon, 83 Labyrinthodonta, 82 Lacerta, 553; L. agilis, 554; L. muralis, 557; L. ocellata, 556 f., 556; L. pater, 556; L. schreiberi, 555; L. tangitana, 556; L. viridis, 555; skull, 550; L. vivipara, 553 Lacertae, 513 f. Lacertidae, 514, 549 f.; skull, 550; distribution, 552 Lacertilia, 491 f.; {660} skeleton, 494 f.; skin, 497; change of colour, 498 Lachesis gramineus, 647; L. lanceolatus, 646, 647 Land-tortoises, 364 f. Lanthanotidae, 514, 541 f. Lanthanotus borneensis, 541 Laosaurus, 427 Lariosaurus, 473, 474; L. balsami, 477 Larvae, of Ichthyophis, 91; of Hypogeophis, 92; of Amblystoma, 112; of Triton waltli, 131 Latreille, on classification, 7, 8 Laurenti, on classification, 7 Leathery Turtle = Sphargis, 333 f., 334 Lechriodonta, distribution of, 95; defined, 102 Lepidobatrachus, 212, 218 Lepidophyma, 547 Lepospondylous, defined, 79 Leptobrachium, 161; L. carinense, 166 Leptodactylus, 212, 218 f.; L. albilabris, 219; L. mystacinus, 219; L. ocellatus, 219; L. typhonius, 219 f. Leptognathus, 624 Leptophis, 618; L. liocerus, 618, 619 Leslie, on Xenopus, 146 Leuckart, on classification, 8 Leydig's duct, defined, 48, 49 Lialis burtoni, 567 Limbs, of Amphibia, 26, 27; Stegocephali, 79, 83; Eryops, 286; Microsauri, 289; Prosauri, 291; Sphenodon, 298; Theromorpha, 302; Pareiasauri, 305; Chelonia, 320, 319, 320; Sphargis, 335; Chelonidae, 379; Dinosauria, 414 f., 418, 420; Compsognathus, 423; Stegosauri, 426 f.; Iguanodon, 428, 428; Eusuchia, 440; Plesiosauria, 475, 475; Lariosaurus, 477; Ichthyosauria, 480; Pterosauria, 485, 485; Lacertilia, 495; Geckones, 505; Chameleons, 568; reduction of, in Lacertilia, 497; in Ophidia, 593, 594, 596 Limnodynastes, 213, 222; spawning, 223 Limnomedusa, 212 Linnaeus, on classification, 7 Liodon haumuriensis, 490 Liolepis belli, 527 Liopelma, 153; L. hochstetteri, 160 Liophryne, 225, 227 Liosaurus, 529 Lissamphibia, 84 f. Lizard, Common English, 553; Emerald, 555; Eyed, 556, 556; Green, 555; Sand, 554; Wall, 557 Lizards, 491 f. Locality, sense of, in Tortoises, 368, 387 Loggerhead Turtle, 387; individual varieties of shields, 327, 388 Longevity, of Testudo daudini, 376; T. graeca, 369; T. ibera, 369; T. sumeirei, 377 Loxocemus bicolor, 598 Loxomma, 83 Lucilia bufonivora, fly infesting Bufo, 176 Lungs, definition, 40; suppression of, 46; of Aglossa, 144; of Lacertilia, 499 Luth, or Leathery Turtle, 333 f., 334 Lycosaurus, 307 Lygosoma, distribution, 501 Lymph-spaces, in the cutis of Anura, 34 Lyriocephalus scutatus, 517, 518 Lytoloma, 336, 380

Mabuia, 562; distribution, 501; eyelids, 494; M. vittata, 562 Macroclemmys, 326; M. temmincki, 340 f., 340 Macroprotodon cucullatus, 624 Macrorhynchidae, 451 Madagascar, Lacertilia of, 502 Malacoclemmys terrapin, 359 f.; commercial breeding-farms, 360 Malpighian, body, 49; stratum, 32 Mammalian affinities of Theromorpha, 303, 309 Manculus, 96, 103, 106; M. quadridigitatus, 106 Mandible, composition of, in Crocodiles, 437; very Mammalian in Gomphognathus, 309 Mantella, 274 Mantophryne, 225, 227 Maps showing geographical distribution, of Coeciliidae, 89; Urodela, 95; Aglossa, 143; Cystignathidae, Discoglossidae, Pelobatidae, 161; Bufonidae, 167; Hylidae, 185; Ranidae, 239; Chelydidae, 332, 333; Chelydridae, 332; Cinosternidae, 332; Dermatemydidae, 332; Pelomedusidae, 332; Platysternidae, 332; Trionychidae, 333; Crocodilia, 446; Geckonidae, 503; Agamidae, 515; Anguidae, 529; Iguanidae, 529; Zonuridae, 529; Varanidae, 543; Lacertidae, 552; Amphisbaenidae, 565; Chamaeleontes, 568; Snakes, dangerously poisonous, 585; Elapinae, 626; Crotalinae, 644; Viperinae, 638 Marbled Newt, 126 Marginal plates of Chelonia, 325, 322, 323 Marginal shields, 326 Marsh, on Axolotl, 115 Marsh Crocodile, 455 Marshall, on distribution of Uropeltidae, 595 Mascarene Islands, tortoises of, 373 f. Mason, on habits of Calotes, 519; on Python legends, 599; on Varanus, 544 Mastodonsaurus, 83 Matamata = Chelys fimbriata, 400, 401 Mauritius, gigantic tortoises, 373 f., 376 Mecodonta, distribution of, 95; {661} defined, 102 Megalixalus, 238, 240 Megalophrys, 161; tadpole, 60 Megalosaurus, 416; M. bucklandi, 421 Megalotriton, 83 Melanerpeton, 81, 289 Melanobatrachus, 226, 228 Melosaurus, 287 Menobranchus lateralis, 132 Menopoma, 97 Mento-Meckelian cartilages, 30 Meroblastic eggs; part of the egg only undergoes the process of cleavage, 53 Merrem, on classification, 8 Mesosauridae, 476 Mesosaurus, 476; M. tenuidens, 476 Metamorphosis of Tadpoles, 56 f. Metasternum of Anura, 26, 25; taxonomic value, 141; definition, 26 Metatarsalia of Theropoda, 420 Metopias, 83 Metopoceros cornutus, 532 Metriorhynchidae, 451 Metriorhynchus, atlas and axis, 283, 431, 451 Metzdorff, on Axolotl, 113 Micrixalus, 241 Microgomphodon, 308, 309 Microhyla, 228 Microsauri, 288 Midwife-toad, 158 Mimosa (plant), 629 Miolania, 390 Mixophyes, 213; spawning, 213 Mixosaurus, limbs, 480, 481, 483 Molge–see Triton, 122 Moloch horridus, 527, 527 Mongoos and Cobra, 629 Monitor, 543 Morosaurus grandis, 419; pelvis, 419 Mosasauri, 489 f. Mosasaurus, 489; M. camperi, 490 Moult of Geckos, 510; of Chameleons, 571; of Snakes, 583 Mud-diver, 165 Mud-turtle, 342 Mugger, 454 Müller, J., on classification, 8 Müllerian duct, 49, 51 Musical appreciation of Tortoises, 368 Myobatrachus, 166, 167, 168; M. gouldi, 184, 227, 236 Mystriosaurus, 432, 451

