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T ‘ = tl es = eu L hit ayesha ; L Minera “4, ~— = e rasa oA Tht » ste tad ts poor re ¥i 2 mmwennvernn ‘Teas 24m, eee eesterey kf ewe hen x4 y : b] Te useaeserel wee aie gon. psn : ie Cee i pee a” Aaa ee oes everette wach SoteTetys Wey. a a & wee EM, yy oer : , : ; ‘ere ft Ak : as, & tt = eet : Vey wh Be SS Ses. z tere = Bee ’ . fm, iy Te Sia f ry 7 oO! = uve? H getiuea® Low ualiem rh Ld “ Ape” oe v weve had ’ Gvgeee Teal My. Th wi gry, eure” A ee veer S ae paveyrty ey | Yh, Wey erty v beh hfe yet af ee : et Tidy || | Lh TobltbbpIY Lob Teh tla vrs eae wert : jel sLchhi COCA ROO, NR ET , www? rorutytye 0! | 6 eT | Ae NT ak -wyuly ¥ vow www? yyrt Mesetraneny Sew eveweMila O \ ate AUTEN soe noe @ A (OR, Nee SE wa we 8 Sra AoC e Sue ee | See Sai cea RE wat at Sar fe 7919 ww 18 UR Ne iit Pe mabey hi Ce iat i OV a Ay i jit i ’ am | | 5 7 p cle \ ‘ i ’ te | hy iy Me 2 Aid i : ¥ MY or, Fy A < aa f = - i a By. | A +s I { . ie a ' i i — d i d ‘y j i ' i} ‘ ; BRITISH §STALK-EYED CRUSTACEA. fe A HISTORY INVERTEBRA tee. op THE YOOLOGY Crustaces BRITISH STALK-EYED CRUSTACEA. BY THOMAS BELL, Src. R.S., F.G.S., F.Z.5., PRESIDENT OF THE LINNEAN SOCIETY ; MEMBER OF THE PHILOMATHIC AND NATURAL HISTORY SOCIETIES OF PARIS; OF THE IMPERIAL ACADEMY CHSAR, LEOPOLD. NATURA CURIOSORUM; OF THE ACADEMY OF SCIENCES OF PHILADELPHIA; OF THE NATURAL HISTORY SOCIETY OF NEW YORK; HONORARY MEMBER OF THE ROYAL ZOOLOGICAL SOCIETY OF DUBLIN, ETC., ETC, PROFESSOR OF ZOOLOGY IN KING’S COLLEGE, LONDON. ILLUSTRATED BY 174 WOOD-ENGRAVINGS. LONDON: JOHN VAN VOORST, 1, PATERNOSTER RQ —-™ = Sqn SOMIAN STH M.DCCC.LIILI. he. F2RUGE | x Aug2d WAP x) Na HOwaL ar seuss / : LONDON: ; WOODFALL AND KINDER, ANGEL COURT, SKINNER STREET, Be i — TO PROFESSOR RICHARD OWEN, THE FAITHFUL AND UNCHANGED FRIEND OF MANY YEARS, THIS LITTLE WORK IS INSCRIBED THE AUTHOR, AS A HUMBLE TOKEN OF HIS LASTING RESPECT AND AFFECTION. fe Ol a PREFACE. I HAVE little to say in this Preface, beyond the ex- pression of my sincere regret for the delay which has occurred in the publication of the work. That delay has arisen from causes which it would not interest the public to be informed of, and which I have no wish to put forward for the sake of deprecating the displeasure or disappointment which it may have excited. A much more agreeable task is that of acknowledging, which I do with feelings of sincere gratification and deep thankfulness, the extensive and valuable assistance which I have received from so many of my fellow-labourers in the field of Natural History. Their names are mentioned in connection with their contributions, in various parts of the work ; and it would be invidious to particularise them here, lest, through inadvertence, any should be omitted. To one and all I beg to offer the tribute of my grateful thanks. SELBORNE, Hanrs. July, 1853. INTRODUCTION. Tuer structure of the Crustacea is so little known to the students of Natural History in this country, and there are so few works which give even the most superficial information on the subject, that it appears very desirable and even necessary to introduce the study of the British species, by a brief account of the general organization and physiology of this class of animals. Not only indeed is the subject itself one of great interest, but without some such introductory information it would not be possible to comprehend the descriptions of the different genera and species; for it will be found that in scarcely any other class of animals, is there a greater variety of form and structure, or more striking apparent anomalies in the modifications of the typical plan of organization, or in some cases greater difficulties in ascertaining the true homologies of the different elements, than in the present. It is not, indeed, a very easy matter even to express, in a clear and definite phrase, the characters which, whilst belonging strictly to all the forms of Crustacea, shall dis- tinctly exclude those of the approximate ones; for the variations which occur in every organ and function, in the different groups belonging to the crustacean type, are so considerable, as to render it almost impossible to include them all within one common and well-defined expression. The typical characters are so astonishingly modified, in some cases being totally changed, and in others absolutely lost, that the inexperienced student examining some aber- xX INTRODUCTION. rant form by the test of the known typical characters, might find it impossible to refer it to its true relations, without an investigation of the intermediate affinities, and an acquaintance with the laws which regulate their variations. The separation of the true Eprzoa from the Crustacea has indeed, in some measure, facilitated the arrangement of the latter class, and enabled the zoologist to restrict within intelligible limits the characters which belong to the group. I shall therefore, in the following sketch, consider