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PERIPATUS
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PERIPATUS , a genus of animals belonging to the See also:air-breathing See also:division of the phylum See also:Arthropoda. It differs, however, from all other Arthropoda in such important respects that a See also:special class, See also:equivalent in See also:rank to the old-established Arthropod classes, had been created for its See also:sole occupancy. This class has been named the Prototracheata or Onychophora (see ARTHROPODA), and may be most appropriately placed in the See also:system in the neighbourhood of the See also:Myriapoda, though it must not be forgotten called the buccal cavity, and is surrounded by an See also:annular tumid that it differs from the Myriapoda more than the Myriapoda differ from other Arthropoda, and that in some respects it presents features which recall the segmented See also:worms (See also:Annelida). The genus has a wide See also:distribution (see below), but it has not been found in See also:Europe or in See also:North See also:America. There is but little variety of structure in the genus, and the See also:species are limited in number. They live beneath the bark of trees, in the crevices of See also:rock and of rotten stumps of trees, and beneath stones. They require a moist See also:atmosphere, and are exceedingly susceptible to drought. They avoid See also:light, and are therefore rarely seen. They move slowly, picking their course by means of their antennae. When irritated they eject with considerable force the contents of their slime reservoirs by means of the sudden contraction of the See also:muscular See also:body-See also:wall. The slime, which appears to be harm-less, is extremely sticky, but it easily comes away from the skin of the See also:animal itself. Locomotion is effected by means of the legs, with the body fully extended. See also:Hutton describes his specimens as sucking the juices of flies, which they had See also:stuck down with their slime, and they have been observed in captivity to devour the entrails which have been removed from their See also:fellows, and to eat raw See also:sheep's See also:liver. They move their mouths in a suctorial manner, tearing the See also:food with their jaws. They have the See also:power of extruding their jaws from the mouth, and of working them alternately backwards and forwards. They are viviparous; the See also:young are fully formed at See also:birth, and differ from the adult only in See also:size and See also:colour. The See also:mother does not appear to pay any special See also:attention to her offspring, which wander away and get their own living. It has lately been stated that some of the Australian species are normally oviparous, but this has not been fully proved. Sexual See also:differences are not strongly marked, and are sometimes absent. There does not appear to be any true copulation. In some species the male deposits small See also:oval spermatophores indiscriminately on any See also:part of the body of the See also:female. It seems probable that in such cases the spermatozoa make their way from the adherent spermatophore through the body-wall into the body, and so by traversing the tissues reach the ovary. In other species which possess receptacula seminis it is probable that fertilization is effected once only in See also:early See also:life before any ova pass into the uterus. See also:External Features.—The anterior part of the body may be called the See also:head, though it is not sharply marked off from the See also:rest of the body (fig. 1). The head carries three pairs of appendages, a pair of See also:simple eyes, and a ventrally placed mouth. The body is elongated and vermiform; it bears a number of paired appendages, each terminating in a pair of claws, and all very much alike. The number varies in the different species. The anus is always at the (After See also:Sedgwick.) posterior end of the body, and the generative opening is on the ventral See also:surface, just in front of the anus; it may be between the legs of the penultimate pair, or between the legs of the last pair, or it may be subterminal. The colour varies considerably in the different species, and even in different individuals of the same species. The skin has a velvety See also:appearance, and is thrown into a number of transverse ridges, along which See also:wart-like papillae are placed. These papillae, which are, found everywhere, are the See also:primary papillae; they are covered with small, See also:scale-like projections called secondary papillae, and are specially See also:developed on the dorsal surface, less so on the ventral. Each papilla carries at its extremity a well-marked spine. Among the primary papillae smaller See also:accessory papillae are sometimes See also:present. The appendages of the head are the antennae, the jaws and the oral papillae. The mouth is