Nails or claws of Amphibia, 32 Naja, 626; N. bungarus s. elaps, 632; N. haje, 628, 632; N. tripudians, 627, 627 Nannobatrachus, 238, 240 Naosaurus claviger, 308 Natterjack, 181 Naultinus elegans, 506 Neck, mode of withdrawing in Chelonia, 328 f. Nectes, 166, 168; N. subasper, 169 Nectophryne, 166, 168; N. afra, 169; N. tuberculosa, 169; N. guentheri, 169; N. hosei, 169; N. misera, 169 Necturus, pelvis, 15, 96, 132; N. maculatus, 132 Neoteny, 63 f.; defined, 64 Nephrostomes, 48, 49 Nephrurus asper, tail, 506 Nerves, spinal, of Amphibia, 38; cranial, 39 Nest, of Crocodilus, 463; of Gavialis, 452 Neural plates, of Chelonia, 323 f., 322, 323; suppression of plates, 324; in Pleurodira, 389; of Dermatemys, 342 Neusticosaurus, 477 Newt, Common, 127; Crested, 125, 125; Marbled, 126; Spotted, 127 Newton, E. T., on fossil Reptiles, 303 n. Nile Crocodile, 461 Nodosaurus, 430 Nose-horned Viper, 640 Notaden, 166, 169; N. bennetti, 167 Notechis scutatus, 634 Nothosauri, 476 f. Nothosauridae, 477 Nothosaurus, 474; N. mirabilis, 477 Notocentrous vertebrae, defined, 19 Notochord = Chorda dorsalis, q.v. Nototrema, 189; N. cornutum, 203; N. marsupiatum, 202; N. oviferum, 202; peculiar gills of embryos, 203; N. pygmaeum, 202; N. testudineum, 202 Nuchal plate of Chelonia, 323 f.; of Pleurodira, 389 Nuchal shield of Chelonia, 326, 327; of Pleurodira, 389, 399 Nuptial excrescences of Anura, 33 Nursing, habits, of Arthroleptis seychellensis, 243; of Chiromantis rufescens, 244; of Rhacophorus, 248; of Rhinoderma, 228 f.; of Pipa, 151; of Hyla faber, 196 f.; of H. nebulosa, 198; of H. goeldii, 198; of Nototrema, 203; of Phyllomedusa, 204 f.; of Leptodactylus, 219 f.; of eggs by Desmognathus, 103, 103; by Autodax, 108 Nyctibatrachus, 240 Nyctimantis rugiceps, 189, 206 Nyctixalus, 238

Occipital condyle, of Reptilia, 278; exaggerated importance of, 285; of Theromorpha, 302; of Pareiasauri, 305; of Cynognathus, 307; of Crateronotus, 307; of Dicynodon, 310; of Eusuchia, 437; of Amphisbaenidae, 496 Odontaglossa, 140 Oligodon, dentition, 593 n. Omosaurus = Stegosaurus, 425 {662} Omosternum of Anura, 25; taxonomic value, 141 Onychodactylus, 96; O. japonicus, 109 Operculum of gills, 44 Ophiderpeton, 81 Ophidia, 491, 581 f. Ophiophagus, 632 Ophiops, 551 Ophioxylon (plant), 629 Ophisaurus, 538; O. apus, 538; O. gracilis, 538 Ophthalmosaurus, limbs, 481, 481, 484 Opisthocoelous, definition, 12 Opisthoglossa, 140 Opisthoglypha, 592, 606 f., 623 f. Oppel, on classification, 7 Oreobatrachus, 241 Oreophrynella, 227 Ornithocheirus, 486 Ornithomimus, 417; O. grandis, 429 Ornithopoda, 425, 426 Ornithopsis, 419 Ornithoscelida, 416 Ornithosuchus, 433 Orthocosta, 288, 289 Orthopoda, 424 Ossifications, dermal, in Anura, 31, 34, 179, 190, 210, 211 Osteoderms = ossifications in the skin, of Sphargis, 337; of Caiman, 337; of Lizards, 504, 513, 514 Osteolaemus, 450; O. tetraspis, 466 Ouaran, 543 Oudenodon, 301; O. rugosus, 310 Ovary, 49 Oviduct, 49, 51 Owen, on fossil Reptiles, 303 n. Oxydactyla, 140 Oxyglossus, 239, 241

