CHAPTER XXI. Pycnogonida[393]

PYCNOGONIDA

Remote, so far as we at present see, from all other Arthropods, while yet manifesting the most patent features of the Arthropod type, the Pycnogons constitute a little group, easily recognised and characterised, abundant and omnipresent in the sea. The student of the foreshore finds few species and seldom many individuals, but the dredger in deep waters meets at times with prodigious numbers, lending a character to the fauna over great areas.

FIG. 262.—Pycnogonum littorale, Ström, × 2. ]

The commonest of our native species, or that at least which we find the oftenest, is Pycnogonum littorale (Phalangium littorale, Ström, 1762). We find it under stones near low water, or often clinging louse-like to a large Anemone. The squat segmented trunk carries, on four pairs of strong lateral processes, as many legs, long, robust, eight-jointed, furnished each with a sharp terminal claw. In front the trunk bears a long, stout, tubular proboscis, at the apex of which is the mouth, suctorial, devoid of jaws; the body terminates in a narrow, limbless, unsegmented process, the so-called “abdomen,” at the end of which is the anal orifice. The body-ring to which is attached the first pair of legs, bears a tubercle carrying four eye-spots; and below, it carries, in the male sex, a pair of small limbs, whose function is to grasp and hold the eggs, of which the male animal assumes the burden, carrying them beneath his body in a flattened coherent mass. In either sex a pair of sexual apertures open on the second joints of the last pair of legs. The integument of body and limbs is very strongly chitinised, brown in colour, and raised into strong bosses or tubercles along the middle line of the back, over the lateral processes, and from joint to joint of the limbs. The whole animal has a singular likeness to the Whale-louse, Cyamus mysticeti (well described by Fr. Martins in 1675), that clings to the skin of the Greenland Whale as does Pycnogonum to the Anemone, a resemblance close enough to mislead some of the older naturalists, and so close that Linnaeus, though in no way misled thereby, named it Phalangium balaenarum. The substance of the above account, and the perplexity attending the classification of the animal, are all included in Linnaeus’s short description: “Simillimus Onisco Ceti, sed pedes omnes pluribus articulis, omnes perfecti, nec plures quam octo. Dorsum rubrum, pluribus segmentis; singulis tribus mucronibus. Cauda cylindrica, brevissima, truncata. Rostrum membranaceum, subsubulatum, longitudine pedum. Genus dubium, facie Onisci ceti; rostro a reliquis diversum. Cum solo rostro absque maxillis sit forte aptius Acaris aut proprio generi subjiciendum.... Habitat in mari norvegico sub lapidibus.”

FIG. 263.—Dorsal view of Nymphon brevirostre, Hodge, × 6. Britain. ]

The common Pycnogonum is, by reason of the suppression of certain limbs, rather an outlying member than a typical representative of the Order, whose common characters are more strikingly and more perfectly shown in species, for instance, of Nymphon. Of this multiform genus we have many British species, some of the smaller being common below tide-marks, creeping among weeds or clinging like Caprellae with skeleton limbs to the branches of Zoophytes, where their slender forms are not easily seen. In contrast to the stouter body and limbs of Pycnogonum, the whole fabric of Nymphon tends to elongation; the body is drawn out so that the successive lateral processes stand far apart, and a slender neck intervenes between the oculiferous tubercle and the proboscis; the legs are produced to an amazing length and an extreme degree of attenuation: “mirum tam parvum corpus regere tam magnos pedes,” says Linnaeus. Above the base of the proboscis are a pair of three-jointed appendages, the two terminal joints of which compose a forcipate claw; below and behind these come a pair of delicate, palp-like limbs of five joints; and lastly, on the ventral side, some little way behind these, we find the ovigerous legs that we have already seen in the male Pycnogonum, but which are present in both sexes in the case of Nymphon. At the base of the claw which terminates each of the eight long ambulatory legs stands a pair of smaller accessory or “auxiliary” claws. The generative orifices are on the second joint of the legs as in Pycnogonum, but as a rule they are present on all the eight legs in the female sex, and on the two hindmost pairs in the male. One of the Antarctic Nymphonidae (Pentanymphon) and one other Antarctic genus less closely related (Decolopoda) have an extra pair of legs. No other Pycnogon, save these, exhibits a greater number of appendages than Nymphon nor a less number than Pycnogonum, nor are any other conspicuous organs to be discovered in other genera that are not represented in these two: within so narrow limits lie the varying characters of the group.

FIG. 264.—Nymphon brevirostre, Hodge. Head, from below, showing chelophores, palps, and ovigerous leg. ]

In framing a terminology for the parts and members of the body, we encounter an initial difficulty due to the ease with which terms seem applicable, that are used of more or less analogous parts in the Insect or the Crustacean, without warrant of homology. Thus the first two pairs of appendages in Nymphon have been commonly called, since Latreille’s time, the mandibles and the palps (Linnaeus had called them the palps and the antennae), though the comparison that Latreille intended to denote is long abandoned; or, by those who leaned, with Kröyer and Milne-Edwards, to the Crustacean analogy, mandibles and maxillae. Dohrn eludes the difficulty by denominating the appendages by simple numbers, I., II., III., ... VII., and this method has its own advantages; but it is better to frame, as Sars has done, a new nomenclature. With him we shall speak of the Pycnogon’s body as constituted of a trunk, whose first (composite) segment is the cephalic segment or head, better perhaps the cephalothorax, and which terminates in a caudal segment or abdomen; the “head” bears the proboscis, the first appendages or “chelophores,” the second or “palps,” the third, the false or “ovigerous” legs, and the first of the four pairs of “ambulatory” legs. The chelophores bear their chela, or “hand,” on a stalk or scape; the ambulatory legs are constituted of three coxal joints, a femur, two tibial joints, a tarsus, and a propodus, with its claws, and with or without auxiliary claws.

=The Body.=—The trunk with its lateral processes may be still more compact than in Pycnogonum, still more attenuated than in Nymphon.

In a few forms (e.g. Pallene, Ammothea, Tanystylum, Colossendeis) the last two, or even more, segments of the trunk are more or less coalescent. In Rhynchothorax the cephalic segment is produced into a sharp-pointed rostrum that juts forward over the base of the proboscis. The whole body and limbs may be smooth, tuberculated, furnished with scattered hairs, or sometimes densely hispid.

FIG. 265.—=A=, Colossendeis proboscidea, Sabine, Britain; =B=, Ammothea echinata, Hodge, Britain; =C=, Phoxichilus spinosus, Mont., Arctic Ocean. (The legs omitted.) ]

The proboscis varies much in shape and size. It may be much longer or much shorter than the body, cylindrical or tumid, blunt or pointed, straight or (e.g. Decolopoda) decurved; usually firmly affixed to the head and pointing straight forwards; sometimes (Eurycide, Ascorhynchus) articulated on a mobile stalk and borne deflexed beneath the body.

=Chelophores.=—The first pair of appendages or chelophores are wanting in the adult Pycnogonum, Phoxichilus, Rhynchothorax, and Colossendeis.

In Ammothea and its allies they are extremely rudimentary in the adult, being reduced to tiny knobs in Tanystylum and Trygaeus, and present as small two-jointed appendages in Ammothea; in this last, if not in the others also, they are present in complete chelate form in the later larval stages.

FIG. 266.—=A=, =B=, Chelophores of Ascorhynchus abyssi, G.O.S. A, Young; B, adult. (After Sars.) =C=, Anterior portion of Ammothea hispida, Hodge, Jersey: late larval stage (= Achelia longipes, Hodge), showing complete chelae. =D=, Chela of Eurycide hispida, Kr. ]

In Eurycide, Ascorhynchus, and Barana they are usually less atrophied, but yet comparatively small and with imperfect chelae, while in some Ascorhynchi (A. minutus, Hoek) they are reduced to stumps.

FIG. 267.—Chelae of species of Nymphonidae: =A=, Nymphon brevirostre, Hodge; =B=, Boreonymphon robustum, Bell; =C=, Chaetonymphon macronyx, G.O.S.; =D=, Nymphon elegans, Hansen. ]

FIG. 268.—Proboscis and chelophores of Cordylochele longicollis, G.O.S. (After Sars.) ]

In Pallenopsis the scape of the chelophore consists of two joints, as also in Decolopoda and some Ascorhynchus: in Nymphon, Phoxichilidium, Pallene, and Cordylochele of one only; in all these the terminal portion or “hand” forms a forcipate “chela,” of which the ultimate joint forms the “movable finger.” In some species of Nymphon the chela is greatly produced and attenuated, and armed with formidable serrate teeth on its opposing edges; in others it is shortened, with blunter teeth; in Boreonymphon robustum the claws are greatly curved, with a wide gap between. In this last, and in Phoxichilidium, the opposing edges are smooth and toothless. In Cordylochele the hand is almost globular, the movable finger being shortened down, and half enclosed by the other.

FIG. 269.—Eurycide hispida, Kr., showing stalked proboscis and zigzag palps. ]

=Palpi.=—The second pair of appendages, or palps, are absent, or all but absent, in the adult Pycnogonum, Phoxichilus, Phoxichilidium, Pallene, and their allies. In certain of these cases, e.g. Phoxichilidium, a knob remains to mark their place; in others, e.g. Pallenopsis, a single joint remains; in a few Pallenidae a sexual difference is manifested, reduction of the appendage being carried further in the female than in the male. The composition of the palps varies in the genera that possess them. In Nymphon there are five joints, and their relative lengths (especially of the terminal ones) are much used by Sars in defining the many species of the genus. The recently described Paranymphon, Caullery, has palps of six or seven joints. In the Ammotheidae the number of joints ranges from five or six in Tanystylum to nine (as a rule) in Ammothea and Oorhynchus, or ten, according to Dohrn, in certain species of Ammothea. Colossendeis and the Eurycididae have a ten-jointed palp, which in this last family is very long and bent in zigzag fashion, as it is, by the way, also in Ammothea. The terminal joints of the palp are in all cases more or less setose, and their function is conjecturally tactile.

=Ovigerous Legs.=—Custom sanctions for these organs an inappropriate name, inasmuch as it is only in the males that they perform the function which the name connotes. They probably also take some part, as Hodgson suggests, in the act of feeding.

FIG. 270.—Ovigerous legs of =A=, Phoxichilus spinosus, Mont.; =B=, Phoxichilidium femoratum, Rathke; =C=, Anoplodactylus petiolatus, Kr.; =D=, Colossendeis proboscideus, Sab. ]

FIG. 271.—Terminal joints of ovigerous leg of Rhynchothorax mediterraneus, Costa. ]

FIG. 272.—Nymphon brevirostre, Hodge. Terminal joints of ovigerous leg, with magnified “tooth.” ]

In Pycnogonum, Phoxichilus, Phoxichilidium, and their immediate allies they are absent in the female; in all the rest they are alike present in both sexes, though often somewhat smaller in the female than in the male. They are always turned towards the lower side of the body, and in many cases even their point of origin is wholly ventral. The number of joints varies: in Phoxichilidium five, Anoplodactylus six, Phoxichilus seven; in Paranymphon eight; in Pycnogonum nine, with, in addition, a terminal claw; in the Ammotheidae from seven (Trygaeus) to ten, without a claw; in Pallenidae ten, with or without a claw; in Rhynchothorax, Colossendeis, Eurycide, Ascorhynchus, Nymphon, ten and a claw. The appendage, especially when long, is apt to be wound towards its extremity into a spiral, and its last four joints usually possess a peculiar armature. In Rhynchothorax this takes the form of a stout toothed tubercle on each joint; in Colossendeis of several rows of small imbricated denticles; in Nymphon and Pallene of a single row of curious serrate and pointed spines, each set in a little membranous socket.

FIG. 273.—Nymphon strömii, Kr. Male carrying egg-masses on his ovigerous legs. ]

FIG. 274.—Terminal joints (tarsus and propodus) of legs. =1=, Chaetonymphon hirtum, Fabr.; =2=, N. strömii, Kr.; =3=, Nymphon brevirostre, Hodge; =4=, Ammothea echinata, Hodge; =5=, Ascorhynchus abyssi, G.O.S. (All after Sars.) ]

=Legs.=—The four pairs of ambulatory legs are composed, in all cases without exception, of eight joints if we exclude, or nine if we include, the terminal claw. They vary from a length about equal to that of the body (Pycnogonum, Rhynchothorax, Ammothea) to six or seven times as much, perhaps more, in Nymphon and Colossendeis, the fourth, fifth, and sixth joints being those that suffer the greatest elongation. The seventh joint, or tarsus, is usually short, but in some Nymphonidae is much elongated; the eighth, or propodus, is usually somewhat curved, and usually possesses a special armature of simple or serrate spines. The auxiliary claws, sometimes large, sometimes small, lie at the base of the terminal claw in Ammotheidae, Phoxichilidae, in Phoxichilidium, in most Pallenidae, in nearly all Nymphonidae. Their presence or absence is often used as a generic character, helping to separate, e.g., Pallene from Pseudopallene and Pallenopsis, and Phoxichilidium from Anoplodactylus; nevertheless they may often be detected in a rudimentary state when apparently absent. The legs are smooth or hirsute as the body may happen to be.

FIG. 275.—Legs of =A=, Pallene brevirostris, Johnston; =B=, Anoplodactylus petiolatus, Kr.; =C=, Phoxichilus spinosus, Mont.; =D=, Colossendeis proboscidea, Sabine; =E=, Ammothea echinata, Hodge, ♂. ]

FIG. 276.—Boreonymphon robustum, Bell. Male with young, slightly enlarged. Faeroe Channel. ]

=Glands.=—In some or all of the appendages of the Pycnogonida may be found special glands with varying and sometimes obscure functions. The glands of the chelophores (Fig. 280, p. 522) are present in the larval stages only. They consist of a number of flask-shaped cells lying within the basal joint of the appendage, and generally opening at the extremity of a long, conspicuous, often mobile, spine (e.g. Ammothea (Dohrn), Pallene, Tanystylum (Morgan), Nymphon brevicollum and N. gracile (Hoek)). They secrete a sticky thread, by means of which the larvae attach themselves to one another and to the ovigerous legs of the male parent. In Nymphon hamatum, Hoek, the several filaments secreted by the separate sacculi of the gland issue separately. In Pycnogonum the spine on which the gland opens is itself prolonged into a long fine filament, and here, according to Hoek, the gland is in all probability functionless and rudimentary. Hoek has failed to find the gland in Ascorhynchus, and also in certain Nymphonidae (e.g. Boreonymphon robustum, Bell), in which the young are more than usually advanced at the time of hatching. The gland has also been described by Lendenfeld and others in Phoxichilidium, whose larvae do not cling together but live a parasitic life; in this genus the long spine or tubercle is absent on which the orifice is usually situated, and, according to Lendenfeld, the secretion issues from many small orifices set along the opposing edges of the chela. Of the two species described by Dohrn as Barana castelli and B. arenicola, the former has the spine of inordinate length, more than twice as long as the whole body, chelophore and all; while in the latter (which species rather resembles Ascorhynchus) the spine is altogether absent.

In the palps and ovigerous legs of the adult are found glandular bodies of a hollow vesicular form with a simple lining of cells, the vesicle being divided within by a septum with a central orifice, the outer and smaller half opening to the exterior. These glands are probably of general occurrence, but they have been but little investigated. They lie usually in the fourth and fifth joints of the palp, and the third and fourth joints of the ovigerous leg. Hoek describes them in Discoarachne (Tanystylum) as lying within the elongated third joint of the palp, and opening by a sieve-plate at the end of the second joint. In Ammothea (Dohrn) and Ascorhynchus (Hoek) they open on a small tubercle situated on the fifth joint of the palp. In Nymphon, Hoek describes them as opening by a small pore on the fourth joint of the ovigerous leg. Dohrn failed to find them in Pycnogonum, but in Phoxichilus, Phoxichilidium and Pallene he discovered the glands appertaining to the palps, though the palps themselves have disappeared in those genera; he has found the glands also in Ammothea, in larvae that have not yet attained their full complement of legs.

The males in nearly all cases are known to possess glands in the fourth joints or thighs of all the ambulatory legs, and these glands without doubt act as cement-glands, emitting, like the chelophoral glands of the larvae, a sticky thread or threads by which the eggs and young are anchored to the ovigerous legs. In some species of Nymphon and of Colossendeis Hoek could not find these, and he conjectures them to be conspicuous only in the breeding season. While in most cases these glands open by a single orifice or by a few pores grouped closely together, in Barana, according to Dohrn, and especially in B. arenicola, the pores are distributed over a wide area of the femoral joint. In Discoarachne (Loman) and Trygaeus they open into a wide chitinised sac with tubular orifice. While the function of these last glands and of the larval glands seems plain enough, that of those which occur in the palps and ovigerous legs of both sexes remains doubtful.

In their morphological nature the two groups of glands are likewise in contrast, the former being unicellular glands, such as occur in various parts of the integument of the body and limbs of many Crustacea; while the latter are segmentally arranged and doubtless mesoblastic in origin, like the many other segmental excretory organs (or coelomoducts) of various Arthropods.

By adding colouring matters (acid-fuchsin, etc.) to the water in which the animals were living, Kowalevsky demonstrated the presence of what he believed to be excretory organs in Phoxichilus, Ammothea, and Pallene. These are small groups of cells, lying symmetrically near the posterior borders of the first three body-segments, and also near the bases of the first joints of the legs, dorsal to the alimentary canal.

FIG. 277.—Longitudinal section through one “antimere” of the proboscis in Phoxichilus charybdaeus. G, g′, Principal and secondary ganglia; h, sieve-hairs; L, lip; mt, oral tooth; N, N′, inner and outer nerve-cords; t, proboscis-teeth. (After Dohrn.) ]

=Alimentary System.=—The proboscis is a very complicated organ, and has been elaborately described by Dohrn. It is a prolongation of the oral cavity, containing a highly developed stomodaeum, but showing no sign of being built up of limbs or gnathites. The mouth, situated at its apex, is a three-sided orifice, formed by a dorsal and two lateral lobes; and hence the proboscis has been assumed by some, on no competent evidence, to be constituted of a degenerate pair of appendages and a labrum or upper lip. Each of the three lobes which bounds the mouth shows the following structures: firstly, a lappet of external chitinised integument, overlapping, as the finger-nail overlaps the finger, a cushion-like lip, ridged after the fashion of a fine-cut file in some species, hairy in others, on the inner surface where the three lips meet to close the orifice of the mouth. Below this again is a prominent tooth (Fig. 277, mt), supported, as are the lips, by a system of chitinous rods, which are but little developed in the genus here figured, though conspicuous and complicated in others. Transverse ridges run across the angles where adjacent lips meet, and the whole mechanism constitutes an efficient valve, preventing the escape of swallowed food. The greater portion of the proboscis is occupied by a masticating or triturating apparatus, the oesophageal cavity expanding somewhat and having its walls densely covered, in three bands corresponding to the antimeres, with innumerable minute spines (h) or needles, sometimes supplemented by large teeth (t) that point forwards somewhat obliquely to the axis of the proboscis.

In the curious East Indian genus Pipetta (Loman) the sucking and sifting mechanism is low down in the proboscis, and the organ is prolonged into a very fine tube, the lips growing together till they leave an aperture of only ·007 mm. for the absorption of liquids.

In some cases, where the proboscis itself is short, as in Pallene, this mechanism is carried backwards into the fore-part of the body; and, in the latter genus, the narrow oesophagus which succeeds the masticatory apparatus is likewise provided with extrinsic muscles.

FIG. 278.—Transverse sections through the proboscis of Ph. charybdaeus. =A=, Anterior, through the principal ganglionic mass (G); =B=, posterior, at the level of the sieve-hairs (h). Coec, Intestinal caeca; Dil. M, dilator muscles; N, inner nerve-ganglion, with circular commissure; N′, outer nerve; or, chitinous lining of oral cavity; R M, Ret.M, retractor muscles. (After Dohrn.) ]

FIG. 279.—Transverse section through the basal joint of the third leg in Phoxichilus charybdaeus, ♀. Cut, Cuticle; Hyp, hypodermis; Int, intestinal caecum; N, nerve-cord; Ov, ovary; Sept, septum. (After Dohrn.) ]

The oesophagus is followed by a long gastric cavity, which sends forth caecal diverticula into the chelophores (when these are present), and four immensely long ones into the ambulatory legs. The caeca are attached to the walls of the limb cavities, especially at their extremities in the tarsi, by suspensory threads of connective tissue, and the whole gut, central and diverticular, is further supported by a horizontal septal membrane, running through body and legs, which separates the dorsal blood-vessel and sinus from the gut, the nervous system and the ventral sinus, giving support also to the reproductive glands. A short and simple rectum follows the gastric cavity.

In Phoxichilus, which lacks the three anterior appendages in the female and the two anterior in the male, two pairs of caeca run from the gut into the cavity of the proboscis (Fig. 278, B, coec.).

=Circulatory System.=—The heart has been especially studied by Dohrn in Phoxichilus. It consists of a median vessel running from the level of the eyes to the abdomen, furnished with two pairs of lateral valvular openings, and sometimes, though not always, with an unpaired one at the posterior end. The walls are muscular, but with this peculiarity that the muscular walls do not extend around the heart dorsally, in which region its lumen is only covered by the hypodermis and cuticle of the back. The blood-spaces of the body are separated into dorsal and ventral halves by the septal membrane already referred to, which is perforated in the region of the lateral processes by slits placing the two cavities in communication; this septal membrane runs through the limbs to their tips, and far into the proboscis, where it is attached to the edge of the superior antimere. The blood is a colourless plasma with several kinds of corpuscles, of which the most remarkable are amoeboid, actively mobile, often coalescing into plasmodia. The course of the circulation is on the whole outwards in the inferior or ventral sinus, inwards towards the heart in the superior, save in the proboscis, where the systole of the heart drives the blood forwards in the dorsal channel. The beat is rapid, two or three times in a second, according to Loman, in Phoxichilidium. Especially in the species with small body and exaggerated legs, the movement of the circulatory fluid is actuated more by the movements of the limbs and the contractions of the intestinal caeca than by the direct impulse of the heart.

=Nervous System.=—The nerve-chain consists of a fused pair of supra-oesophageal ganglia, which innervate (at least in the adult) the chelophores, and of ventral ganglia, whence proceed the nerves to the other limbs. The ganglia of the second and third appendages are fused with one another, sometimes also with the ganglia of the first ambulatory legs; the ganglia of the three posterior pairs of legs are always independent (though the development of their longitudinal commissures varies with the body-form), and they are succeeded by one or two pairs of ganglia, much reduced in size, situated in the abdomen, of which the posterior one innervates the muscles of the abdomen and of the anal orifice. Each lateral nerve divides into two main branches, which supply the parts above and below the septal membrane. The nerve-supply of the proboscis is very complicated. Its upper antimere is supplied from the pre-oral, its two lateral antimeres from the first post-oral, ganglion, and each of these three nerves divides into two branches, of which the inner bears six to eight or more small ganglia, which annular commissures passing round the pharynx connect one to another. Of these ganglia and commissures the anterior are the largest, and with these the outer lateral nerve-branches of the proboscis merge. The immediate origin of the nerves to the chelophores is from the median nerve that springs from the under side of the supra-oesophageal ganglion to run forward into the proboscis, but it is noteworthy that the chelophores receive twigs also from the lateral nerves of the proboscis which arise from the post-oral ganglia.

=Eyes.=—Eyes are the only organs of special sense known in the Pycnogons. The deep-water Pycnogons, in general those inhabiting depths below four or five hundred fathoms, have in most cases imperfect organs, destitute of lens and of pigment, so imperfect in many cases as to be described as wanting. It is rare for the eyes to be lacking in shallow-water species, as they are, for instance, in Ascorhynchus minutus, Hoek, dredged by the Challenger in 38 fathoms, but, on the other hand, it is no small minority of deep-water species that possess them of normal character and size, even to depths of about 2000 fathoms.

In all cases where eyes are present, they are simple or “monomeniscous” eyes, four in number, and are situated in two pairs on an “oculiferous tubercle,” sometimes blunt and low, sometimes high and pointed, placed on the so-called cephalothorax, or first, compound, segment of the body. The anterior pair are frequently a little larger, sometimes, as in Phoxichilidium mollissimum, Hoek, very much larger, than the posterior. The minute structure of the eye has been investigated by Dohrn, Grenacher, Hoek, and Morgan. The following account is drawn in the first instance from Morgan’s descriptions.

The eye of a Pycnogon (Phoxichilidium) is composed of three layers, an outer layer of specialised ectoderm cells (hypodermis) that secrete the cuticular lens, a middle layer of visual or retinal elements, and an inner layer of pigment-cells. The elements of the middle layer consist of much elongated cells, whose branching outer ends are connected with nerve-fibrils and interwoven in a protoplasmic syncytium, whose middle parts are occupied by the nuclei and whose inwardly directed ends form the retinal rods or bacilli. The pigment-cells of the inner layer are of various forms, those towards the middle of the eye being small and flattened, those at the sides being, for the most part, long and attenuated, so seeming, as Morgan remarks, to approximate in character to the retinal elements. The pigment-layer is easily dispersed and reveals beneath it a median vertical raphe, caused by the convergence of the cells of the middle layer from either side, and along the line of this raphe the optic nerve joins the eye, though its subsequent course to its connection with the retinal elements is obscure. It is at least clear that the retina is an “inverted” retina, with the nerve-connected bases of its cells lying outwards and their bacillar extremities directed inwards.

In a longitudinal vertical section of the eye of a larva (Tanystylum), at a stage when three pairs of walking legs are present, Morgan shows us the pigment-layer apparently continuous with the hypodermis just below the eye, and in close connection with the middle layer at the upper part of the eye. From this we are permitted to infer a development by invagination, in which the long invaginated sac is bent and pushed upwards till it comes into secondary contact with the hypoderm, so giving us the three layers of the developed eye. This manner of formation is precisely akin to that described by Parker, Patten, Locy, and others for the median eyes of Scorpions and of Spiders, and the organ is structurally comparable to the Nauplius- or median eye of Crustacea. But neither in these cases nor in that of the Pycnogon is the whole process clear, in consequence chiefly of the obscurity that attends the course of the optic nerve in both embryo and adult. For various discussions and accounts, frequently contradictory, of these phenomena, the reader is referred to the authors quoted, or to Korschelt and Heider’s judicious summary.

There seems to be a small structure, of some sort or other, between the ocelli on either side. Dohrn thought it might be auditory, Loman that it might be secretory, but its use is unknown.

=Integument.=—The chitinised integument is perforated by many little cavities, some of them conical and tapering to a minute external pore, the others more regularly tubular. Sometimes, but according to Hoek rarely, the tubular pore-canals communicate with, or arise from, the conical cavities. The pore-canals transmit a nerve for the supply of sensory hairs, often forked, which arise from the orifice of the canal in little groups of two or more, sometimes in rosettes of eight or nine. These setae are small or rudimentary in Ascorhynchus and totally wanting in Colossendeis; they appear to be extremely large and stellate in Paranymphon. The conical cavities contain proliferated epithelial cells, blood corpuscles, and cells of more doubtful nature that are perhaps glandular. According to Dohrn, glands exist in connection with both kinds of integumentary perforations, and he suspects that they secrete a poisonous fluid in response to stimuli affecting the sensory hairs; Hoek, on the other hand, is inclined to ascribe a respiratory function to the cavities; but indeed, as yet, we must confess that their use is undetermined.

=Reproductive Organs.=—In each sex the generative organs consist of a pair of ovaries or testes lying above the gut on either side of the heart; in the adult they are fused together posteriorly at the base of the abdomen, and send long diverticula into the ambulatory legs. In the female Phoxichilidium, at least, as Loman has lately shown, the fusion is complete, and the ovary forms a thin broad plate, spreading through the body and giving off its lateral diverticula. The diverticula of the testes reach to the third joint of the legs, those of the ovaries to the fourth, or sometimes farther. The ova ripen within the lateral diverticula, chiefly, and sometimes (Pallene) exclusively, in the femora or fourth joints of the legs, which, in many forms, are greatly swollen to accommodate them; the spermatozoa, on the other hand, are said to develop both within the legs and within the thoracic portions of the testis. The genital diverticula may end blindly within the leg, or communicate through a duct with the exterior by a valvular aperture placed on the second coxal joint. Such apertures occur, as a rule, on all the legs in the females, in Rhynchothorax and Pycnogonum on the last only. In the males an aperture is present on all the legs in Decolopoda and Phoxichilidium; on the last three in Nymphon and Phoxichilus; in most genera on the last two; in Pycnogonum and Rhynchothorax on the last only.

Very commonly the female individuals are somewhat larger than the males, and in some species (Ammothea, Trygaeus) the latter are distinguished by a greater development of spines or tubercles on the body and basal joints of the legs (Dohrn).

The act of fecundation has been observed by Cole in Anoplodactylus. The animal reproduces towards the end of August. Consorting on their Eudendrium (Hydroid) colony, the male climbs upon the female and crawls over her head to lie beneath her, head to tail; and then, fertilisation taking place the while, the hooked ovigerous legs of the male fasten into the extruding egg-masses and tear them away. The whole process is over in five minutes. The fresh egg-masses are more or less irregular in shape, and white in colour like little tufts of cotton.

Each ball of eggs that the male carries represents the entire brood of one female, and in Phoxichilidium Loman has seen a male carrying as many as fourteen balls. Fertilisation is external, taking place while the eggs are being laid. The spermatozoa have small rounded heads and long tails, and are thus unlike the spermatozoa of most Crustacea.