at the hinder end of a depression See also:lip, raised into papilliform ridges and bearing a few spines (fig. 2). Within the buccal cavity are the two jaws. They are See also:short, stump-like, muscular structures, armed at their See also:free extremities by a pair of cutting See also:blades or claws, and are placed one on each See also:side of the mouth. In the median See also:line of the buccal cavity in front is placed a thick muscular protuberance, which may be called the See also:tongue, though attached to the dorsal instead of to the ventral wall of the mouth (fig. 2). The tongue bears a See also:row of small, chitinous See also:teeth. The See also:jaw-claws (See also:figs. 3 and 4), which resemble in all essential points the claws See also:borne by the feet, and, like these, are thickenings of the cuticle, are sickle-shaped. They have their See also:convex edge directed forwards, and their See also:concave, or cutting edge, turned backwards. The inner cutting See also:plate (fig. 3) usually bears a number of cutting teeth. The oral papillae are placed at the sides of the head (fig. 2). The ducts of the slime-glands open at their free end. They possess two See also:main rings of projecting See also:tissue, and their extremities See also:bear papillae irregularly arranged. The See also:ambulatory appendages vary in number. There are seventeen pairs in P. capensis and eighteen in P. balfouri, while in P. jamaicensis the number varies from twenty-nine to See also:forty-three. They consist of two main divisions, which we may See also:call the See also:leg and the See also:foot (fig. 5). The leg (1) has the See also:form of a truncated See also:cone, the broad end of which is attached to (After See also:Balfour.) (After Balfour.) P. capensis. • P. capensis. the ventro-lateral wall of the body, of which it is a prolongation. It is marked by a number of rings of papillae placed transversely to its See also:long See also:axis, the dorsal of which are pigmented like the dorsal surface of the body, and the ventral like the ventral surface. At the narrow distal end of the leg there are on the ventral surface three or four (rarely five) spiniferous pads, each of which is continued dorsally into a row of papillae. The foot is attached to the distal end of the leg. It is slightly narrower at its attached extremity than at its free end. It bears two
sickle-shaped claws, and at its distal end three (rarely four) papillae. The part of the foot which carries the claws is especially retractile, and is generally found more or less telescoped into the proximal part. The legs of the See also:fourth and fifth pairs differ from the others in the fact that the third See also:pad (counting from the distal end of the leg) carries the opening of the enlarged nephridia
of these segments. In some species FIG. 5.—Ventral view of last certain of the legs bear on their leg of a male P. capensis. ventral sides furrows with tumid lips and lined by smooth non-tuberculate epithelium; they are called coxal See also:organs, and it appears that they can
be everted. The See also:males are generally
smaller and less numerous le of this species:
f, Foot; 1, leg; p, spiniferous pads. The See also: Breeding.—As already stated, Peripatus is viviparous. The Australasian species come nearest to laying eggs, inasmuch as the eggs are large, full of yolk, and enclosed in a See also:shell; but development normally takes See also:place in the uterus, though abnormally, incompletely developed eggs are extruded. The uterus always contains several young, which are usually at different stages of development and are See also:born,at different times of the See also:year. In most of the See also:African species, however, the embryos of the uterus are almost of the same See also:age and are born at a definite See also:season. The young of P. capensis are born in See also:April and May. They are almost colourless at birth, excepting the antennae, which are See also:green, and their length is to to 15 mm. A large female will produce See also:thirty to forty young in one year. The See also:period of gestation is thirteen months, that is to say, the ova pass into the oviducts about one See also:month before the young of the preceding year are born. See also:Anatomy.