Pachytriton, 96, 115; P. brevipes, 132 Painted Terrapin, 347, 348; rate of growth, 349 Palaeobatrachus, vertebral column, 22, 145 Palaeohatteria longicaudata, 291; skull, 280, 304 Paludicola, resembles Engystomops, 166, 212, 220; P. fuscomaculata, 220; P. biligonigera, 221 Paludina, as food of Trionyx, 407 Parasternum = the sum total of the Abdominal ribs, q.v.; of Sphenodon, 298; of Crocodilia, 440; of Ichthyosauria, 480 Parasuchia, 433 Pareiasauri, 301, 302, 304 Pareiasaurus baini, 304 Parrots, feathers dyed with poison of Dendrobates, 272 Pelobates, variation of vertebrae, 19; sacral vertebra, 22, 161 f.; P. fuscus, 162; P. cultripes, 163, 164; P. syriacus, 164 Pelobatidae, 139, 160 f.; distribution, 161 Pelodytes, 161, 165; P. punctatus, 165; P. caucasicus, 166 Pelomedusa galeata, 391 Pelomedusidae, 313, 314; distribution, 332, 390 f. Pelosaurus, 81 Pelvic, plexus of Anura, 39 Pelvis, of Urodela, 15; of Anura, 22, 27; of Eryops, 286; of Microsauri, 289; of Sphenodon, 298; of Theromorpha, 302; of Pareiasauri, 305; of Cynognathus, 307; of Dicynodon, 310; of Chelonia, 319, 319, 320; of Pleurodira, 388, 389; of Dinosauria, 414; of Eusuchia, 441; of Plesiosauria, 476; of Ichthyosauria, 480; of Pterosauria, 485; of Pythonomorpha, 489; of Lacertilia, 496 Perennibranchiata, 8, 9; not a natural group, 65 Petrels living with Sphenodon, 299 Petrobates, 288, 289 Phalanges, number of, in Urodela, 15; in Anura, 26, 27, 238; in Stegocephali, 79; in Palaeohatteria, 291; in Chelonia, 320, 321; in Chelone, 379; in Scelidosaurus, 425; in Camptosaurus, 427; in Laosaurus, 427; in Iguanodon, 428; in Eusuchia, 441; in Plesiosauria, 475; in Lariosaurus, 477; in Ichthyosauria, 481, 481; in Pterosauria, 485, 485; shape in Anura, 138; peculiar in Pipa, 151 Phaneroglossa, 152 Phanéroglosses, 139 Phanerotis, 213 Phisalix, on poison of Amphibia, 37 Pholidosaurus, 451 Phractamphibia, 78 f. Phrynaglosses, 139 Phrynella, 227; Ph. pollicaris, 233 Phryniscus, 226, 227, 230; Ph. nigricans, 230 Phrynobatrachus, 241 Phrynocara, 235, 236 Phrynocephalus, 521; deserticolous, 493; coloration, 494; Ph. helioscopus, 522; Ph. interscapularis, 522; Ph. mystaceus, 522 Phrynoderma, 241 Phrynomantis, 226, 228 Phrynopsis, 241 Phrynosoma, 305, 533; Ph. coronatum, 534, 535; Ph. cornutum, 533, 534 Phyllobates, 242; Ph. bicolor, 242; Ph. trinitatis, 242 Phyllodactylus, 507; Ph. europaeus, 507 Phyllodramus, 238, 242 Phyllomedusa, 189, 203 f.; Ph. bicolor, 203; Ph. dacnicolor, 203; Ph. hypochondrialis, breeding habits and development, 204; {663} Ph. iheringi, 205; breeding habits, 206 Phylogeny, of Amphibia, 66; of Anura, 142 f.; of Reptilia, 282; of Lacertilia, 515; of Ophidia, 592 Physignathus lesueuri, 523, 524 Pigment in the skin, 34 Pipa, 143, 144, 149 f., 150 Pit-Vipers, 644 Placodontia, 311 Placodus, 301; P. gigas, 311 Plastron, of Chelonia, 315, 321, 321; provided with hinges, 323; sexual characters of, 331; movable in Emys, 350; of Chelonidae, 321, 321, 322, 380; of Pelomedusidae, 390; of Chelydidae, 399; of Trionychoidea, 406 Platecarpus, 490 Platemys, suppression of neural plates, 324; skull, 399 Plathander = Xenopus, 146 f. Platurus fasciatus s. colubrinus, 637 Platydactyla, 140 Platydactylus facetanus, 509, 508 Platyhyla, 236 Platypelis, 235, 236 Platysternidae, 314, 326, 345 Platysternum megacephalum, 345 Plectromantis, 212 Plesiochelys, 380, 389 Plesiosauri, 477 f. Plesiosauria, 473 f.; vertebrae, 474 Plesiosauridae, 478 Plesiosaurus, 475, 478; P. conybeari, 478; P. dolichodirus, 478 Plethodon, 94, 96, 104, 106; P. erythronotus, 107; P. glutinosus, 106 Plethodontinae, 102, 103 Plethodontohyla, 235, 236 Pleurodira, 313, 388 f. Pleurosaurus, 294 Pleurosternum, 390 Plioplatecarpus, 489 Pliosauridae, 477 Pliosaurus grandis, 477 Plover, Egyptian, and Crocodile, 462 Podocnemis, 390, 391; P. expansa, 391 f.; Bates, on habits of, 392 f. Poikilothermous, defined, 67 Poison, of Amphibia, 37, 38; peculiar use of, 272 Poison-apparatus, of Heloderma, 540; of Snakes, 586 f. Polacanthus, 425 Polychrus marmoratus, 529 Polyodontophis, 605 n. Portschinsky, on parasitic flies, 177 n. Postpubis, of Dinosaurs, 414, 424, 426 Pouchet, quoted, 571 Predentary bone, of Dinosaur, 424 Prehallux, of Anura, 28 Prepubis, of Dinosaurs, 414, 424, 426 Proganochelys, 389 Proganosauria, 476 Proreptilia, 285 Prosauri, 290 Prosauria, 288 Prostherapis, 242 Protection of Amphibia by poison, 38 Proteidae, 94, 96, 132 f. Proteroglossa, 140 Proteroglypha, 625 Proteus, 96; P. anguinus, 133, 134 Protorosauri, 290, 304 Protorosaurus lincki, 291 Protosphargis, 336 Protostega, 336 Protriton, 80, 81 Psammodromus hispanicus, 558; P. algirus, 558 Psammosaurus, 543 Psephoderma, 337 Psephophorus, 336, 337 Pseudechis porphyriaceus, 634 Pseudis, 212, 213; P. paradoxa, 213 f. Pseudobranchus, 96; P. striatus, 137 Pseudocentrous, defined, 79 Pseudophryne, 166, 167, 168; spawning, 223; P. australis, 168; P. bibroni, 168 Pseudopus, aberrant scaling, 495; P. pallasi, 538 Pseudosphargis, 336 Pseudosuchia, 432 Ptenopus, 507; deserticolous, 494 Pteranodon longiceps, 487 Pteranodontes, 487 Pternohyla, 179, 189; P. fodiens, 207 Pterodactyli, 486 Pterodactylus longirostris, 487; P. spectabilis, 487 Pterosauri, 486 Pterosauria, 484 f. Ptyas = Zamenis, 611 Ptychozoon, tail, 506; P. homalocephalum, 512, 512; adhesive apparatus, 505 Pubis, of Dinosaurs, 414, 424, 426 Puff Adder, 639, 639 Pygopodidae, 514, 567 Pygopus lepidopus, 567 Python, 598; P. molurus, 600, 600; P. regius = P. sebae, 601; P. reticulatus, 598; P. spilotes, 598, 599 Pythoninae, 598 f. Pythonomorpha, 487 f. Pyxis arachnoides, 365