=Development.=—Until the hatching of the embryo, the eggs of the Pycnogons are carried about, agglutinated by cement-substance into coherent packets, on the ovigerous legs of the males. They are larger or smaller according to the amount of yolk-substance present, very small in Phoxichilidium and Tanystylum (Morgan), where they measure only ·05 mm. in diameter; larger in Pallene (·25 mm.); larger still (·5–·7 mm.) in Nymphon. In Pallene each egg-mass commonly contains only two eggs; in the other genera they are much more numerous, rising to a hundred or more in Ammothea (Dohrn). The egg-masses may be one or more on each ovigerous leg, sometimes (Phoxichilidium angulatum, Dohrn) a single egg-mass is held by both legs; they are extremely numerous in Phoxichilus, and in Pycnogonum they coalesce to form a broad pad beneath the body. The fact that it is the male and not the female that carries the eggs was only announced in 1877 by Cavanna; before, and by some even after his time, the two sexes were constantly confused.

FIG. 280.—Young larva (nat. size ·1 mm.) of Ammothea fibulifera, Dohrn. C.G, Brain; gl, gld, gland and duct of chelophore; pr, proboscis; I, II, III, IV, appendages. (After Dohrn.) ]

Segmentation is complete, symmetrical in the forms with smaller eggs, unequal in those burdened with a preponderance of yolk (Morgan). In Pallene, as in the Spider’s egg, what is described as at first a total segmentation passes into a superficial or centrolecithal one by the migration outwards of the nuclei and the breaking down of the inner ends of the wedge-shaped segmentation-cells. The blastoderm so formed becomes concentrated at the germinal pole of the egg. A thickened portion of the blastoderm (which Morgan compares to the “cumulus primitivus” of the Spider’s egg) forms an apparently blastoporal invagination (though Morgan calls it the stomodaeum), and from its sides are budded off the mesodermal bands. Meisenheimer has recently given a minute account of the early development of Ammothea, a form with small yolkless eggs. Here certain cells of the uniform and almost solid blastosphere grow inwards till their nuclei arrange themselves in an inner layer of what (so far as they are concerned) is a typical gastrula, but without any central cavity. The inner layer subsequently, but slowly, differentiates into the mid-gut, and into dorsal and lateral offshoots, the sources of the heart and of the muscles and connective tissues respectively. The further development of the egg takes place, as is usual in Arthropods, by the appearance, in a longitudinal strip or germ-band which enwraps the yolk, of paired thickenings which represent the cerebral and post-oral ganglia, and of others from which arise the limbs. Of these latter, the chelophores are the first to appear, on either side of the mouth; in Pallene the fourth pair appears next in order, followed by the fifth and sixth, and by the third and seventh just before the hatching out of the embryo; the second is lacking in this particular genus. Thus in Pallene (Dohrn, Morgan), and in some others, e.g. Nymphon brevicollum (Hoek), the free larva is from the first provided with its full complement of limbs. Certain other species of Nymphon hatch out in possession of four or five pairs of limbs, but in the great majority of cases studied the larval Pycnogon is at first provided with three pairs only, the three anterior pairs of the typical adult. Numerical coincidence, and that alone, has often led this “Protonymphon” larva to be compared with the Crustacean Nauplius. In the annexed figure of a young larval Ammothea (Achelia), we see the unsegmented body, the already chelate chelophores (furnished with the provisional cement-glands already described), the other two pairs of appendages each with a curious spine at its base, the gut beginning to send out diverticula (of which the first pair approach the chelophores) but still destitute of the anus (which is only to be formed after the development of the abdomen), the proboscis, and one pair of eyes situated close over the pre-oral ganglia. The subsequent changes are in this genus extremely protracted, and terminate with the loss of the chelae, a process which occurs so late in life that the chelate individuals were long looked upon as belonging to a separate genus, the original Ammothea of Hodge, until Hoek proved their identity with the clawless Achelia.

The developmental history of Phoxichilidium and Anoplodactylus is peculiar. The young larvae have the claws of the second and third appendages hypertrophied to form enormous stiff tendril-like organs, with which they affix themselves to the bodies of Hydroid Zoophytes (Coryne, Eudendrium, Tubularia, Hydractinia, etc.), feeding as the adults do: afterwards losing these elongated tendrils in a moult, they pass into the gastral cavity of the Hydroid; in our native species the larva issues from the Hydroid and begins its independent life at a stage when three pairs of ambulatory legs are present and the fourth is in bud. The Phoxichilidium larvae were first noticed by Gegenbaur in Eudendrium, again by Allman in Coryne eximia. George Hodge made detailed and important observations, and showed, in opposition to Gegenbaur, that it was the larva which entered the Hydroid and not the egg that was laid therein.

FIG. 281.—Larva of Phoxichilidium sp., showing tendril-like appendages of the larval palps and ovigerous legs. (After Dohrn.) ]

Moseley has the following interesting note in his Challenger Report: “The most interesting parasite observed was a form found in the gastric cavities of the gastrozoids of Pliobothrus symmetricus (West Indies, 450 f.), contained in small capsules. These capsules were badly preserved, but there seemed little doubt that they contained the remains of larvae of a Pycnogonid, so that the deep-sea Pycnogonids, which are so abundant, very possibly pass through their early stages in deep-sea Stylasteridae.... The gastrozoids containing the larvae were partly aborted.”

A Pycnogon larva, doubtfully ascribed to Nymphon, has been found living in abundance ectoparasitically on Tethys in the Bay of Naples.

=Habits.=—Of the intimate habits of the Pycnogons we can say little. Pycnogonum we often find clinging, as has been said, close appressed to some large Anemone (Tealia, Bolocera, etc.), whose living juices it very probably imbibes. The more slender species we find climbing over sea-weeds and Zoophytes, where sometimes similarity of colour as well as delicacy of form helps to conceal them; thus Phoxichilidium femoratum (Orithyia coccinea, Johnston) is red like the Corallines among which we often find it, P. virescens green like the filamentous Ulvae, the Nymphons yellowish like the Hydrallmania and other Zoophytes which they affect. On the New England coast, according to Cole, the dark purple Anoplodactylus lentus, Wilson (Phoxichilidium maxillare, Stimpson), is especially abundant on colonies of Eudendrium, whose colour matches its own, the yellowish Tanystylum orbiculare frequents a certain yellowish Hydroid, and of these two species neither is ever found on the Hydroid affected by the other; while, on the other hand, Pallene brevirostris, whose whitish, almost transparent body is difficult to see, is more generally distributed. The deep-sea Pycnogons (Colossendeis, Nymphon) are generally (if not universally) of a deep orange-scarlet colour, a common dress of many deep-sea Crustacea.

The movements of the Pycnogons are singularly slow and deliberate; they are manifestly not adapted to capture or to kill a living prey. Linnaeus accepted from J. C. König the singular statement that they enter and feed upon bivalve shells, “Mytilorum testes penetrat et exhaurit”; but the statement has never been reaffirmed.

Loman describes Phoxichilidium as feeding greedily on Tubularia larynx, and especially on the gonophores. It grasps them with its claws, sucks them in bit by bit till the proboscis is filled as far as the sieve, whereupon that part of the proboscis squeezes and kneads the mass, letting only juices and fine particles pass through into the alimentary canal. The lateral caeca and the rectum are separated by sphincter muscles from the stomach; the former are in turn filled with food and again emptied; the contents of the alimentary canal are in constant rolling movement, and the faeces are eliminated by the action of a pair of levatores ani, in round pellets.

The Pycnogons, or some of them, can swim by “treading water,” and Pallene is said by Cole to swim especially well; they more often progress half by swimming, half by kicking on the bottom. They move promptly towards the light, unless they have Hydroids to cling to, and Cole points out that when they crawl with all their legs on the bottom they move forwards towards the light, but backwards when they swim in part or whole. The legs move mostly in a vertical plane, horizontal movements taking place chiefly between the first and second joints. Tanystylum is uncommonly sluggish and inert; it sinks to the bottom, draws its legs over its back and remains quiet, while Pallene, by vigorous kicks, remains suspended.

The long legs of the Pycnogons are easily injured or lost, and easily repaired or regenerated. This observation, often repeated, is as old as Fabricius: “Mutilatur etiam in libertate sua, redintegrandum tamen; vidi enim in quo pedes brevissimi juxta longiores enascentes, velut in asteriis cancris aliisque redintegratis.” In such cases of redintegration of a leg, the reproductive organ, the genital orifice, and the cement-gland are not restored until the next moult.

=Systematic Position.=—To bring this little group into closer accord with one or other of the greater groups of Arthropods is a problem seemingly simple but really full of difficulty.

The larval Pycnogon, with its three pairs of appendages, resembles the Crustacean Nauplius in no single feature save this unimportant numerical coincidence; nor is there any significance in the apparent outward resemblance to isolated forms (e.g. Cyamus) that induced some of the older writers, from Fabricius downwards and including Kröyer and the elder Milne-Edwards, to connect the Pycnogons with the Crustacea. To refer them, or to approximate them to the Arachnids, has been a stronger and a more lasting tendency. Linnaeus (1767) included the two species of which he was cognisant in the genus Phalangium, together with P. opilio. Lamarck, who first formulated the group Arachnida (1802), let it embrace the Pycnogons; and Latreille (1804, 1810), who immediately followed him, defined more clearly the Pycnogonida as a subdivision of the greater group, side by side with the subdivision that corresponds to our modern Arachnida (“Arachnides acères”), and together with a medley of lower Crustacea, Myriapoda, Thysanura, and Parasitic Insects; he was so cautious as to add “j’observerai seulement, que je ne connais pas encore bien la place naturelle des Pycnogonides et des Parasites,” and Cuvier, setting them in a similar position, adds a similar qualification.

Leach (1814), whose great service it was to dissociate the Edriophthalmata and the Myriapoda from the Latreillian medley, left the group Arachnida as we still have it (save for the inclusion of the Dipterous Insect Nycteribia), and divided the group (with the same exception) into four Orders of which the Podosomata, i.e. the Pycnogonida, are one. Savigny (1816), less philosophical in this case than was his wont, assumed the Crustacean type to pass to the Arachnidan by a loss of several anterior pairs of appendages, and appears to set the Pycnogons in an intermediate grade, marking the pathway of the change. He considered the seven pairs of limbs of the Pycnogons to represent thoracic limbs of a Malacostracan, and, like so many of his contemporaries, was much biased by the apparent resemblance of Cyamus to Pycnogonum. The reader may find in Dohrn’s Monograph a guide to many other opinions and judgments, some of them of no small morphological interest and historical value; but it behoves us to pass them by, and to inspect, in brief, the case as it stands at present. The obvious features in which a Pycnogon resembles a Spider or other typical Arachnid, are the possession of four pairs of walking legs, and the pre-oral position and chelate form of the first pair of appendages; we may perhaps also add, as a more general feature of resemblance, the imperfect subservience of limbs to the mouth as compared with any of the Crustacea. The resemblance would still be striking, in spite of the presence of an additional pair of legs in a few Pycnogons, were it not for the presence of the third pair of appendages or ovigerous legs of the Pycnogon, whose intercalation spoils the apparent harmony. We are neither at liberty to suppose, with Claus, that these members, so important in the larva, have been interpolated, as it were, anew in the Pycnogon; nor that they have arisen by subdivision of the second pair, as Schimkewitsch is inclined to suppose; nor that they have dropped out of the series in the Arachnid, whose body presents no trace of them in embryo or adult. In a word, their presence precludes us from assuming a direct homology between the apparently similar limbs of the two groups, and at best leaves it only open to us to compare the last legs of the Pycnogon with the first abdominal, or genital, appendages of the Scorpion and the Spider. On the other hand, if we admit the seventh (as we must admit the occasional eighth) pair of appendages of Pycnogons to be unrepresented in the prosoma of the Arachnids, then, in the cephalothorax of the former, with its four pairs of appendages, we may find the homologue of the more or less free and separate part of the cephalothorax in Koenenia, Galeodes, and the Tartaridae. There is a resemblance between the two groups in the presence of intestinal diverticula that run towards or into the limbs, as in Spiders and some Mites, and there are certain histological and embryological resemblances that have been in part referred to above; but these, such as they are, are not adequate guides to morphological classification. We must bear in mind that such resemblances as the Pycnogons seem to show are not with the lower Arachnids but with the higher; they are either degenerates from very advanced and specialised Arachnida, or they are lower than the lowest. Confronted with such an issue, we cannot but conclude to let the Pycnogons stand apart, an independent group of Arthropods; and I am inclined to think that they conserve primitive features in the usual presence of generative apertures on several pairs of limbs, and probably also in the non-development of any special respiratory organs. But inasmuch as the weight of evidence goes to show that subservience of limbs to mouth is a primitive Arthropodan character, the fact that the basal elements of the anterior appendages have here (as in Koenenia) no such relation to the mouth must be taken as evidence, not of antiquity, but of specialisation. In like manner the suctorial proboscis cannot be deemed a primitive character, and the much reduced abdomen also is obviously secondary and not primitive.

=Classification.=—No single genus more than another shows signs of affinity with other groups, and no single organ gives us, within the group, a clear picture of advancing stages of complexity. On the contrary, the differences between one genus and another depend very much on degrees of degeneration of the anterior appendages, and we have no reason to suppose that these stages of degeneration form a single continuous series, but have rather reason to believe that degeneration has set in independently in various ways and at various points in the series. But while we are unable at present to form a natural classification of the Pycnogons, yet at the same time a purely arbitrary or artificial classification, conveniently based on the presence or absence of certain limbs, would run counter to such natural relationships as we can already discern.

The classification here adopted is a compromise between a natural system, so far as we can detect it, and an artificial one.

Two forms, separated from one another by many differences, show a minimum of degeneration, namely Decolopoda on the one hand, and the Nymphonidae on the other. The former genus has five pairs of legs, and this peculiarity is shared by Pentanymphon. In both groups the three anterior limbs are all present and well formed, save only that the ovigerous legs, which have ten joints in Decolopoda, are reduced to five joints in the Nymphons, and their denticulate spines, of which several rows are present in the former, are reduced to one row in the latter; on the other hand, a greater or a less degeneration of these limbs marks each and all of the other families.

Decolopoda is very probably the most primitive form known, though it has characters which seem to be the reverse of primitive in the dwarfish size of its chelophores and the crowded coalescent segmentation of the trunk. Colossendeis, in spite of its vanished chelophores, is probably closely allied: the shape and segmentation of the body and the several rows of smooth denticles on the ovigerous legs are points in common. The Eurycydidae are closely allied to Colossendeidae; they agree with Decolopoda in the two-jointed scape of the chelophore, and with Ammotheidae in the deflexed mobile proboscis. The true position of Rhynchothorax is very doubtful.

The Nymphonidae and Pallenidae are closely allied, and the Phoxichilidiidae have points of resemblance, especially with the latter. Nymphon compares with Decolopoda in the completeness of its parts, and is more typical in its long well-segmented body, and in its highly-developed chelae; but it already shows reduction in the scape of the chelophore, in the palps, and in the armature of the ovigerous legs.

The Phoxichilidae and Pycnogonidae (Agnathonia, Leach; Achelata, Sars), though differing greatly in aspect, are not improbably allied to one another; and whether this be so or not, the complete absence of chelophores and of palps affords an arbitrary character by which they are conveniently separated from all the rest.

The following table epitomises the chief characters of the several families:—

┌────────────────────┬──────────┬────────────┬───────────┬─────────┐ │ PYCNOGONIDA. │Proboscis.│Chelophores.│ Palps. │Ovigerous│ │ │ │ │ │ legs. │ ├────────────────────┼──────────┼────────────┼───────────┼─────────┤ │ │ │ │ │ │ ├────────────────────┼──────────┼────────────┼───────────┼─────────┤ │(=Cryptochelata=, │ │ │ │ │ │Sars)— │ │ │ │ │ │ DECOLOPODIDAE │ Fixed, │ Complete, │ 10 joints │10 joints│ │ │ decurved │small, scape│ │ ♂, ♀ │ │ │ │ 2–jointed │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ COLOSSENDEIDAE │ Somewhat │ 0 │ 10 │ 10 ♂, ♀ │ │ │ mobile, │ │ │ │ │ │sometimes │ │ │ │ │ │ decurved │ │ │ │ │ EURYCIDIDAE │ Mobile, │ Scape │ 10 │ 10 ♂, ♀ │ │ │ stalked, │ 2–jointed, │ │ │ │ │ deflexed │ chelae │ │ │ │ │ │rudimentary │ │ │ │ Hannonia │ „ │Rudimentary │ 0 │ 10 ♂, ♀ │ │ │ │ │ │ │ │ AMMOTHEIDAE │ Mobile, │ „ │ 4–9 │ 10 (or │ │ │ deflexed │ │ │less) ♂, │ │ │ │ │ │ ♀ │ │ │ │ │ │ │ │ ? RHYNCHOTHORACIDAE│ Large, │ 0 │ 8 (5) │ 10 ♂, ♀ │ │ │ fixed, │ │ │ │ │ │ aberrant │ │ │ │ ├────────────────────┼──────────┼────────────┼───────────┼─────────┤ │(=Euchelata=, Sars)—│ │ │ │ │ │ NYMPHONIDAE │ Large, │Large, scape│ 5 (7) │8–10 ♂, ♀│ │ │ fixed │ 1–jointed │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ PALLENIDAE │ „ │ „ │ 0 or │ 10 ♂, ♀ │ │ │ │ │rudimentary│ │ │ │ │ │ │ │ │ PHOXICHILIDIIDAE │ „ │ „ │ 0 │ 5–6 ♂ │ │ │ │ │ │ │ │ │ │ │ │ │ ├────────────────────┼──────────┼────────────┼───────────┼─────────┤ │(=Achelata=, Sars) │ │ │ │ │ │ PHOXICHILIDAE │ Large, │ 0 │ 0 │ 7 ♂ │ │ │ fixed │ │ │ │ │ │ │ │ │ │ │ PYCNOGONIDAE │ „ │ 0 │ 0 │ 9 ♂ │ │ │ │ │ │ │ └────────────────────┴──────────┴────────────┴───────────┴─────────┘

┌────────────────────┬──────────┬─────┬───────────────┬─────────┐ │ PYCNOGONIDA. │ Teeth on │Legs.│Trunk-segments.│ Genital │ │ │ do. │ │ │Openings.│ ├────────────────────┼──────────┼─────┼───────────────┼────┬────┤ │ │ │ │ │ ♂ │ ♀ │ ├────────────────────┼──────────┼─────┼───────────────┼────┼────┤ │(=Cryptochelata=, │ │ │ │ │ │ │Sars)— │ │ │ │ │ │ │ DECOLOPODIDAE │Four rows,│ 5 │ Condensed, │ 1, │ 1, │ │ │ simple │ │ coalescent │ 2, │ 2, │ │ │ │ │ │ 3, │ 3, │ │ │ │ │ │ 4, │4, 5│ │ │ │ │ │ 5, │ │ │ COLOSSENDEIDAE │Many rows,│ 4 │ Coalescent │ 1, │ 1, │ │ │ simple │ │ │ 2, │ 2, │ │ │ │ │ │3, 4│3, 4│ │ │ │ │ │ │ │ │ EURYCIDIDAE │More than │ 4 │Well segmented │3, 4│ 1, │ │ │ one row, │ │ │ │ 2, │ │ │ serrate │ │ │ │3, 4│ │ │ │ │ │ │ │ │ Hannonia │Scattered │ 4 │ „ │ „ │ „ │ │ │ spines │ │ │ │ │ │ AMMOTHEIDAE │ Few, │ 4 │ Condensed, │ „ │ „ │ │ │scattered,│ │ segmented │ │ │ │ │serrate or│ │ │ │ │ │ │ smooth │ │ │ │ │ │ ? RHYNCHOTHORACIDAE│ Toothed │ 4 │ „ │ 4 │ 4 │ │ │tubercles │ │ │ │ │ │ │ │ │ │ │ │ ├────────────────────┼──────────┼─────┼───────────────┼────┼────┤ │(=Euchelata=, Sars)—│ │ │ │ │ │ │ NYMPHONIDAE │ One row, │ 4–5 │Well segmented │ 2, │ 1, │ │ │ serrate │ │ │3, 4│ 2, │ │ │ │ │ │(5) │3, 4│ │ │ │ │ │ │(5) │ │ PALLENIDAE │ „ │ 4 │ „ │(1, │ „ │ │ │ │ │ │2), │ │ │ │ │ │ │3, 4│ │ │ PHOXICHILIDIIDAE │ One row, │ 4 │ „ │ 1, │ „ │ │ │ simple │ │ │ 2, │ │ │ │ │ │ │3, 4│ │ ├────────────────────┼──────────┼─────┼───────────────┼────┼────┤ │(=Achelata=, Sars) │ │ │ │ │ │ │ PHOXICHILIDAE │Scattered,│ 4 │Well segmented │ 2, │ 1, │ │ │ simple │ │ │3, 4│ 2, │ │ │ │ │ │ │3, 4│ │ PYCNOGONIDAE │ Small, │ 4 │ Segmented, │ 4 │ 4 │ │ │irregular │ │ condensed │ │ │ └────────────────────┴──────────┴─────┴───────────────┴────┴────┘

CLASS PYCNOGONIDA.

Marine Arthropoda, with typically seven (and very exceptionally eight) pairs of appendages, of which none have their basal joints subservient to mastication, the first three are subject to suppression, the first (when present) are chelate, the second palpiform, the third ovigerous, and the rest form ambulatory limbs, usually very slender and long; with a suctorial proboscis, a limbless, unsegmented abdomen, and no manifest respiratory organs.

FIG. 282.—Decolopoda australis, Eights. =A=, × 1: from a specimen obtained at the South Shetlands by the Scotia Expedition. =B=, First appendage, or chelophore. (=A=, original; =B=, after Hodgson.) ]

=Fam. 1. Decolopodidae.=—Appendage I. dwarfed, but complete and chelate, scape with two joints; II. 9–10–jointed; III. well developed in both sexes, 10–jointed, the terminal joints with about four rows of teeth; five pairs of legs, destitute of accessory claws; genital apertures on all the legs (Bouvier).

Decolopoda australis, Eights (1834), a remarkable form from the South Shetlands, recently re-discovered by the Scotia expedition. The animal is large, seven inches or more in total span, in colour scarlet; it was found in abundance in shallow water and cast upon the shore. The body is greatly condensed, the proboscis is “clavate, arcuated downwards,” and beset with small spines. A second Antarctic species, D. antarctica, has been described by Bouvier. The presence of a fifth pair of legs distinguishes Decolopoda from all known Pycnogons, except Pentanymphon. Stebbing would ally Decolopoda with, or even include it in, the Nymphonidae; but the presence of a second joint in the chelophoral scape, the number of joints in, and the armature on, the ovigerous legs, and the deflexed proboscis, are all characters either agreeing with or tending towards those of the Eurycididae; while the Colossendeidae would be very like Decolopoda were it not for the complete suppression of the chelophores. It seems convenient to constitute a new family for this remarkable form.

=Fam. 2. Colossendeidae= (=Pasithoidae=, Sars).—Appendage I. absent in adult; appendage II. very long, 10–jointed; appendage III. 10–jointed, clawed, with many rows of teeth; auxiliary claws absent; segments of trunk fused; proboscis very large, somewhat mobile; genital apertures, in at least some cases, on all the legs.

Pasithoe, Goodsir (1842), which Sars assumes as the type of the family, is here relegated to Ammothea. Colossendeis, Jarszynsky (1870) (Anomorhynchus, Miers (1881), Rhopalorhynchus, Wood-Mason (1873)), remains as the only genus commonly accepted: large, more or less slender short-necked forms; world-wide, principally Arctic, Antarctic, and deep-sea; about twenty-five species. The largest species, C. gigas, Hoek, from great depths in the Southern Ocean, has a span of about two feet. The North Atlantic C. proboscidea and Antarctic C. australis are very closely related to one another. Carpenter would retain the genus Rhopalorhynchus for R. kröyeri, W.-M. (Andamans), R. clavipes, Carp. (Torres Straits), and R. tenuissimus, Haswell (Australia), all more or less shallow-water species, excessively attenuated, with the second and third body-segments elongated, the caudal segment excessively reduced, the club-shaped proboscis on a slender stalk, and other common characters. Pipetta weberi, Loman (1904), is a large and remarkable form from the Banda Sea, apparently referable, in spite of certain abnormal features, to this family; the proboscis is extraordinarily long and slender; the palps have eight joints, the ovigerous legs eleven.

=Fam. 3. Eurycididae= (=Ascorhynchidae=, Meinert).—Appendage I. more or less reduced; appendage II. 10–jointed (absent in Hannonia); appendage III. 10–jointed, clawed, with more than one tow of serrated teeth; proboscis movably articulated and more or less bent under the body; auxiliary claws absent.

FIG. 283.—Eurycide hispida, Kr.; side view. ]

Eurycide, Schiödte (1857) (Zetes, Kröyer, 1845): Appendage I. with two-jointed scape, without chelae in adult; one species (E. hispida, (Kr.)), from the North Atlantic and Arctic, and two others from the East Indies, recently described by Loman. Barana arenicola, Dohrn (1881), is nearly allied. Ascorhynchus, G. O. Sars (1876) (Gnamptorhynchus, Böhm, 1879; Scaeorhynchus, Wilson, 1881), very similar to Eurycide, with which, according to Schimkewitsch, it should be merged, includes large, smooth, elongated forms, with long neck and expanded frontal region, and a long proboscis lacking the long scape that supports the proboscis in Eurycide; about twelve species, world-wide, mostly deep-water. Barana castelli, Dohrn, from Naples is akin to the foregoing genera, but seems to deserve generic separation from B. arenicola. Ammothea longicollis, Haswell, from Australia, is, as Schimkewitsch has already remarked, almost certainly a Eurycide, as is also, probably, Parazetes auchenicus, Slater, from Japan.

Hannonia typica, Hoek (1880), from Cape Town, is a remarkable form, lately redescribed by Loman. The chelophores are much reduced, the palps are absent; the ovigerous legs are 10–jointed, and clawed; the terminal joints of the latter bear long straight spines, scattered over their whole surface; the proboscis is borne on a narrow stalk, and sharply deflexed. The eggs form a single flattened mass, as in Pycnogonum. While the lack of palps would set this genus among the Pallenidae, the remarkable proboscis seems to be better evidence of affinity with Ascorhynchus and Eurycide.

Nymphopsis, Haswell (1881), is a genus of doubtful affinities, placed here by Schimkewitsch. The first appendage is well-developed and chelate; the palps are 9–jointed, the ovigerous legs are 7–jointed, none of the joints being provided with the compound spines seen in Nymphon and Pallene. It is perhaps an immature form. Schimkewitsch has described another species, N. korotnevi, and Loman a third, N. muscosus, both from the East Indies.

=Fam. 4. Ammotheidae.=—Akin to Eurycididae in having the proboscis more or less movably jointed to the cephalic segment, and appendage I. reduced, non-chelate in the adult; the body is compact and more or less imperfectly segmented; appendage II. 4–9–jointed; appendage III. clawless, and the number of joints sometimes diminished, with a sparse row of serrated spines; auxiliary claws usually present.

Ammothea, Leach (1815) (including Achelia, Hodge (1864) = the old non-chelate individuals): appendage I. very small, 2–jointed; appendage II. 8–9–jointed; caudal segment fused with last body-segment; about eighteen species, four from the South Seas, two or three from the East Indies, the rest mostly Mediterranean and North Atlantic, in need of revision. Ammothea longipes, Hodge, is the young of Achelia hispida, Hodge; and Ammothea magnirostris, Dohrn, is apparently the same species. A. fibulifera, Dohrn, seems identical with Achelia echinata, Hodge (of which A. brevipes, Hodge, is the young), and so probably is A. achelioides, Wilson; Endeis didactyla, Philippi (1843), is very probably the same species. A. uniunguiculata, Dohrn (? Pariboea spinipalpis, Philippi (1843)), has no auxiliary claws. Leionymphon, Möbius (1902), contains nine Antarctic forms, allied to Ammothea (including A. grandis, Pfeffer, and Colossendeis gibbosa, Möb., which two are probably identical), with characteristic transverse ridges on the body, a large proboscis, a 9–jointed palp, and somewhat peculiar ovigerous legs. Cilunculus, Fragilia, and Scipiolus are new genera more or less allied to Leionymphon, described by Loman (1908) from the Siboga Expedition. Tanystylum, Miers (1879) (including Clotenia, Dohrn (1881), and Discoarachne, Hoek (1880)), has appendage I. reduced to a single joint or a small tubercle, and appendage II. 4–6–jointed; world-wide; about eight species. Austrodecus glacialis and Austroraptus polaris are two allied Antarctic species, described by Hodgson (1907), the former a curious little form with a pointed, weevil-like proboscis, no chelophores, and 6–jointed palp. Trygaeus communis, Dohrn (1881), from Naples, has a 7–jointed, and Oorhynchus aucklandiae, Hoek (1881), a 9–jointed palp; the former has only seven joints in the ovigerous leg. Lecythorhynchus armatus, Böhm (1879), with rudimentary 2–jointed chelophores, and L. (Corniger) hilgendorfi, Böhm, with small tubercles in their place, both from Japan, have also 9–jointed palps: the former, at least, is apparently an Ammothea. Several insufficiently described genera, Phanodemus, Costa (1836), Platychelus, Costa (1861), Oiceobathes, Hesse (1867), and Böhmia, Hoek (1880), seem to be referable to this group; all have chelate mandibles, and may possibly be based on immature forms.

Goodsir’s Pasithoe vesiculosa is, in my opinion, undoubtedly Ammothea hispida, Hodge, and so also, I believe, is his Pephredo hirsuta; P. umbonata, Gould (Long Island Sound), is, with as little doubt, Tanystylum orbiculare, Wilson.