—The alimentary See also:canal (fig. 6). The buccal cavity, as explained above, is a secondary formation around the true mouth, which is at its dorsal posterior end. It contains the dG tongue and the jaws, which have T or already been described, and into P • the See also:hind end of it there open J . - + L ventrally by a median opening s.d the salivary glands. The mouth leads into a muscular pharynx, p. h F ¢ which is connected by a short e.e See also:oesophagus with the See also:stomach . The stomach forms by far the largest part of the alimentary canal. It is a dilated soft-walled See also:tube, and leads behind into the short narrow rectum, which opens at the anus. There are no glands opening into the alimentary canal. The central See also:nervous system, the anterior part of which is shown in fig. 7, is of the " rope-See also:ladder " type, and the ventral cords meet over the rectum. The cuticle is a thin layer, of which the spines, jaws and claws are special developments. Its surface is not, however, smooth, but is everywhere, with the exception of the perioral region, raised into See also:minute secondary See also:vie atn (After Balfour.) A, Anus; at, antenna; F.r, F.2, first and second feet; j, jaws; L, lips; oe, oesophagus; or.p, oral papilla; ph, pharynx; R, rectum; s.d, salivary duct; s.g, salivary gland; sl.d, slime See also:reservoir; sl.g, portion of tubules of slime gland; st, stomach ; T, tongue in roof of mouth. papillae, which in most instances bear at their free extremity a somewhat prominent spine. The epidermis, placed immediately within the cuticle, is composed of a single row of cells. The pigment which gives the characteristic colour to the skin is deposited in the See also:protoplasm of the See also:outer ends of the cells in the form of small granules. Beneath the epidermis is a thin cutis, which is followed by the muscular layers (external circular and See also:internal See also:longitudinal). The muscular See also:fibres of the jaws are transversely striated, the other muscles are unstriated. The apertures of the tracheal system are placed in the depressions between the papillae or ridges of the skin. Each of them leads into a tube, which may be called the tracheal See also:pit (fig. 8) ; the walls (After Balfour.) those lining the tracheal pits, which occur at intervals along the course of the tracheae; tr.o, Tracheal stigma; tr.p, Tracheal pit. of this are formed of See also:epithelial cells, bounded towards the lumen of the pit by a very delicate cuticular membrane continuous with the cuticle covering the surface of the body. Internally it expands in the transverse See also:plane, and from the See also:expanded portion the tracheal tubes arise in diverging bundles. The tracheae are minute tubes exhibiting a faint transverse striation which is probably the indication of a See also:spiral fibre. They appear to See also:branch, but only exceptionally. The tracheal apertures are diffused over the surface of the body, but are especially developed in certain regions. The vascular system consists of a dorsal tubular See also:heart with paired See also:ostia leading into it from the pericardium, of the pericardium, and the various other divisions of the perivisceral cavity (fig. 12, D). As in all Arthropoda, the perivisceral' cavity is a haemocoele, i.e. contains See also:blood, and forms part of the vascular system. It is divided by septa into See also:chambers (fig. 12, D), of which the most important are the central chamber containing the alimentary canal and the dorsal chamber or pericardium. Nephridia are present in all the legs. In all of them (except the first three) the following parts may be recognized (fig. 9) : (I) a vesicular portion as% o.s, External opening of segmen- s.c.z, s.c.2, S.c.3, s.c.4, Successive tal See also:organ. regions of coiled portion of p.f, Internal opening of nephrid- nephridium. ium into the body cavity s.o.t, Third portion of nephridium (lateral compartment). broken off at p.f from the in- s, Vesicle of segmental organ. ternal vesicle, which is not shown. (s) opening to the exterior on the ventral surface of the legs by a narrow passage (s.d) ; (2) a coiled portion, which is again subdivided into several sections (s.c) ; (3) a See also:section with closely-packed nuclei ending by a somewhat enlarged opening (p.f) ; (4) the terminal portion, which consists of a thin-walled vesicle. The nephridia of the first three pairs of legs are smaller than the rest, consisting only of a vesicle and duct. The fourth and fifth pairs are larger than those behind, and are in other respects See also:peculiar; for instance, they open on the third pad (counting from the distal end of the co (After Balfour.) atn, Antennary nerves; co, commissures between ventral cords; d, ventral appendages of See also:brain; E, See also:eye; en, nerves passing outwards from ventral See also:cord; F.g.z, ganglionic enlargements from which nerves to feet pass off; jn, nerves to jaws; org, ganglionic enlargement from which nerves to oral papillae pass off; orn, nerves to oral papillae; pc, posterior See also:lobe of brain; pn, nerves to feet; sy, sympathetic nerves. leg), and the external vesicular portion is not dilated. The external The development has been worked out in P. capensis, to which opening of the other nephridia is placed at the outer end of a trans- species the following description refers. The segmentation is See also:verse groove at the See also:base of the legs. The salivary glands are the peculiar, and leads to the formation of a solid gastrula, consisting modified nephridia of the segment of the oral