the Crustacea, the Erszoa, and the Crrrivepes, as constituting three distinct types of form; with this restriction the Crustacea may be defined as articulated animals, having each segment of the external skeleton furnished with ar- ticulated appendages; they are all of them free or loco- motive; the respiration is branchial, and they are, with very few exceptions, aquatic in their habits; the circula- tion is carried on by means of a complete vascular system, and is of a mixed character, the blood being received into an aortic heart, both from the branchiz and from the system, and circulated in a mixed or partially decarbo- nized condition. The nervous system resembles, in its general principles, that of the Insects. It is ganglionic, longitudinal, and generally distinctly developed. The sexes are separate. Such are the general characters by which the Crustacea proper may be distinguished, and which appear to be sufficiently defined, as far as our present knowledge ex- tends. A further insight into the structure of each system of organs, as existing in the different orders and families of the class, will show how various and startling are some of their modifications. INTRODUCTION. Xl The construction of the skeleton in this class of animals is for the most part very distinct from that of all others, although in some of the abnormal forms there is a remark- able deviation from the typical structure, and a corre- sponding approximation to that of other classes; as, for instance, in the segments of certain Lsopoda, which re- semble, in general character, some forms amongst the Myriapoda. In the greater number of them, and es- pecially in the higher forms, the tegumentary skeleton is formed of a hard, solid, calcareous crust, the earthy por- tion of which consists of carbonate of lime, with a small portion of phosphate of the same earth. The colours by which the crust is, in many cases, very beautifully marked, depend upon a pigment which pervades different parts of the substance, and offers various hues, and sometimes curious and grotesque markings, in different species. The colouring matter, in these as in most other animals, is more intense on the upper than on the under surface, the latter being, in many, nearly pure white, whilst the former is deeply and brightly coloured. The earthy matter is deposited upon, and produced by, an organized vascular membrane or coriwm. In many of the smaller Crustacea, even amongst the higher forms, as in most of the Palemonide or prawns, and other allied families, as well as in most of the lower groups, as the Lsopoda, and others, the crust retains its semi-transparent, elastic, and flexible nature, resembling thin horn or parchment, the earthy matter being deposited in very small quan- tities, Although this difference is not wholly correlative with the groups in which it principally obtains,—as for instance, in the genus Palemon, in which the crust of some species, as the common prawn, has scarcely any earthy matter, whilst in others, it is almost as solidly calcareous Xil INTRODUCTION. as in the lobster itself,—yet it would appear to bear a near relation to their habits; the presence of the cal- careous substance hardening and solidifying the skeleton, and thus rendering it an efficient protection against the rocks and waves of the more exposed parts of the sea, be- ing found in the greatest proportion in species exposed to such agents; whilst the others are either small, active creatures, swimming with great ease and constancy in more open and shallow situations, or creeping safely amongst fuci or under stones, and other protecting sub- stances, or even attaching themselves to the surface of different species of fish. The annulose character, typical of the great group to which it gives its designation, has, in a great number of the species composing this class, reached its maximum of development. The segments which surround the body are more complete, and more separately movable, whilst they possess a greater degree of individual solidity than in any others. They are also furnished with articulated appen- dages ; each segment, whether remaining distinct or in- timately united to others, bearing a single pair, in a more or less developed, or in a merely rudimentary condition. In numerous instances, from this intimate union or solder- ing together of two or more segments, the only indi- cation of their theoretical separate existence is the presence of the normal number of these appendages; but with this aid it rarely happens, in the higher forms of Crus- tacea, that they cannot be proved to exist. The true normal number of the segments, taking the whole class, appears to be twenty-one, of which, accord- ing to our present knowledge, seven must be considered as belonging to the head, and an equal number respectively to the thorax and the abdomen. Now, although it is INTRODUCTION. Xiil trne that there is not a single known species in which all these segments