=Fam. 5. Rhynchothoracidae.=—The animal identified by Dohrn as Rhynchothorax mediterraneus, Costa (1861), is a minute and very remarkable form, without chelophores, with large 8–jointed palps, reduced by fusion to five joints, and 10–jointed, clawed ovigerous legs, which last are provided on the last five joints with peculiar toothed tubercles. The general aspect of the body is somewhat like that of an Ammothea, which genus it resembles in the ventral insertion of the ovigerous legs and the somewhat imperfect segmentation of the body. It differs from Ammotheidae in the possession of a claw on appendage III. It is highly peculiar in the structure of the mouth, in having a long forward extension of the oculiferous tubercle jutting out over the proboscis, in the extreme shortness of the intestinal caeca and ovaries which scarcely extend into the legs, and in the absence of cement-glands from the fourth joint of the legs; these last are present only in the third joint of the penultimate legs. A single pair of generative orifices are found on the last legs. A second species, R. australis, Hodgson, comes from the Antarctic.

FIG. 284.—Rhynchothorax mediterraneus, Costa. =A=, Body and bases of legs; =B=, terminal joints of palp. (After Dohrn.) ]

=Fam. 6. Nymphonidae.=—Appendage I. well-developed, chelate; II. well-developed, usually 5–jointed; III. well-developed in both sexes, usually 10–jointed, the terminal joints with one row of denticulated spines.

Nymphon, Fabr. (1794), about forty-five recognised species, of which some are but narrowly defined. Closely allied are Chaetonymphon, G. O. Sars (1888), including thick-set, hairy species, about eight in number, from the North Atlantic, Arctic, and Antarctic; and Boreonymphon, G. O. Sars (1888), with one species (B. robustum, Bell, Fig. 276), also northern, in which the auxiliary claws are almost absent. Nymphon brevicaudatum, Miers (= N. horridum, Böhm), an extraordinary hispid form from Kerguelen, is also peculiar. Pentanymphon, Hodgson (1904), from the Antarctic (circumpolar), differs in no respect save in the presence of a fifth pair of legs; one species.

The only other genus is Paranymphon, Caullery (1896) (one species, Gulf of Gascony, West of Ireland, Greenland), in which the palp is (6–)7–jointed, the ovigerous leg 8–jointed, and the auxiliary claws are absent.

=Fam. 7. Pallenidae.=—As in Nymphon, but appendage II. absent or rudimentary.

FIG. 285.—Pallene brevirostris, Johnston, ♀, Plymouth. ]

Pallene, Johnston (1837): about ten species (Mediterranean, North Atlantic, Arctic, Australia). P. languida, Hoek, Australia, lacks auxiliary claws, and is otherwise distinct; but P. novaezealandiae, G. M. Thomson, is typical. Pseudopallene, Wilson (1878): appendage III. clawed; auxiliary claws absent; four (or more) species (North Atlantic, Arctic, Antarctic). P. (Phoxichilus) pygmaea, Costa (1836), and P. spinosa, Quatref., seem to belong to this genus or to Pallene. Cordylochele, G. O. Sars (1888): closely allied, but with front of cephalic segment much expanded and chelae remarkably swollen, includes three very smooth, elongated, northern species, to which Bouvier has added one from the Antarctic; Pallene laevis, Hoek, from Bass’s Straits, is somewhat similar. Neopallene, Dohrn (1881): as in Pallene, but with a rudimentary second appendage in the female, and no generative aperture on the last leg in the male (one species, Mediterranean). Parapallene, Carpenter (1892): as in Pallene, but without auxiliary claws, and with the two last segments of the trunk (which in Pallene are coalesced) independent (about ten species, East Indies and Australia); Pallene grubii, Hoek (Phoxichilidium sp., Grube, 1869), is probably congeneric. Pallenopsis, Wilson (1881): appendage I. 2–jointed; appendage II. rudimentary, 1–jointed; appendage III. clawless; auxiliary claws present; slender forms, including some formerly referred to Phoxichilidium; about fifteen species, world-wide. Pallene dimorpha, Hoek, from Kerguelen, with 4–jointed palps, deserves a new generic appellation. P. longiceps, Böhm, from Japan, with rudimentary 2–jointed palps in the male, is also peculiar.

FIG. 286.—Phoxichilidium femoratum, Rathke, Britain. =A=, The animal with its legs removed; =B=, leg and chela. ]

=Fam. 8. Phoxichilidiidae.=—Appendage I. well-developed; II. absent; III. present only in the male, having a few simple spines in a single row. The last character is conveniently diagnostic, but nevertheless the Phoxichilidiidae come very near to the Pallenidae, with which, according to Schimkewitsch and others, they should be merged; the two families resemble one another in the single row of spines on the ovigerous legs and in the extension of the cephalic segment over the base of the proboscis.

Phoxichilidium, M.-E. (1840): appendage III. 5–jointed; five or six species (Mediterranean, North Atlantic, Arctic, Australia, Japan). Anoplodactylus, Wilson (1878): appendage III. 6–jointed; auxiliary claws absent or very rudimentary; about twelve species, cosmopolitan, of which many were first referred to Phoxichilidium. A. neglectus, Hoek, comes from 1600 fathoms off the Crozets. Oomerus stigmatophorus, Hesse (1874), from Brest, seems to belong to one or other genus, but is unrecognisable. Anaphia, Say (1821), is in all probability identical with Anoplodactylus, and if so the name should have priority. Halosoma, Cole (1904), is an allied genus from California.

FIG. 287.—Anoplodactylus petiolatus, Kr., Britain. =A=, Dorsal view; =B=, side view. ]

=Fam. 9. Phoxichilidae.=—Appendage I. and II. absent; appendage III. present only in the males, 7–jointed, with minute scattered spines; auxiliary claws well-developed; body and legs slender. The only genus is Phoxichilus (auctt., non Latreille, Chilophoxus, Stebbing, 1902); the type is P. spinosus, Mont. (non Quatrefages), from the N. Atlantic, and P. vulgaris, Dohrn, P. charybdaeus, Dohrn, and P. laevis, Grube, are all very similar. Endeis gracilis, Philippi (1843), is probably identical with P. spinosus, or one of its close allies. There are also known P. meridionalis, Böhm, P. mollis, Carp., and P. procerus, Loman, from the East Indies; P. australis, Hodgson, from the Antarctic; P. böhmii, Schimk., of unknown locality; and forms ascribed to P. charybdaeus by Haswell and by Schimkewitsch from Australia and Brazil.

=Fam. 10. Pycnogonidae.=—Appendages I. and II. absent; appendage III. present only in the male, 9–jointed, with small, simple spines; auxiliary claws absent or rudimentary; body and legs short, thick-set.

The only genus is Pycnogonum, Brünnich (1764) (Polygonopus, Pallas, 1766); the type is P. littorale, Ström, of the N. Atlantic (0–430 fathoms), to which species have also been ascribed forms from various remote localities, e.g. Japan, Chile, and Kerguelen. P. crassirostre, G. O. Sars, a northern and more or less deep-sea form, is distinct, and so also are P. nodulosum and P. pusillum, Dohrn, from Naples. P. stearnsi, Ives, from California, is like P. littorale, except for the rostrum, which resembles that of P. crassirostre. P. magellanicum, Hoek, P. magnirostre, Möbius, both from the Southern Ocean; P. microps, Loman, from Natal, and four others described by Loman from the East Indies, are the other authenticated species. Of P. philippinense, Semper, I know only the bare record; and P. australe, Grube, is described only from a larval form with three pairs of legs. P. orientale, Dana (first described as Astridium, n.g.), is also described from an immature specimen, and more resembles a Phoxichilus.

=The British Pycnogons.=

Dr. George Johnston, the naturalist-physician of Berwick-on-Tweed, Harry Goodsir, brother of the great anatomist, who perished with Sir John Franklin, and George Hodge of Seaham Harbour, a young naturalist of singular promise, dead ere his prime, were in former days the chief students of the British Pycnogons. Of late, Carpenter has studied the Irish species; and the cruises of the Porcupine, Triton, and Knight Errant have given us a number of deep-water species from the verge of the British area.

In compiling the following list, I have had the indispensable advantage of access to Canon Norman’s collection, and the still greater benefit of his own stores of endless information.

Pseudopallene circularis, Goodsir: Firth of Forth.

Phoxichilidium femoratum, Rathke (P. globosum, Goodsir; Orithyia coccinea, Johnston) (Figs. 270, B; 286): East and West coasts, Shetland, Ireland.

Anoplodactylus virescens, Hodge (? Phoxichilidium olivaceum, Gosse): South coast.

A. petiolatus, Kr. (Figs. 270, C; 275, B; 287) (Pallene attenuata and pygmaea, Hodge; Phoxichilidium exiguum and longicolle, Dohrn): Plymouth, Firth of Forth, Cumbrae, Irish coasts.

Ammothea (Achelia) echinata, Hodge (Fig. 265, B; 274, 4; 275, E): Plymouth, Channel Islands, Isle of Man, Cumbrae, Durham (Hodge), West of Ireland. We have not found it on the East of Scotland. A. brevipes, Hodge, is presumed to be the young. Two of Dohrn’s Neapolitan species, A. fibulifera and A. franciscana, are in my opinion not to be distinguished from one another, nor from the present species.

A. hispida, Hodge (Fig. 266, C) (A. longipes, Hodge (juv); A. magnirostris, Dohrn;? Pasithoe vesiculosa, Goodsir;? Pephredo hirsuta, Goodsir): Cornwall and Devon (Hodge and Norman), Jersey. The form common on the East of Scotland would seem to be this species. The Mediterranean A. magnirostris, Dohrn, appears to be identical.

A. laevis, Hodge: Cornwall (Hodge), Devon (Norman), Jersey (Sinel).

Tanystylum orbiculare, Wilson (Clotenia conirostre, Dohrn): Donegal (Carpenter).

Phoxichilus spinosus, Mont. (Fig. 265, C; 270, A; 275, C): South Coast, Moray Firth, Firth of Clyde, Ireland. A smaller and less spiny form occurs, which Carpenter records as P. laevis, Grube, but Norman unites the two under the name of Endeis spinosus (Mont.).

Pycnogonum littorale, Ström (Fig. 262): on all coasts, and to considerable depths (150 fathoms, West of Ireland).

Nymphon brevirostre, Hodge (N. gracile, Sars) (Figs. 263, 264, 267, A; 272, 274, 3): common on the East Coast; Herm (Hodge), Dublin, Queenstown (Carpenter). Our smallest species of Nymphon.

N. rubrum, Hodge (N. gracile, Johnston; N. rubrum, G. O. Sars): common on the East Coast; Oban (Norman), Ireland (Carpenter).

N. grossipes, O. Fabr., Johnston (N. johnstoni, Goodsir): Northumberland, East of Scotland, Orkney, etc., not uncommon.

N. gracile, Leach (N. gallicum, Hoek; ♂ N. femoratum, Leach): South of England, West of Scotland, and Ireland.

N. strömii, Kr. (N. giganteum, Goodsir) (Figs. 273, 274, 2): East Coast, from Holy Island to Shetland.

Chaetonymphon hirtum, Fabr. (Fig. 274, 1): Northumberland (Hodge), Margate (Hoek), East of Scotland, and Ireland, not uncommon. There seems to be no doubt that British specimens agree with this species as figured and identified by Sars. N. spinosum, Goodsir (East of Scotland, Goodsir; Belfast, W. Thompson), is, according to Norman, the same species. Sars’ Norwegian specimens figured under the latter name are not identical, and have been renamed by Norman C. spinosissimum, but are said by Meinert and Möbius to be identical with C. hirtipes, Bell.

Hodge (1864) records Nymphon mixtum, Kr., and N. longitarse, Kr., from the Durham coast. His full list of the recorded species of other authors also includes the following doubtful or unrecognised species: N. pellucidum, N. simile, and N. minutum, all of Goodsir.

Pallene brevirostris, Johnston (P. empusa, Wilson;? P. emaciata, Dohrn) (Figs. 275, A; 285): all coasts. Examples differ considerably in size and proportions, as do Dohrn’s Neapolitan species one from another. We have specimens from the Sound of Mull that come very near, and perhaps agree with, Sars’ P. producta, a species that scarcely differs from P. brevirostris, save in its greater attenuation; the same species has also been recorded from Millport and from Port Erin.

P. spectrum, Dohrn: Plymouth (A. H. Norman).

Besides the above, all of which are littoral or more or less shallow-water species, we have another series of forms, or, to speak more correctly, we have two other series of forms, from the deep Atlantic waters within the British area. In the cold area of the Faeroe Channel we have Boreonymphon robustum, Bell; Nymphon elegans, Hansen; N. sluiteri, Hoek; N. stenocheir, Norman; Colossendeis proboscidea, Sabine; C. angusta, Sars. In the warm waters south and west of the Wyville-Thomson ridge we have Chaetonymphon spinosissimum, Norman; Nymphon gracilipes, Heller (non Fabr.); N. hirtipes, Bell; N. longitarse, Kr.; N. macrum, Wilson; Pallenopsis tritonis, Hoek (= P. holti, Carpenter); Anoplodactylus oculatus, Carpenter, and A. typhlops, G. O. Sars; and to the list under this section Canon Norman has lately made the very interesting addition of Paranymphon spinosum, Caullery, from the Porcupine Station XVII., S.S.E. of Rockall, in 1230 fathoms. Lastly, and less clearly related to temperature, we have Chaetonymphon tenellum, Sars; N. gracilipes, Fabr.; N. leptocheles, Sars; N. macronyx, Sars; N. serratum, Sars; and Cordylochele malleolata, Sars.

Of the species recorded in the above list as a whole, Anoplodactylus virescens, Nymphon gracile, and Pallene spectrum reach their northern limit in the southern parts of our own area; Ammothea echinata, Anoplodactylus petiolatus, Pallene brevirostris, and Phoxichilus spinosus (or very closely related forms) range from the Mediterranean to Norway, the last three also to the other side of the Atlantic; Nymphon brevirostre and N. rubrum range from Britain, where they are in the main East Coast species, to Norway. Of the Atlantic species, other than the Arctic ones, the majority are known to extend to the New England coast.

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.

Abalius, 312

Abdomen, of Malacostraca, 110; of Acantholithus, =178=; of Birgus, =176=; of Cenobita, =176=; of Dermaturus, =178=; of Hapalogaster, =178=; of Lithodes, =178=; of Pylopagurus, =178=; of Trilobites, 235; of Scorpions, 297; of Pedipalpi, 309; of Spiders, 317; of Palpigradi, 422; of Solifugae, 426; of Pseudoscorpions, 431; of Podogona, 440; of Phalangidea, 440, 443; of Acarina, 457; of Pentastomida, 489; of Pycnogonida, 502

Abdominal glands, of Chernetidea, 432

Abyssal region (marine), 204; (lacustrine), 209

Acantheis, 418

Acanthephyra, 163

Acanthephyridae, 163

Acanthoctenus, 415

Acanthodon, 388

Acanthogammarus, 138

Acantholeberis, 53

Acantholithus, 181; A. hystrix, =178=

Acanthophrynus, 313

Acari, 454 (= Acarina, q.v.)

Acaridea, 454 (= Acarina, q.v.)

Acarina, 258, 454 f.; parasitic, 455; external structure, 457; spinning organs, 457; internal structure, =459=; metamorphosis, 462; classification, 464

Acaste, 249

Accola, 390

Acerocare, 247

Achelata, 529

Achelia, 534; A. longipes, =506=

Achtheres, 75; A. percarum, =75=

Acidaspidae, 251

Acidaspis, 226, 227, 230, 231, 235, 241, 251; A. dufrenoyi, =250=; A. tuberculata, larva, =240=; A. verneuili, 231; A. vesiculosa, 231

Aciniform glands, =335=, 349

Acoloides saitidis, 367

Acroperus, 53; A. leucocephalus, =52=

Acrosoma, 410

Acrothoracica, 92

Actaea, 191; habitat, 198

Actinopodinae, 387

Actinopus, 387

Aculeus, of scorpion, 303

Admetus, 313

Aegidae, 126

Aegisthus, 61

Aeglea laevis, 169; distribution, 212

Aegleidae, 169

Aeglina, 227, 249; Ae. prisca, =248=

Agelena, 416; A. brunnea, 367; A. labyrinthica, 352, 353, 378, 380, 381, 416; A. naevia, 339

Agelenidae, 325, 352, 353, 415

Ageleninae, 416

Aggregate glands, 335, 349

Aglaspis, 279

Agnathaner, 66

Agnathonia, 529

Agnostidae, 244

Agnostini, 243

Agnostus, 222, 223, 225, 231, 234, 245; A. integer, =245=

Agraulos, 247

Agroeca, 397; A. brunnea, cocoon, =358=

Albunea, 171; respiration, 170; distribution, 201

Albuneidae, 171

Alcippe, 92; A. lampas, =92=, 93

Alcock, on Oxyrhyncha, 192; on phosphorescence, 151

Alepas, 89

Alima, larva of Squilla, 143

Alimentary canal, of Crustacea, 14; of Phyllopoda, 28; of Cladocera, 42; of Squilla, 142; of Malacostraca, 110; of Trilobites, 222; of Arachnida, 256; of Limulus, 268; of Scorpions, 304; of Pedipalpi, 310; of Spiders, 329; of Solifugae, 427; of Pseudoscorpions, 134; of Phalangidea, 444; of Acarina, 459; of Tardigrada, 480; of Pentastomida, 491; of Pycnogous, 513

Alitropus (Aegidae), habitat, 211

Allman, on larvae of Pycnogons, 523

Alloptes, 466

Alona (including Leydigia, Alona, Harporhynchus, Graptoleberis), 53

Alonopsis, 53

Alpheidae, 163; habitat, 198

Alpheus, 163; reversal of regeneration, 156

Alveolus, of palpal organ of Spiders, 322

Amaurobius, 399; A. fenestralis, 399; A. ferox, 399; A. similis, 399; spinnerets, =326=

Amblyocarenum, 388

Amblyomma, 470; A. hebraeum, 456, 470

Amblypygi, 312

Ammothea, 505, 534; A. achelioides, 534; A. brevipes, 541; A. echinata, =505=, =509=, =510=, 534, 541, 542; A. fibulifera, =522=, 534, 541; A. franciscana, 541; A. grandis, 534; A. hispida, 534, 535, 541; A. laevis, 541; A. longicollis, 533; A. longipes, =506=, 534, 541; A. magnirostris, 534, 541; A. typhlops, 542; A. uniunguiculata, 534

Ammotheidae, 534

Amopaum, 452

Ampharthrandria, 61

Amphascandria, 57

Amphion, 251

Amphipoda, 136 f.; pelagic, 202; fresh water, 211

Ampullaceal glands, 335, 349

Ampycini, 243

Ampyx, 231, 245; A. roualti, =230=

Anabiosis, in Tardigrada, 484

Analges, 455, 466

Analgesinae, 466

Ananteris, 306

Anaphia, 539

Anaspidacea, 115; distribution, 211, 217

Anaspidae, 89

Anaspides, 115, 117; relation to Schizopoda, 112; distribution, 211; A. tasmaniae, 115, =116=; habitat, 211

Anaspididae, 115

Anelasma squalicola, 89

Anelasmocephalus, 452

Angelina, 247

Anisaspis bacillifera, 387

Anisopoda, 122

Anomalocera pattersoni, =60=; distribution, 202, 203

Anomopoda, 51

Anomorhynchus, 532

Anomura, 167; relation to Thalassinidea, 167

Anoplodactylus, 511, 538; A. lentus, 524; A. neglectus, 539; A. oculatus, 542; A. petiolatus, =508=, =510=, =539=, 541, 542; A. virescens, 540, 542

Anopolenus, 247

Antarctic zone (marine), 200

Antarctica, evidence on, 200, 217

Antennae, of Crustacea, 5, 8; of Phyllopoda, 24; of Cladocera, 37; of Copepoda, 55; of Cirripedia, 81 f.; of Ostracoda, 107; of Malacostraca, 110; of Anomura, 168; of Corystes cassivelaunus, 170, 183, 189; used in respiration, 170; of Trilobites, 237

Antennary gland, 13 (= green gland, q.v.)

Anthrobia, 406; A. mammouthia, 334, 366

Anthura, 124

Anthuridae, 124

Ants and spiders, 370

Anyphaena accentuata, 397

Aphantochilinae, 414

Aphantochilus, 414

Apoda, 94

Apodidae, 19, 21, 22, 23, 27, 28, 29, 31, 36, 241

Aponomma, 470

Appendages (incl. legs, limbs), of Crustacea, 7; of Entomostraca, 18; of Phyllopoda, 24; of Cladocera, 40; of Copepoda, 55; of Cirripedia, 80 f.; of Ostracoda, 107; of Malacostraca, 110; of Nebalia, 111; of Eumalacostraca, 113; of Anaspides, 115; of Mysidacea, 118 f.; of Cumacea, 120; of Isopoda, 121 f.; of Amphipoda, 136 f.; of Stomatopoda, 142; of Euphausiacea, 144 f.; of Decapoda, 152; of Macrura, 153; of their larvae, 159; of Anomura, 167 f.; of Birgus, 175; of Brachyura, 181 f.; alterations caused by parasites, 100 f.; by hermaphroditism, 102 f.; of Trilobita, 236, =237=; of Arachnida, 255 f.; of Limulus, =262=, 263; of Eurypterus, 285 f.; of Scorpions, 301, 303; of Pedipalpi, 309; of Spiders, 319; of Palpigradi, 422; of Solifugae, 426; of Pseudoscorpions, 432; of Podogona, 440; of Phalangidea, 443; of Acarina, 458; of Tardigrada, 479; of Pentastomida, 493; of Pycnogons, 503 f.

Apseudes spinosus, =123=

Apseudidae, 122

Apstein, 335

Apus, 21, 23, 25, 28, 30, 32, 34, 36, 221, 242, 243; segmentation, 6; A. australiensis, 36; A. cancriformis, 36; habitat, 34

Arachnida, introduction to, 255; segmentation of body, 255–6; primitive, 256–7; coxal glands, 257; endosternite, 257; sense-organs, 257; classification, 258

Araneae, 258, 314 f.

Araneida, 314

Araneina, 314

Araneus, 408 n.

Aratus pisonii, 195

Arbanitis, 388

Archaeolepas, 84; A. redtenbacheri, =84=

Archea, 411; A. paradoxa, 383; A. workmani, 411

Archeidae, 321, 411

Archisometrus, 306

Arctic zone, 199

Arcturidae, 127

Arcturus, 127

Arcyinae, 410

Arcys, 410

Arethusina, 223, 230, 251; A. konincki, =250=

Argas, 457, 469; A. persicus, 469; A. reflexus, 469

Argasidae, 469

Arges, 252

Argiope, 408; A. aurelia, 340, =379=; A. bruennichi, 408; A. cophinaria, 349, 365; A. trifasciata, 408

Argiopidae, 406 n.

Argiopinae, 408

Argulidae, 76

Argulus foliaceus, =77=

Argyrodes, 402; A. piraticum, 367; A. trigonum, 367

Argyrodinae, 402

Argyroneta, 336, 415; A. aquatica, 357, 415

Ariadna, 395

Ariamnes, 402; A. flagellum, =318=

Arionellus, 247

Aristaeus, 162; A. crassipes, 159; A. coruscans, phosphorescence, 151

Armadillidium, 129

Artema, 401

Artemia, 23, 24, 35; A. fertilis, anal region, =23=; head, =26=; limb, 27; A. salina, 23, 33, 36; A. urmiana, 23

Arthrolycosa antiqua, 383

Arthropoda, 4; segmentation, 7; a natural group, 17

Arthrostraca, 121

Asagena, 404

Asaphellus, 249

Asaphidae, 249

Asaphini, 243

Asaphus, 222, 225, 227, 229, 235, 236, 249; A. cornigerus, 227; A. fallax, eye, =228=; A. kowalewskii, 227; A. megistos, 236; A. platycephalus, 236

Ascidicola rosea, 66

Ascidicolidae, 66

Asconiscidae, 130

Ascorhynchus, 505, 533; A. abyssi, =506=, =509=, 519; A. cryptopygius, 513 n.; A. minutus, 517; A. ramipes, 513 n.

Ascothoracica, 93

Asellidae, 128

Asellota, 127

Asellus, 127; habitat, 209, 211; A. aquaticus, 127, 209; A. cavaticus, 209, 210; A. forelii, 209

Aspidoecia, 76

Astacidae, 157; distribution, 213, 216

Astacoides, 157; distribution, 213

Astacopsis, 157; distribution, 213; A. franklinii, 214

Astacus, 104, 157; appendages, =10=; distribution, 213; hermaphroditism, 104

Astacus gammarus (= Homarus vulgaris), 154

Asterocheres violaceus, =67=

Asterocheridae, 67

Asterope oblonga, =108=

Astia, 421; A. vittata, =381=

Astigmata, 465

Astridium, 540

Atax, 462, 472; A. alticola, =472=; A. bonzi, 472

Atelecyclidae, 190

Atelecyclus, 191; respiration, 189

Atops, 247

Attidae, 376, 381, 419

Attus, 421; A. pubescens, 372, 421; A. saltator, 372, 421

Atya, 163

Atyephyra, 163; habitat, 210

Atyidae, 159, 163; distribution, 212

Atypidae, 390

Atypoides, 391

Atypus, 391; A. abboti, 356; A. affinis, 356, =391=; A. beckii, 391

Auditory organ, of Anaspides, 116; of Decapoda, 153; of Mysidae, 119

Augaptilus filigerus, 59

Austrodecus glacialis, 535

Austroraptus polaris, 535

Autotomy, 155

Avicularia, 389

Aviculariidae, 316, 327, 386; bite of, 365; poisonous hairs of, 365

Aviculariinae, 389

Axial furrows, 223

Baglivi, 361

Baikal, Lake, Crustacea of, 212

Balanus, 91; B. porcatus, shell, =90=; B. tintinnabulum, 91; anatomy, =90=

Ballus variegatus, =420=

Barana, 506, 513, 533; B. arenicola, 512, 513, 533; B. castelli, 512, 513 n., 533

Barnacles, origin of term, 79

Barrande, J., on development of Trilobites, 238; on their classification, 243

Barrandia, 249

Barrois, 435 n.

Barrus, 429

Barychelinae, 389

Basse, on Tardigrada, 481

Baster, Job, 503

Bates, 373

Bathynomus giganteus, 126; habitat, 205

Bathynotus, 247

Bathyphantes, 406

Bdella lignicola, =471=

Bdellidae, 458, 471

Beecher, C. E., on facial sutures of Agnostus and Olenellus, 225; on development of Trilobites, 238; on their classification, 243

Beetle-mites, 467

Beetle-parasites, 470

Belinurus, 275, 279; B. reginae, =278=

Belisarius, 308

Belt, 368, 371

Beltina, 283 n.

Bernard, 311, 424, 426, 433 n., 434 n.

Bertkau, 323, 365, 395 n.

Beyrich, E., on facial suture of Trinucleus, 226

Billings, E., on appendages of Trilobites, 236

Bipolarity, 200

Birds and Spiders, 370

Birds’ feather Mites, 466

Birgus, 181; B. latro, habits, 174; structure, =175=, =176=

Black Corals, Cirripedia parasitic on, 93, 94

Blackwall, 348, 359 n., 365, 368, 385

Blindness, in Crustacea, 149, 209, 210; in Spiders, 334

Blood, haemoglobin supposed in, 30, 68

Boas, on classification of Malacostraca, 113

Boeckella, distribution, 216

Boeckia, 138

Böhmia, 535

Bolocera, Pycnogonum with, 524

Bolyphantes, 406

Bomolochidae, 71

Bomolochus, 71, =72=

Bon, 360

Bont-tick, 456

Boophilus, 456, 469; B. australis, capitulum of, =468=

Bopyridae, 130, 133

Bopyrina, 129, 130, 132

Bopyrus fougerouxi, 133; male, =133=; adult female, =134=

Bopyrus larva, of Bopyrina, 129, 133

Boreomysis, 120; B. scyphops, distribution, 201

Boreonymphon, 536; B. robustum, =506=, 507, =511=, 512, 542

Bosmina, =52=, 53; occurrence in Southern hemisphere, 216; B. longirostris, habitat, 206

Bosminidae, 53; appendages, 41; alimentary canal, 42

Bothriuridae, 306, 308

Bothriurus, 308

Bouvier, 528 n.

Boys, 348, 360, 376

Brachybothrium, 391

Brachymetopus, 251

Brachythele, 390

Brachyura, 181; eyes, 150

Branchiae (= gills) of Crustacea, 16; of Decapoda, 152; of Limulus, 269; of Eurypterids, 288

Branchinecta, 25, 35; B. paludosa, 35; range, 34

Branchiopoda, 18 f.

