Part 32

The Scaphites have a singular boat-shaped form, wound with contiguous whorls in one part, which is detached at the last chamber, and projects in a more or less elongated condition.

Hamites, Crioceras, and Ancyloceras have club-like terminations at both extremities; they may almost be considered as non-involuted Ammonites with the spiral evolutions disconnected or partially unrolled, as in the engraving (Figs. 125 and 132). Ancyloceras Matheronianus seems to have had spines projecting from the ridge of each of the convolutions.

(Living form.)]

(Chalk.)]

The Toxoceras had the shell also curved, and not spiral.

The Baculites had the shell differing from all Cephalopods, inasmuch as it was elongated, conical, perfectly straight, sometimes very slender, and tapering to a point.

The Turrilites have the shell regular, spiral, and sinistral; that is, turning to the left in an oblique spiral of contiguous whorls. The engraving will convey the idea of their form (Fig. 134).

Among others, as examples of form, we append Figs. 133, 135, 136.

This analysis of the marine fauna belonging to the Néocomian formation might be carried much further, did space permit, or did it promise to be useful; but, without illustration, any further merely verbal description would be almost valueless.

a, back view; b, side view.]

Numerous Reptiles, a few Birds, among which are some “Waders,” belong to the genera of Palæornis or Cimoliornis; new Molluscs in considerable quantities, and some extremely varied Zoophytes, constitute the rich fauna of the Lower Chalk. A glance at the more important of these animals, which we only know in a few mutilated fragments, is all our space allows; they are true medals of the history of our globe, medals, it is true, half effaced by time, but which consecrate the memory of departed ages.

In the year 1832 Dr. Mantell added to the wonderful discoveries he had made in the Weald of Sussex, that of the great Lizard-of-the-woods, the hylæosaurus (ὑλη, wood, σαυρος, lizard). This discovery was made in Tilgate forest, near Cuckfield, and the animal appears to have been from twenty to thirty feet in length. The osteological characters presented by the remains of the Hylæosaurus are described by Dr. Mantell as affording another example of the blending of the Crocodilian with the Lacertian type of structure; for we have, in the pectoral arch, the scapula or omoplate of a crocodile associated with the coracoid of a lizard. Another remarkable feature in these fossils is the presence of the large angular bones or spines, which, there is reason to infer, constituted a serrated crest along the middle of the back; and the numerous small oval dermal bones which appear to have been arranged in longitudinal series along each side of the dorsal fringe.

The Megalosaurus, the earliest appearance of which is among the more ancient beds of the Liassic and Oolitic series, is again found at the base of the Cretaceous rocks. It was, as we have seen, an enormous lizard, borne upon slightly raised feet; its length exceeded forty feet, and in bulk it was equal to an elephant seven feet high.

The Megalosaurus found in the ferruginous sands of Cuckfield, in Sussex, in the upper beds of the Hastings Sands, must have been at least sixty or seventy feet long. Cuvier considered that it partook both of the structure of the Iguana and the Monitors, the latter of which belong to the Lacertian Reptiles which haunt the banks of the Nile and tropical India. The Megalosaurus was probably an amphibious Saurian. The complicated structure and marvellous arrangement of the teeth prove that it was essentially carnivorous. It fed probably on other Reptiles of moderate size, such as the Crocodiles and Turtles which are found in a fossil state in the same beds. The jaw represented in Fig. 137 is the most important fragment of the animal we possess. It is the lower jaw, and supports many teeth: it shows that the head terminated in a straight muzzle, thin and flat on the sides, like that of the Gavial, the Crocodile of India. The teeth of the Megalosaurus were in perfect accord with the destructive functions with which this formidable creature was endowed. They partake at once of the nature of a knife, sabre, and saw. Vertical at their junction with the jaw, they assume, with the increased age of the animal, a backward curve, giving them the form of a gardener’s pruning-knife (Fig. 138; also c. Fig. 179). After mentioning some other particulars, respecting the teeth, Buckland says: “With teeth constructed so as to cut with the whole of their concave edge, each movement of the jaws produced the combined effect of a knife and a saw, at the same time that the point made a first incision like that made by a point of a double-cutting sword. The backward curvature taken by the teeth at their full growth renders the escape of the prey when once seized impossible. We find here, then, the same arrangements which enable mankind to put in operation many of the instruments which they employ.”