are found in a distinct and tangible con- dition—there being in all the forms, more or fewer of them so inseparably united together as to offer no other means by which to predicate their existence, than those already alluded to—yet, on the other hand, there is not one which may not be found distinctly formed in some or other of the species. The appendages, too, which have already been slightly mentioned, are no less subject to the most extraordinary variation both of form and office ; many of them serving in one case the purposes of loco- motion, in another the reception and preparation of the food, in another the attachment of the branchiz, in another the support and protection of the eggs. When, therefore, we consider the almost endless diversity of form, under which the species composing this class of animals appear, the astonishing discrepancy which exists in the forms and relative proportions of the different regions of the body, and other parts of their organization, for the performance of offices and functions equally various, and see that all these diversities are produced only by mo- difications of a typical number of parts, we cannot but be struck by so remarkable and interesting an illustration of the great economical law, as it may be termed, that the typical structure of any group being given, the different habits of its component species or minor groups are provided for, not by the creation of new organs or the destruction of others, but by the modification, in form, structure, or place, of organs typically belonging to the group. Of this law numerous examples will be exhibited in the course of this work, in the structural characters of every order and of every family; but for the sake of offering a single comprehensible illustration, the various modifi- X1V INTRODUCTION. cations of the thoracic appendages may be selected. The typical structure of these may be considered as subserving the purposes of locomotion. This is the office which they fulfil, either wholly or in part, in all cases; and in some instances the whole of them are thus employed. In the Isopoda, for instance, the body consists very principally of the seven thoracic segments, and their appendages consti- tute seven pairs of true feet. In the Amphipoda the first or second pairs become modified in the male into strong holders by the greater development of the hand, and the movable character of the terminal articulation, and its ap- plicability to a strong corresponding process from the penultimate articulation. In several of the Lamodipoda five pairs only of the thoracic appendages are developed into members, of which the first and second pairs consti- tute true hands or graspers, and the third and fourth are destined to a totally different office; forming respiratory sacs, to supply the place of the abdominal appendages in the Isopoda, the abdomen in the present instance being reduced to a mere rudiment. In the Decapoda there are only five pairs of true thoracic members, and these answer to the five posterior segments of the thorax; but the ap- pendages to the segments anterior to these are rendered subservient to mastication, or to the preparation of the food, in the form of footjaws or pedipalps. I have only enumerated a few of the more conspicuous modifications of these organs, for the purpose of conveying at a glance some idea of the extraordinary aberrations from the typical structure which will meet us at every step, in the inves- tigation of these animals, whose habits and requirements are so varied, The composition of the segments in the Crustacea, although modified to a great extent in the different forms, INTRODUCTION. XV is yet susceptible of being reduced to a perfect theoretical idea. Indeed, in many forms, the parts of which each segment is composed are distinctly appreciable by careful examination ; and it is found that these parts consist in two arches, a superior and an inferior, each of which is formed of two middle and two la- ————5 ibe A ° Yo a a \ b teral pieces. The superior central <<“ SS pair, @ a, constitute the tergum, IN r , Le the lateral are called epimera, 6 6. Sia oa Of the inferior arch, the two central pieces form the ster- num, cc, and to the lateral, dd, the name of episternum has been applied. As we have already seen, in enume- rating the segments themselves which compose the different regions of the body, that some or other of them are always found to be so intimately combined together that their dis- tinction is lost, so in the present case also, some or other of the theoretical elements of the segments are either actu- ally wanting, or certain of them are so intimately united that the normal number cannot be distinguished. It is also necessary, in order to obtain a correct idea of the actual structure of the skeleton or supporting organs in the Crustacea, to consider those processes of crustaceous matter which, in the form of internal lamina, form the parietes of the cells