Radde's "law of the steppe," 493 Rana, 241, 249 f.; sacral vertebrae, 22; shoulder-girdle, 25; urino-genital organs, 49; Tadpoles' horny teeth, 58; vocal sacs, 250; nuptial excrescences, 250; large glandular complexes, 250; distribution, 251; species with finger-discs, 250; R. afghana, 250; {664} R. agilis, 257; R. albolabris, 250; R. alticola, 250; R. arvalis, 257; R. catesbiana, 261; R. chalconota, 250; R. chloronota, 250; R. clamata, 262, 263; R. corrugata, 250; R. curtipes, 250; R. cyanophlyctis, 250; R. elegans, 250; R. erythraea, 250; R. esculenta, 263; mechanism of tongue, 268; vocal sacs, 269; var. chinensis, 267; var. lessonae, 265; var. ridibunda, 264; var. typica, 265; R. fontinalis, 262; R. glandulosa, 250; R. gracilis, 261; R. graeca, 259; R. guppyi, 261; R. halecina, 263; R. hexadactyla, 250; R. iberica, 258; R. latastei, 259; R. liebigi, 250; R. mascareniensis, 250; R. montezumae, 250; R. mugiens, 261; R. opisthodon, 260; R. oxyrhynchus, 250; R. rugosa, 250; R. silvatica, 259; R. temporalis, 250; R. temporaria, 251 f., 255; R. tigrina, 261 Ranidae, 139, 237 f. Ranidens, 96; R. sibiricus, 109 Raniformes, 139, 140 Raninae, 139, 237, 238 f.; distribution, 239 Rappia, 241 Rat Snake, 611, 612 Rattle of Rattle-Snake, 644 Rattle-Snake, 648 f., 648, 650 Reduction of limbs, in Urodela, 16; in Lacertilia, 497 Regeneration, in Amphibia, 66 f.; of tail in Sphenodon, 298; of shell in Chelonia, 329; of horny shields in Chelonia, 329, 386; of tail in Lacertilia, 495; of tail in Geckos, 506 Regions, geographical, 74 f. Reproduction of Tortoise-shell, 386 Reptilia, defined, 277; principal characters of, 278; classification of, 279; diagram of affinities of principal groups, 282; affinities to Mammalia, 303, 309 Respiration, mode of, in Chelonia, 331; assisted by anal sacs, 330 Respiratory organs, of Amphibia, 40 Rhachiodontinae, 622 Rhacophorus, 151, 186, 238, 241, 244, 246; Rh. leucomystax, 247; tadpoles, 249; Rh. maculatus, nesting, 248; Rh. madagascariensis, 245; Rh. maximus, 245; Rh. pardalis, 246, 246; Rh. reinwardti, 247; Rh. reticulatus, 248; Rh. schlegeli, nesting, 248 Rhampholeon spectrum, 580 Rhamphorhynchus longicaudatus, 486; Rh. phyllurus, 486; Rh. muensteri, 487 Rhamphosuchus crassidens, 453 Rhinatrema, 89 Rhinemys, 389, 399 Rhinochelys, 390 Rhinoderma, 226, 227, 228; Rh. darwini, 228 f. Rhinophis, 91; Rh. sanguineus, 596 Rhinophrynus, 166, 168; Rh. dorsalis, 185, 227 Rhinophrys, 167 Rhombophryne, 225, 227 Rhynchocephali, 292 Rhynchosaurus, 292 Rhytidosteus, 83 Ribs, of Urodela, 14; of Anura, 21; of Microsauri, 288; of Sphenodon, 297; of Theromorpha, 302; of Cynognathus, 307; of Microgomphodon, 309; of Chelonia, 315, 320, 324; of Dinosauria, 413; of Crocodilia, 438; of Parasuchia, 434; of Eusuchia, 439; of Lacertilia, 495; of Geckones, 504; much elongated in certain Iguanidae, 529; meeting ventrally in Chameleons, 568 Ridewood, on hyoid apparatus of Anura, 31 Ringhals, 632, 633 Ritter and Miller, on Autodax, 107 Robinson, on peculiar use of Varanus, 546 Rodriguez, gigantic tortoises, 374 Rostral bone of Ceratopsia, 430 Round Island snake, 603