papillae. of a cortex of ectoderm nuclei surrounding a central endodermal The male generative organs (fig. io) consist of a pair of testes See also:mass, which is exposed at one point—the blastopore. The enteron (Sc), a pair of seminal vesicles (v), See also:vasa deferentia (v.d.), and acces- arises as a space in the endoderm, and an opacity—the See also:primitive spry glandular tubules (f). All the above parts See also:lie in the central streak—appears at the hind end of the blastopore (fig. II, B). The See also:elongation of the embryo is accompanied by an elongation of the blastopore, which soon becomes dumb-See also:bell shaped (fig. ii, C). At the same See also:time the mesoblastic somites (embryonic segments of mesoderm) make their appearance in pairs at the hind end, and gradually travel forwards on each side of the blastopore to the front end, where the somites of the anterior pair soon meet in front of the blastopore (fig. II, D). Meanwhile the narrow See also:middle part of the blastopore has closed by a See also:fusion of its lips, so that the blastopore is represented by two openings, the future mouth and anus. A primitive groove makes its appearance behind the blastopore (fig. II, D). At this See also:stage the hind end of the body becomes curved ventrally into a spiral (fig. E), and at the same time the appendages appear as hollow processes of the body-wall, a mesoblastic somite being prolonged into each of them. The first to appear are the antennae, into which the praeoral somites are prolonged. The See also:remainder appear from before backwards in See also:regular See also:order, viz. jaw, oral papillae, legs 1-17. The full number of somites and their appendages is not, however, completed until a later stage. The nervous system is formed as an annular thickening of ectoderm passing in front of the mouth and behind the anus, and lying on each side of the blastopore along the lines of the somites. The praeoral part of this thickening, which gives rise to the cerebral ganglia, becomes pitted inwards on each side (fig. ii, F, c.g.). These pits are eventually closed, and form the hollow ventral appendages of the suprapharyngeal ganglia of the adult (fig. 7, d). The lips are formed as folds of the side wall of the body, extending from the praeoral lobes to just behind the jaw (fig. li, F, L). They enclose the jaws (j), mouth (M), and opening of the salivary glands (o.$), and so give rise to the buccal cavity. The embryo has now lost its spiral curvature, and becomes completely doubled upon itself, the hind end being in contact with the mouth (fig. ii, G). It remains in this position until birth. The just-born See also:rung are from io to 15 mm. in length, and have green antennae, but the rest of the body is either quite white or of a reddish colour. This red colour differs from the colour of the adult in being soluble in spirit. The mesoblastic somites are paired sacs formed from the anterior lateral portions of the primitive streak (fig. Ii, C). As they are formed they become placed in pairs on each side of the (After Balfour.) a.g, Enlarged crural glands of last p, See also:Common duct into which vasa pair of legs. deferentia open. F. z6, 17, Last pair of legs. te, Testes. v, Seminal vesicles. f, Small accessory glandular v.c, See also:Nerve-cord. tubes. v.d, Vas deferens. compartment of the body cavity. The ovaries consist of a pair of tubes closely applied together, and continued posteriorly into the oviducts. Each oviduct, after a short course, becomes dilated into the uterus. The two uteri join behind and open to the exterior by a median opening. The ovaries always contain spermatozoa, some of which project through the ovarian wall into the body cavity. Spermatozoa are not found in the uterus and oviducts, and it appears probable, as we have said, that they reach the ovary directly by See also:boring through the skin and traversing the body cavity. In all the species except the African species there is a globular receptaculum seminis opening by two short ducts See also:close together into the oviduct, and in the neotropical species there is in addition a small receptaculum ovorum, with extremely thin walls, opening into the oviduct by a short duct just in front of the receptaculum seminis. The epithelium of the latter structure is clothed with actively moving See also:cilia. There appear to be present in most, if not all, of the legs some accessory glandular structures opening just externally to the nephridia. They are called the crural glands. Development.