Branchiopodopsis, 35; B. hodgsoni, 35

Branchiostegite, 152

Branchipodidae, 19, 22, 35, 241

Branchipus, 25, 35, 233, 242, 511 n.; thoracic limb, =10=; nervous system, 30; B. spinosus, habitat, 33; B. stagnalis, 35; eggs, 32

Branchiura, 76

Brauer, on development of Scorpions, 263, 301 n., 305

Breeding (see Reproduction)

British forms, of Cladocera, 51; of Pycnogons, 540

Bronteidae, 249

Bronteus, 228, 235, 249; B. brongniarti, eye, 229; B. palifer, eye, 229; B. polyactin, hypostome, =233=; B. irradians, macula, =233=

Brood-pouch, of Cladocera, 46, 47; of Peracarida, 118

Broteas, 308

Broteochactas, 308

Brünnich, 502

Buckler, 330

Bucranium, 414

Bulb, of palpal organ of Spiders, 322

Bumastus, 235, 236, 249

Bunodella, 279

Bunodes, 279

Buthidae, 306

Buthinae, 306

Buthus, 306; B. occitanus, =299=, =300=, =302=

Bythotrephes, 38, 54; reproduction, 47; B. cederströmii, =42=

Cabiropsidae, 130

Caecidotea nickajackensis, habitat, 210; C. stygia, habitat, 210

Caeculinae, 472

Caeculus, 472

Calamistrum, =326=, 354, 385, 392, 399, 410

Calanidae, 57

Calanus, 57; C. finmarchicus, distribution, 203, 204; C. hyperboreus, 55, =56=, 58

Calappa, 187; respiration, 186; habitat, 198; distribution, 201; C. granulata, =186=

Calappidae, 187

Calathocratus, 452

Calathura brachiata (Anthuridae), Duplorbis parasitic on, 95

Calicurgus annulatus, 369

Caligidae, 73

Caligus nanus, =74=; C. rapax, 74; C. lacustris, 74

Callianassa, 167; habitat, 198; C. subterranea, 167; gut, 14

Callianassidae, 167

Callinectes, 191; C. sapidus, 191

Calman, on classification of Crustacea, 112, 113

Calocalanus plumulosus, =58=

Caloctenus, 418

Calommata, 391

Calymene, 225, 230, 235, 249; C. senaria, 236; C. tuberculata, =224=

Calymenidae, 247

Calyptomera, 38, 51

Calyptopis, larva of Euphausia pellucida, =144=

Cambaroides, distribution, 213

Cambarus, 157; hermaphroditism, 103; distribution, 213; C. stygius, distribution, 213

Camerostome, 452

Campbell, 327

Camptocercus, 53; C. macrurus, 48

Cancer, 191; C. pagurus, 191

Cancerilla, 68; C. tubulata, 68

Cancridae, 191

Candace, 60; C. pectinata, 60

Candacidae, 60

Candona, 107; C. reptans, =107=

Canestrini, 464

Canthocamptus, 62; habitat, 206

Capitulum, of Cirripedia, 81; of Acarina, 457, 468, 471

Caponia natalensis, 395

Caponiidae, 395

Caponina, 395

Caprella acutifrons, 140; C. grandimana, =139=

Caprellidae, 139

Carapace, of Phyllopoda, 19 f.; of Cladocera, 38; absence of, in Copepoda, 55; of Malacostraca, 114

Carcinoplacidae, 195

Carrinoscorpius, 277; C. rotundicauda, 277

Carcinus, 191; C. maenas, 188, 191; gut, 14; respiration, 189, 190; distribution, 198; Portunion parasitic in, =135=; Sacculina parasitic on, 96

Cardisoma, 196; distribution, 201

Caridea, 158, 163; metamorphosis, 161

Caridina, 163; C. nilotica, distribution, 212

Carniola, caves of, 34

Carpenter, on segmentation of Arthropods, 6, 263; on affinities of Trilobites, 242; on Irish Pycnogons, 540

Caruncle, 470

Caspian Sea, Crustacea of, 215

Caspiocuma, 121

Catometopa, 193 f.; habits, 194, 195

Catophragmus, =91=

Caudal organs, 311

Caullery, on Liriopsidae, 132 n.

Causard, 332

Cavanna, 520

Cecrops, 74

Cenobita, 181; relation to Birgus, =176=

Cenobitidae, 181

Centropages hamatus, 203; C. typicus, distribution, 203

Centropagidae, 58

Centropelma, 416

Centropleura, 247

Centrurinae, 306

Centrurus, 306

Cephalic shield, 223

Cepheus ocellatus, =467=

Cerataspis, 162

Ceratolichas, 252

Ceratopyge, 247

Cercophonius, 308

Ceriodaphnia, 37, 39, 51

Ceroma, 429

Chactas, 308

Chactidae, 306, 307

Chaerilidae, 306, 307

Chaerilus, 307

Chaetolepas, 89

Chaetonymphon, 536; C. hirtipes, 541; C. hirtum, =509=, 541; C. macronyx, =506=; C. spinosissimum, 541, 542; C. tenellum, 542

Chaetopelma, 389

Charontinae, 313

Chasmops, 249

Cheeks, of Trilobites, 223, 225

Cheese-mites, 466

Cheiracanthium, 397

Cheiruridae, 250

Cheirurus, 235, 251; C. insignia, =250=; C. pleurexacanthus, 236

Chelicerae, of Xiphosura, 263 f.; of Eurypterida, 285; of Scorpions, 303; of Pedipalpi, 309; of Spiders, 319; of Palpigradi, 422; of Solifugae, 426; of Pseudoscorpions, 432; of Podogona, 439; of Phalangids, 443; of Acarina, 458

Chelifer, 436, 437; development, =435=; C. cancroides, 437; C. cyrneus, =437=; C. ferum 437

Chelifera, 122

Cheliferidae, 436

Chelophores, of Pycnogons, 505

Chernes, =432=, 436, 437, 438

Chernetes, 430

Chernetidea, 258, 430 f.

Cheyletinae, 473

Cheyletus, 458, 473

Chilaria, 260, 271, 287, 292

Chilobrachys, 390; C. stridulans, =328=, 329

Chilophoxus, 539

Chiltonia, 139; distribution, 217

Chiridium, 432, 436, 437; C. museorum, =437=

Chirocephalus, 35; C. diaphanus, =20=, =24=, =25=, =27=, 29, 32, 33, 35

Chlorodinus, habitat, 198

Chlorodius, 191

Chondracanthidae, 72

Chondracanthus zei, =72=

Choniostoma, 76

Choniostomatidae, 76

Chthonius, 436, 438

Chun, on phosphorescence and eyes, 150

Chydorus, 54

Cilunculus, 535

Circulatory (= vascular) system, of Crustacea, 11; of Arachnids, 256; of Limulus, 268 f.; of Tardigrada, 482; of Pentastomida, 491; of Pycnogons, 516

Cirolana, 126

Cirripedia, 79 f.; metamorphosis, 80; anatomy, 83; sex, 87, 105

CLADOCERA, 19, 37 f.; carapace, 38; dorsal organ, 39; appendages, 40 f.; alimentary canal, 42; heart, 43; reproduction, 43–50; British genera, 51–54; extra-European, 54; pelagic, 207, 208

Claparède, 331, 462 n.

Clarke, J. M., on the eye of Calymene senaria, 229; of Harpes, 231

Claus, on Copepoda, 55; on Nebalia, 111; on discovery of metamorphosis of Decapods, 153 n.; on Pycnogonida, 527

Claw-tufts, 389

Clerck, 384, 408 n.

Clibanarius, 181

Clotenia conirostre, 541

Clubiona, 337, 368, 397; C. compta, 397; C. corticalis, =396=, 397

Clubioninae, 397

Clypeus, 316

Clytemnestra, 61

Coelotes atropos, 416

Cole, 520, 524, 525, 528 n.

Colossendeis, 505, 532; C. angusta, 542; C. australis, 533; C. gibbosa, 534; C. gigas, 532; C. gracilis, 505 n.; C. proboscidea, =505=, =508=, =510=, 533, 542

Colour, adaptation in, of Crustacea, 159

Colulus, =317=, 319

Commensalism, of Hermit-crabs, 172; of Pinnotheres, 195

Complemental males, of Cirripedes, 83, 86, 99, 106

Conchoderma, 88; C. virgata, =88=

Conocephalidae, 247

Conocoryphe, 231, 247; C. sulzeri, =248=

Conocoryphidae, 247

Conolichas, 252

Conothele, 388

Constantia (Macrohectopus), 138; occurrence, 212

Cook, 425 n.

Copepoda, 55 f.; fresh-water, 59, 62; pelagic, 202; life-cycle of fresh-water, 209

Copilia vitrea, 69, =70=

Cordylochele, 506, 537; C. longicollis, =507=; C. malleolata, 542

Corniger hilgendorfi, 535

Coronula diadema, 91

Corophiidae, 139

Corophium, 139

Corycaeidae, 69

Corystes, 188, 190; habitat, 198; C. cassivelaunus, respiration, 170, 189; metamorphosis, =182=, =183=

Corystidae, 190

Cosmetidae, 449

Costa, da, 221

Coxal glands, 257; of Limulus, 270; of Scorpions, 306; of Pedipalpi, 311; of Spiders, 337

Coxopodite, of Trilobites, 237

Crab, Hermit-, 171–173; River-, 214; Robber-, 174; Shore-, 188, 189, 198; Edible, 188; Spider-, 191; Land-, 195; enemies of, 192

Crab-spiders, 412 (= Thomisidae, q.v.)

Crangon, 164; C. antarcticus, distribution, 200; C. franciscorum, distribution, 200; C. vulgaris, 158, 164; distribution, 199

Crangonidae, 164; distribution, 199

Crangonyx, 138

Crayfish, 154, 157; distribution, 213, 215

Crevettina, 137

Cribellatae, 324, 385, 386 n.

Cribellum, =326=, 354, 385, 386, 392, 398, 410

Croneberg, 460

Cruregens, 124; C. fontanus, habitat, 210

Crustacea, organisation, 1 f.; segmentation, 5; appendages, 8 f.; body-cavity and coelom, 11; kidneys, 13; alimentary canal, 14; reproductive organs, 15; respiratory organs, 16; compound eyes, 146; growth and sex in, 100; metabolism, 104; distribution, 197; pelagic, 202, 207; littoral, 197, 206; abyssal, 204, 209; fresh-water, 205; subterranean and cave, 209

Crustacés aranéiformes, 501 n.

Cryphaeus, 249

Cryphoeca, 416

Cryptocellus, 439; C. simonis, =439=

Cryptocerus, 414

Cryptoniscidae, 130

Cryptoniscina, 129, 130

Cryptoniscus, larva of Epicarida, 129, =131=, 132

Cryptophialus, 92; C. minutus, 92, 93; C. striatus, 93

Cryptostemma westermannii, 439

Cryptostemmatidae, 440

Cryptothele, 400

Ctenidae, 418

Cteninae, 418

Cteniza, 388; C. ariana, 355

Ctenizinae, 388

Ctenocephalus, 247

Ctenophora, 412

Ctenopoda, 51

Ctenopyge, 232, 247

Ctenus, 418

Cucullus, 440

Cuma, 121

Cumacea, 114, 120; of the Caspian, 215

Cumidae, 121

Cyamidae, 140

Cyamus ceti, 140

Cybaeinae, 415

Cybele, 251

Cyclaspis, 121

Cyclestheria, 37; C. hislopi, 37

Cyclodorippe dromioides, eyes, 149

Cyclograpsus, 196; distribution, 200

Cyclometopa, 188 f.; respiration, 189, 190

Cyclopidae, 61, 62; subterranean, 209

Cyclops, 62; C. fuscus, habitat, 207; C. strenuus, habitat, 207, 208; C. stygius, habitat, 210

Cyclosa conica, 409

Cyclosternum, 389

Cydrela, 399

Cymodoce, 126

Cymonomus, 188; C. granulatus, =185=; eyes, 149, 186; C. normani, 186; C. quadratus, 186

Cymothoa, 126; habitat, 211

Cymothoidae, 126

Cyphaspis, 251

Cyphophthalmi, 443, 444, 447

Cypridae, 107; subterranean, 209

Cypridinidae, 108

Cypris, 107; C. reptans, parthenogenesis, 108

Cypris larva, of Cirripedia, 80, =82=; of Sacculina, =97=, =99=

Cyrtauchenius, 388; C. elongatus, funnel of, =356=

Cythere dictyon, 108

Cytherellidae, 109

Cytheridae, 107

Dactylopisthes digiticeps, =405=

Dactylopus tisboides, 62

Daesia, 429

Daesiinae, 429

Dajidae, 130

Dalmanites, 249; D. imbricatulus, eye, =228=; D. limulurus, =250=; D. socialis, larvae, =240=

Danalia curvata, 130, =131=, =132=

Daphnella, 51; testes, 44

Daphnia, 37, 38, 39, 51; ovary, =45=, 48; D. magna, 50; D. obtusa, =51=

Daphniidae, 51; appendages, 40; alimentary canal, 42; reproduction, 48; reactions, 50

Darwin, on Cirripedia, 80, 85, 86, 92, 94

Dasylobus, 450

Decapoda, 152 f.; systematic position, 114; alimentary canal, 14; pelagic, 202; subterranean, 210; Rhizocephala parasitic on, 95, 101; Bopyridae parasitic on, 133

Dechenella, 251

Decolopoda, 504, 529, 532; D. antarctica, 532; D. australis, =531=, 532

Decolopodidae, 531

Defective orb-webs, 349

Deiphon, 235, 251; D. forbesi, =250=

Delena, 414

Delobranchiata, 258, 259 f.

Demodex, 465; D. folliculorum, =465=

Demodicidae, 455, 465

Dendrogaster astericola, 94

Dermacentor, 469

Dermanyssinae, 471

Dermanyssus avium, 471

Dermaturus, 181; D. hispidus, =178=

Desis, 415

Deutovum, 462

Development, of Monstrillidae, 64; of Cirripedia, 80; of Rhizocephala, 96; of Epicarida, 130; of Stomatopoda, 142; of Shrimps and Prawns, 159; of Loricata, 165; of Hermit-Crabs, 179; of Brachyura, 181; of Trilobites, 238 f.; of Limulus, 275; of Scorpio, 305; of Pseudoscorpions, 434; of Mites, 462; of Tardigrada, 483; of Pentastomida, 493; of Pycnogons, 520

Diaea, 412; D. dorsata, 413

Diaphragm, of Solifugae, 427

Diaptomus, 59; distribution, 208, 216; D. caeruleus, habitat, 208; D. castor, habitat, 206; D. gracilis, habitat, 206

Diastylidae, 121

Diastylis, 121; D. goodsiri, 121; D. stygia, =120=

Dichelaspis, 88

Dichelestiidae, 68; classification, 63

Dichelestium, 68

Dick, 363

Dicranogmus, 252

Dicranolasma, 452

Dictyna, 398; D. arundinacea, 399; D. uncinata, 399

Dictynidae, 352, 353, 398

Digestive system, = alimentary canal, q.v.

Dikelocephalus, 247

Dimorphism, high and low; in Decapoda, 103; in Tanaids, 123

Dindymene, 251

Dinopinae, 410

Dinopis, 410

Dinorhax, 429

Diogenes, 181

Dionide, 245

Diphascon, 485; D. alpinum, 487; D. angustatum, 487; D. bullatum, 487; D. chilenense, =486=, 487; D. oculatum, 487; D. scoticum, 487; D. spitzbergense, 487

Diplocentrinae, 306, 307

Diplocentrus, 307

Diplocephalus bicephalus, =405=

Diplostichous eyes, 301

Diplura, 390

Diplurinae, 390

Dipoena, 403

Discoarachne, 512, 535

Distribution, of Crustacea, 197 f.; (stratigraphical) of Trilobites, 222

Doflein, on eyes of deep-sea Crustacea, 148, 150

Dohrn, 504, 513, 519

Doleschall, 365

Dolichopterus, 283, 291

Doliomelus, 415

Dolomedes fimbriatus, 416

Dolops, 78

Domed webs, 350

Donachochara, 406

Donnadieu, 457

Dorippe, 185, 188

Dorippidae, 188

Doropygus, 66; D. pulex, =66=

Dorsal organ, of Phyllopoda, 22; of Cladocera, 39

Doublure, 232

Doyère, on Tardigrada, 481; on their systematic position, 483

Doyeria, 485; D. simplex, 480, 487

Drassidae, 324, 396

Drassinae, 396

Drassus, 397; D. lapidosus, =396=, 397

Drepanothrix, 53

Dromia, 184; D. vulgaris, =184=

Dromiacea, 183; metamorphosis, 182; relation to Macrura, 184; habitat, 198

Dromidia, distribution, 200

Dromiidae, 184

Drymusa, 393

Dufour, 385

Dujardin, 464 n.; on systematic position of Tardigrada, 483

Duplorbis, 95; D. calathurae, 99

Dynomene, 184

Dynomenidae, 184

Dysdera, 394; D. cambridgii, 394; D. crocota, 395

Dysderidae, 317, 319, 336, 394

Dysderina, 394

Dysderinae, 394

Ebalia, 188

Echiniscoides, 485; E. sigismundi, 477, 486

Echiniscus, 480, 485; E. arctomys, 486; E. gladiator, 486; E. granulatus, 486; E. islandicus, 486; E. muscicola, 486; E. mutabilis, 486; E. oihonnae, 486; E. quadrispinosus, 486; E. reticulatus, 486; E. spinulosus, =479=; E. spitzbergensis, 486; E. testudo, =478=; E. wendti, 486

Echinoderms, Dendrogaster parasitic on, 94

Echinognathus, 283

Ecribellatae, 385

Ectatosticta davidi, 393

Ectinosoma, 62

Edriophthalmata, 112, 121

Eggs, of Phyllopoda, 32; of Cladocera, 44; of Copepoda, 59, 62, =66=, =67=, =71=, =74=; of Branchiura, 77; of Syncarida, 114; of Peracarida, 123; of Hoplocarida, 141; of Eucarida, 144; of Trilobites, 238; of Limulus, 275; of Pedipalpi, 309; of Spiders, 358; of Solifugae, 424; of Pseudoscorpions, 434; of Phalangidea, 442; of Acarina, 456; of Tardigrada, 478; of Pentastomida, 493; of Pycnogons, 520

Ehrenberg, on systematic position of Tardigrada, 483

Eleleis crinita, 396

Ellipsocephalus, 224, 235, 247; E. hoffi, =248=

Embolobranchiata, 258, 259, 297 f.

Emmerich, on facial suture of Trinucleus, 226

Encephaloides, 193; E. armstrongi, 192, =193=; habitat, 205

Encrinuridae, 251

Encrinurus, 227, 235, 251

Endeis didactyla, 534; E. gracilis, 539; E. spinosus, 541

Endite, 9, =10=

Endopodite, 9, =10=; of Trilobites, =237=

Endosternite, 257, 305, 330

Endostoma, of Eurypterus, 287

Engaeus, 157; E. fossor, distribution, 213

Enoplectenus, 418

Enterocola, 67; E. fulgens, =67=

Entomostraca, defined, 6; diagnosis, 18; of littoral zone, 197; fresh-water, of southern hemisphere, 216

Entoniscidae, 130, 134

Enyo, 400

Enyoidae, 399

Eoscorpius, 298

Epeira, 409; E. angulata, =315=, =409=; E. basilica, 350, 351; web of, =351=; E. bifurcata, 359; E. caudata, 359; E. cornuta, 409; E. cucurbitina, 372, 409; E. diademata, 335, 340, 343, 345, 359, 366, 380, 409; anatomy, =332=; cocoon, =358=; silk, 360; spinnerets, =325=; E. labyrinthea, 350; E. madagascarensis, 360; E. mauritia, 349; E. pyramidata, 409; E. quadrata, 366, 409; E. triaranea, 350; E. umbratica, 409

Epeiridae, 376, 377, 406

Epeirinae, 408

Ephippium, =48=

Epiblemum, 420

Epicarida, 129; sex in, 105

Epicaridian, larva of Epicarida, =130=

Epicoxite, of Eurypterus, 287

Epidanus, 449

Epigyne, 319, 333, 378

Epipharynx, 459

Epipodite, 9, =10=

Episininae, 402

Episinus truncatus, 403

Epistome, of Eurypterida, 291; of Pseudoscorpions, 431, 436; of Phalangidea, 443

Erber, 355, 356

Eremobates, 429

Eremobatinae, 429

Eresidae, 398

Eresus cinnaberinus, 398

Eriauchenus, 411

Erichthoidina, larva of Stomatopod, =143=

Ericthus, larva of Stomatopod, =143=

Erigone, 405

Erigoninae, 404

Eriophyes, 465; E. ribis, 455, =465=; E. tiliae, 465

Eriophyidae, 464

Eriphia, 191; E. spinifrons, 191

Erlanger, von, on development and position of Tardigrada, 483

Ero, 411; E. furcata, 366, 411; cocoon, =358=; E. tuberculata, 412

Eryonidae, 158; habitat, 204

Eryonidea, 157

Erythraeinae, 473

Estheria, 21, 22, =23=, 36; E. gubernator and E. macgillivrayi, habitat, 33; E. tetraceros, 36

Eucarida, 114, 144 f.

Euchaeta norwegica, 58

Eucopepoda, 57 f.

Eucopia australis, =119=

Eucopiidae, 113, 114, 118

Eudendrium, Pycnogons on, 520

Eudorella, 121

Eukoenenia, 423; E. augusta, 423; E. florenciae, 423; E. grassii, 423

Eulimnadia, 36; E. mauritani, 36; E. texana, 36

Euloma, 230

Eumalacostraca, 112 f.

Eupagurinae, 180

Eupagurus, 180; E. bernhardus, commensalism, 172; distribution, 199; E. excavatus, parasitic castration of, 101; E. longicarpus, metamorphosis, =179=; E. prideauxii, commensalism, 172; E. pubescens, distribution, 199

Euphausia pellucida, 145, =146=

Euphausiacea, 144

Euphausiidae, 113, 114, 144; larval history, 145; eyes, 150

Eupodes, 471

Euproöps, 278

Eurycare, 232, 247

Eurycercus, 53; alimentary canal, 42; E. lamellatus, habitat, 207

Eurycide, 505, 533; E. hispida, =506=, =507=, =533=

Eurycididae, 533

Eurydium, 485

Euryopis, 404

Eurypelma, 389; E. hentzii, 361, 370

Euryplax, 195

Eurypterida, 258, 278, 283 f.

Eurypteridae, 290 f.

Eurypterus, 283 f., 290, 291, 292; E. fischeri, =284=, =286=, =289=

Eurytemora, 59; E. affinis, habitat, 206

Eusarcus, 283, 291

Euscorpiinae, 308

Euscorpius, 298, 308; E. carpathicus, 299

Eusimonia, 429

Euterpe acutifrons, 61, =61=; distribution, 203

Euthycoelus, 389

Evadne, 54; young, 47

Excretory system (including Renal organs), in Crustacea, 12; in Arachnids, 257; in Limulus, 270; in Tardigrada, 481; in Pentastomida, 491

Exner, on mosaic vision, 148

Exopodite, 9, =10=; of Trilobites, =237=

Eyes, compound, of Crustacea, 146, =147=; physiology of, 148; of deep-sea Crustacea, 149; connexion with phosphorescent organs, 151; regeneration of, 6; of Trilobites, 227 f., =228=; of Limulus, 271; of Eurypterida, 285; of Scorpions, 301; of Pedipalpi, 309; of Spiders, 315, 334; of Solifugae, 426; of Pseudoscorpions, 431; of Phalangidea, 442; of Acarina, 458; of Pycnogons, 517

Fabre, on habits of Spiders, 298 f.; of Tarantula, 361 f.; on Wasp v. Spider, 368 f.

Facet, of Trilobites, 235

Facial suture, 225 f., 232

Falanga, 424

False articulations, 444

False-scorpions, 430

Fecenia, 399

Filistata, 391; F. capitata, 392; F. testacea, 392

Filistatidae, 319, 336, 391

Finger-keel, 303

Fixed cheek, 225, 226, 227

Flabellifera, 124 f.

Flabellum, 270

Flacourt, 363

Flagellum, in Solifugae, 426, 428; in Pseudoscorpions, 433

Forbes, 374

Ford, S. W., on development of Trilobites, 238

Forel, on Lake of Geneva, 206

Formicina, 405

Formicinae, 405

Formicinoides brasiliana, =318=

Fragilia, 535

Free cheek, 225, 226, 227

Fresh-water, Crustacea, 205 f.; Spiders, 357

Furcilia (Metazoaea), larva of Euphausia, 145

Fusulae, 325, 335

Galathea, 169, 170; G. intermedia, Pleurocrypta parasitic on, =133=; G. strigosa, =170=; gut of, 15

Galatheidae, 169

Galatheidea, 169

Galea, 433, 436

Galena, 412

Galeodes, 429, 527; nervous system, =428=; chelicera, =429=; G. arabs, 425; G. araneoides, 425

Galeodidae, 428

Gall-mites, 455, 464

Gamasidae, 470

Gamasinae, 470

Gamasus, 460, 461, 463, 470; G. coleoptratorum, 470; G. crassipes, 470; G. terribilis, 461

Gammaridae, 138

Gammarus, 137, 138; of Lake Baikal, 212; of Australia, 216; G. locusta, 138, =138=; G. pulex, 138

Gampsonyx, 115, 118

Garstang, on respiration of crabs, 186 n.

Garypinae, 436, 437

Garypus, 431, 436, 437, 438; chelicera, =432=; G. littoralis, 430

Gaskell, 270, 277, 334

Gasteracantha, 410; G. minax, =410=

Gasteracanthinae, 317, 409

Gastrodelphys, 73

Gastrolith, of Lobster, 155

Gaubert, 525 n.

Gebia littoralis, 167

Gecarcinidae, 196

Gecarcinus, 194, 195, 196

Gegenbaur, 523

Gelanor, 411, 412

Gelasimus, 194, 196; habitat, 198; distribution, 210; G. annulipes, =194=

Genal angle, 225

Gené, 461

Genital operculum, of Eurypterida, 288, =289=, 291

Genysa, 388

Gerardia, Laura parasitic on, 93

Geryon, 195

Giardella callianassae, 73

Gibocellidae, 448

Gibocellum sudeticum, 447

Giesbrecht, on Copepoda, 57; on phosphorescence, 59

Gigantostraca, 258, 283 f.

Gill-book, =270=

Glabella, 223

Glabella-furrows, 223

Glands, of Tardigrada, 481; of Pentastomida, 490, 491; of Pycnogons, 511; coxal, of Arachnids, 257, 270, 337; green, of Malacostraca, 110; poison-, of Arachnids, 337, 360; spinning, of Spiders, 335; of Pseudoscorpions, 434

Glaucothoe, larva of Eupagurus, =179=, 180

Gluvia, 429

Glycyphagus, 466; G. palmifer, 466; G. plumiger, 466

Glyphocrangon, 164; G. spinulosa, 158, =164=

Glyphocrangonidae, 164

Glyptoscorpius, 283, 291, 294

Gmelina, 138

Gmogala scarabaeus, 394

Gnamptorhynchus, 533

Gnaphosa, 397

Gnathia maxillaris, 124; life-history of =125=

Gnathiidae, 124

Gnathobase, 10, 264

Gnathophausia, 119, 256 n.; maxillipede of, =10=

Gnathostomata, 56

Gnosippus, 429

Goldsmith, 362

Gonads, = reproductive organs, q.v.

Gonodactylus, 143; G. chiragra, 143

Gonoplacidae, 195

Gonoplax, 195; G. rhomboides, 195

Gonyleptidae, 442, 448, 449

Goodsir, Harry, 535, 540

Gordius, parasitic in Spiders, 368

Gossamer, 342

Graells, 364

Graeophonus, 309

Graff, von, on position of Tardigrada, 483

Grapsidae, 193, 195; habitat, 198, 201

Graptoleberis, 53

Grassi, 422

Green gland, 110 (= antennary gland, q.v.)

Gregarious Spiders, 340

Grenacher, 517

Griffithides, 251

Gruvel, on Cirripedia, 80, 86

Guérin-Méneville, 439

Gurney, on Copepoda, 62; on Brachyuran metamorphosis, 181 n.

Gyas, 450

Gylippus, 429

Gymnolepas, 89

Gymnomera, 38, 54

Gymnoplea, 57

Hadrotarsidae, 394

Hadrotarsus babirusa, 394

Haeckel, on plankton, 203

Haemaphysalis, 469

Haematodocha, 322

Haemocera, 64; H. danae, life-history, =64=, =65=

Haemocoel, 5, 11

Hahnia, 325, 416

Hahniinae, 416

Halacaridae, 472

Halocypridae, 108

Halosoma, 539

Hannonia typica, 533

Hansen, on Choniostomatidae, 76; on Cirripede Nauplii, 94; on classification of Malacostraca, 113

Hansen and Sörensen, 422, 439, 443, 448

Hapalogaster, 181; H. cavicauda, =178=

Hapalogasterinae, 181

Harpactes hombergii, 395

Harpacticidae, 61, 62; habitat, 206

Harpedidae, 245

Harpes, 225, 226, 230, 231, 234, 246; H. ungula, =248=; H. vittatus, eyes, =228=

Harporhynchus, 53

Harvest-bugs, 454, 473

Harvestmen, 440, = Phalangidea, q.v.

Harvest-spiders, 440, = Phalangidea, q.v.

Harvesters, 440, = Phalangidea, q.v.

Hasarius falcatus, 421

Haustellata, 501 n.

Haustoriidae, 137

Haustorius arenarius, 137

Hay, on name Lydella, 486 n.

Heart, of Phyllopoda, 29; of Cladocera, 43; of Nebalia, 112; of Syncarida, 115; of Peracarida, 118; of Isopoda, 122; of Danalia, 132; of Amphipoda, 136; of Squilla, 142; of Eucarida, 144; of Limulus, 268; of Scorpions, 305; of Pedipalpi, 311; of Spiders, 331; of Solifugae, 427; of Pseudoscorpions, 434; of Phalangidea, 445; of Acarina, 460; of Pycnogons, 516

Heart-water, 470

Hedley, on home of cocoa-nut, 174

Heligmonerus, 388

Heller, 455

Hemeteles fasciatus, 367; H. formosus, 367

Hemiaspis, 278; H. limuloides, =278=

Hemioniscidae, 130

Hemiscorpion lepturus, 307

Hemiscorpioninae, 306, 307

Henking, 447, 460

Hentz, 367

Herbst, on regeneration of eye, 6 n.