Sacral vertebrae of Anura, 21, 22 Salamandra, 115 f.; trunk-vertebra, 14; skull, 17; lower jaw, 17; distribution, 96, 115 f.; S. atra, 119 f.; S. caucasica, 121; S. maculosa, 115 f. Salamandrella, 96, 109; S. keyserlingi, 109; S. schrenki, egg-sac, 110 Salamandridae, 94, 102 Salamandrina, 96, 115; S. perspicillata, 122; skull, 17 Salamandrinae, 102, 115 Sarasin, P. and F., 10; on Coeciliae, 88; on Ichthyophis, 90 Sauria, 491 f. Saurichnites salamandroides, 83 Sauropoda, 418 Sauropsida, 5, 277 Sauropterygia, 476 Saurosternum, 291 Scales of Apoda, 87 Scaling, aberrant, 495 Scaphiophryne, 225, 226, 227 Scaphiopus, 161, 164; S. solitarius, 165 Scapteira, deserticolous, 494 Scapula, attached to thoracic vertebrae, 487 Scelidosaurus, 416; S. harrisoni, 425 Scheuchzer, on Homo diluvii testis, 84 Schlegel, on Cryptobranchus, 100 Schuberg, on mechanism of finger-discs of Hylidae, 187 Schwalbe, on Salamandra atra, 120 Scincidae, 514, 559 f. Scincus officinalis, 561 {665} Sciurus bicolor, squirrel, 248 Scolecomorphus, 90 Sea Snakes, 635 Seeley, on fossil Reptiles, 303 n. Seeleya, 81, 289 Segmental duct, 49 Sense-organs, of Chelonia, 329 f.; of Crocodiles, 445 f. Sepedon haemachates, 632, 633 Seps, 562 Seychelles, gigantic tortoises of, 373 Shell of Chelonia, 321 f., 319, 320, 321, 322, 323, 327; partial regeneration of, 329; correlated changes, 328 Shields, horny, of Chelonia, 322, 323, 325 f., 327; evolution of, 326 f.; individual variation in, 326, 327; periodical peeling of, 328 Shoulder-girdle, of Urodela, 14; of Anura, 24, 25, 138 f.; arciferous, 24, 25, 138; firmisternal, 24, 25, 138; of Aglossa, 144; of Microsauri, 289; of Protorosauri, 290; of Theromorpha, 302; of Pareiasauri, 305; of Dicynodon, 310; of Chelonia, 318, 319, 320; of Dinosauria, 414; of Eusuchia, 440; of Plesiosauria, 474; of Cryptoclidus, 475; of Ichthyosauria, 480, 481; of Pterosauria, 485; of Pteranodon, 487; of Pythonomorpha, 488; of Lacertilia, 496 Shufeldt, on Axolotl, 114; on Heloderma, 540 n. Simosaurus, 477 Siphonops, 86, 87, 90 Siredon (Axolotl), 112 Siren, 96; S. lacertina, 136, 136 Sirenidae, 94, 96, 136 Sistrurus miliarius, 647 Skeleton, figured, of Testudo, 319; of Chelone, 320; of Brontosaurus, 418; of Ceratosaurus, 422; of Stegosaurus, 426; of Iguanodon, 428; of Triceratops, 430; of Pterodactylus, 485 Skin, of larval Amphibia, 31; shedding of, 32; glands, 32; pigment, 34; change of colour, 35; poison, 36; of Apoda, 87; of Pipa, 149; forms receptacles for eggs, 151, 248; of Eusuchia, 441 f. Skin-glands, of Crocodiles, 443; of Lacertilia, 497; of Geckones, 504; of Snakes, 583 Skull, of Urodela, 16 f., 17; of Amblystoma, 17; of Salamandrina, 17; of Salamandra, 17; of Anura, 28 f.; of Apoda, 84, 85 Skull, of Reptilia, 280, 281: –of Proreptilia: Cricotus, 287; Eryops, 286: –of Microsauri, 289: –of Protorosauri, 280; Palaeohatteria, 280, 291: –of Rhynchocephali (Sphenodon), 280, 295, 295: –of Theromorpha, 280, 301, 303; Elginia, 280, 305 f.; Cynognathus, 280, 306; Gordonia, 280, 310; Dicynodon, 280, 310; Theriodontia, 306; Mammalian resemblances, 308 f.; Lycosaurus 307; Endothiodon, 307; Gomphognathus, 308; Anomodontia, 309, 280; Oudenodon, 310; Placodus, 311: –of Mammalia, generalised, 281: –of Chelonia, 316 f., 280; Sphargis, 