—Peripatus is found in See also:Africa, in See also:Australasia, in See also:South America and the See also:West Indies, in New See also:Britain, and in the See also:Malay See also:Peninsula and See also:Sumatra. The species found in these various localities are closely similar in their anatomical characters, the See also:principal differences See also:relating to the structure of the female generative organs and to the number of the legs. They, however, differ in the most striking manner in the structure of the ovum and the early development. In all the Australasian species the See also:egg is large and heavily charged with food-yolk, and is surrounded by a tough membrane. In the Cape species the eggs are smaller, though still of considerable size; the yolk is much less developed, and the egg membrane is thinner though dense. In the New Britain species the egg is still smaller (.r mm.), and there is a large trophic vesicle. In the neotropical species the egg is minute, and almost entirely devoid of yolk. The unsegmented uterine ovum of P. novae zealandiae See also:measures 1.5 mm. in length by •8 mm. in breadth; that of P. capensis is .56 mm. in length: and that of P. trinidadensis .04 mm. in See also:diameter. In See also:correspondence with these differences in the ovum there are differences in the early development, though the later stages are closely ,similar. of somites have moved to the front end of the body. E, side view of later embryo. At, Antenna; d, dorsal See also:projection; p.s., praeoral somite. F, Ventral view of head of embryo, intermediate between E and G. At, Antennae; c.g, cerebral groove ; j, jaws ; j.s. swelling at base of jaws; L, lips ;M, mouth ; or.p, oral papillae; o.s, opening of salivary gland. G, side view of older embryo. blastopore. The somites of the first pair eventually obtain a position entirely in front of the blastopore (Fig. II, D). They form the somites of the praeoral lobes. The full See also:complement of somites is acquired at about the stage of fig. II, E. The relations of the mesoblastic somites are. shown in fig. 12, A, which represents a transverse section taken between the mouth and anus of an embryo of the stage of fig. i1, D. The See also:history of these somites is an exceedingly interesting one, and may be described shortly as follows: They See also:divide into two parts—a ventral part which extends into the appendage, and a dorsal part (fig. 12, B). Each of the ventral parts acquires an opening to the exterior, just outside the nerve-cord, A 0 (After Sedgwick.) A, Gastrula stage, ventral view, showing blastopore. B, Older gastrula stage, ventral view, showing elongated blastopore and primitive streak. C, Ventral view of embryo with three pairs of mesoblastic somites, dumb-bell shaped biastopore and primitive streak. D, Vent ra 1 view of embryo, in which the blastopore has completely closed in its middle portion. The anterior pair and becomes entirely transformed into a nephridium (fig. 12, D, 2'). The dorsal part shifts dorsalwards and diminishes relatively in size (fig. 12, C). Its See also:fate differs in the different parts of the body. In the anterior somites it dwindles and disappears, but in the posterior part it unites with the dorsal divisions of contiguous somites of the same side, and forms a tube—the generative tube (fig. 12, D, 2). The last section of this tube retains its connexion with the ventral portion of the somite, and so acquires an external opening, which is at first lateral, but soon shifts to the middle line, and fuses with its See also:fellow, to form the single generative opening. The praeoral somite develops the rudiment of a nephridium, but eventually entirely disappears. The jaw somite also disappears; the oral papilla somite forms ventrally the salivary glands, which are thus serially homologous with nephridia. The various divisions of the perivisceral cavity develop as a See also:series of B spaces between the ectoderm and endoderm, and later in the mesoderm. The mesoderm seems to be formed entirely from the proliferation of the cells of the mesoblastic somites. It thus appears that in Peripatus the coelom does not develop a perivisceral portion, but gives rise only to the renal and reproductive organs. The genus Peripatus was established in 1826 by L. Guilding, who first obtained specimens of it from St See also:Vincent in the See also:Antilles. He regarded it as a mollusc, being no doubt deceived by the slug-like appearance given by the antennae. Specimens were subsequently obtained from other parts of the neotropical region, and from South Africa and See also:Australia, and the animal was variously assigned by the zoologists of the See also:day to the Annelida and Myriapoda. Its true place in the system, as a primitive member of the See also:group Arthropoda, was first established in 1874 by H. N. Moseley, who discovered the tracheae. Peripatus is an Arthropod, as shown by (I) the presence of appendages modified as jaws; (2) the presence of paired lateral ostia perforating the wall of heart and putting its cavity in communication with the pericardium; (3) the presence of a vascular body cavity and pericardium (haemocoelic body cavity); (4) See also:absence of a perivisceral section of the coelom. Finally, the tracheae,though not characteristic of all the classes of the Arthropoda, are found