and canals which are found in the interior of these animals, and many of which serve the office of bones, as the solid surfaces to which the muscles are attached. These have received the name of apodema. ‘* They arise in all cases from the junction of two con- tiguous pieces of one segment, or from the union of two rings. They are produced by a duplicature of the tegu- mentary membrane, which dips more or less deeply amongst the internal organs, and which becomes encrusted with calcareous matter with the rest of the shell; they are con- XVi INTRODUCTION. sequently always formed of two layers, soldered, as it were, together.” * Of the various segments composing the three principal portions of the body, the head, the thorax, and the abdo- men, some are found always to support similar, or rather identical, organs. Thus the first cephalic segment or ring invariably bears the peduncle of the eyes, and the second, or antennary, as constantly supports a pair of the antenne. Of those which follow, there are the most extraordinary and unlooked-for modifications in the different groups; and no one who has only formed a theoretical notion of these parts could recognise in the simple piece of which the whole cephalic region is composed in the Hdriophthalma, or in the carapace or shell of the brachyurous Decapoda, as in the common crab for instance, the mere combination of two or more of the cephalic segments which iu other forms are found to be distinct. For a full and clear account of all these modifications, the reader is referred to the admi- rable work of Dr. Milne Edwards, so often quoted and referred to. This author has, with great propriety, considered the genus Squilla as offering the form in which the different segments before enumerated are most distinctly exhibited ; but even in this form there are some which are, as it were, soldered together, and the normal number is consequently not to be traced. The first cephalic segment, which, as before observed, is invariably destined to support the ocular peduncles, and is therefore termed the ophthalmic segment, is here quite distinct from the second, which is also very distinctly articulated with the third; the latter is, however, confounded with the next, and the following ones are only to be distinguished by dissection.- But the * Edw. Hist. Nat. des Crust. i. p. 18. Tf Deapelios INTRODUCTION. XVI last eleven are complete and perfectly distinct, and each of them, without exception, bears its appropriate pair of members. Amongst the higher forms of Crustacea, it is in the Brachyura, where the nervous system is found in the most concentrated condition, that the condensation of the rings of which the body is composed, is carried to the greatest extent. It is indeed somewhat difficult, at first sight, to determine the homologies of the segments of which the carapace, as it is termed, is theoretically composed. This large enveloping buckler in fact covers the whole of the thorax, and even the abdomen itself is folded underneath it, so that the whole animal is hidden, when viewed from above, by this extraordinary development of two of the cephalic segments; and although in the Brachyura the first two segments, the ophthalmic and the antennary, are soldered to the carapace, yet, as we find that in some other forms these two are entirely distinct, it would appear that the carapace is essentially composed of the third and fourth rings, composing what Dr. Milne Edwards terms the antenno-maxillary segment. This remarkable portion of the tegumentary system, covering, as it does, the whole of the viscera, is found to be more or less distinctly divided into regions, which are indicated by elevations, separated from each other by grooves; and to these regions have been given names derived from the different organs which are immediately covered by them. As reference is frequently made to these regions in generic and specific descriptions, I here give an illustration of them.* * The gastric or stomachal region is marked rs ; the branchial, rb; the hepatic, rh; the genital, rg ; the cardiac rc; the intestinal, ri. XVill INTRODUCTION, The thorax in the Decapods in general is externally only visible under- neath, the upper part being covered by the carapace, and being in that part incomplete. The number of obvi- ous segments in these higher forms is five, and as each segment bears its proper pair of appendages, which here are true ambula- tory legs, the character of Decapods is thus produced. The superior surface of the thoracic segments is limited to the epimera, the tergum being absolutely wanting: Upon this upper surface on each side lie the branchiz, or gills. In this brief sketch it is only n@gessary to refer to the apodemata as consti- tuting the large cells of the thorax, formed by a dupli- INTRODUCTION. X1X cature of the walls dipping into the thoracic cavity, and filled by the muscles which move the limbs. The abdomen of the Brachyura is very moderately de- veloped.