335; Chelydridae, 280, 338; Chelydra, 280, 338; Chelonidae, 317, 378, 379; Chelone, 317, 378; Thalassochelys, 379; Clemmys, 356; Testudo, 364; Chelys, 400, 344; Trionyx, 405, 404; Chrysemys, 280, 346; Cistudo, 280, 361; Pleurodira, 388, 400; Pelomedusidae, 390; Chelydidae, 399, 400; Trionychoidea, 404, 405: –of Dinosauria, 412 f., 422; Anchisaurus, 421; Ceratosaurus, 422; Diplodocus, 419: –of Crocodilia, 280; Pseudosuchia, 432; Parasuchia, 433; Eusuchia, 434 f.; Gavialis, 452; Crocodilus americanus, 466; C. niloticus, 460; C. palustris, 455; C. porosus, 458; Alligator, 468: –of Plesiosauria, 473; Nothosaurus, 477: –of Ichthyosauria, 479; Ichthyosaurus, 281: –of Pterosauria, 484; Dimorphodon, 281: –of Pythonomorpha, 488; Clidastes, 281: –of Lacertilia, 281; Geckones, 504; Agamidae, 281, 515; Uromastix, 281; Iguanidae, 528; Anguidae, 537; Helodermatidae, 540; Varanidae, 281, 542, 543; Varanus, 281; Tejidae, 547; Lacertidae, 281, 550, 550; Lacerta, 281; Scincidae, 559; Amphisbaenidae, 565; Chamaeleontes, 568, 569: –of Ophidia, 281, 596, 597, 588; Eunectes, 596, 597; Crotalus, 588 Slow-worm, 539, 539 Slugs eaten by tortoises, 363 Smell, sense of, of Chelonia, 330 Smith, the, = Hyla faber, peculiar nursing habits, 196 f. Smooth Snake, 619, 620 Snakes, 581 f.; skull, 581 f., 281, 588, 596, 597 f.; vertebrae, 582; general anatomical structure, 583 f.; geographical distribution, 585 f., 585; classification, 592 f. Snake-charming, 631 Snake-poison, 586 f. Snake-stones, 629 f. Snapping Turtle, 338 f. Soft-shelled Turtle, 408 Sound produced by rubbing of scales of Teratoscincus, 507 Spade-foot, 162 Spelerpes, 94, 96, 97, 103, 104, 106; S. altamazonicus, 104; S. bilineatus, 104; S. fuscus, 104, 105; tongue, 106; S. infuscatus, 104; S. lineolus, 104; S. parvipes, 104; {666} S. porphyriticus, 105; S. salmoneus, 105; S. subpalmatus, 104; S. uniformis, 104 Spencer, on habits of Chiroleptes, 221 f. Spermatophores, 53, 128 Spermatozoa of Amphibia, 52 f. Sphargidae, 313, 314, 333 f.; affinities, 336; morphology of shell, 337 Sphargis coriacea, 333 f., 334; absence of horny shields, 325 Sphenodon, 288, 290, 305, 306, 432; S. punctatum, 293, 294; skull, 295; cervical vertebrae, 297; habits, 298 f. Sphenophryne, 225, 227 Sphenosaurus, 82, 287 Spiny-tailed Lizard, 524 f. Spiracle, development, 45 Spotted Newt, 127 Spy-Slange, 632 St. Helena, gigantic tortoises introduced, 375 Stagonolepis, 434 Stannius, 8, 139; on vertebrae of Pelobates, 20 Staurotypus salvini, 342 Stegocephali, 78 f.; St. Lepospondyli, 80 f.; St. Temnospondyli, 81 f.; St. Stereospondyli, 83 f.; vertebrae, 78 f.; shoulder-girdle, 79; dermal armour, 79 Stegosauri, 425 Stegosaurus armatus, 425; S. ungulatus, 426, 426 Stenodactylus, deserticolous, 494; sleeping attitude, 509 Stereocyclops, 227, 231; S. incrassatus, 231 Stereorhachis, 308 Stereospondylous vertebrae, defined, 284 Sternothaerus, 324, 389, 390; S. derbianus, 391; shields of, 327 Sternum, of Urodela, 15; of Anura, 25; taxonomic value, 141, 142; of Sphenodon, 297 f.; Protorosauri, 290; Dinosauria, 414; Eusuchia, 440 Stewart, quoted, on Heloderma, 540 n. Stinkpot Terrapin, 342 Suboccipital (first spinal nerve) of Anura, 144 Subregions, geographical, 74 f. Surinam Toad, 149, 150 Syrrhopus, 212 Systomata, 139