nowhere outside that group, and constitute a very important additional See also:reason for uniting Peripatus with it. Peripatus, though indubitably an Arthropod, differs in such important respects from all the old-established Arthropod classes, that a special class, equivalent in rank to the others, and called Prototracheata or Onychophora, has had, as we have seen, to be created for its sole occupancy. This unlikeness to other Arthropoda is mainly due to the Annelidan See also:affinities which it presents, but in part to the presence of the following peculiar features: (I) the number and See also:diffusion of the tracheal apertures; (2) the restriction of the jaws to a single pair; (3) the dis- position of the generative organs; (4) the texture of the skin; and (5) the simplicity and similarity of all the segments of the body behind the head. The Annelidan affinities are superficially indicated in so marked a manner by the thinness of the cuticle, the dermomuscular body-wall, the hollow appendages, that, as already stated, many of the earlier zoologists who examined Peripatus placed it among the segmented worms; and the See also:discovery that there is some solid morphological basis for this determination constitutes one of the most interesting points of the See also:recent See also:work on the genus. The Annelidan features are: (1) the paired nephridia in every segment of the body behind the first two (Saenger, Balfour); (2) the presence of cilia in the generative tracts (Gaffron). It is true that neither of these features is absolutely distinctive of the Annelida, but when taken in See also:conjunction with the Annelidan disposition of the See also:chief systems of organs, viz. the central nervous system, and the main vascular See also:trunk or heart, they may be considered as indicating affinities in that direction. the Gaboon), New See also:Zealand, Australia and See also:Tasmania, New Britain, South and Central America and the West Indies, the Malay Peninsula [and in Sumatra ?]. The genus Peripatus, so far as adult conformation is concerned, is a very homogeneous one. It is true, as was pointed out by Sedgwick, that the species from the same part of the See also:world resemble one another more closely than they do species from other regions, but recent researches have shown that the line between them cannot be so sharply See also:drawn as was at first supposed, and it is certainly not desirable in the present See also:state of our knowledge to divide them into generic or subgeneric See also:groups, as has been done by some zoologists. (The following genera have been See also:pro-posed: Peripatus for the neotropical species, Peripatoides for the Australasian, Peripatopsis and Opisthopatus for the African, Paraperipatus for the New Britain, Eoper'patus for the Malayan species, and Ooperipatus for the supposed oviparous species of Australia and New Zealand.) The colour is highly variable in species from all regions; it is perhaps more See also:constant in the species from the neotropical region than in those from elsewhere. The number of legs tends to be variable whenever it exceeds 19 praegenital pairs: when the number is less than that it is usually, though not always, constant, More constant points of difference are the form of the jaws, the position of the generative orifice, the presence of a receptaculum seminis and a receptaculum ovorum, the arrangement of the primary papillae on the distal end of the feet, and above all the early development. South African Species.—With three spinous pads on the legs, A to show the relations of the coelom at successive stages. PERIPATUS (Guilding).—Soft-bodied vermiform animals, A, Early stage; no trace of the vascular space; endoderm and ectoderm m with one pair of ringed antennae, one pair of jaws, one contact. pair of oral papillae, and a varying number of claw- B, Endoderm has separated from the dorsal and ventral ectoderm. The bearing ambulatory legs. Dorsal surface arched and more somite is represented as having divided on the See also:left side into a dorsal and darkly pigmented than the See also:flat ventral surface. Skin transversely ridged and beset by wart-like spiniferous ventral portion. papillae. Mouth anterior, ventral ; anus posterior, terminal. C, The haemocoele (3) has become divided up into a number of spaces, the Generative opening single, median, ventral and posterior. arrangement of which is unimportant. The dorsal part of the somite has one pair of simple eyes. Brain large, with two ventral travelled dorsalwards, and now constitutes a small space (triangular in hollow appendages; ventral cords widely divaricated, section) just dorsal to the gut. The ventral portion (2) has assumed a without distinct ganglia. Alimentary canal simple, untubular See also:character, and has acquired an external opening. The internal coiled. Segmentally arranged paired nephridia are present. vesicle is already indicated, and is