Two-thirds natural size.]

(Upper Greensand.)]

The Iguanodon, signifying Iguana-toothed (from the Greek word, οδους, tooth), was more gigantic still than the Megalosaurus; one of the most colossal, indeed, of all the Saurians of the ancient world which research has yet exposed to the light of day. Professor Owen and Dr. Mantell were not agreed as to the form of the tail; the former gentleman assigning it a short tail, which would affect Dr. Mantell’s estimate of its probable length of fifty or sixty feet; the largest thigh-bone yet found measures four feet eight inches in length. The form and disposition of the feet, added to the existence of a bony horn (Fig. 139), on the upper part of the muzzle or snout, almost identifies it as a species with the existing Iguanas, the only Reptile which is known to be provided with such a horn upon the nose; there is, therefore, no doubt as to the resemblance between these two animals; but while the largest of living Iguanas scarcely exceeds a yard in length, its fossil congener was probably fifteen or sixteen times that length. It is difficult to resist the feeling of astonishment, not to say incredulity, which creeps over one while contemplating so striking a disproportion as that which subsists between this being of the ancient world and its ally of the new.

a, young tooth; b, c, teeth further advanced, and worn.

(Wealden.)]

The Iguanodon carried, as we have said, a horn on its muzzle; the bone of its thigh, as we have seen, surpassed that of the Elephant in size; the form of the bone and feet demonstrates that it was formed for terrestrial locomotion; and its dental system shows that it was herbivorous.

1, Beryx Lewesiensis; 2, Osmeroides Mantelli.]

The teeth (Fig. 141), which are the most important and characteristic organs of the whole animal, are imbedded laterally in grooves, or sockets, in the dentary bone; there are three or four sockets of successional teeth on the inner side of the base of the old teeth. The place thus occupied by the edges of the teeth, their trenchant and saw-like form, their mode of curvature, the points where they become broader or narrower which turn them into a species of nippers or scissors--are all suitable for cutting and tearing the tough vegetable substances which are also found among the remains buried with this colossal reptile, a restoration of which is represented in PLATE XXI., p. 296.

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The Cretaceous seas contained great numbers of Fishes, among which some were remarkable for their strange forms. The Beryx Lewesiensis (1), and the Osmeroides Mantelli (2) (Fig. 142), are restorations of these two species as they are supposed to have been in life. The Odontaspis is a new genus of Fishes which may be mentioned. Ammonites rostratus (Fig. 140), and Exogyra conica (Fig. 147), are common shells in the Upper Greensand.

The seas of the Lower Cretaceous period were remarkable in a zoological point of view for the great number of species and the multiplicity of generic forms of molluscous Cephalopods. The Ammonites assume quite gigantic dimensions; and we find among them new species distinguished by their furrowed transverse spaces, as in the Hamites (Fig. 132). Some of the Ancyloceras attained the magnitude of six feet, and other genera, as the Scaphites, the Toxoceras, the Crioceras (Fig. 125), and other Mollusca, unknown till this period, appeared now. Many Echinoderms, or sea-urchins, and Zoophytes, have enriched these rocks with their animal remains, and would give its seas a condition quite peculiar.

On the opposite page an ideal landscape of the period is represented (PLATE XXI.), in which the Iguanodon and Megalosaurus struggle for the mastery in the centre of a forest, which enables us also to convey some idea of the vegetation of the period. Here we note a vegetation at once exotic and temperate--a flora like that of the tropics, and also resembling our own. On the left we observe a group of trees, which resemble the dicotyledonous plants of our forests. The elegant Credneria is there, whose botanical place is still doubtful, for its fruit has not been found, although it is believed to have belonged to plants with two seed-leaves, or dicotyledonous, and the arborescent Amentaceæ. An entire group of trees, composed of Ferns and Zamites, are in the background; in the extreme distance are some Palms. We also recognise in the picture the alder, the wych-elm, the maple, and the walnut-tree, or at least species analogous to these.

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The Néocomian beds in France are found in Champagne, in the departments of the Aube, the Yonne, the Haute-Alps, &c. They are largely developed in Switzerland at Neufchatel, and in Germany.