Tadpoles, horny teeth of, 58 f.; of Megalophrys, 59, 60; absorption of tail, 61 f.; of Xenopus, 147, 148; of Bombinator, 157; of Alytes, 159; of Hyla arborea, 193; of H. versicolor, 195; of Bufo viridis, 181; of B. calamita, 183; of B. vulgaris, 176; of Thoropa miliaris, 209; of Pseudis paradoxa, 213; of Hylodes martinicensis, 214; of Rhinoderma darwini, 229; of Arthroleptis seychellensis, 243; of Rana temporaria, 255; of R. opisthodon, 260; of R. esculenta, 270 Tail, of Anura, 21, 24; its absorption, 61; of Chelonia, 328; of Geckos, various shapes, 506; reproduction of, 506 Tarentola mauritanica, 508, 509 f. Tarsus (see also Limbs), of Chelonia, 319, 320, 321; of Dinosauria, 416, 418, 420, 421, 423, 426; of Theropoda, 420; of Compsognathus, 423; of Iguanodon, 428 Teeth, of Anura, 30, 138, 139; substitutes for, 30, 58, 218, 237; of Apoda, 86; of Rhynchosaurus, 292; of Homoeosaurus, 292; of Rhynchocephali, 292; of Sphenodon, 296; of Theromorpha, 301; of Elginia, 306, 280; of Cynognathus, 306, 280; of Lycosaurus, 307; of Galesaurus, 307; of Endothiodon, 307; of Empedias, 308; of Stereorhachis, 308; of Gomphognathus, 308; of Tritylodon, 309; Mammalian resemblances, 309; of Anomodontia, 309; of Dicynodon, 280, 310; of Gordonia, 280; of Placodus, 311; of Sauropoda, 418 f., 419; of Theropoda, 420 f., 422; of Orthopoda, 424 f.; of Eusuchia, 437; of Ichthyosauri, 479; of Snakes, 582 Tejidae, 514, 547 f. Teju, 548, 548 Teleosauridae, 450 Teleosaurus, 451 Telerpeton elginense, 291 Temnospondylous vertebrae, defined, 284 Temperature of blood, 67 f.; of water for Crocodiles, 460 Tennent, on immunity of Cobras, 629 f.; on turtles at Ceylon, 384, 386; on habits of Crocodilus palustris, 456 f.; on habits of C. porosus, 459; on peculiar use of Varanus, 545; on habits of Gecko, 511 Tentacular apparatus of Apoda, 45, 86, 88 Tephrometopon, 493 Teratoscincus, deserticolous, 493; eye, 494; T. scincus, 507 Terrapin, 359 f. Testis, 49 Testudinidae, 313, 314, 345; distribution, 332 Testudo, 365; skeleton, 322, 323; shields of, 327; T. abingdoni, 376, 378; T. atlas, 372, 377; T. daudini, 375, 376; T. elegans, 370 f.; T. elephantina, 374; T. elephantopus, 378; T. ephippium, 378; T. gigantea, 374; T. graeca, 365 f.; habits, 367; eggs, 369; great age, 369; T. grandidieri, 373; T. horsfieldi, 370; T. ibera, 366; age attained, 369; rate of growth, 370; T. marginata, 367; T. perpigniana, 372; T. polyphemus, 371 f.; {667} T. sumeirei, 376; T. vosmaeri, 373, 377 Tetradactylus, 559; T. africanus, 559; T. seps, 559 Tetrapoda, Credner's name for "four-footed" creatures in opposition to the fishes, which have fins, 4, 11 Thalassemydidae, 380 Thalassochelys caretta, individual variation of shields, 326, 327, 387; skull, 379 Thecophora, definition of term, 337, 338 Theobald, on Varanus, 544 Theriodontia, 306 Theromorpha, 300, 301; skull, 280, 301; their affinity to Mammals, 303 f., 309 Theropoda, 420 Thilenius, quoted, 571 n. Thoracosaurus, 451 Thorius, 96, 103; Th. pennatulus, 103 Thoropa, 186, 189; Th. miliaris, 209 Tiger Snake, 634 Tiliqua s. Cyclodus, 561 Toad, see Bufo, 169; common Toad, 170, 172 Toes, number of, in Urodela, 16; in Anura, 28; of Geckos, structure, 505, 505 Tomistoma, 435, 450; T. schlegeli, 453 Tongue, of Amphibia, nerve-supply, 39; shape of, in Anura, 47; of Spelerpes, 106; absent in Aglossa, 145; of Rana esculenta, 268; of Crocodiles, 443; of Lacertilia, 498; of Chameleons, 569 f. Tortoise, Greek, 365 f.; habits, 367 f.; Moroccan, 366; habits, 367 f.; Starred, 370 f.; Gopher, 371 f.; Gigantic Land-Tortoises, 372 f. Tortoises = Chelonia, 312 f. Tortoise-shell of commerce, 386 Trachea, of Crocodiles, 443 Trachysaurus, 560, 560; T. rugosus, 560, 561 Tree-frogs, 185 f.; change of colour, 35 Trematosaurus, 80, 83 Triceratops, 413; T. prorsus, 430, 430; T. flabellatus, 430 Trichobatrachus, 240; T. robustus, 271 Trigonocephalus cenchris, 645, 645, 646, 646 Trimerorhachis, 82 Trionychidae, 313; distribution, 333 Trionychoidea, 313, 314, 404 f.; habits, 407 Trionyx, nuchal plate, 324; skull, 405; plastron, 406; number of costal plates, 325; T. ferox, 408, 409; T. formosa, 411, 411; T. gangeticus, 410, 410; T. hurum, 410; T. triunguis, 410 Triprion, 179, 185, 189; T. petasatus, 207 Trirhachiodon, 309 Triton, 122 f., 96, 115, 125, 128, 131; fossil, 83; spermatophores, 53; T. alpestris, 123, 126; T. asper, 123, 130; T. blasii, 126; T. boscai, 123, 127; T. cristatus, 122, 125, 125; T. hagenmuelleri, 123; T. helveticus, 127; T. italicus, 127; T. marmoratus, 122, 126; T. montadoni, 127; T. montanus, 123, 130; T. palmatus, 127; T. poireti, 123; T. punctatus = vulgaris, 127; T. pyrenaeus, 130; T. pyrrhogaster, 123, 128; T. rusconii, 123, 130; T. sinensis, 123, 128; T. taeniatus = vulgaris, 127; T. torosus, 123, 128; T. viridescens, 123, 128; egg, 128; T. vittatus, 122, 128; T. vulgaris, 123, 127; T. waltli, 123, 130, 131 Tritylodon, 301, 309 Tropidonotus, 607; T. natrix, 608 f.; T. ordinatus, 611; T. sirtalis, 610, 611; T. tesselatus, 611 Tropidosaura, 558 Tuatera, 293 Tupinambis, 548; T. teguixin, 548; T. nigropunctatus, 548, 548 Turtles, 378 f.; skull, 317, 379; skeleton, 320; plastron, 321; on Laysan Islands, 383; Green or Edible, 381 f.; Hawksbill, 384, 385 Tylototriton, 96, 115; T. andersoni, 130; T. verrucosus, 132 Tympanic cavity, reduction of, in Anura, 30; in Ophidia, 583 Tympanum of Aglossa, 143 Typhlomolge, 96; T. rathbuni, 135 Typhlonectes, 87, 90; T. compressicauda, 93 Typhlopidae, 592, 593 f. Typhlops, 91; T. braminus, 594; T. vermicularis, 594 Typhlosaurus, 564 Typhlotriton, 94, 96, 102; T. spelaeus, 103