* It folds entirely underneath the thorax, against which it is ordinarily closely applied. It consists, essen- tially, of seven segments, of which, however, in many cases, a greater or less number are so united as to be scarcely distinguishable. In the Macroura* they are far more extended, and serve the purposes of locomotion, being elongated, very moveable upon each other, and furnished at the extremity with a fan-shaped fin, formed of five pieces, of which the centre is the terminal ab- dominal segment. In the lower forms, as the Edriophthalma, the rings of the body are more similar to each other, and constitute a nearly regular series of more or less perfect rings. ‘Those of the head, however, are ordinarily much condensed, and soldered together; whilst the thorax consists of seven very distinct moveable segments, and the abdomen of either the same number, or nearly so; as in some Cases the seventh is wanting, and in others the two anterior ones are united. Between these two extreme cases, there are numerous intermediate modifications, which will be seen in the various families and genera. The members or appendages to the different segments or annuli above described, form a very interesting and important part of the tegumentary system of these ani- mals. Theoretically speaking, every segment has its pair of appendages, and, vice versd, each pair of appendages, * See the figures of the various species. xX INTRODUCTION. whenever they exist, presupposes a segment or ring to which they belong. In many cases, where a coalescence takes place between any of the contiguous segments, their distinct existence can only be predicated by the occurrence of the members which belong to them; thus, in the Brachyura, the carapace involves not only the third and fourth rings, enormously developed, but also the first two, which bear the eyes and antennz, and which are indissolubly blended with the succeeding ones. Normally there are twenty-one pairs of appendages or limbs: generally speaking, even in the higher forms, twenty only are perceived, as the terminal joint of the abdomen, which forms the central piece of the fan-like fin, has none which are perceptible. I have, however, observed them frequently in the common prawn, Pale- mon serratus,* in the form of extremely minute points attached to the very extremity of the segment, and moveable. The first pair exist only in the Podophthalma or stalk- eyed forms, and constitute the peduncles upon which the eyes are elevated; they are moveable, and in many cases are of considerable length, lying, when at rest, in grooves, or sockets, formed for their reception. The two following pairs are of great importance, forming, in most cases, organs of sense. These are the antenne. One or both pairs exist in all the forms of true Crustacea; ordinarily * I have often separated the whole twenty-one pairs of appendages in this species, and placed them seriatim ona card. They consist very clearly of the ocular peduncles, the anterior and posterior antenne, the mandibles, the two pairs of maxilla, the three pairs of foot-jaws, the five pairs of thoracic legs, the five pairs of abdominal false feet, the appendages to the sixth abdominal segment forming the lateral caudal flap, and the two minute rudimentary appendages above alluded to. INTRODUCTION. XX1 they are slender, elongated, moveable, and multiarticulate. They are, however, subject, in some forms even of the higher orders, to extraordinary modifications ; thus in the genera Scyllarus and Ibacus, the external pair are de- veloped into broad, flat organs of natation, and probably also constitute a pair of shovels for the purpose of burrow- ing: and in some Amphipoda, they are much elongated, serving as a pair of swimming or sustaining arms. The fourth pair always appertain to the mouth, and form man- ducating organs: these are the mandibles. The two pairs of jaws, or maxille, follow, and are also employed in the comminution of the food. Theoretically speaking, the next pair ought to be considered as belonging to the cephalic division of the body; these, as well as the pre- vious and two following pairs, are, in the Decapoda, sub- servient to nutrition. The eighth and ninth pairs are, therefore, properly speaking, the first and second thoracic members, and, with the seventh, constitute the three pairs of footjaws or pedipalps, leaving, in this particular class, the five remaining thoracic appendages to serve the office of ambulatory locomotion, or of claws for the apprehen- sion and tearing of the food, or of weapons of defence, In most of the Edriophthalma the normal arrangement obtains, and the thorax bears seven pairs of ambulatory members. The remaining appendages, which seldom ex- ceed six pairs, belong to the abdominal portion of the body, and in the higher forms are very small and slightly developed, in comparison with those of the thoracic di- vision. In the female Decapoda they constitute the sup- port of the