shown in the See also:diagram by the thinner Body cavity is continuous with the vascular system, and See also:black line: 1, gut; 2, somite; 2', nephridial part of coelom; 3, haemocoele; does not communicate with the paired nephridia. Heart 3', part of haemocoele which will form the heart—the part of the tubular, with paired ostia. Respiration by means of haemocoele on each side of this will form the pericardium; 4, nerve-cord; tracheae. Dioecious; males smaller and generally less 01041 1. Alll;flilui rp i 3 liIINMA11AI PI114 4, slime glands. numerous than females. Generative glands tubular, See also:con-D represents the conditions at the time of birth. The coelom is represented tinuous with the ducts. Viviparous. Young born fully as surrounded by a thick black line, except in the part which forms the developed. Distribution : Africa (Cape See also:Colony, See also:Natal, and internal vesicle of the nephridium. and feet with two primary papillae on the anterior side and one on the posterior side; outer jaw with one See also:minor tooth at the base of the main tooth, inner jaw with no See also:interval between the large tooth and the series of small ones; last fully developed leg of the male with enlarged crural gland opening on a large papilla placed on its ventral surface; coxal organs absent; the nephridial openings of the 4th and 5th pairs of legs are placed in the proximal spinous pad. Genital opening subterminal, behind the last pair of fully developed legs; oviduct without receptacula seminis or receptacula ovorum; the terminal unpaired portion of vas deferens short. Ova of considerable size, but with only a small quantity of yolk. The embryos in the uterus are all nearly of the same age, except for a month or two before birth, when two broods overlap. The following species are aberrant in respect of these characters: Peripalus (Opisthopatus) cinctipes, See also:Purcell (Cape Colony and Natal), presents a few Australasian features; there is a small receptaculum seminis on each oviduct, some of the legs are provided with well-developed coxal organs, the feet have one anterior, one posterior and one dorsal papilla, and the successive difference in the ages of the embryos in the uterus, though nothing like that found in the neotropical species, is slightly greater than that found in othe investigated African species. Several pairs of legs in the middle region of the body are provided with enlarged crural glands which open on a large papilla. Male with four accessory glands, opening on each side of and behind the genital See also:aperture. P. tholloni, See also:Bouvier, (See also:Equatorial West Africa [Gaboon]), shows some neotropical features; there are 24 to 25 pairs of legs, the genital opening is between the penultimate legs, and though there are only three spinous pads the nephridial openings of the 4th and 5th legs are proximal to the 3rd pad, coxal organs are present, and the jaws are of the neotropical type; the oviducts have receptacula seminis. The following South African species may be mentioned: 2. capensis (Grube), with 17 (rarely 18) pairs of claw-bearing legs; P. balfouri (Sedgw.) with 18 (rarely 19) pairs; P. moseleyi (See also:Wood-M.), with 20 to 24 pairs. Australasian Species.—With 14, 15 or 16 pairs of claw-bearing ambulatory legs, with three spinous pads on the legs, and nephridial opening of the 4th and 5th legs on the proximal pad; feet with one anterior, one posterior and one dorsal primary papilla; inner jaw without diastema, outer with or without a minor tooth. Last leg of the male with or without a large white papilla on its ventral surface for the opening of a gland, and marked papillae for the crural glands are sometimes present on other legs of the male; well-developed coxal glands absent. Genital opening between the legs of the last pair; oviducts with receptacula seminis, without receptacula ovorum; the terminal portion of the vas deferens long and complicated ; the accessory male glands open between the genital aperture and the anus, near the latter. Ova large and heavily charged with yolk, and provided with a stoutish shell. The uterus appears to contain embryos of different ages. Specimens are recorded from West Australia, See also:Queensland, New South See also:Wales, See also:Victoria and New Zealand. The Australasian species are in some confusion. The number of claw-bearing legs varies from 14 to 16 pairs, but the number most often found is 15. Whether the number varies in the same species is not clear. There appears to be See also:evidence that some species are occasionally or normally oviparous, and in the supposed oviparous species the oviduct opens at the end of a papilla called from its supposed See also:function an ovipositor, but the oviparity has not yet been certainly proved as a normal occurrence. Among the species described may be mentioned P. leuckarti (Saenger), P. insignis (Dendy), P. oviparus (Dendy), P. viridimaculatus (Dendy), P. novae zealandiae (Hutton), but it is by no means certain that future See also:research will maintain these. Mr J. J.See also:Fletcher, indeed, is of See also:opinion that the Australian forms are all varieties of one species, P. leuckarti. Neotropical Species.