Hermacha, 388

Hermaphroditism, 15; caused by parasite, 101, 102; partial and temporary, 102; normal, 105; in Cymothoidae, 126; in Isopoda Epicarida, 129; in Entoniscidae, 135; in Caprella, 140

Hermippus, 317, 399; H. loricatus, =400=

Hermit-crab, 167, 171; commensalism, 172; reacquisition of symmetry, 173; regeneration of limbs, 156

Hermit-lobster, 167

Herrick, on the Lobster, 154

Hersilia (Araneae), 401; H. caudata, =400=

Hersiliidae (Araneae), 326, 400

Hersiliidae (Copepoda), 73

Hersiliola, 401

Heterarthrandria, 58

Heterocarpus alphonsi (Pandalidae), phosphorescence, 151

Heterochaeta papilligera, 60

Heterocope, 59

Heterogammarus, 138

Heterometrus, 307

Heterophrynus, 313

Heteropoda venatoria, 414

Heterostigmata, 471

Heterotanais, 123

Hexameridae, 91

Hexathele, 390

Hexisopodidae, 429

Hexisopus, 429, =429=

Hexura, 391

Hippa, 171; H. emerita, distribution, 202

Hippidae, 171

Hippidea, 170; habitat, 198

Hippolyte, 164; distribution, 200; H. varians, 164

Hippolytidae, 164; distribution, 199

Hodge, George, 523, 540

Hodgson, 508

Hoek, on Cirripedia, 80; on Pycnogons, 505, 512, 513

Holm, G., on Agnostus, 225; on Eurypterus, 285 n.

Holmia, 236, 242, 247; H. kjerulfi, 242, =246=

Holochroal eye, 228

Holopediidae, 51

Holopedium, 38, 51

Homalonotus, 222, 249; H. delphinocephalus, =223=

Homarus, 154; habitat, 200; excretory glands, 13; H. americanus, 154; H. vulgaris, 154

Homoeoscelis, 76

Homola, 184; distribution, 205

Homolidae, 184

Homolodromia, 184; H. paradoxa, resemblance to Nephropsidae, 184

Hood, of Phalangidea, =442=, 452

Hoplocarida, 114, 141

Hoploderma, 468; H. magnum, =467=

Hoplophora, 468

Horse-foot crab, = Limulus, q.v.

Hoyle, on classification of Pentastomids, 495

Hughmilleria, 283, 290, 292

Humboldt, on Porocephalus, 488 n.

Hutton, 424

Huttonia, 398

Hyale, 139

Hyalella, 137, 139; distribution, 211, 217

Hyalomma, 469

Hyas, 192, 193; distribution, 200

Hyctia nivoyi, 421

Hydrachnidae, 472

Hydractinia, Pycnogons on, 523

Hydrallmania, Pycnogons on, 524

Hymenocaris, 112

Hymenodora, 163

Hymenosoma, 193; distribution, 200

Hymenosomatidae, 193

Hyperina, 140

Hypochilidae, 393

Hypochilus, 336, 393; H. thorelli, 393

Hypoctonus, 312

Hypoparia, 243

Hypopus, 463

Hypostome, of Trilobites, 233, 237; of Bronteus, =233=; of Acarina, 469

Hyptiotes, 349, 411; H. cavatus, snare, =350=; H. paradoxus, 350, =411=

Iasus, 165, 167; distribution, 200

Ibacus, 167

Ibla, 88; I. cumingii, =88=; I. quadrivalvis, 88, 89

Ichneumon flies, and Spiders, 367

Icius, 421; I. mitratus, =382=

Idiops, 388

Idothea, habitat, 211

Idotheidae, 127

Ihle, J. E. W., 526 n.

Ilia, 188; I. nucleus, =188=; respiration, 187

Illaenus, 229, 231, 235, 249; I. dalmanni, =248=

Ilyocryptus, 40, 53

Inachus, 192, 193; I. mauritanicus, Sacculina parasitic on, 97 f.; parasitic castration in, =101=; temporary hermaphroditism of, =103=; Danalia and Sacculina parasitic on, =131=

Integument, of Pycnogons, 518

Irregular Spider-snares, 351

Ischnocolus, 389

Ischnothele dumicola, =390=

Ischnurinae, 306, 307

Ischnurus ochropus, 307

Ischnyothyreus, 394

Ischyropsalidae, 451

Ischyropsalis, 444, 451

Isokerandria, 69 f.

Isometrus europaeus, 306

Isopoda, 121 f., 242

Ixodes, 469; I. ricinus, =469=

Ixodidae, 469

Ixodoidea, 455, 462, 468

Janulus, 403

Jaworowski, on vestigial antennae in a Spider, 263

Johnston, George, 540

Jumping-Spiders, 419

Karshia, 429

Karshiinae, 429

Katipo, 363, 403

King-crab, =Limulus, q.v.

Kingsley, on Trilobites, 239, 243 n.; on breeding habits of Limulus, 271

Kishinouye, on Limulus, 274, 275

Klebs, on the frequency of human Pentastomids, 494

Knight Errant, 540

Koch, C., 397 n.

Koch, L., 397 n.

Kochlorine, 92; K. hamata, 93

Koenenia, 422, 527, 528; K. mirabilis, =423=

Koltzoff, 15

König, 524

Koonunga cursor, 117; distribution, 211

Koonungidae, 117

Korschelt and Heider, on neuromeres in Arachnids, 263

Kowalevsky, 513

Kraepelin, 303, 306, 312 n., 428

Kramer, 460

Kröyer, 504, 526

Labdacus, 418

Labochirus, 312

Labrum, of Trilobites, 233

Labulla, 406

Laches, 399

Lachesis, 399

Lacinia mobilis, 114

Laemodipoda, 139

Laenger, on the frequency of human Pentastomids, 494

Lakes, characters of fauna of, 206; English, 207, 208; Baikal, 212; Great Tasmanian, 216

Lambrus, 192, 193; L. miersi, =193=

Lamproglena, 68

Lampropidae, 121

Lamprops, 121

Langouste, 165

Laniatores, 448

Lankester, on Crustacean limb, 9; on classification of Arachnids, 258, 277; on Limulus, 274, 305

Laophonte littorale, 62; L. mohammed, 62

Laseola, 404

Lathonura, 53

Latona, 51

Latreille, 385, 408 n., 412, 504, 526

Latreillia, 185; distribution, 205

Latreillopsis, 185; L. petterdi, 185

Latreutes ensiferus, habitat, 202

Latrodectus, 362, 403; L. 13–guttatus, 364, 403; L. mactans, =362=, 363, 403; L. scelio, 403

Laura, 93; L. gerardiae, 93

Laurie, 309 n., 310, 311

Leach, 526

Lecythorhynchus armatus, 535

Leeuwenhoek, on desiccation in Tardigrada, 484

Leionymphon, 534

Lendenfeld, von, 512, 523

Lepas, 87; metamorphosis, 80; anatomy, 82; L. australis, Cypris, =82=; L. fascicularis, Nauplius, =81=; L. pectinata, pupa, =82=

Lephthyphantes, 327, 406

Lepidurus, 23, 24, 36; heart, 29; L. glacialis, range, 34; L. patagonicus, 36; L. productus, 36; carapace, 20; telson, =23=; L. viridis, 36

Leptestheria, 36; L. siliqua, 37

Leptochela, 163

Leptochelia, 122; L. dubia, dimorphism, 123

Leptoctenus, 418

Leptodora, 54; appendages, 42; alimentary canal, 43; ovary, 44, =45=; L. hyalina, =54=

Leptodoridae, 54

Leptoneta, 393

Leptonetidae, 393

Leptopelma, 389

Leptoplastus, 247

Leptostraca, 111, 242; defined, 6; segmentation, 7

Lernaea, 74; L. branchialis, =74=, =75=

Lernaeascus, 73

Lernaeidae, 74

Lernaeodiscus, 95

Lernaeopoda salmonea, 76

Lernaeopodidae, 75

Lernanthropus, 68; blood, 30, 68

Lernentoma cornuta, =72=

Leuckart, on Pentastomida, 490, 492; on development of, 494; on sub-genera of, 495

Leuckartia flavicornis, 59

Leucon, 121

Leuconidae, 121

Leucosia, 188

Leucosiidae, 188; respiration, 187; habitat, 199

Leydigia, 53

Lhwyd, Edward, on Trilobites, 221

Lichadidae, 252

Lichas, 222, 252

Lichomolgidae, 70

Lichomolgus, 71; L. agilis, =71=; L. albeus, 71

Ligia oceanica, =128=

Ligidium, 129

Lilljeborg, on Cladocera, 51 n.

Limnadia, 21, 22, 36; L. lenticularis, 22, 36

Limnadiidae, 20, 23, 28, 29, 36

Limnetis, 20, 21, 22, 36; L. brachyura, =21=, 24, 36

Limnocharinae, 472

Limnocharis aquaticus, 472

Limulus, 256, 292; nervous system, 257; classification, 260, 276; segmentation, 260, =261=, =262=, =266=, =270=, 272; appendages, 263; habits, 265, 271; food, 267; digestive system, 268; circulatory system, 268; respiratory system, 269; excretory system, 270; nervous system, 270, =272=; eggs and larvae, 274, =275=; ecdysis, 274; used as food, 275–6; affinities, 277; fossil, 277; L. gigas, 276; L. hoeveni, 277; L. longispina, 264, 274; L. moluccanus, 264, 274, 276, 277; L. polyphemus, =261=, =262=, 264, 271; L. rotundicauda, 275, 277; L. tridentatus, 276

Lindström, on facial suture of Agnostus and Olenellus, 225; on eyes of Trilobites, 228 f.; on blind Trilobites, 231 f.; on maculae of Trilobites, 233

Lingua, 459

Linguatula, 488 n., 495; L. pusilla, 496; L. recurvata, 496; L. subtriquetra, 496; L. taenioides, 489, 492, 493, 494, 496; frequency of, 489; larvae of, 489, 494; hosts of, 496

Linnaeus, 408 n., 502

Linyphia, 406; L. clathrata, 406; L. marginata, 406; L. montana, 406; L. triangularis, 406

Linyphiinae, 405

Liobunum, 447, 450

Liocraninae, 397

Liocranum, 397

Liphistiidae, 386

Liphistioidae, 383

Liphistius, 317, 383, 385, 386; L. desultor, =386=

Liriopsidae, 130

Lispognathus thompsoni, eyes, 149

Lister, M., 341, 342

Lithodes, 181; L. maia, 176, =177=, =178=

Lithodidae, 181; evolution of, 176 f.

Lithodinae, 181; distribution, 199, 201

Lithoglyptes, 92; L. varians, 93

Lithotrya, 87; L. dorsalis, =87=

Lithyphantes, 404

Littoral region, of sea, 197; of lakes, 206

Liver (gastric glands), of Crustacea, 14; of Branchiopods, 29; of Limulus, 268; of Arachnids, 304 f., 331

Lobster, distribution, 199; Mysis stage, 153; natural history, 154 f.

Lockwood, on habits of Limulus, 265, 271

Loeb, 525 n.

Loman, 331, 514, 525

Lönnberg, 425

Lophocarenum insanum, =405=

Lophogaster, 119

Lophogastridae, 113, 114, 119

Loricata, 165

Lounsbury, 456, 461

Love-dances, among spiders, 381

Lovén, on Trilobites, 226

Loxosceles, 393

Lubbock, 375

Lucas, 364

Lucifer, 162

Lung-books, 297, 308, 336; origin of, 305

Lupa, 191; L. hastata, =191=; resemblance to Matuta, 187, 189

Lycosa, 417; L. arenicola, 357; L. carolinensis, turret of, =357=; L. fabrilis, =417=; L. ingens, 418; L. narbonensis, 361, 366; L. picta, 357, 372, =417=; L. tigrina, 357, 369

Lycosidae, 359, 375, 381, 417

Lydella, 479, 485; L. dujardini, 477, 486

Lynceidae, 53; alimentary canal, 43; winter-eggs, 48; reproduction, 49

Lyncodaphniidae, 53

Lyonnet, 319, 320

Lyra, 328

Lyriform organs, 325, 422

Lysianassa, 137

Lysianassidae, 137

Lysianax punctatus, commensal with hermit-crab, 172

M‘Cook, 334, 339, 340, 346, 350, 352 n., 365 n., 366, 367 n., 369 n.

M‘Coy, F., on facial suture of Trinucleus, 226; on free cheek of Trilobites, 227

M‘Leod, 336 n.

Macrobiotus, 480, 485; M. ambiguus, 487; M. angusti, 486; M. annulatus, 486; M. coronifer, 487; M. crenulatus, 487; M. dispar, 487; M. dubius, 487; M. echinogenitus, 487; M. harmsworthi, 487; M. hastatus, 487; M. hufelandi, 480, =482=, =483=, 486; M. intermedius, 486; M. islandicus, 487; M. macronyx, 477, 483, 487; M. oberhäuseri, 486; M. orcadensis, 487; M. ornatus, 487; M. papillifer, 487; M. pullari, 487; M. sattleri, 487; M. schultzei, =480=; M. tetradactylus, =478=; M. tuberculatus, 487; M. zetlandicus, 486

Macrocheira kämpferi, 192

Macrohectopus (= Constantia), 138, 212

Macrophthalmus, 196

Macrothele, 390

Macrothrix, 37, 53

Macrura, 153 f.

Macula, 233

Maia, 193; distribution, 205; M. squinado, 192; alimentary canal, 15

Maiidae, 193

Malacostraca, 110 f.; defined, 6; classification, 113, 114; fresh-water, 210 f.

Malaquin, on Monstrilla, 63 n.

Male Spider, devoured by female, 380

Malmignatte, 364, 403

Malpighian tubes or tubules, 12, 257, 311, 331, 427, 434, 460

Mandibles, of Crustacea, 8; of Arachnida, 319

Mange, 465

Maracaudus, 449

Margaropus, 469

Marine Spiders, 415

Marpissa, 421; M. muscosa, =420=; M. pomatia, 421

Martins, Fr., 502

Marx, 350

Masteria, 390

Mastigoproctus, 312

Mastobunus, 449

Matthew, G. F., on development of Trilobites, 238

Matuta, 188; habitat, 198; M. banksii, =187=

Maxilla, 8; of Decapoda, 152; of Spiders, 321

Maxillary gland, 13

Maxillipede, 8; of Copepoda, 55, 78; of Malacostraca, 113; of Zoaea, 180, 181, 182

Mecicobothrium, 391

Mecostethi, 443, 447, 448

Mecysmauchenius segmentatus, 411

Meek, 363

Megabunus, 450, 451

Megacorminae, 308

Megacormus granosus, 308

Megalaspis, 222, 249

Megalopa, compared to Glaucothoe, 180; of Corystes cassivelaunus, =183=

Mégnin, 455, 457

Megninia, 466

Meinert, 522 n.

Meisenheimer, 511 n.

Melanophora, 397

Mena-vodi, 362

Menge, 319, 368, 385

Menneus, 410

Mermerus, 449

Merostomata, 258, 259 f.

Mertens, Hugo, 524 n.

Mesochra lilljeborgi, 62

Mesonacis, 247; M. asaphoides, larva, =240=

Mesosoma, of Arachnida, 256; of Limulus, 260, 263; of Eurypterus, 288; of Scorpion, 302

Mesothelae, 386

Meta segmentata, 408

Metamorphosis, of Cirripedia, 80; of Sacculina, 97; of Epicarida, 130, 133, =135=; of Squilla, 142, 143; of Euphausia, 144; discovery of, in Decapoda, 153; of Lobster, 156; of Crayfish, 157; of Peneus, 159; primitive nature of, in Macrura, 161; of Loricata, 165, 166; of Hermit-crab, =179=; of Brachyura, 181, =182=; of Dromiacea, 182; of Trilobites, =239=; of Limulus, 275; of Pseudoscorpions, 435; of Acarina, 462; of Pentastomida, 493 f.; of Pycnogons, 521 f.

Metasoma, of Arachnida, 256; of Limulus, 260, 263; of Eurypterus, 289; of Scorpion, 303

Metastigmata, 467

Metastoma, of Trilobites, 234; of Eurypterida, 287, 292

Metazoaea, 182

Metopobractus rayi, =405=

Metopoctea, 452

Metridia, 59; M. lucens, distribution, 203

Metronax, 398

Metschnikoff, 435 n.

Miagrammopes, 411

Miagrammopinae, 411

Micaria, 397; M. pulicaria, =396=, 397; M. scintillans, 372

Micariinae, 397

Micariosoma, 397

Michael, 460, 461, 462, 466 n.

Micrathena, 410

Microdiscus, 225, 231, 245

Microlyda, 486 n.

Micrommata, 414; M. virescens, =413=, 414

Microneta, 406

Microniscidae, 130

Migas, 387

Miginae, 387

Milne-Edwards, 504

Milnesium, 480, 485; M. alpigenum, 487; M. tardigradum, 487

Miltia, 396

Mimetidae, 411

Mimetus, 411; M. interfector, 368

Mimicry, in Spiders, 372

Mimoscorpius, 312

Miopsalis, 448

Misumena, 412; M. vatia, 371, 373, 412

Mites, = Acarina, q.v.

Moggridge, 354, 355 n.

Moggridgea, 387

Moina, 37, 52; reproduction, =46=, =47=, 48, 49; M. rectirostris, =46=, =47=, =52=

Mole-crab, 170

Monochetus, 465

Monolistra (Sphaeromidae), habitat, 211

Monopsilus, 54

Monostichous eyes, 301

Monstrilla, 64

Moustrillidae, 63

Morgan, 517, 518, 521

Mortimer, Cromwell, on Trilobites, 221

Mosaic vision, 147

Moseley, 523

Moulting (Ecdysis), 154, 155, 225, 338

Mouth, of Trilobites, 234

Mud-mites, 472

Müller, F., on Tanaids, 123

Müller, O. F., on position of Tardigrada, 483

Munidopsis, 170; eyes, 149; M. hamata, =168=

Munnopsidae, 128

Munnopsis typica, =127=

Murray, 455

Murray, J., on British Tardigrada, 485

Muscular system, in Tardigrada, 481; in Pentastomida, 490

Mygale, 337, 386 n., 389

Mygalidae, = Aviculariidae, q.v.

Myrmarachne formicaria, 421

Myrmecium, 397

Myrtale perroti, 387

Mysidacea, 118

Mysidae, 113, 114, 119; habitat, 201; relation to Nebalia, 112

Mysis, 120; maxillipede, =10=, 11; resemblance to Paranaspides, 117; M. oculata, var. relicta, 120, 210; M. vulgaris, 118

Mysis-larva, of Lobster, 156; of Peneus, =161=

Mytilicola, 68

Nanodamon, 313

Nauplius, of Haemocera danae, =64=; of Lepas fascicularis, =81=; of Sacculina, =97=; of Euphausia, 144; an ancestral larval form, 145; of Peneus, =159=; compared with Protaspis, 239

Nebalia, 111, 112, 114; segmentation, 6, 7; limbs, =10=, 11; relation to Cumacea, 120; compared with Trilobita, 242; N. geoffroyi, =111=

Nebo, 307

Neck-furrow, 224

Nemastoma, 443, 451; N. chrysomelas, 452; N. lugubre, =452=

Nemastomatidae, 451

Nematocarcinus, 163

Nemesia, 388; N. congena, 355, 357

Neolimulus, 278, 279

Neoniphargus, distribution, 216

Neopallene, 537

Nephila, 408; N. chrysogaster, 380; N. plumipes, 366

Nephilinae, 408

Nephrops, 154; N. andamanica, distribution, 205; N. norwegica, 205

Nephropsidae, 154; resemblance to Dromiacea, 184

Neptunus, 191; N. sayi, habitat, 202

Nereicolidae, 73

Nervous system, of Crustacea, 5; of Branchiopoda, 30; of Squilla, 142; of Arachnida, 257; of Limulus, 270; of Scorpions, 305; of Pedipalpi, 311; of Spiders, =332=, 333; of Solifugae, =428=; of Pseudoscorpions, 434; of Phalangidea, 445, =446=; of Acarina, 460; of Tardigrada, 482; of Pentastomida, 491; of Pycnogons, 516

Neumann, 470

Nicodaminae, 416

Nicodamus, 416

Nicothoe astaci, 68

Nileus, 229, 249; N. armadillo, eye, =228=

Niobe, 249

Niphargoides, 138

Niphargus, 137, 138; distribution, 216; N. forelii, 138; N. puteanus, habitat, 209, 210

Nogagus, 73

Nops, 315, 336, 395

Norman, A. M., 540

Notaspis, 467

Nothrus, 468

Notodelphys, 66

Notostigmata, 473

Nyctalops, 312

Nycteribia (Diptera), 526

Nymph, 463

Nymphon, 503, 536; N. brevicaudatum, 507, 536; N. brevicollum, 511, 521; N. brevirostre, =503=, =504=, =506=, =508=, =509=, 541, 542; N. elegans, =506=, 542; N. femoratum, 541; N. gallicum, 541; N. gracile, 511, 541, 542; N. gracilipes, 542; N. grossipes, 541; N. hamatum, 512; N. hirtipes, 542; N. horridum, 537; N. johnstoni, 541; N. leptocheles, 542; N. longitarse, 541, 542; N. macronyx, 542; N. macrum, 542; N. minutum, 541; N. mixtum, 541; N. pellucidum, 541; N. rubrum, 541, 542; N. serratum, 542; N. simile, 541; N. sluiteri, 542; N. spinosum, 541; N. stenocheir, 542; N. strömii, =509=, 541

Nymphonidae, 536

Nymphopsinae, 535 n.

Nymphopsis, 534, 535 n.; N. korotnevi, 534; N. muscosus, 534

Obisiinae, 436, 437

Obisium, 436, 438

Ochyrocera, 393

Octomeridae, 91

Octomeris, 91

Ocyale mirabilis, 416

Ocypoda, 194, 196; habitat, 198; distribution, 201

Ocypodidae, 196

Oecobiidae, 386 n., 392

Oecobius, 392; Oe. maculatus, =392=

Oehlert, on facial suture of Trinucleus, 226

Ogovia, 448

Ogygia, 249

Oiceobathes, 535

Oithona, 61; O. nana, 203; O. plumifera, 203

Olenelloides, 247; O. armatus, =247=

Olenellus, 225, 227, 232, 236, 247

Olenidae, 247

Olenus, 232, 247; O. truncatus, =248=

Oligolophus, 450; O. agrestis, 450; O. spinosus, =441=, 450, =451=

Olpium, 436, 437; O. pallipes, =437=

Ommatoids, 310, 311, 312

Oncaea, 69; O. conifera, phosphorescence, 60

Oncaeidae, 69

Oniscoida, 128

Oniscus, 129

Ononis hispanica, Spiders on, 419

Onychium, 324

Oomerus stigmatophorus, 539

Oonopidae, 336, 393

Oonops, 394; O. pulcher, 366, 394

Oorhynchus, 507, 535; O. aucklandiae, 535

Oostegites, of Malacostraca, 114

Operculata, 89, =91=

Ophiocamptus (Moraria), 62; O. brevipes, 62

Opilioacarus, 454, 473; O. arabicus, 473; O. italicus, 473; O. platensis, 473; O. segmentatus, 473

Opiliones (= Phalangidea, q.v.), 440

Opisthacanthus, 307

Opisthoparia, 244

Opisthophthalmus, 307

Opisthothelae, 386

Opopaea, 394

Orchestia, 139; hermaphroditism, 104; O. gammarellus, 137, 139; habitat, 211

Orchestina, 394

Oribata, 467

Oribatidae, 457, 458, 459, 460, 462, 467; anatomy, =459=

Orithyia coccinea, 524, 540

Ornithodoros, 469; O. megnini, 469; O. moubata, 469; O. talaje, =469=; O. turicata, 469

Ornithoscatoides, 374

Orometopus, 226, 245; O. elatifrons, =230=

Ortmann, on Brachyura, 181 n.; on bipolarity, 200; on crayfishes, 213; on Pycnogons, 513 n.

Ostracoda, 107; pelagic, 202

Oudemans, 528 n.

Ovary, of Cladocera, 44, =45=; of Danalia, =132=; of Spiders, =332=

Oxynaspis, 88

Oxyopes, 419; O. lineata, 419

Oxyopidae, 419

Oxyptila, 412

Oxyrhyncha, 191 f.; habits, 192; enemies, 192; habitat, 198

Oxystomata, 185 f.; respiration, 186, 187

Pachycheles, 170; P. panamensis, distribution, 202

Pachygnatha, 407; P. clerckii, 407; P. degeerii, 407; P. listeri, 407

Pachygrapsus, 196; P. marmoratus, 193, =194=, 196

Pachylasma giganteum, 91

Pachylomerus, 388

Pachysoma, 69

Pagurian, 180; eyes of deep-sea, 149, 150

Paguridea, 171

Pagurinae, 180

Palaemon, 164; excretory glands, 13; fresh-water, 212; P. serratus, 158, 164; Bopyrus parasitic on, 133

Palaemonetes, 164; P. antrorum, habitat, 210; P. varians, 161; distribution, 212

Palaemonidae, 159, 164

Palaeocaris, 115, 118

Palaeophonus, 294, 298

Palamnaeus, 307; P. swammerdami, tarsus, =304=

Palinuridae, 167

Palinurus, 165, 167; habitat, 198, 202; P. elephas, 167; P. quadricornis, embryo, =165=

Pallene, 505, 537; P. attenuata, 541; P. brevirostris, =510=, 524, =537=, 541, 542; P. dimorpha, 538; P. emaciata, 541; P. empusa, 541; P. grubii, 538; P. languida, 537; P. longiceps, 538; P. novaezealandiae, 537; P. producta, 542; P. pygmaea, 537, 541; P. spectrum, 542; P. spinosa, 537

Pallenidae, 537

Pallenopsis, 506, 511; P. holti, 542; P. tritonis, 542

Palp, of Pycnogons, 507

Palpal organ, =322=, 378

Palpebral lobe, 227

Palpigradi, 258, 422

Palpimanidae, 323, 325, 398

Palpimanus, 398

Panamomops diceros, 405

Pandalidae, 164

Pandalus, 164; P. annulicornis, 164

Pandinus, 307

Panoplax, 195

Pantopoda, 501 n. (= Pycnogonida, q.v.)

Panulirus, 165, 167

Parabolina, 232, 247

Parabolinella, 247

Parabuthus, 298; P. capensis, 298, 299

Paradoxides, 222, 232, 236, 247; P. bohemicus, =246=

Paragaleodes, 429

Paralomis, 179, 181

Paranaspides, 117; P. lacustris, 117; distribution, 210; habitat, 210

Paranebalia, 242

Paranephrops, 157; distribution, 213

Paranthura, 124

Parantipathes, Synagoga parasitic on, 94

Paranymphon, 507; P. spinosum, 542

Parapagurus, 180

Parapallene, 537

Parapeneus, 162; P. rectacutus, 159

Parapylocheles scorpio, eyes, 149

Parasiro, 448; P. corsicus, =448=

Parasites, in Tardigrada, 484

Parasitic castration, 100, 136

Parastacidae, 157; distribution, 213

Parastacus, 157; distribution, 213

Paratropidinae, 387

Paratropis scrupea, 387

Parazetes auchenicus, 533

Pardosa, 417; female carrying young, =341=; P. amentata, =417=, 418; P. lugubris, 418

Pariboea spinipalpis, 534

Parthenogenesis, in Phyllopoda, 32; in Cladocera, 44, 46, 49; in Ostracoda, 108

Parthenope, 193; P. investigatoris, 192

Parthenopidae, 193

Pasiphaea, 163

Pasiphaeidae, 163

Pasithoe, 532; P. umbonata, 535; P. vesiculosa, 535, 541

Pasithoidae, 532

Patten, 270, 271, 277

Patten and Redenbaugh, on Limulus, =266=, 270, =272=

Paturon, 319, =320=

Peckham, 376, 377, 378, 381, 382

Pecten, 328

Pectines, of Scorpions, 302, =302=; function of, 299; of Glytoscorpius, 294

Pedicle, 317

Pedipalpi, 258, 308; habits, 309; external structure, 309; legs, 309; internal structure, 310; alimentary canal, 310; nervous system, 311; classification, 312

Pedipalpi (appendages), 263, 303, 309, 321, 422, 426, 433, 440, 458

Pedunculata, 84

Pelagic Crustacea, marine, 202; lacustrine, 207

Pelops, 467

Peltiidae, 63

Peltogaster, 95; structure, =95=; males, 99; castration caused by, 100; P. curvatus, castration caused by, 100; P. sulcatus, 95

Peltura, 247

Peneidae, 162

Peneidea, 158, 162; metamorphosis, 159

Penella sagitta, 74

Peneus, 158, 162; metamorphosis, 159, =159=, =160=, =161=

Pentanymphon, 504, 537

Pentaspidae, 87

Pentastoma, 488 n.; P. denticulatum, 489, 494; P. emarginatum, 489; P. serratum, 489

Pentastomida, 258, 488 f.; structure, 489; habitat, 488; life-history, 488, 493; hosts of, 496, 497

Pephredo hirsuta, 535, 541

Peracantha, =43=, 53; alimentary canal, 43

Peracarida, 114, 118

Pereiopod, defined, 110; reduced hind, in Galatheidea, 168; in Hippidea, 170; in Paguridea, 172; in Dromiacea, 184; in Oxystomata, 185

Periegops hirsutus, 393

Peroderma cylindricum, 75

Petrarca bathyactidis, 93

Pettalus, 448

Pezomachus gracilis, parasitic in cocoons of Spiders, 367

Phacopidae, 249

Phacopini, 243

Phacops, 223, 232, 235, 249; P. latifrons, =227=; P. sternbergi, =248=

Phaeocedus braccatus, 397

Phagocytes, in Danalia, 132

Phalangidea, 258, 440 f.; habits, 441; external structure, 442; internal structure, 444; nervous system, =446=; classification, 447; British species, 453

Phalangiidae, 449

Phalangiinae, 450

Phalangium, 444, 450, 526; mouth-parts, =443=; P. balaenarum, 502; P. cornutum, 450; P. littorale, 501; P. opilio, 445, 446, 450, 526

Phalangodes, 449; P. armata, 449; P. terricola, =449=

Phalangodidae, 448

Phanodemus, 535

Phidippus, 421; P. morsitans, 365, 421

Philichthyidae, 73

Philichthys, 73; P. xiphiae, 73 n.