Uraeotyphlus, 86, 89 Ureter, 48 f., 49 Urino-genital organs, 48 f., 49 Urocordylus, 81, 288 Urodaeum of Chelonia, 330 Urodela, 94 f.; geographical distribution, 96 Uromastix, 524; U. acanthinurus, 526, 526; U. hardwicki, 525 Uropeltidae, 592, 595 Uropeltis, 595; U. grandis, 595 Uroplates, 512 Uroplatinae, 512 Urostyle, of Anura, 23; of Chelonia, 328

Varanidae, 514, 542 f.; skull, 542; distribution, 543 Varanus, 543; V. gouldi, 546; V. griseus, skull, 542; V. niloticus, 543; V. salvator, 543 f., 546 Vas deferens, 48 f., 49 Vertebrae, procoelous, definition, 19, 138; acentrous, i.e. without a centre or body, 4; {668} amphicoelous, defined, 12; of Urodela, 11; gastrocentrous, defined, 282; lepospondylous, 5; defined, 78; notocentrous, 4; defined, 19; opisthocoelous, defined, 12, 138; pseudocentrous, 4, 78; stereospondylous, defined, 79, 284; temnospondylous, 13; defined, 79, 284; development of–in Urodela, 12, 13; in Anura, 19; of trunk of Salamandra, 14; epichordal, 20; sacral, of Anura, 22; shifting forwards of sacral attachment of ilium, 23; of Reptilia, composition of, 283, 288; trunk-vertebrae of Eryops, 283, 286, 286; of Cricotus, 287; of Microsauri, 289; of Sphenodon, 294, 296, 297; atlas and axis of Sphenodon, 283; of Theromorpha, 302; of Pareiasauri, 305; atlas fused with axis in Cynognathus, 307; of Dimetrodon, with peculiar processes, 308; of Chelonia, 314 f.; atlas of Trionyx, 283; of Chelys, 283; of Dinosauria, 413; hollow in Dinosaurs, 415, 420; of Eusuchia, 438 f.; atlas and axis of Crocodilus, 283; of Metriorhynchus, 283; of Pterosauria, 485; of Ichthyosauria, 480; of Pythonomorpha, 488; of Lacertilia, 494; of Geckones, 503; of Snakes, 582 Vertebral column, instance of greatest shortening, 144; of Urodela, 11, 13; of Stegocephali, 78; of Anura, 18 f., 21, 22; Palaeobatrachus, 22; Pipa, 22, 143; Hymenochirus, 22, 143; Bombinator, 22; Xenopus, 21, 143; of Apoda, 86; number of vertebrae of Protorosaurus, 291; of Palaeohatteria, 291; of Homoeosaurus, 292; of Sphenodon, 297; of Cynognathus, 306; of Iguanodon, 428; of Eusuchia, 440; of Plesiosauria, 474; of Elasmosauridae, 478 Vesiculae seminales, 49, 51 Viper, Common, 641 f., 620, 642 Vipera, 641; V. ammodytes, 641, 643; V. aspis, 643; V. berus, 641, 642, 620; V. latastei, 643; V. russelli, 643 Viperidae, 592, 593, 637 Viperinae, 638 Viperine Snake, 610 Vis, de, on Chlamydosaurus, 523 Viviparous, Chameleon, 572; Lacertilia, 499; Geckos, 506 Vocal sacs, 47 f.; of Paludicola, 220; of Rhinoderma, used as brood-pouches, 228 Voeltzkow, on nesting of Crocodiles, 462 f.; on Testudo daudini, 375 Voice, 47

Wagler, 8 Wallace, on Rhacophorus, 246 f. Wall-Lizard, 557 Warning, attitudes, of Bombinator, 157; colours, 38, 116, 156; of Heloderma, 541 Water-Viper, 645, 645 Weismann, on Axolotl, 64, 114 Werner, on Eryx, 604 White's aged Tortoise, 369 Wilder, on Desmognathus, 103

Xantusia, 547 Xantusiidae, 514, 547 Xenobatrachus, 225; X. ophiodon, 228 Xenopeltidae, 593, 605 Xenopeltis unicolor, 605 Xenopus, 143; distribution, 143, 144, 146 f.; X. calcaratus, 146; X. laevis, 146 f., 147; X. muelleri, 146 Xenorhina, 228 Xenosauridae, 513, 536 Xenosaurus grandis, 536

Zachaenus, 212 Zamenis constrictor, 613; Z. gemonensis s. viridiflavus, 612; Z. hippocrepis, 613; Z. mucosus, 611, 612 Zanclodon, 417, 421 Zander, on habits of Agama, 520; of Phrynocephalus, 522; of Eryx, 604 Zaocys carinatus, 614, 615 Zatachys, 82 Zeller, on spermatophores, 53; on Proteus, 134 Zonuridae, 513, 536 Zonurus derbianus s. giganteus, 536, 537

END OF VOL. VIII

Printed by R. & R. CLARK, LIMITED, Edinburgh.

THE CAMBRIDGE NATURAL HISTORY

EDITED BY

S. F. HARMER, Sc.D., F.R.S. and A. E. SHIPLEY, M.A., F.R.S.

In Ten Volumes. Fully Illustrated. Medium 8vo. 17s. net each.

PROTOZOA, COELENTERATES, ECHINODERMS, etc.