—With three to five spinous pads on the legs, nephridial opening of the 4th and 5th legs usually proximal to the 3rd pad, and feet either with two primary papillae on the anterior side and one on the posterior, or with two on the anterior and two on the posterior; outer jaw with small minor tooth or teeth at the base of the main tooth, inner jaw with diastema. A variable number of posterior legs of the males anterior to the genital opening with one or two large papillae carrying the openings of the crural glands; well-developed coxal organs present on most of the legs. The primary papillae usually divided into two portions. Genital opening between the legs of the penultimate pair; oviduct provided with receptacula seminis and ovorum; unpaired part of vas deferens long and complicated; accessory organs of male opening at the sides of the anus. Ova minute, with little food-yolk; embryos in the uterus at very different stages of development. The number of legs usually if not always variable m the same species; the usual number is 28, to 32 pairs, but in some species 40 to 43 pairs are found. The neotropical species appear to fall into two groups: (1) the so-called Andean species, viz. those which inhabit the high plateaus or Pacific slope of the See also:Andes; in these there are 4 (sometimes 5) pedal papillae, and the nephridial openings of the 4th and 5th legs are on the third pad; and (2) the Caribbean species, viz. the remaining neotropical species, in which there are 3 papillae on the foot and the nephridial openings of the4th and 5th legs are between the 3rd and 4th pads. The Andean species are. P. eisenii (Wh.), P. tuberculatus (Bouv.), P. lankesteri (Bouv.), P. quitensis (Sehm.), P. corradi (See also:Cam.), P. cameranoi (Bouv.) and P. balzani (Cam.). Of the remaining species, which are the See also:majority, may be mentioned P. edwardsii (Blanch), P. jamaicensis (Gr. and See also:Cock.), P. trinidadensis (Sedgw.), P. torguatus (See also:Ken.), P. See also:im thurmi (Scl.). New Britain Peripatus.—With 22 to 24 pairs of claw-bearing legs, with three spinous pads on the legs, and nephridial openings of legs 4 and 5 (sometimes of 6 also) on the proximal pad; feet with one primary papilla on the anterior, one on the posterior side, and one on the dorsal side (median or submedian) ; outer jaw with a minor tooth, inner jaw without diastema; crural glands absent; well-developed coxal organs absent. Genital opening subterminal behind the last pair of legs; oviduct with receptaculum seminis, without receptaculum ovorum; unpaired part of vas deferens very short; accessory glands two, opening medianly and dorsally. Ova small, • 1 mm. in diameter, with little yolk, and the embryos provided with large trophic vesicles (Willey). Embryos in the uterus of very different ages, and probably born all the year See also:round. One species only known, P. novae britanniae (Willey). Sumatran Peripatus.-Peripatus with 24 pairs of ambulatory legs, and four spinous pads on the legs. The primary papillae of the neotropical character with conical bases. Generative opening between the legs of the penultimate pair. Feet with only two papillae. Single species. P. sumatranus (Sedgw.). The existence of this species is doubtful. Peripatus from the Malay Peninsula.—With 23 to 25 pairs of claw-bearing legs, four spinous pads on the legs, and nephridial openings of legs 4 and 5 in the middle of the proximal pad or on its proximal side; feet with two primary papillae, one anterior and one posterior; outer jaw with two, inner jaw with two or three minor teeth at the base of the main tooth, separated by a diastema from the row of small teeth; crural glands present in the male only, in the two pairs of legs preceding the generative opening; coxal glands present. Genital opening between the penultimate legs; oviduct with receptacula seminis and ovorum; unpaired part of vas deferens long; male accessory glands two, opening medianly between the legs of the last pair. Ova large, with much yolk and thick membrane, like those of Australasian species; embryos with slit-like blastopore and of very different ages in the same uterus, probably born all the year round. The species are P. weldoni (See also:Evans), P. horsti (Evans) and P. butleri (Evans). It will thus be seen that the Malay species, while resembling the neotropical species in the generative organs, differ from these in many features of the legs and feet, in the important characters furnished by the size and structure of the ovum, and by their early development. Additional information and CommentsThere are no comments yet for this article.
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