Phillipsia, 251; P. gemmulifera, =250=

Philodrominae, 413

Philodromus, 413; P. aureolus, 413; P. margaritatus, =413=

Philoscia muscorum, 129

Pholcidae, 336, 401

Pholcus, 320, 401; P. phalangioides, 401

Phoroncidia, 404; P. 7–aculeata, =318=

Phoroncidiinae, 317, 404

Phosphorescence, of Copepoda, 59; relation to eyes in deep-sea Crustacea, 150, 151

Phosphorescent organs, of Euphausiidae, 145; of Stylocheiron mastigophorum, =151=

Phoxichilidae, 539

Phoxichilidiidae, 538

Phoxichilidium, 506, 512, 520, 521 n., =523=, 525, 538; P. angulatum, 520; P. exiguum, 541; P. femoratum, =508=, 524, =538=, 540; P. globosum, 540; P. mollissimum, 517; P. olivaceum, 540

Phoxichilus, 505, 512, 539; P. australis, 539, 540; P. böhmii, 539; P. charybdaeus, 514, 515, 539; P. laevis, 537, 539, 541; P. meridionalis, 539; P. mollis, 539; P. proboscideus, 532; P. procerus, 539; P. spinosus, =505=, =508=, =510=, 537, 539, 541, 542; P. vulgaris, 539

Phreatoicidae, 136; distribution, 211, 217

Phreatoicidea, 136

Phreatoicopsis, 136; distribution, 211

Phreatoicus, 136; distribution, 210, 211, 217; P. assimilis, habitat, 210; P. typicus, habitat, 210

Phronima, 140; P. sedentaria, =140=

Phrynarachne, 414; P. decipiens, 374, 414

Phrynichinae, 313

Phrynichus, 313

Phrynidae, 309, 310, 312

Phrynopsis, 313

Phrynus, 312

Phryxidae, 130

Phyllocarida, 111, 242

Phyllocoptes, 465

Phyllopoda, 19 f.; appendages, 24 f.; alimentary canal, 29; vascular system, 29; nervous system, 30; reproductive organs, 31; habitat, 32; genera, 35

Phyllosoma, larva of Palinurus, =166=

Phytoptidae, 464

Phytoptus, 464 n., 495 (= Eriophyes, q.v.)

Pickard-Cambridge, F., 352

Pickard-Cambridge, O., 318, 321 n., 323 n., 359 n., 372, 374, 380, 385, 401 n., 436, 438, 450, 451, 452

Pillai, 375

Pilumnus, 191

Pinnotheres pisum, 195

Pinnotheridae, 195

Pipetta, 514, 533; P. weberi, 533

Pirata, 417

Piriform glands, =335=, 349

Pisa, 193

Pisaura mirabilis, 416

Pisauridae, 416

Placoparia, 251

Plagiostethi, 443, 447, 449, 452

Plagula, 317

Planes minutus, habitat, 202

Plankton, characters of, 203; fresh-water, 207, 216; Cladocera in, 50

Plastron, 316

Plate, on Tardigrada, 481, 482, 484

Plator insolens, 415

Platoridae, 415

Platyarthrus hoffmannseggii, 129

Platyaspis, 121

Platybunus, 450, 451

Platycheles, 535

Plectreurys, 393

Pleopod, defined, 110

Pleura, 234 f.

Pleurocrypta microbranchiata, =133=

Pleuromma, 59; P. abdominale, 59; P. gracile, 59

Pliobothrus symmetricus, Pycnogon larvae in, 523

Pocock, 298, 308 n., 312, 328, 329, 425 n., 534 n.

Podasconidae, 130

Podogona, 258, 439

Podon, 54

Podophthalmata, 112

Podoplea, 61

Podosomata, 501 n. (= Pycnogonida, q.v.)

Poecilotheria, 390

Poisonous hairs, of Spiders, 365

Pollicipes, 84; fertilisation, 86; P. cornucopia, 85; P. mitella, =85=

Pollock, 340

Poltyinae, 410

Poltys, 410; P. ideae, =318=

Polyartemia, 36; antennae, 26, 28; range of, 34; P. forcipata, 36

Polyaspidae, 84

Polycopidae, 109

Polygonopus, 539

Polyphemidae, 54; appendages, 42; ovary, 47; reproduction, 49

Polyphemus, 47, 54; P. pediculus, habitat, 206, 208

Polysphincta carbonaria, parasitic on Spiders, 368

Pompeckj, on Calymenidae, 244

Pompilus, 368

Pontellidae, 60

Pontoporeia, 137; distribution, 212; P. affinis, 138; P. femorata, 138; P. loyi, 138; P. microphthalma, 138

Porcellana, 168, 170; Zoaea, 168; P. platycheles, 170

Porcellanidae, 170; habitat, 198

Porcellio, 129

Porcupine, 540

Porhomma, 406

Porocephalus, 488 n., 495; P. annulatus, =490=, 496; P. aonycis, 496; P. armillatus, 496; P. bifurcatus, 496; P. clavatus, 496; P. crocidura, 496; P. crotali, 496; P. geckonis, 496; P. gracilis, 496; P. heterodontis, 496; P. indicus, 496; P. lari, 496; P. megacephalus, 497; P. megastomus, 497; P. moniliformis, 497; P. najae sputatricis, 497; P. oxycephalus, 497; P. platycephalus, 497; P. proboscideus, =493=, 494; larvae of, 493, =494=; hosts of, 496; P. protelis, larva, =495=; P. subuliferus, 497; P. teretiusculus, 489, =491=, 492, =492=, 497; P. tortus, 497

Portunidae, 191

Portunion, 134; P. maenadis, 134; life-history, =135=, 136

Portunus, 191

Potamobius (= Astacus), 157; distribution, 213

Potamocarcinus, 191; distribution, 213

Potamon, 191

Potamonidae, 191

Praniza, larva of Gnathia, 125

Prawn, 151, 153, 158, 164, 198; fresh-water, 212, 214

Pre-epistome, 443

Prestwichia (Euproöps), 275, =278=, 279

Preyer, on anabiosis in Tardigrades, 484

Prionurus, 298, 299

Prismatic eye, of Trilobites, 229

Procurved eyes, 316

Prodidomidae, 395

Prodidomus, 396

Proëtidae, 251

Proëtus, 251; P. bohemicus, =248=

Prokoenenia, 423; P. chilensis, 423; P. wheeleri, 423

Prolimulus, 279

Promesosternite, in Limulus, 264

Proparia, 244

Prosalpia, 450

Prosoma, of Arachnida, 260; of Limulus, 260, 263; of Eurypterida, 285; of Scorpion, 301

Prosthesima, 397

Prostigmata, 471

Protaspis, 239, =239=, =240=

Proteolepas, 94; P. bivincta, =94=

Protocaris, 243

Protolenus, 247

Protolimulus, 279

Protolycosa anthrocophila, 383

Przibram, on regeneration in Crustacea, 156

Psalidopodidae, 164; habitat, 204

Psalidopus, 164

Psalistops, 389

Psechridae, 399

Psechrus, 399

Pseudalibrotus, 137

Pseudidiops, 388

Pseudocuma, 121; distribution, 215

Pseudocumidae, 121

Pseudoniscus, 279

Pseudopallene, 511, 537; P. circularis, 540; P. spinipes, 537 n.

Pseudoscorpiones, 258, 430 f.; habits, 430; external structure, 431, =432=; internal structure, 433; development, 434, =435=; classification, 436; British species, 438

Pseudo-stigmatic organs, 467

Pseudozoaea, larva of Stomatopod, 143

Pterocuma, 121

Pterolichus, 466

Pteronyssus, 466

Pterygometopus, 249

Pterygotus, 283, 291, 292; P. osiliensis, =290=

Ptychoparia, 247

Pucetia viridis, 419

Pupa, of Cirripedia, 81, =82=

Purcellia, 448

Pychnogonides, 501 n.

Pycnogonida, 501 f.; body, 505; chelophores, 505; palpi, 507; ovigerous legs, 507; glands, 511; alimentary system, 513; circulatory system, 516; nervous system, 516; eyes, 517; integument, 518; reproductive organs, 519; eggs, 520; development, 520; habits, 524; systematic position, 525; classification, 528 f.; British species, 540 f.

Pycnogonidae, 539

Pycnogonum, 503, 539; P. australe, 540; P. crassirostre, 540; P. littorale, =501=, 540, 541; P. magellanicum, 540; P. magnirostre, 540; P. microps, 540; P. nodulosum, 540; P. orientale, 540; P. philippinense, 540; P. pusillum, 540; P. stearnsi, 540

Pygidium, 235

Pylocheles, 180; P. miersii, =173=

Pylochelidae, 180; habitat, 204

Pylopagurus, 180; relation to Lithodidae, 177, =178=

Pyrgoma, 92

Rachias, 388

Railliet, on classification of Pentastomids, 495

Ranina dentata, 188

Raninidae, 188

Rastellus, 320, 387

Ratania, 68; mouth, 63

Réaumur, 360

Recurved eyes, 316

Red spider, 455, 472

Red-water, 456

Regeneration, of Crustacean limbs, 155, 156

Regillus, 414

Reichenbach, on embryology of Astacus, 12

Reighardia, 495, 497; hosts of, 497

Remipes, 171; R. scutellatus, =171=

Remopleurides, 232, 247; R. radians, 229, =248=

Reproduction (incl. Breeding), of Cladocera, 43 f.; of Anaspides, 116; of Lobster, 156; of Limulus, 274; of Spiders, 365; of Ticks, 461; of Pycnogons, 520

Reproductive (generative) organs, of Crustacea, 15; of Phyllopods, 31; of Cladocera, 43; of Arachnids, 257; of Limulus, 271; of Scorpions, 305; of Spiders, 333; of Solifugae, 428; of Phalangidea, 446; of Acarina, 461; of Tardigrada, 482; of Pentastomida, 492; of Pycnogons, 519

Respiration, of Crustacea, 16; of Anaspides, 115; of Albunea, 170; of Corystes, 170, 189 of Birgus, 174; of Oxystomata, 186, 187; of Catometopa, 194, 195; of Arachnids, 256. (See also Respiratory organs.)

Respiratory organs, of Arachnids, 256; of Limulus, 269, =270=; of Eurypterids, 288; of Scorpions, 305; of Spiders, 336; of Tardigrada, 482; of Pentastomida, 491. (See also Respiration.)

Rhagodes, =425=, 429

Rhagodinae, 429

Rhax, 429

Rhipicentor, 469

Rhipicephalus, 469; R. sanguineus, 470

Rhizocephala, 95 f.; compared with Monstrilla, 66; with Anelasma, 89; castration caused by, 100; males, 106; association with Entoniscidae, 136

Rhomphaea, 402

Rhopalorhynchus, 532; R. clavipes, 533; R. kröyeri, 533; R. tenuissimus, 533

Rhynchothoracidae, 535

Rhynchothorax, 505, 535; R. australis, 536; R. mediterraneus, =508=, 535, =536=

Ricinulei, 439

Robber-crab, 173

Roncus, 436, 438

Rucker, 423

Rudolphi, on Pentastoma, 488 n.

Sabacon, 451

Sabelliphilus, 71

Sacculina, 95; life-history, 96 f.; males, =99=; castration caused by, 100 f.; S. carcini, 96; S. neglecta, Nauplius, =97=; Cypris, =97=; internal stages, =98=; with parasitic Danalia, 130, =131=

Saitis, 421; S. pulex, 382, 421

Salter, on facial suture of Trinucleus, 226; on classification of Trilobites, 243

Salticidae, 419

Salticus, 420; S. scenicus, 372, 376, =420=

Sao, 235, 247; S. hirsuta, development, =239=

Sapphirina, 69; colour, 60; S. opalina, 69

Sarcoptes, 466; S. mutans, =466=

Sarcoptidae, 455, 466

Sarcoptinae, 466

Sars, G. O., on Calanidae, 58; on Isopoda, 122; on Crustacea of the Caspian, 215; on Pycnogons, 504

Savigny, 526

Scaeorhynchus, 533

Scalidognathus, 388

Scalpellum, 84, 85; complemental male, =86=; sex, 86, 105 f.; S. balanoides, sex, 86; S. ornatum, sex, 87; S. peronii, male, =86=; sex, 87, 105; S. velutinum, sex, 87; S. vulgare, 85, =86=; male, =83=; sex, 86, 87

Scaphognathite, 152

Scapholeberis, 39, 52; S. mucronata, =52=

Schimkewitsch, 527, 534

Schizochroal eye, =228=, 229

Schizonotidae, 310, 312

Schizonotus, 312

Schizopoda, 112; re-classification, 113; relation to Macrura, 162

Schizorhynchus, 121

Schmeil, on fresh-water Copepoda, 59, 62

Schultze, on position of Tardigrada, 483

Scipiolus, 535

Sclerocrangon, distribution, 200

Sclerosoma, 450; S. quadridentatum, =450=

Sclerosomatinae, 449

Scodra, 390

Scopula, 324, =324=, 389 n.

Scorpio, 305, 307; S. boehmi, 307; S. maurus, 307

Scorpion, 297 f.

Scorpionidae, 306

Scorpionidea, 258, 297 f.; habits, 298; senses, 299; poison, 299, 301; mating habits, 300; external structure, 301; prosoma, 301; pre-cheliceral segment, 301; development of eyes, 301; mesosoma, 302; metasoma, 303; appendages, 303; pedal spurs, =304=, 306, 307, 308; tibial spurs, =304=, 306, 307, 308; internal anatomy, 304; alimentary canal, 304; vascular system, 305; nervous system, 305; endosternite, 305; generative organ, 305; development of, 305; classification, 306; fossil, 298; resemblance to Eurypterids, 292

Scorpioninae, 306, 307

Scorpiops, 308

Scotinoecus, 390

Scott, on fish-parasites, 69 n.

Scourfield, on Cladocera, 51 n.

Scutum, of Spiders, 317, 394; of Ticks, 469

Scyllarus, 167; S. arctus, =165=, 167

Scytodes thoracica, 393

Scytodidae, 393

Segestria, 395; S. perfida, 369; S. senoculata, 395

Segestriinae, 395

Segmentation, of Crustacea, 5 f.; of Trilobites, 223 f.; of Arachnida, 256; of Limulus, 263; of Pycnogons, 501 f.

Selenopinae, 414

Selenops, 414

Semper, 521 n.

Senoculidae, 418

Senoculus, 418

Sense-organs, of Arachnids, 257; of Limulus, 271, =272=; of Tardigrada, 482; of Pentastomida, 491 (see also Auditory organ, Eyes)

Sergestes, 162

Sergestidae, 162; Zoaea, 161; distribution, 204

Serolidae, 126

Serolis, 126; distribution, 200; S. antarctica, S. bronleyana, S. schytei—eyes, 149

Serrula, 322, 433

Sesarma, 196; distribution, 213

Setella, 61

Sex, in Crustacea, 100; in Trilobites, 235

Sexual dimorphism, of Copepoda, 57, 67, 75; of Inachus, 103; of Tanaidae, 123; of Gnathia, 125; of Prawns, 159; of Gelasimus, 194; of Spiders, 379

Sheet-webs, 352

Shell-gland, 13

Shipley, A. E., introduction to Arachnida, 253 f.; on Xiphosura, 259 f.; on Tardigrada, 475 f.; on Pentastomida, 488 f.

Shrimp, 153, 158, 164, 198, 199

Shumardia, 245

Shumardiidae, 245

Sicariidae, 327, 393

Sicarius, 393

Sida, 51; reproduction, 49; S. crystallina, 22, 39, =40=

Sididae, 51; appendages, 40; heart, 43

Siebold, von, 464 n.

Sigilla, 410

Silvestri, 473 n.

Simocephalus, 52; S. vetulus, =38=, =39=; appendages, =41=

Simon, 303, 314 n., 326, 385, 386 n., 387, 391 n., 397 n., 400, 401 n., 406, 408 n., 414 n., 418, 431, 433, 449, 452

Singa, 409

Sintula, 406

Siphonostomata, 56

Siriella, 120

Siro, 448

Sironidae, 448

Sitalces, 449

Slimonia, 283, 290, 292; S. acuminata, =291=

Smith, F., 367

Smith, G. on Crustacea, 1 f.

Smith, H., 373

Smith and Kilborne, 456

Snouted Mites, 458, 471

Solenopleura, 247

Solenysa, 405

Solifugae, 258, 423 f.; habits, 423; climbing habits, 425; doubtfully poisonous, 424; external structure, 425; internal structure, 427; classification, 428

Solpuga, 429; S. sericea, 425

Solpugae, 423

Solpugidae, 429

Solpuginae, 429

Spallanzani, on desiccation of Tardigrada, 484

Sparassinae, 323, 414

Sparassus, 414

Spencer, on Pentastomida, 489 n., 490

Spermatheca, 15

Spermatophore, 15

Spermatozoa, of Crustacea, 15; of Malacostraca, 114

Spermophora, 401

Sphaerexochus, 251

Sphaeroma, habitat, 211

Sphaeromidae, 126

Sphaeronella, 76

Sphaerophthalmus, 232, 247; S. alatus, eye, =228=

Spiders, 314 f.; external structure, 314, =316=, =317=; appendages, 319 f.; rostrum, 320; maxilla, 321; palpal organs, 321; tarsi, =324=; spinnerets, =325=; stridulating organs, =327=, 404; internal anatomy, 329, =330=; alimentary system, 329; vascular system, 331; generative system, 333; nervous system, 333; sense-organs, 333; eyes, 315, 334, 375; spinning glands, 335; respiratory organs, 318, 336; coxal glands, 337; poison-glands, 337; ecdysis, 338; early life, 338; ballooning habit, 341, =342=; webs, 343 f.; nests, 354; cocoons, 358, =358=; commercial use of silk, 359; poison, 360; fertility, 365; cannibalism, 367; enemies, 368; protective coloration, 371; senses, 375 f.; sight, 375; hearing, 376; touch, 334; intelligence, 377; mating habits, 378; fossil, 383; classification, 384 f.

Spinning glands, =335=

Spinning Mites, 472

Spiroctenus, 388

Spongicola, 162

Squilla, 141, =141=, 142, 143; S. desmaresti, 141; S. mantis, 141

Squillidae, 114, 143; compared with Loricata, 166

Stalita, 395

Stasinopus caffrus, 387

Staurocephalus, 251

Steatoda, 404; S. bipunctata, =327=, 404

Stebbing, on Amphipods, 137; on Pycnogons, 503 n., 527 n.

Stecker, 447

Stegosoma testudo, =318=

Stenochilus, 398

Stenochotheres, 76; S. egregius, 76, =76=

Stenocuma, 121

Stenopodidae, 162

Stenopus, 162

Stenorhynchus, 192, 193

Stephanopsinae, 414

Stephanopsis, 414

Stiles, on larval Pentastomids, 493, 494

Stomatopoda, 114, 141 f.

Storena, 399

Strabops, 283; eyes, 290

Strauss-Durckheim, on Limulus, 277

Streblocerus, 53

Streptocephalus, 25, 35; range of, 34; S. torvicornis, 35

Stridulating organs, in Arachnids, 257, 327, =327=, 404

Stygina, 249

Style, of palpal organ of Spiders, 322

Stylocellus, 448

Stylonurus, 283, 291; S. lacoanus, =293=

Sunaristes paguri, 63

Sun-spiders, 423

Sybota, 410

Sylon, 95; sex, 99

Symphysurus, 249

Synageles, 421; S. picata, 366, 373

Synagoga mira, 94

Syncarida, 114

Synemosyna, =420=, 421; S. formica, 373

Synhomalonotus, 249

Syringophilus, 455, 473

Tachidius brevicornis, 62; T. littoralis, 62

Tachypleinae, 276

Tachypleus, 276; T. gigas, 276; T. hoeveni, 277; T. tridentatus, 276

Talitridae, 139

Talitrus, 139; T. sylvaticus, 139; habitat, 211

Talorchestia, 139

Tanaidae, 122

Tanais, 122

Tanganyika, Lake, prawns of, 212

Tanystylum, 505, 535; T. orbiculare, 524, 535, 541

Taracus, 451

Tarantella, 361

Tarantism, 361

Tarantula (Spider), 361

Tarantula, 313; T. reniformis, 312

Tarantulidae, 310, 312

Tarantulinae, 313

Tardigrada, 258, 477 f.; occurrence, 477; how to capture, 477; powers of resisting drying up, 484; classification, 485; British species, 486, 487

Tarentula, 417

Tarsonemidae, 471

Tartaridae, 312, 527

Tealia, Pycnogonum on, 524

Tegenaria, 416; T. civilis, 352; T. domestica, 416; palp, =321=; T. parietina, 352, 416

Telema tenella, 393

Telson, 6, 7; of Phyllopoda, 22

Temora longicornis, distribution, 203

Tethys (Mollusca), Pycnogon larva on, 524

Tetrabalius, 312

Tetrablemma, 315, 404; T. medioculatum, =318=

Tetraclita, =91=, 92

Tetragnatha, 407; T. extensa, 372

Tetragnathinae, 407

Tetrameridae, 92

Tetranychinae, 472

Tetranychus, 472; T. gibbosus, =472=; T. telarius, 455, 472

Tetraspidae, 88

Teutana, 404

Teuthraustes, 308

Texas fever, 456, 470

Thalassinidea, 167

Thamnocephalus, 36; range of, 34; T. platyurus, 36

Thanatus, 414; T. formicinus, 414; T. hirsutus, 414; T. striatus, 414

Thaumasia, 416

Thelphusa, 191; T. fluviatilis, development, 190; distribution, 213

Thelphusidae, 191

Thelyphonellus, 312

Thelyphonidae, 309, 312

Thelyphonus, =309=, 310, 312; resemblance to Eurypterids, 294

Theotina, 393

Theraphosa, 389; T. leblondi, 366, 389

Theraphosae, 319

Theraphosidae, 391 n.

Theridiidae, 327, 351, 401

Theridion, 376, 403; T. bimaculatum, 403; T. formosum, 403; T. pallens, cocoon, =358=; T. riparium, 403; T. sisyphium, 340, 351, 359, 403; T. tepidariorum, 352, 368, 403

Theridioninae, 403

Theridiosoma argenteolum, 407

Theridiosomatinae, 407

Thersites gasterostei, =71=

Thomisidae, 323, 324, 369, 371, 381, 412

Thomisinae, 412

Thomisus, 412; T. onustus, 413

Thompson, D’A. W., on Pycnogonida, 499 f.

Thoracica, 84

Thorax, of Trilobites, 234

Thorell, 383

Thyas petrophilus, 460

Tibellus, 414; T. oblongus, 371, =413=, 414

Tick fever, 469

Ticks, 468 f.; habits, 455, 461; synopsis of genera, 470

Titanodamon, 313

Tityus, 298, 306

Tmeticus, 406

Tomoxena, 403

Torania, 414

Tracheae, in Arachnida, 256; in Peripatus, 256; in Spiders, 336; in Phalangids, 446; in Acarina, 462

Trap-door Spiders, 354, 387, 388

Trechona venosa, 390

Triarthrus, 230, 234, 236, 247; thoracic limb, =10=; T. becki, =237=; Protaspis, =240=

Trichoniscus, 129

Trigonoplax, 193

Trilobita, 219 f.

Trilobite larva, of Limulus, 275, =276=

Trimerocephalus, 249; T. volborthi, 229

Trinucleidae, =230=, 245

Trinucleus, 225, 226, 230, 231, 236, 238, 245; T. bucklandi, =230=, 231; T. seticornis, 231

Tripeltis, 312

Trithena tricuspidata, =404=

Trithyreus, 312

Triton, cruise of the, 540

Trochantin, 433, 436, 449, 451, 452

Trochosa, 417; vestigial antennae in, 256, 263

Troglocaris, 163; T. schmidtii, habitat, 210

Trogulidae, 439, 442, 444, 452

Trogulus, 452; T. aquaticus, =452=; T. tricarinatus, 452, 453

Trombidiidae, 472

Trombidiinae, 473

Trombidium, 473; T. gymnopterorum, 455; T. holosericeum, 455, 473

Tropical zone (marine), 201

Trouessart, 455

Trygaeus, 506, 535; T. communis, 535

Tubicinella trachealis, 91

Tubularia, Pycnogons on, 522, 525

Tubuliform glands, =335=, 349

Tulk, 445, 446, 461 n.

Turret-spider, 357

Turrilepas, 84; T. wrightianus, =84=

Tylaspis, 179

Typhlocarcinus, 195

Typopeltis, 312

Tyroglyphidae, 466 n.

Tyroglyphinae, 466

Tyroglyphus, 464, 466, 481; T. longior, 466; T. siro, 466

Uliodon, 418

Uloboridae, 350, 410

Uloborinae, 410

Uloborus, 352, 410; snare of, =352=; U. republicanus, 411; U. walckenaerius, 411

Unguis, 319, =320=

Uroctea, 392; U. durandi, =392=

Urocteidae, 386, 392

Urodacinae, 306, 307

Urodacus, 307

Uroplectes, 306

Uropoda, 471

Uropodinae, 471

Uroproctus, 312

Uropygi, 312

Usofila, 393

Valvifera, 127

Vancoho, 362

Vectius, 415

Vejdovský, 435 n.

Vejovidae, 306, 308

Vejovis, 308

Vermiformia, 464

Verruca, 89, 91

Verrucidae, 91

Vesicle, of Scorpion, 303

Vinson, 349, 360, 362

Virbius, 164; V. acuminatus, 164; habitat, 202

Virchow, on human Pentastomids, 494

Viscid globules, on Spider web, =347=

Waite, 13

Walckenaer, 365, 386 n., 408 n.

Walckenaera, 405; W. acuminata, =405=

Walcott, on appendages of Trilobites, 236; on their development, 238; on early forms of Eurypterids, 283 n.

Wallace, 381

Wall-spider, 369

Warburton, C., on Arachnida, 295 f., 344 n., 349 n., 378 n.

Ward, on Reighardia, 495

Wasps and Spiders, 368

Water-mites, 460, 471, 472

Water-spider, 357, 415

Weismann, on Cladocera, 44, 49

Weldon, W. F. R., on excretory glands, 13; on Branchiopoda, 18 f.; on respiration in Carcinus, 189

Westring, 327, 384

Whale-louse, 502

Whip scorpions, 309

White, Gilbert, 342

Wilder, 366

Willemoesia, 157; W. inornata, =158=

Winkler, 463

With, 473 n.

Wolf-spiders, 341, 356, 359, 369, 375, 377, 381, 417

Wood-Mason, 328

Woods, H., on Trilobita, 219 f.; on fossil Xiphosura, 277 f.; on Eurypterida, 281 f.

Xanthidae, 191

Xantho, 191; habitat, 198

Xenobalanus globicipitis, 92

Xiphocaris, 163; distribution, 210

Xiphosura, 258, 259 f.; classification, 260, 276; fossil, 277 f.; affinities with Eurypterida, 292

Xiphosura, 276; X. polyphemus, 276

Xiphosuridae, 276

Xiphosurinae, 276

Xysticus, 412; X. cristatus, 412; X. pini, =413=

Zacanthoides, 247

Zaeslin, on the frequency of human Pentastomids, 494

Zeriana, 429

Zilla, 409; Z. x-notata, 359, 409

Zimris, 396

Zoaea, compared with Cumacea, 120; with Erichthus, 143; Calyptopis of Euphausia, =144=; of Peneus, =160=; of Sergestidae, 161; of Porcellana, =169=; of Birgus, 174; of Eupagurus, =179=; of Corystes cassivelaunus, =182=

Zodariidae, 317, 399

Zodarion, 399

Zora, 397; Z. spinimana, =396=

Zoropsis, 415

Zoropsidae, 415

END OF VOL. IV

Printed by R. & R. CLARK, LIMITED, Edinburgh.

-----

Footnote 1:

The muscles are to a certain extent segmented in correspondence with the limbs; and the heart, in Phyllopoda and Stomatopoda, may have segmentally arranged ostia.

Footnote 2:

Herbst, Arch. Entwick. Mech. ii., 1905, p. 544.

Footnote 3:

Quart. J. Micr. Sci. xlix., 1906, p. 469.

Footnote 4:

Present in Nebalia.

Footnote 5:

As many as 37 ambulatory appendages may be present.

Footnote 6:

Quart. J. Micr. Sci. xxi., 1881, p. 343.

Footnote 7:

Abhandl. Senckenberg. Nat. Gesellsch. xiv., 1886.

Footnote 8:

The Cumacea, Anaspidacea, and certain Isopods possess a maxillary gland only.

Footnote 9:

Quart. J. Micr. Sci. xxxii., 1891, p. 279.

Footnote 10:

Arch. Zool. Exp. (2) x., 1892, p. 57.

Footnote 11:

Bull. Mus. Comp. Zool. Harvard, xxxv., 1899, p. 152.

Footnote 12:

Arch. f. mikr. Anat. lxvii., 1906, p. 364.

Footnote 13:

Vol. x., 1897, pp. 97, 264.

Footnote 14:

For this use of the term Branchiopoda, cf. Boas, Morph. Jahrb. viii., 1883, p. 519.

Footnote 15:

Bernard, “The Apodidae,” Nature Series, 1892.

Footnote 16:

Arb. Zool. Inst. Wien, vi., 1886, p. 267.

Footnote 17:

I do not understand Packard’s account of the telson in Thamnocephalus.

Footnote 18:

The nomenclature here adopted is not that of Lankester.

Footnote 19:

Footnote 20:

Zeitschr. wiss. Zool. lxxi., 1902, p. 508.

Footnote 21:

Cf. Gaskell, Journ. Anat. Physiol. x., 1876, p. 153.

Footnote 22:

Bernard’s statement that Apus is hermaphrodite seems based on insufficient evidence.

Footnote 23:

Sayce has since described it, Proc. Roy. Soc. Victoria, xv., 1903, p. 229.

Footnote 24:

A. cancriformis had been supposed to have disappeared from the British fauna for many years, but it was found in Scotland in 1907. See R. Gurney, Nature, lxxvi., 1907, p. 589.

Footnote 25:

Branchipodides has been described by H. Woodward, from Tertiary strata.

Footnote 26:

Consult Baird, “Monograph of the Branchiopodidae,” Proc. Zool. Soc. 1852, p. 18. Packard, 12th Ann. Rep. U.S. Geol. Survey, part i., 1879.

Footnote 27:

Arch. f. Math. og Naturvidensk. xx., 1898, Nos. 4 and 6. Thiele, Zool. Jahrb. System. xiii., 1900, p. 563.

Footnote 28:

Bernard, loc. cit. p. 19; Baird, Proc. Zool. Soc. 1852, p. 1; Sayce, Proc. Roy. Soc. Victoria, xv., 1903, p. 224.

Footnote 29:

Sars, Arch. f. Math. og Naturvidensk. xx., 1898, Nos. 4 and 6.

Footnote 30:

Sars, Christiania Vidensk. Forhand. 1887. For Australian Phyllopods, see Sars, Arch. f. Math. og Naturvid. xvii., 1895, No. 7, and Sayce, loc. cit. p. 36.

Footnote 31:

Simocephalus vetulus anchors itself to weeds, etc., by a modified seta on the exopodite of the second antenna. It does not employ a dorsal organ for purposes of fixation. [G. S.]

Footnote 32:

Zeitschr. wiss. Zool. xxiv., 1874, p. 1.

Footnote 33:

Zeitschr. wiss. Zool. xxvii., xxxiii., 1876, 1879.

Footnote 34:

Consult Lilljeborg, Nov. Acta Reg. Soc. Upsalensis, 1901; Scourfield, J. Quekett Micr. Club, 1903–4.

Footnote 35:

More properly =Chydoridae=, but the universally known name Lynceidae is convenient.

Footnote 36:

Grundzüge der Zoologie, 4. Aufl. 1880, p. 543.

Footnote 37:

Fauna and Flora G. v. Neapel, Monograph 19, 1892.

Footnote 38:

Ibid. Monograph 25, 1899.

Footnote 39:

Norwegian North Polar Exp. Sci. Results, vol. i. part v., 1900.

Footnote 40:

They may assist the animal by retarding its sinking. Cf. Chun, “Aus den Tiefen des Weltmeeres,” 1905.

Footnote 41:

Schmeil, Bibliotheca Zoologica, Hefte 11, 15, and 21.

Footnote 42:

Giesbrecht, Mitth. Zool. Stat. Neap. xi., 1895, p. 648.

Footnote 43:

Loc. cit. p. 59.

Footnote 44:

Claus, Copepodenstudien, 1. Heft, Vienna, 1889.

Footnote 45:

Malaquin, Arch. Zool. Exp. (3), ix., 1901, p. 81.

Footnote 46:

Canu, Trav. Inst. Zool. Litte. vi., 1892.

Footnote 47:

Giesbrecht, Fauna and Flora G. v. Neapel, Monogr. 25, 1899.

Footnote 48:

Arb. Zool. Inst. Wien, ii. 1879, p. 268.

Footnote 49:

Ibid. xv., 1905, p. 1.

Footnote 50:

Heller, Reise der Novara, vol. iii., 1868.

Footnote 51:

For fish-parasites in British waters consult Scott, Fishery Board for Scotland, Scientific Investigations, xix., 1900 et seq.

Footnote 52:

Canu, loc. cit. p. 66.

Footnote 53:

The Cambridge Museum possesses two specimens of Philichthys xiphiae, from the frontal bones of a Swordfish (Xiphias gladius) taken off Lowestoft in 1892.

Footnote 54:

Claus, Arb. Zool. Inst. Wien, vii., 1888, p. 281.

Footnote 55:

Proc. Biol. Soc. Liverpool, i., 1887.

Footnote 56:

Zeitschr. wiss. Zool. xlix., 1890, p. 71.

Footnote 57:

The genus Pennella also includes parasites on the whales Hyperoodon and Balaenoptera.

Footnote 58:

Claus, Schriften d. Gesellsch. Marburg. Suppl. 1868.

Footnote 59:

Claus, Zeitschr. wiss. Zool. xi., 1861, p. 287.

Footnote 60:

Hansen, “The Choniostomatidae,” Copenhagen.

Footnote 61:

Claus, Zeitschr. wiss. Zool. xxv., 1875, p. 217.

Footnote 62:

C. B. Wilson, Proc. U.S. Nat. Museum, xxv., 1902, p. 635.

Footnote 63:

Max Müller (Science of Language, 2nd series, p. 534) gives references to a number of old authors who vouch for the truth of this legend, going back as far as Giraldus Cambrensis in the twelfth century. The legend appears to be of Scotch or Irish origin. Giraldus complains of the clergy in Ireland eating Barnacle geese at the time of fasting under the pretext that they are not flesh, but born of fish living in the sea. The form of the legend varies, certain authors alleging that the geese are produced from the fruits of a tree which drop into the water, others that they grow in shells (Barnacles) attached to floating logs. Aldrovandus (De Avibus, T. iii., 1603, p. 174) ingeniously combines both versions in a woodcut representing undoubted Barnacles growing on a tree with luxuriant foliage at the water’s edge, below which a number of liberated geese are swimming. Müller ascribes an etymological origin to the legend, the Barnacle goose (deriv. Hibernicula, bernicula = Irish goose) being confounded with pernacula, bernacula, a little shell.

Footnote 64:

“A Monograph of the Cirripedia,” vols. i. and ii., Ray Society, 1851, 1853.

Footnote 65:

“Rep. on the Cirripedia, H.M.S. ‘Challenger,’” vols. viii. and x., 1883.

Footnote 66:

“Monographie des Cirrhipèdes,” Paris, 1905, in which will be found full references to literature.

Footnote 67:

Arch. Biol. xvi., 1899, p 27.

Footnote 68:

Berndt, Sitzb. Ges. Naturfr. Berlin, 1903, p. 436.

Footnote 69:

Arch. Zool. Exp. viii., 1880, p. 537.

Footnote 70:

Quart. J. Micr. Sci. xxx., 1890, p. 107.

Footnote 71:

Plankton Expedition, ii. G. d. 1899.

Footnote 72:

Y. Delage, Arch. Zool. Exp. (2), ii., 1884, p. 417; G. Smith, Fauna u. Flora G. von Neapel, Monogr. 29, 1906.

Footnote 73:

G. Smith, Fauna u. Flora d. Golfes v. Neapel, Monogr. xxix., 1906, pp. 60–64, 119–121.

Footnote 74:

Bull. Sc. Dép. Nord (2), 10 Ann. xviii., 1887, p. 1. Ibid. (3), i., 1888, p. 12; and other papers.

Footnote 75:

G. Smith, loc. cit. chap. v. I. scorpio should be I. mauritanicus throughout this Monograph.

Footnote 76:

F. A. Potts, Quart. J. Micr. Sci. l., 1906, p. 599.

Footnote 77:

Faxon, Ann. Mag. Nat. Hist. (5), xiii., 1884, p. 147.

Footnote 78:

G. Smith, Mitth. Zool. Stat. Neapel, xvii., 1905, p. 312.

Footnote 79:

C. L. Boulenger, Proc. Zool. Soc. 1908, p. 42.

Footnote 80:

Garnier, C. R. Soc. Biol. liii., 1901, p. 38.

Footnote 81:

Gruvel, Monographie des Cirrhipèdes, 1905, p. 152.

Footnote 82:

Claus, Untersuchungen zur Erforschung des Crustaceensystems, Wien, 1876. Brady and Norman, “Monograph of the Marine and Fresh-Water Ostracoda of the N. Atlantic,” Trans. R. Dublin Soc. (2) iv., 1889, p. 63. Müller, Fauna und Flora G. von Neapel, Monogr. xxi., 1894; “Deutschlands Süsswasser-Ostracoden,” Chun’s Zoologica, xii., 1900.

Footnote 83:

“The Germ Plasm,” Contemp. Science Series, 1893, p. 345.

Footnote 84:

The term pereiopod is applied to those thoracic limbs which are used in locomotion, and are not specially differentiated for any other purpose.

Footnote 85:

Claus, Arb. Inst. Wien, viii., 1889, p. 1.

Footnote 86:

Robinson, Quart. J. Micr. Sci. 1., 1906, p. 383.

Footnote 87:

Morphol. Jahrb. viii., 1883, p. 485.

Footnote 88:

Ann. Mag. Nat. Hist. (7), xiii., 1904, p. 144.

Footnote 89:

The lacinia mobilis is a movable tooth-like structure jointed on to the biting face of the mandible.

Footnote 90:

Trans. Linn. Soc. (2), vi., 1894–1897, p. 285.

Footnote 91:

Trans. Roy. Soc. Edinburgh, xxxviii., 1897, p. 787.

Footnote 92:

G. Smith, Proc. Roy. Soc. 1908.

Footnote 93:

This characteristic is found in the Crustacea elsewhere only in the Argulidae and certain Euphausiidae.

Footnote 94:

The Victorian Naturalist, xxiv., 1907, p. 117.

Footnote 95:

Challenger Reports, vol. xiii., 1885, p. 55.

Footnote 96:

Sars, “Crustacea of Norway,” iii., 1900.

Footnote 97:

Sars, “Crustacea Caspia,” Bull. Acad. Imp. Sci. St. Pétersbourg, series 4, xxxvi., 1894, and “Crustacea of Norway,” iii., 1900, p. 120.

Footnote 98:

“Crustacea of Norway,” vol. ii., Isopoda, 1899, in which many references to literature will be found.

Footnote 99:

Smith, Mitth. Zool. Stat. Neapel, xvii., 1905, p. 312.

Footnote 100:

G. Smith, Mitth. Zool. Stat. Neapel, xvi., 1903, p. 469.

Footnote 101:

Mayer, Mitth. Zool. Stat. Neapel, i., 1879, p. 165.

Footnote 102:

Beddard, Challenger Reports, vol. xi., 1884.

Footnote 103:

Hansen, Quart. J. Micr. Sci. xlix., 1906, p. 69.

Footnote 104:

A useful little book on British Woodlice by Webb and Sillem (1906) may be profitably consulted. Budde Lund’s Isopoda Terrestria, 1900, is useful to the specialist.

Footnote 105:

The pleopods are traversed by a system of minute tubes called pseudotracheae, somewhat resembling the tracheae of Insects.

Footnote 106:

Bonnier, Trans. Inst. Zool. Lille, viii., 1900.

Footnote 107:

G. Smith, Fauna and Flora Neapel, Monograph 29, chap. vi.; M. Caullery, Mitth. Zool. Stat. Neapel, xviii., 1908, p. 583.

Footnote 108:

M. Caullery (loc. cit. p. 130) questions the truth of this observation, but I am convinced of its accuracy.

Footnote 109:

Trav. Inst. Lille, v., 1887.

Footnote 110:

Chilton, Trans. Linn. Soc. vi., 1894, p. 185.

Footnote 111:

Spenser and Hall, Proc. Roy. Soc. Victoria, ix. p. 12.

Footnote 112:

“Das Tierreich,” 21, Amphipoda Gammaridea, 1906.

Footnote 113:

Cf. P. Mayer, Fauna u. Flora G. von Neapel, Monogr. vi., 1882; xvii., 1890.

Footnote 114:

Abhandl. königl. Gesellsch. Göttingen, xvi., 1871.

Footnote 115:

Mem. Nat. Acad. Sci. v., 1891.

Footnote 116:

Sars, Challenger Reports, xiii., 1885; Chun, Bibliotheca Zoologica, xix., 1896, p. 139.

Footnote 117:

Die Physiologie der facettierten Augen von Krebsen und Insecten. Leipzig, Wien, 1891.

Footnote 118:

Valdivia Expedition, vol. vi., 1904.

Footnote 119:

Ann. Sci. Nat. (Zool.) (7), xiii., 1892, p. 185.

Footnote 120:

A Naturalist in Indian Seas, 1902.

Footnote 121:

“Atlantis,” Bibliotheca Zoologica, Heft 19, 1896, p. 193.

Footnote 122:

Loc. cit. p. 150.

Footnote 123:

Bell, A History of the British Stalk-eyed Crustacea, 1853; Heller, Die Crustaceen des Südlichen Europa, 1863.

Footnote 124:

Cf. Claus, Würzburger Naturwiss. Zeitschr. ii., 1861, p. 23.

Footnote 125:

Arch. f. Naturg. vi., 1840, p. 241.

Footnote 126:

Spence Bate’s Challenger Reports.

Footnote 127:

Some of the pereiopods remain biramous in certain Peneidea and Caridea (see p. 163).

Footnote 128:

Bull. U.S. Fish Commission, xv., 1895.

Footnote 129:

Zool. Bulletin, i., 1898, p. 287.

Footnote 130:

Archiv für Entw. Mech. xi., 1901, p. 321.

Footnote 131:

Challenger Reports, xxiv., 1888.

Footnote 132:

Loc. cit. p. 150.

Footnote 133:

Keeble and Gamble, Phil. Trans., Ser. B, cxcvi., 1904, p. 295. The chromatophores are also directly responsive to light, but the lasting adaptations to colour-backgrounds are brought about indirectly, the stimulus being transmitted through the eyes and nervous system. The influence of light may also affect the metabolism of the animal, the chromatophores being accompanied by a ramifying fatty tissue, which disappears if the animal is kept in the dark.

Footnote 134:

Challenger Reports, xxiv., 1881.

Footnote 135:

Borradaile’s useful paper on the classification of the Decapoda (Ann. Mag. Nat. Hist. (7), xix., 1907, p. 457) should be consulted for this and other Decapod groups. Also Alcock’s Cat. of the Indian Mus., “Decapod Crustacea.”

Footnote 136:

Giard and Bonnier, Compt. Rend. Soc. Biol. 1892.

Footnote 137:

Coutière, Fauna and Geogr. Maldive and Laccadive Archipelagos, ii., 1905, p. 852.

Footnote 138:

Keeble and Gamble, Phil. Trans. Ser. B., cxcvi., 1904, p. 295. In the young a constant and very simple chromatophore-system is present, but in the adult a barred, lined, or monochrome colour-pattern may be present, which is ultimately induced by the nature of the environment, and does not subsequently change. In other species of Hippolyte, and in Palaemon and Crangon, only one adult colour-pattern occurs. Thus H. varians, besides reacting to light by its chromatophores, possesses a permanent colour-pattern, which is also determined by environment.

Footnote 139:

Claus, Unt. z. Erforschung d. genealog. Grundlage d. Crustaceensystems. Vienna, 1876.

Footnote 140:

Milne Edwards and Bouvier, Ann. Sci. Nat. (7), xvi., 1894, p. 91.

Footnote 141:

Garstang, Quart. J. Micr. Sci. xl., 1897, p. 211.

Footnote 142:

Milne Edwards and Bouvier, Bull. Soc. Philomath. Paris (8), ii., 1889; and Expédition du Talisman, “Crustacés Décapodes,” 1900.

Footnote 143:

Alcock, loc. cit.; Borradaile, op. cit. p. 162; i. p. 64.

Footnote 144:

Brandt, Bull. Phys. Math. Acad. St. Pétersbourg, i. p. 171, and viii. p. 54; Boas, K. Dansk. Vidensk. Selskab. Skrift. Naturvid. og Math. Afd. 6, Bd. 2, 1880; Bouvier, Ann. Sci. Nat. (Zool.) (7) xviii. p. 157.

Footnote 145:

Vol. xxvii. p. 81.

Footnote 146:

Proc. Boston Soc. Nat. Hist., xxxi., 1904, p. 147.

Footnote 147:

For general literature consult Ortmann in Bronn’s Tier-Reich, v. 2, 1901, p. 778. See also Reports of Challenger, Valdivia, and Talisman Expeditions, etc.

Footnote 148:

Gurney, Quart. J. Micr. Sci. xlvi., 1902, p. 461.

Footnote 149:

Bouvier, Bull. Soc. Philomath. Paris, (8) viii., 1896.

Footnote 150:

Loc. cit. p. 183.

Footnote 151:

M‘Culloch, Rec. Australian Mus. vi. part 5, 1907, p. 353.

Footnote 152:

Lankester, Quart. J. Micr. Sci. xlvii., 1903, p. 439.

Footnote 153:

Garstang, Quart. J. Micr. Sci. xl., 1897, p. 211, and Journ. Mar. Biol. Ass. iv., 1895–97, p. 396.

Footnote 154:

Loc. cit. p. 181.

Footnote 155:

Rep. Brit. Ass. for 1898, p. 887.

Footnote 156:

Naturalist in Indian Seas, 1902.

Footnote 157:

There appears to be some doubt on this point, as Westwood (see p. 153) described direct development in a Gecarcinus. Possibly different species behave variously.

Footnote 158:

Kingsley, Proc. Acad. Nat. Sci. Philadelphia, 1880, p. 187.

Footnote 159:

American Naturalist, xxxiii., 1899, p. 583.

Footnote 160:

Planktonstudien, Jena, 1890.

Footnote 161:

“Report on the Plankton,” Internat. Inst. Marine Biol. 1903.

Footnote 162:

Internat. Inst. Mar. Biol. 1903.

Footnote 163:

A Naturalist in Indian Seas.

Footnote 164:

Scourfield, J. Quekett Micr. Club, 1903–4, gives a useful list of British Fresh-water Entomostraca. For the identification of fresh-water Cladocera, Lilljeborg’s “Cladocera Sueciae,” Nov. Act. Reg. Soc. Upsalensis, 1901; for Copepoda, Schmeil’s “Süsswasser Copepoden,” in Bibliotheca Zoologica, iv., v., and viii., 1892, 1893, and 1895 are recommended.

Footnote 165:

Trans. Norfolk and Norwich Nat. Soc. vii.

Footnote 166:

Le Lac Leman, 3 vols., Lausanne, 1892.

Footnote 167:

Consult Apstein, “Das Süsswasserplankton,” Kiel and Leipzig, 1896; and Arch. f. Hydrobiologie u. Planktonkunde, numerous papers.

Footnote 168:

Mr. C. H. Martin points out to me that in the Scottish lochs, which from their geological nature are evidently not connected with subterranean waters, none of them nor similar forms occur; nor do they in the Tasmanian lakes which are on igneous diabase, so that Forel’s conclusion would seem to be of wide application.

Footnote 169:

See Chilton, Trans. Linn. Soc. (2) vi., 1894, p. 163, with review of literature.

Footnote 170:

S. F. Harmer, Trans. Norfolk and Norwich Nat. Soc. ii., 1899, p. 489.

Footnote 171:

Mem. Nat. Acad. Washington, iii., 1886, p. 1.

Footnote 172:

Arch. Zool. Exp. (4), ii., 1904, p. 1.

Footnote 173:

See Calman, Proc. Zool. Soc. 1906, p. 187.

Footnote 174:

The Crayfish, Internat. Scient. Series.

Footnote 175:

Mem. Harvard. Mus. x., 1885.

Footnote 176:

Proc. Amer. Phil. Soc. xli., 1902, p. 267, and xliv., 1905, p. 91.

Footnote 177:

G. O. Sars, “Crustacea Caspia,” Bull. Acad. Imp. Sc. St. Pétersbourg (4), xxxvi., 1893–4, pp. 51 and 297; (5) i., 1894, pp. 179 and 243; also Crustacea of Norway, vol. ii. Isopoda, 1900, p. 73.

Footnote 178:

Daday, Termés Füzetek, xxv., 1902, pp. 101 and 436.

Footnote 179:

Daday, Bibliotheca Zoologica, Heft 44, 1905.

Footnote 180:

On the cheek the furrow represents a pleural groove, and does not form the limit of the posterior cephalic segment.

Footnote 181:

M‘Coy, Synop. Sil. Foss. Ireland, 1846, p. 56, and Brit. Pal. Foss., 1851, p. 146, pl. 1 E, fig. 16; Salter, Quart. Journ. Geol. Soc. iii., 1847, p. 251.

Footnote 182:

Figures showing this suture are given by Oehlert, Bull. Soc. géol. de France (3), xxiii., 1895, pl. 1, figs. 9, 12, 15.

Footnote 183:

Ann. Mag. Nat. Hist. (2) iv., 1849, p. 396.

Footnote 184:

Lindström, “Visual Organs of Trilobites,” Svenska Vet. Akad. Handl. xxxiv., 1903. Exner, Physiol. d. facett. Augen v. Krebsen u. Insecten, 1891, p. 34, pl. ii. figs. 18, 19.

Footnote 185:

Journ. Morphol. ii., 1889, p. 253, pl. 21.

Footnote 186:

Watase, Johns Hopkins Univ. Studies, Biol. Lab. iv., 1890, p. 290. Lindström, op. cit. p. 27.

Footnote 187:

A suture is said to be present at the external margin of the flattened cephalic border.

Footnote 188:

Goldfuss, “Beitr. zur Petrefaktenkunde,” 1839, p. 359, pl. 33, fig. 2d.

Footnote 189:

Spencer, Geol. Mag. 1903, p. 489.

Footnote 190:

For an example of this see Salter, Mon. Brit. Trilobites, 1864–83, pls. 15, 16.

Footnote 191:

Bull. Mus. Comp. Zool. Harvard, viii., 1881, p. 191.

Footnote 192:

Studies in Evolution, 1901, pp. 197–225; Geol. Mag. 1902, p. 152. Walcott, Proc. Biol. Soc. Washington, ix., 1894, p. 89.

Footnote 193:

Syst. Sil. Bohême, i., 1852, pp. 257–276.

Footnote 194:

American Geologist, xx., 1897, p. 34.

Footnote 195:

Proc. R. Irish Acad. xxiv., 1903, p. 332, and Quart. Journ. Micr. Sci. xlix., 1906, p. 469.

Footnote 196:

This has received some support from H. Milne Edwards, Ann. Sci. Nat. Zool. (6), xii., 1881, p. 33; H. Woodward, Quart. Journ. Geol. Soc. xxvi., 1870, p. 487, and vol. 1., 1894, p. 433; Bernard, ibid. vol. 1. p. 432.

Footnote 197:

Kingsley does not admit this relationship, and regards the Trilobita as a group quite distinct from all other Crustacea. See American Naturalist, xxviii., 1894, p. 118, and American Geologist, xx., 1897, p. 33.

Footnote 198:

Zittel states that Apus appears first in the Trias.

Footnote 199:

Monogr. Brit. Trilobites, 1864, p. 2.

Footnote 200:

“A Natural Classification of Trilobites,” Amer. Jour. Sci. (4), iii., 1897, pp. 89–106, 181–207. Reprinted in Beecher’s Studies in Evolution, 1901, p. 109. A classification based on the character of the pygidium has been proposed by Gürich, Centralbl. für Min. Geol. u. Pal. 1907, p. 129. A classification based on the minute structure of the test has been given by Lorenz, Zeitschr. d. deutsch. geol. Gesellsch. lviii., 1906, p. 56.

Footnote 201:

Neues Jahrb. für Min. Geol. u. Pal. 1898, i. p. 187.

Footnote 202:

Lake, Brit. Cambrian Tril. 1907, p. 45.

Footnote 203:

The British Carboniferous Proëtidae are described by H. Woodward, Monogr. Brit. Carb. Trilobites, Palaeont. Soc. 1883–84.

Footnote 204:

This can be maintained in the Crustacea by counting the seventh abdominal segment, which appears in Gnathophausia; but this is not universally regarded as a true segment. See also Nebalia (p. 111).

Footnote 205:

This and the following Sub-class correspond with Lankester’s Sub-class Euarachnida. The Delobranchiata have gills patent and exposed, and adapted for breathing oxygen dissolved in water. The Embolobranchiata have either the gill-books (now termed lung-books) sunk into their body, or the gill-books are wholly or partially replaced by tracheae. In either case the members of this Sub-class breathe atmospheric oxygen.

Footnote 206:

Woodward, “On some Points in the Structure of the Xiphosura, having reference to their relationship with the Eurypteridae,” Quart. J. Geol. Soc. xxiii., 1867, p. 28, and xxviii., 1871, p. 46. Milne Edwards, A., “Recherches sur l’anat. des Limules,” Ann. Sci. Nat. (5), xvii., 1873, Art. 4. Lankester, E. R., “Limulus an Arachnid,” Quart. J. Micr. Sci. xxi., 1881, p. 504. Kingsley, J. S., “The Embryology of Limulus,” Journ. Morph. vii. p. 35, and viii. p. 195, 1892–3. Kishinouye, “On the Development of Limulus longispina,” Journ. Coll. Sci. Japan, v., 1892, p. 53. Patten, W., and Redenbaugh, W. A., “Studies on Limulus,” Journ. Morph. xvi., 1900, pp. 1, 91.

Footnote 207:

Quart. J. Micr. Sci. xlviii., 1905, p. 165.

Footnote 208:

μηρός = a thigh.

Footnote 209:

This segment, though present in embryo Scorpions, has disappeared in the adults of those animals.

Footnote 210:

Quart. J. Micr. Sci. xlix., 1906, p. 469.

Footnote 211:

Zool. Anz. xiv., 1891, pp. 164, 173.

Footnote 212:

Zeitschr. wiss. Zool. lix., 1895, p. 351.

Footnote 213:

They are described in great detail in Lankester’s article, “Limulus an Arachnid,” Quart. J. Micr. Sci. xxi., 1881, p. 504.

Footnote 214:

Tr. Linn. Soc. xxviii., 1872, p. 471.

Footnote 215:

Tr. Linn. Soc. xxviii., 1872, p. 472.

Footnote 216:

A rudimentary ninth pair of ostia are described anteriorly.

Footnote 217:

J. Morph. vii., 1892, p. 35.

Footnote 218:

Kingsley, loc. cit.

Footnote 219:

J. Coll. Tokyo, v., 1893, p. 53.

Footnote 220:

Lockwood, Amer. Nat. iv., 1870–71, p. 261.

Footnote 221:

For a diagnosis of the species and a list of synonyms, see Pocock, Ann. Mag. Nat. Hist. (7), ix., 1902, p. 256.

Footnote 222:

Quart. J. Micr. Sci. xxxi., 1890, p. 379; Proc. Cambr. Phil. Soc. ix., 1895–1898, p. 19; J. Anat. Physiol. xxxiii., 1899, p. 154.

Footnote 223:

Quart. J. Micr. Sci. xxxi., 1890, p. 317.

Footnote 224:

I am indebted to Mr. Henry Woods for these paragraphs on fossil Xiphosura.

Footnote 225:

The British fossil forms of this group are described and figured by H. Woodward, “Monograph of the Merostomata,” Palaeontogr. Soc. 1866–78, and Geol. Mag. 1907, p. 539.

Footnote 226:

Packard, “Carb. Xiphos. N. America,” Mem. Nat. Acad. Sci. Washington, iii., 1885, p. 146, pl. vi. fig. 1a, pl. v. fig. 3a (restoration). Williams, Amer. Journ. Sci. (3), xxx., 1885, p. 45. Fritsch, Fauna d. Gaskohle, iv., 1901, p. 64, pl. 155, figs. 1–3, and text-figures, 369, 370.

Footnote 227:

Walcott has described, under the generic name Beltina, imperfect specimens from the Algonkian (pre-Cambrian) of Montana, which he thinks may be the remains of Eurypterids (Bull. Geol. Soc. America, x., 1899, p. 238).

Footnote 228:

Walcott, Amer. Jour. Sci. (3), xxiii., 1882, p. 213.

Footnote 229:

Descriptions and figures of British Eurypterids are given in the following works:—Huxley and Salter, “Pterygotus,” Mem. Geol. Survey, Brit. Org. Remains, i., 1859; H. Woodward, “Monograph of the Merostomata,” Palaeont. Soc. 1866–78, and Geol. Mag. 1879, p. 196; 1887, p. 481; 1888, p. 419; 1907, p. 277; Peach, Trans. Roy. Soc. Edinb. xxx., 1882, p. 511; Laurie, ibid. xxxvii., 1892, p. 151; xxxvii., 1893, p. 509; and xxxix., 1899, p. 575.

Footnote 230:

A detailed account of Eurypterus fischeri has been given by G. Holm, Mém. Acad. Impér. Sci. St. Pétersbourg (8), viii. 2, 1898. See also F. Schmidt, ibid. (7), xxxi. 5, 1883. Descriptions of American forms of Eurypterus are given by Hall, “Nat. Hist. New York,” Palaeont. iii., 1859, p. 395; ibid. vii., 1888, p, 156; and Second Geol. Survey Pennsylvania, “Report of Progress,” PPP., 1884; Whiteaves, Geol. and Nat. Hist. Surv. Canada, “Palaeozoic Foss.,” iii., 1884, p. 42.

Footnote 231:

It was this ornamentation found on fragments of Pterygotus anglicus which led the Scotch quarrymen to apply the name “Seraphim” to that Eurypterid. On this subject Hugh Miller writes: “The workmen in the quarries in which they occur, finding form without body, and struck by the resemblance which the delicately waved scales bear to the sculptured markings on the wings of cherubs—of all subjects of the chisel the most common—fancifully termed them ‘Seraphim’” (The Old Red Sandstone, ed. 6, 1855, p. 180).

Footnote 232:

The third leg in the male possesses on the fifth joint a curved appendage which extends backwards to the proximal end of the second joint. This structure may have been a clasping organ.

Footnote 233:

It has been suggested that the metastoma really belongs to a pregenital segment of the mesosoma which is absent in the adult, but has been found in the embryo of Scorpions.

Footnote 234:

Sarle, New York State Museum, Bulletin 69, Palaeont. 9, 1903, p. 1087.

Footnote 235:

Beecher, Geol. Mag. 1901, p. 561.

Footnote 236:

Peach, Nature, xxxi., 1885, p. 295; Pocock, Quart. Journ. Micr. Sci. xliv., 1901, p. 291; Laurie, Trans. Roy. Soc. Edinb. xxxix., 1899, p. 575.

Footnote 237:

Peach, Trans. Roy. Soc. Edinb. xxx., 1882, p. 516.

Footnote 238:

Cf. p. 258.

Footnote 239:

Nature, xlviii., 1893, p. 104.

Footnote 240:

Souvenirs entomologiques, Sér. 9, 1907, p. 229.

Footnote 241:

Brauer, Zeitschr. wiss. Zool. lix., 1895, p. 355.

Footnote 242:

Das Tierreich, 8. Lief., 1899, p. 4.

Footnote 243:

Arachnides de France, vii., 1879, p. 84.

Footnote 244:

Fauna of British India, “Arachnida,” 1900, p. 8.

Footnote 245:

Tr. Zool. Soc. xi. part x., 1885, p. 373.

Footnote 246:

Zeitschr. wiss. Zool. lix., 1895, p. 351.

Footnote 247:

Das Tierreich, 8. Lief., 1899.

Footnote 248:

Pocock, Fauna of British India, “Arachnida.” London, 1900.

Footnote 249:

Laurie, J. Linn. Soc. Zool. xxv., 1894, p. 30.

Footnote 250:

See M. Laurie in J. Linn. Soc. Zool. xxv., 1894, p. 20.

Footnote 251:

Tr. Linn. Soc. (2) vi., 1896, p. 344.

Footnote 252:

Bernard, loc. cit. p. 366.

Footnote 253:

J. Linn. Soc. xxv., 1894, p. 29.

Footnote 254:

See Pocock, Ann. Nat. Hist. (6), xiv., 1894, p. 120.

Footnote 255:

Kraepelin, Das Tierreich, Berlin, 8. Lief., 1899, p. 234.

Footnote 256:

The term mostly in use is Araneida, which should mean Araneus-like animals. This is clearly not allowable, unless there is a genus Araneus or Aranea. For many years there has been no such genus recognised, but Simon now attempts to re-establish it, inadmissibly, as it appears to us. (See note, p. 408).

Footnote 257:

Mém. Mus. d’Hist. Nat. xviii., 1829, p. 377.

Footnote 258:

Pickard-Cambridge (Spiders of Dorset, 1879–1881) omits the coxal joint, which, with its lobe, he calls the maxilla, and therefore gives only five joints, which he names axillary, humeral, cubital, radial, and digital.

Footnote 259:

Pickard-Cambridge, in his Spiders of Dorset, names them exinguinal, coxal, femoral, genual, tibial, metatarsal, and tarsal.

Footnote 260:

Nat. Hist. Tidsskr. iv., 1843, p. 349.

Footnote 261:

J. Linn. Soc. xv., 1881, p. 155.

Footnote 262:

Proc. Asiat. Soc. Beng. 1875, p. 197.

Footnote 263:

Tijdschr. v. d. Nederl. Dierkundige Ver. (2), i., 1885–1887, p. 109.

Footnote 264:

Études sur la circulation du sang chez les Aranées du genre Lycose. Utrecht, 1862.

Footnote 265:

Recherches sur l’appareil circulatoire des Aranéides. Lille, 1896.

Footnote 266:

Arch. f. Naturg. 55 Jahrg., i., 1889, p. 29.

Footnote 267:

M‘Leod, Bull. Ac. Belg. (3), iii., 1882, p. 779.

Footnote 268:

American Spiders and their Spinning Work, ii., 1890, p. 208.

Footnote 269:

Ann. Nat. Hist. (3), xv., 1865, p. 459.

Footnote 270:

Voyage of the Beagle.

Footnote 271:

Correspondence of John Ray, p. 77.

Footnote 272:

Warburton, Q. J. Micr. Sci. xxi., 1890, p. 29.

Footnote 273:

Rep. Brit. Ass. 1844, p. 77.

Footnote 274:

Nature, xl., 1889, p. 250.

Footnote 275:

See Warburton, Quart. J. Micr. Sci. xxi., 1890, p. 29.

Footnote 276:

Aranéides de la Réunion, Maurice et Madagascar, Paris, 1863, p. 238.

Footnote 277:

M‘Cook, American Spiders and their Spinning Work, i., 1889, p. 351; F. O. Pickard-Cambridge, J. Micr. and Nat. Sci. July 1890.

Footnote 278:

Moggridge, Harvesting Ants and Trap-door Spiders. London, 1873, p. 120.

Footnote 279:

Verh. Ges. Wien, xviii., 1868, p. 905 (Abstract in Zool. Rec. v., 1868, p. 175).

Footnote 280:

The figure of this cocoon has been accidentally inverted in the works of both Blackwall and Pickard-Cambridge.

Footnote 281:

Fabre, Nouveaux souvenirs entomologiques, ch. xi.

Footnote 282:

Aranéides de la Réunior, Maurice et Madagascar, Paris, 1863, p. xlvi.

Footnote 283:

Hist. de la grande île de Madagascar, 1658, p. 156.

Footnote 284:

Science Gossip, 1877, p. 46.

Footnote 285:

Insect Life, i., 1889, p. 205.

Footnote 286:

Ann. Soc. ent. France, xi., 1842, p. 205. Translated from the Spanish by L. Fairmaire.

Footnote 287:

M‘Cook, American Spiders and their Spinning Work, ii., 1890, p. 188.

Footnote 288:

M‘Cook, t.c. p. 389.

Footnote 289:

British Spiders, 1861, p. 102.

Footnote 290:

Ann. Nat. Hist. (1), xi., 1843, p. 1.

Footnote 291:

Naturalist in Nicaragua, 2nd ed., 1888, p. 134.

Footnote 292:

Nouveaux souvenirs entomologiques, ch. xii.

Footnote 293:

M‘Cook, t.c. p. 384.

Footnote 294:

The Naturalist in Nicaragua, p. 19.

Footnote 295:

Spiders of Dorset, 1879–1881, p. 292.

Footnote 296:

Ibid. p. 360.

Footnote 297:

Naturalist on the Amazon, 1873, p. 54.

Footnote 298:

Protective Resemblances and Mimicry in Animals, 1873, p. 4.

Footnote 299:

Nature, lxviii., 1908, p. 631.

Footnote 300:

J. Morph. (Boston, U.S.A.) i., 1887, p. 403.

Footnote 301:

Nature, xxiii., 1880, p. 149.

Footnote 302:

Warburton, Ann. Nat. Hist. (6), viii., 1891, p. 113.

Footnote 303:

Spiders of Dorset, 1879–1881, p. xxvii.

Footnote 304:

Spiders, their Structure and Habits, 1883, p. 98.

Footnote 305:

Sexual Selection in Spiders, p. 37. (Occasional Papers of the Nat. Hist. Soc. of Wisconsin, I., 1889.)

Footnote 306:

Arachnides de France (vol. i., published 1874). Histoire naturelle des araignées (2nd ed. vol i., published 1892).

Footnote 307:

Simon’s Cribellatae comprise Hypochilidae, Uloboridae, Psechridae, Zoropsidae, Dictynidae, Oecobiidae, Eresidae, Filistatidae.

Footnote 308:

The Spider genus Mygale was established by Walckenaer in 1802, but the name was preoccupied, having been used by Cuvier (Mammalia) in 1800.

Footnote 309:

Hist. Nat. des Araignées (2nd ed.), i., 1892, p. 76.

Footnote 310:

The “scopula” is the pad of close-set thick hairs which covers the under surface of the tarsus and often of the metatarsus. The “claw-tufts” are groups of longer hairs, often extending beyond the claws, and giving the foot a bifid appearance.

Footnote 311:

The three families mentioned above constitute the “Araneae Theraphosae” of Simon, the remaining families being distinguished as “Araneae Verae.” The Aviculariidae and the Atypidae are united by some authors to form the Theraphosidae.

Footnote 312:

According to Bertkau (in a letter to Simon, cited in Hist. Nat. des Ar. i. p. 327), two pairs of linear stigmata under the anterior part of the abdomen lead, to pulmonary sacs, but to tracheae.

Footnote 313:

L. Koch replaced Melanophora by Prosthesima, believing the former to be preoccupied, but according to Simon (Hist. Nat. des Ar. i. p. 341) C. Koch’s use of Melanophora for an Arachnid was antecedent (1833) to Meigen’s employment of it for Diptera, 1838.

Footnote 314:

Hist. Nat. des Ar. i. p. 416.

Footnote 315:

Pickard-Cambridge, Spiders of Dorset, p. 77.

Footnote 316:

Hist. Nat. des Ar. i. p. 594.

Footnote 317:

Hist. Nat. des Ar. i. p. 692.

Footnote 318:

The Erigoninae, Formicinae, and Linyphiinae, together with the Epeiridae, form Simon’s family of Argiopidae.

Footnote 319:

I.e. as developed in the course of the work, not as set forth on p. 594 of vol. i., where five sub-families are established (Theridiosomatinae, Arciinae, Eurycorminae, Amazulinae, Poltyinae), which are afterwards merged in the Argiopinae.

Footnote 320:

Simon’s treatment of this group in his Hist. Nat. Ar. does not appear to us satisfactory. He revives the name Araneus as a generic term, a proceeding to which there are very valid objections, and merges in it, in whole or in part, about twenty-five generally received genera, including 800 species. He then proceeds to break up the genus Araneus into six entirely artificial “series,” according to the eyes. However unsatisfactory the merged genera may be, nothing seems to be gained by this proceeding. The facts about “Araneus” are these. Clerck and Linnaeus used the name “Araneus” for every member of the order. Latreille, in subdividing the order, retained the name for A. (Epeira) diademata (1804), but later (1827) transferred it to A. (Tegenaria) domestica. Walckenaer, seeing the impropriety of using Araneus as a generic term, discarded it, establishing Epeira, which has since obtained universal recognition.

Footnote 321:

Simon, in his Histoire naturelle des araignées, removes the Sparassinae and the Selenopinae to the Clubionidae, considering that, notwithstanding the direction of their legs, they have a greater affinity with that group than with the other Thomisidae.

Footnote 322:

Ent. Tidsskr. xviii., 1897, p. 223, pl. iv.

Footnote 323:

Zool. Anz. xxiv., 1901, p. 537.

Footnote 324:

Quart. J. Micr. Sci. xlvii., 1904, p. 215.

Footnote 325:

Trans. Linn. Soc. (2), vi., 1896, p. 323.

Footnote 326:

Nature, xlvi., 1892, p. 247.

Footnote 327:

Ann. Nat. Hist. (1), xii., 1843, p. 81.

Footnote 328:

Pocock, Nature, lvii., 1897, p. 618.

Footnote 329:

Cook, Nature, lviii., 1898, p. 247.

Footnote 330:

Öfv. Ak. Förh. lvi., 1899, p. 977.

Footnote 331:

Trans. Linn. Soc. (2), vi., 1896, p. 310.

Footnote 332:

Das Tierreich, Berlin, 12. Lief., Arachnoidea, 1901, p. 4.

Footnote 333:

Arachnides de France, vii., 1879, p. 2.

Footnote 334:

Arachnides de France, vii., 1879, p. 5.

Footnote 335:

See Bernard, J. Linn. Soc. xxiv. (Zool.), 1893, p. 410.

Footnote 336:

See Bernard, J. Linn. Soc. xxiv. (Zool.), 1893, p. 422.

Footnote 337:

For the embryology of Chernetidea, see J. Barrois, “Mém. sur le développement des Chélifers,” Rev. Suisse de Zool. iii., 1896. Metschnikoff, Zeitschr. wiss. Zool. xxi., 1876, p. 514; and Vejdovský, Congrès zool. international de Moscou, 1892, p. 120, may also be consulted.

Footnote 338:

Monograph of the British Species of Chernetidea, Dorchester, 1892.

Footnote 339:

Revue Zoologique par la Société Cuvierienne, p. 10.

Footnote 340:

Arachnides de France, vii., 1879, p. 122.

Footnote 341:

On two Orders of Arachnida, Cambridge University Press, 1904.

Footnote 342:

Mag. Nat. Hist. (i.), xii., 1843, p. 325.

Footnote 343:

Zool. Jahrb. iii., 1888, p. 319.

Footnote 344:

T. C. pp. 67–75.

Footnote 345:

Long sternum (μῆκος = length; στῆθος = breast).

Footnote 346:

Arachnides de France, vii., 1879.

Footnote 347:

Transverse sternum (πλάγιος = transverse).

Footnote 348:

Monograph of the British Phalangidea, Dorchester, 1890.

Footnote 349:

The single exception is Opilioacarus, see p. 473.

Footnote 350:

C. R. Ac. Sci. cxxv., 1897, p. 879.

Footnote 351:

“The Biology of the Cattle Tick,” Journ. Compar. Med. and Vet. Archives, 1891, p. 313.

Footnote 352:

Entomological News (Philadelphia), vol. xi., Jan. 1900.

Footnote 353:

For the Protozoa to which these and similar diseases are due, cf. vol. i. pp. 120 f.

Footnote 354:

C. R. Soc. Biol. Paris (7), iv., 1882, p. 305.

Footnote 355:

Ann. Soc. Linn. Lyon, xxii., 1876, p. 29.

Footnote 356:

Bull. Soc. Nat. de Moscou, liv. 1879, pt. i. p. 234.

Footnote 357:

Z. wiss. Zool. xxxvii., 1882, p. 553.

Footnote 358:

P. Z. S., 1895, p. 174.

Footnote 359:

Arch. f. Naturg. i., 1876, p. 65.

Footnote 360:

Tr. Linn. Soc. (2), v. Zool., 1890, p. 281.

Footnote 361:

See account given by Tulk in Mag. Nat. Hist. xviii., 1846, p. 160.

Footnote 362:

Entomological News (Philadelphia), vol. xi., Jan. 1900.

Footnote 363:

Michael, British Oribatidae (Ray Soc.), i., 1883, p. 176.

Footnote 364:

Loc. cit. p. 168.

Footnote 365:

Claparède, Z. wiss. Zool. xviii., 1868, p. 455. Michael, British Oribatidae, i., 1883, p. 73, writes it “Deutovium.”

Footnote 366:

Atti Ist. Veneto, ii., 1891, p. 699.

Footnote 367:

Rev. Sci. Nat. Ouest, ii., 1892, p. 20.

Footnote 368:

Eriophyes, v. Siebold, Jahresber. Schles. Ges. xxviii., 1850, p. 89; Phytoptus, Dujardin, Ann. Sci. Nat. (3), xv., 1851, p. 166.

Footnote 369:

See Michael, British Tyroglyphidae, published by the Ray Society, 1901–2.

Footnote 370:

The first paper appeared in Mém. Soc. Zool. ix., 1896, pp. 1–44.

Footnote 371:

“Ticks, a Monograph of the Ixodoidea.” Part I. Argasidae, 1908.

Footnote 372:

With, Vid. Medd. 1904, p. 137.

Footnote 373:

Silvestri, Redia, ii., 1904, fasc. 2, p. 257.

Footnote 374:

Arch. mikr. Anat. Bd. i., 1865, p. 428.

Footnote 375:

A. Basse, Zeitschr. wiss. Zool. lxxx., 1906, p. 259.

Footnote 376:

Ann. Sci. nat. (2), xiv., 1840, p. 269, and xvii., 1842, p. 193.

Footnote 377:

Zool. Jahrb. Anat. iii., 1889. This paper contains a bibliography.

Footnote 378:

Morph. Jahrb. xxii., 1895, p. 491.

Footnote 379:

C. R. Ac. Sci. cxviii., 1894, p. 817.

Footnote 380:

Tr. R. Soc. Edinb. xlv., 1908, p. 641. This contains a Bibliography of recent literature. See also Richters, Zool. Anz. xxx., 1906, p. 125, and Heinis, Zool. Anz. xxxiii., 1908, p. 69.

Footnote 381:

P. Zool. Soc. 1897, p. 790.

Footnote 382:

Hay, in P. Biol. Soc. Washington, xix., 1906, p. 46, states that the name Lydella, Dujardin, is preoccupied, and suggests as a substitute Microlyda.

Footnote 383:

The animals included in this group are usually called Linguatulidae or Pentastomidae after the two genera or sub-genera Linguatula and Pentastoma. But the animal which Rudolphi in 1819 (Synopsis Entozoorum) named Pentastoma had been described, figured, and named Porocephalus by Humboldt (Recueil d’observations de zoologie et anatomie comparee, i. p. 298, pl. xxvi.) in 1811. The familiar name Pentastoma may, however, be preserved by incorporating it in the designation of the group.

Footnote 384:

This description is mainly based on the account of P. teretiusculus given by Spencer, Quart. J. Micr. Sci. xxxiv., 1893, p. 1.

Footnote 385:

Zeitschr. wiss. Zool. lii., 1891, p. 85. This contains a very full bibliography, of 143 entries.

Footnote 386:

Centrbl. Bakter. xl., 1906, p. 368; v. also Thiroux, C. R. Soc. Biol. lix., 1905, p. 78.

Footnote 387:

Shipley, Arch. parasit. i., 1898, p. 52. This contains lists of synonyms and of memoirs published since Stiles’ paper, etc.

Footnote 388:

H. B. Ward, P. Amer. Ass. 1899, p. 254.

Footnote 389:

Nouv. Dict. de méd., de chir. et d’hyg. vétérinaires, xii. 1883.

Footnote 390:

Tr. R. Soc. Edinb. xxxii., 1884, p. 165.

Footnote 391:

Lohrmann, Arch. Naturg. Jahrg. 55, i., 1889, p. 303.

Footnote 392:

Von Linstow, J. R. Asiat. Soc. Bengal, ii., 1906, p. 270.

Footnote 393:

Pycnogonides, Latreille, 1804; Podosomata, Leach, 1815; Pychnogonides ou Crustacés aranéiformes, Milne-Edwards, 1834; Crustacea Haustellata, Johnston, 1837; Pantopoda, Gerstaecker, 1863.

Footnote 394:

Syst. Nat. ed. xii. 1767, vol. ii. p. 1027.

Footnote 395:

Brünnich’s description (“Entomologia,” 1764), is still more accurate, and is worthy of transcription as an excellent example of early work. “Fig. iv. Novum genus, a R[ev.] D[on.] Ström inter phalangiis relatum, Söndm. Tom. i. p. 209, t. 1, f. 17. Exemplar hujus insecti, quod munificentia R. Autoris possideo, ita describo; Caput cum thorace unitum, tubo b excavato cylindrico, antice angustiore, postice in thoracem recepto, prominens; Oculi iv. dorsales, a, in gibbositate thoracis positi; c, Antennae 2 tubo breviores moniliformes, subtus in segmento thoracis, cui oculi insident, radicatae; segmenta corporis, excepto tubo, iv., cum tuberculo e medio singuli segmenti prominulo. Pedes viii., singuli ex articulis vii. brevissimis compositi, ungue valido terminati. Ex descriptione patet insectum hoc a generibus antea notis omnino differre, ideoque novum genus, quod e crebris articulationibus Pycnogonum dico, constituit.” The confusion between Cyamus and Pycnogonum seems to have arisen with Job Baster, 1765; cf. Stebbing, Knowledge, February 1902, and Challenger Reports, “Amphipods,” 1888, pp. 28, 30, etc.

Footnote 396:

Hoek, Chall. Rep. p. 15, mentions a specimen of Colossendeis gracilis, Hoek, “furnished with a pair of distinctly three-jointed mandibles; and the specimen was the largest of the three obtained.”

Footnote 397:

As a rare exception, Hoek has found the eggs carried on the ovigerous legs in a single female of Nymphon brevicaudatum, Miers.

Footnote 398:

Meisenheimer (Zeitsch. wiss. Zool. lxxii., 1902, p. 235) compares these with certain glands described in Branchipus by Spangenberg and by Claus.

Footnote 399:

Ortmann, who would unite Barana with Ascorhynchus, observes: “Bei dieser Gattung [Ascorhynchus] konnte ich die Kittdrüsen beobachten, die bei A. ramipes mit dem von Barana castelnaudi [castelli] Dohrn, bei A. cryptopygius mit Barana arenicola übereinstimmen und also die primitivsten Formen der Ausbildung zeigen.”—Zool. Jahrb. Syst. v., 1891, p. 159.

Footnote 400:

Mém. Acad. Sci. St-Pétersb. (vii.), xxxviii., 1892.

Footnote 401:

Fauna und Flora G. von Neapel, iii. Monogr. 1881, p. 46; see also Loman, J. C. C., Tijdschr. D. Ned. Dierk. Ver. (2), viii., 1907, p. 259.

Footnote 402:

The dorsal lobe is absent in Rhynchothorax.

Footnote 403:

For a very detailed account of this mechanism, here epitomised in the merest outline, and for an account of its modifications in diverse forms, the student must consult Dohrn’s Monograph (t. cit. pp. 46–53).

Footnote 404:

Dohrn, t. cit. p. 55.

Footnote 405:

Biol. Stud. Johns Hopkins Univ. v., 1891, p. 49.

Footnote 406:

Vergl. Entwickl. d. wirbellosen Tiere, Jena, 1893, p. 664.

Footnote 407:

In the second joint in Ascorhynchus abyssi, Sars, and A. tridens, Meinert.

Footnote 408:

Biol. Bulletin Woods Holl, vol. ii., Feb. 1901, p. 196.

Footnote 409:

Studi e ricerche sui Picnogonidi, Firenze, 1876.

Footnote 410:

Semper came near to discovering the fact when he saw, at Heligoland, ripe eggs in a Phoxichilidium that was, nevertheless, totally destitute of ovigerous legs. The animal, he says, was adult and sexually mature: “Trotzdem fehlen dem Tiere die Eierträger vollständig; es muss sich also das Tier noch mindestens ein Mal häuten vor der Eierablag, und dabei müssen die Eierträger gebildet werden.” (Arb. Inst. Würzburg, 1874, p. 273).

Footnote 411:

The correspondence is not universally admitted. Meinert (Ingolf Expedition, 1899) believes that the second and third appendages of the larva disappear, and that the palps and ovigerous legs are new developments; so giving to the normal Pycnogon nine instead of seven appendages. See also Carpenter “On the Relationship between the Classes of the Arthropoda,” Proc. R. Irish Acad. xxiv., 1903, pp. 320–360. The latest observer (Loman) inclines to the older view.

Footnote 412:

A slightly different account is given of the Australian P. plumulariae by v. Lendenfeld (Zeitschr. wiss. Zool. xxxviii., 1883, pp. 323–329).

Footnote 413:

Zur Lehre vom Generationswechsel und Fortpflanzung bei Medusen und Polypen, 1854.

Footnote 414:

Rep. Brit. Ass. 1859; cf. “Gymnoblastic Hydroids,” Ray Soc. pl. vi. fig. 6.

Footnote 415:

Trans. Tyneside Field Club, v. (1862–3), 1864, pp. 124–136, pls. vi., vii.; Ann. Mag. Nat. Hist. (3), ix., 1862, p. 33.

Footnote 416:

See also Hallez, Arch. Zool. Exp. (4), v., 1905, p. 3; Loman, Tijdschr. Ned. Dierk. Ver. (2), x., 1906, p. 271, etc.

Footnote 417:

“On Hydroid and other Corals,” 1881, p. 78.

Footnote 418:

Hugo Mertens, Mitth. Zool. Stat. Neapel, xviii., 1906, pp. 136–141.

Footnote 419:

One is tempted to explain such cases as the above of harmonious or identical coloration by the simple passage of pigments unchanged from the food.

Footnote 420:

Fabricius says of his Pycnogonum (Nymphon) grossipes, “Vescitur insectis et vermibus marinis minutis; quod autem testas mytilorum exhauriat mihi ignotum est, dum nunquam intra testam mytili illud inveni, licet sit verisimile satis,” Fauna Groenlandica, p. 231.

Footnote 421:

Loeb (Arch. Entw. Mech. v. 2, 1897, p. 250) also says that the Pycnogons are positively heliotropic.

Footnote 422:

See also P. Gaubert, “Autotomie chez les Pycnogonides,” Bull. Soc. Zool. Fr. xvii., 1892, p. 224.

Footnote 423:

Cf. Carpenter, Proc. R. Irish Acad. xxiv., 1903, p. 320; Lankester, Quart. J. Micr. Sci. xlviii., 1904, p. 223; Bouvier, Exp. Antarct. Fr., “Pycnogonides,” 1907, p. 7, etc.

Footnote 424:

“Nous ne les plaçons ici qu’avec doute,” Règne Anim. éd. 3, tom. vi. p. 298.

Footnote 425:

Cf. also J. E. W. Ihle, “Phylogenie und systematische Stellung der Pantopoden,” Biol. Centralbl., Bd. xviii., 1898, pp. 603–609; Meisenheimer, Verh. zool.-bot. Ges. Wien, xii., 1902, pp. 57–64; also Stebbing, in Knowledge, 1902.

Footnote 426:

The chelate form of the foremost appendages is of little moment. A chela consists merely of a more or less mobile terminal joint flexing on a more or less protuberant penultimate one, and in the Scorpions, in Limulus, throughout the Crustacea, and even in Insects (cf. vol. vi. p. 554), we see such a structure arising independently on very diverse appendages.

Footnote 427:

Cf. Oudemans, Tijdschr. d. Ned. Dierk. Ver. (2), i., 1886, p. 41: “Jedermann weiss nun, dass diese Tiere eine ganz besondere Urgruppe bilden, ohne alle Verwandschaft mit irgend einer anderen Arthropodengruppe.”

Footnote 428:

Cole (Ann. Mag. Nat. Hist. (7), xv., 1905, pp. 405–415) has attempted such a phylogenetic classification, starting with Decolopoda, and leading in two divergent lines, through Nymphon and Pallene to the Pycnogonidae, and through Eurycide and Ammothea to Colossendeis. This hint is in part adopted in the subjoined classification. Bouvier, in his recent Report on the Pycnogons of the French Antarctic Expedition (t. cit.), gives reasons for separating the Decolopodidae and Colossendeidae from all the rest. Loman, in Die Pantopoden der Siboga Expedition, 1908, has recently suggested another, and in many respects novel, classification of the whole group.

Footnote 429:

See (inter alia) Dohrn, l.c.; E. B. Wilson, Rep. U.S. Fish. Comm. (1878), 1880; Hoek, Chall. Report, 1881; G. O. Sars, Norw. N. Atl. Exp. 1891; Meinert, Ingolf Exped. 1899; Möbius, Fauna Arctica, 1901, Valdivia Exped. 1902; Cole, Harriman Alaska Exped. 1904; Hodgson, Discovery Exped. 1907; Bouvier, Exp. Antarct. Fr. 1907.

Footnote 430:

Boston Journ. Nat. Hist. i., 1834, p. 203; Cf. Hodgson, Pr. R. Phys. Soc. Edinburgh, xvi., 1905, p. 35; Zool. Anz. xxv., 1905, p. 254; Discovery Exp., “Pycnogonida,” 1907; Bouvier, Exp. Antarct. Fr. 1907.

Footnote 431:

See pp. 535, 541. Cf. Dohrn (t. cit.), p. 228.

Footnote 432:

The first known species was described as Phoxichilus proboscideus, Sabine, from the shores of the North Georgian Islands (1821).

Footnote 433:

Pocock (Encycl. Brit., 10th ed., Art. “Arachnida”) makes Hannonia the solitary type of a family. Cf. Loman, Zool. Jahrb., Syst., xx., 1904, p. 385.

Footnote 434:

Loman conjoins all these genera, and also Lecythorhynchus, with Nymphopsis, as a sub-family Nymphopsinae of Ammotheidae.

Footnote 435:

Edinb. New Phil. Journal, Oct. 1842, p. 367 (P. capillata on Plate).

Footnote 436:

Proc. Boston Nat. Hist. Society, vol. i., 1841–44, p. 92.

Footnote 437:

Found by Sir John Ross’s expedition in 1840, and subsequently by the Challenger expedition and other visitors.

Footnote 438:

Stebbing has recently shown (Knowledge, Aug. 1902, p. 157) that the genus Phoxichilus was instituted by Latreille (Nouv. Dict. d’hist. nat. 1804) for the Pycnogonum spinipes of Fabricius, now Pseudopallene spinipes, auctt. Hence he changes Pseudopallene to Phoxichilus, Latr., and Phoxichilidae and Phoxichilus, auctt., to Chilophoxidae, etc.; it also follows that the family known to all naturalists as Pallenidae should, according to the letter of the law of priority, be henceforth known as the Phoxichilidae. In my opinion this is a case where strict adherence to priority would serve no good end, but would only lead to great and lasting confusion (cf. Norman, J. Linn. Soc. xxx., 1908, p. 231).

Footnote 439:

Vide note 2, p. 537.

Footnote 440:

Mag. Nat. Hist. vi., 1838, p. 42; Mag. Zool. and Bot. i., 1837, p. 368.

Footnote 441:

Edinb. New Phil. Journ. xxxii., 1842, p. 136; xxxiii., 1842, p. 367; Ann. Mag. Nat. Hist. (1), xiv., 1844, p. 4.

Footnote 442:

Ann. Mag. Nat. Hist. (3), xiii., 1864, p. 113.

Footnote 443:

Proc. R. Dublin Soc. (N.S.), viii., 1893, p. 195; Fisheries, Ireland, Sci. Invest. 1904, No. iv. (1905).

Footnote 444:

Cf. A. M. Norman, J. Linn. Soc. xxx., 1908, pp. 198–238.

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