eggs, after their exclusion, and as long as they continue attached to the parent. In their full development, each of these organs consists XXll INTRODUCTION. of three distinct parts. The Stalk, which constitutes the essential part, and which is usually multiarticulate ; the Palp, which is an appendage to the stalk, and ordinarily arises from its basal segment; and the Lash. It is not in all cases that these three portions exist, and in the Bra- chyura, for example, the foot-jaws are the only ones in which they are all present. The ambulatory thoracic legs in these are obviously composed only of the stalk, without either of the other members, and consist of six distinct joints. In the Macroura, however, the ambulatory feet, in some genera, have all the three elements ; in others, one of them is wanting. Their modifications are almost innumerable, and often it would be impossible to distin- guish their homologues, without extensive comparative examination. It is impossible, in a mere sketch, introductory to a local Fauna, to enter, at any detail, into the various modi- fications now merely alluded to, but perhaps there is scarcely any group of animals in which the homologies are more recondite, the variations more interesting, and the relations between those variations and the habits and requirements of the animals more beautiful and instructive. In order to give a general idea of the extent of these modifications, it may be stated that the ocular peduncles are the only appendages which are never devoted to any but their normal objects. ‘The antenne are, as has been before observed, sometimes modified into locomotive organs. The cephalic appendages about the mouth, the mandibles and maxill, are sometimes rudimentary, at other times they are modified into mere organs of appre- hension. The thoracic members are sometimes locomo- INTRODUCTION. XXill tive organs, at others they subserve the nutritive function: the remaining thoracic members are, in some cases, pre- hensile, in others ambulatory, in others natatory, in others partially branchiophorous, and so on. The abdominal sometimes serve the purpose of swimming, at others of bearing and protecting the eggs, at others they are partially converted into branchiw. Besides these modi- fications, some or other of them are, in many forms, either wholly wanting or rudimentary. The digestive system appears under very various phases in the different groups of the Crustacea. The extremes of this diversity are found in those two primary divisions, the food of which is most opposite in its kind. In the one group, the whole of which are parasitic upon other animals, and which I have in this Introduction considered as belonging to a distinct class, the aliment consists of the juices of the creatures to which they are attached, and is obtained by suction. In these the normal elements of the organs for procuring or preparing the food for diges- tion are either rudimentary or wanting. In the higher forms of the true Crustacea, on the contrary, which sub- sist upon solid and often hard substances, and in many cases on living prey, the organs for pursuing, seizing, tearing, and comminuting the food, are carried to a high degree of development, and a corresponding difference is also found in the digestive organs themselves. The most elaborate condition of these organs is exhibited in the Decapoda, and especially in the Brachyura. It has been already stated that the appendages belonging to certain of the cephalo-thoracic segments are variously modified to serve their several offices; and in the latter order they have XXIV INTRODUCTION. been shown to consist of six pairs, of which some are actual organs of mastication, as the mandibles or the true jaws, the foot-jaws or pedipalps generally serving to keep the food in contact with the former, whilst it is being broken up by them. The buccal orifice in the Brachyura occupies the in- ferior face of the cephalic division of the body, and is bounded anteriorly by a crustaceous lamina of determi- nate form, which has been termed the upper lip, and pos- teriorly by another termed the lower lip. The mandibles occupy the sides of the opening. After these, and ex- ternal to them, are the first, and then the second pair of true jaws, followed by the three pairs of pedipalps or foot-jaws, the last of which, when at rest, close the mouth, and include the whole of the preceding ones. In the Macroura, the pedipalps are very different mm their forms, and have the aspect of very simple feet. In the Stoma- poda they not only have the form, but the office also of the other locomotive organs, and hence the increased number of legs which appear to appertain to these, and especially to the Myside. In the Edriophthalma, and the other lower forms, the parts about the mouth are fewer, and more simple. At the back of the mouth, a short cesophagus opens into the stomach, which is a very ca- pacious cavity, occupying the whole depth of the body in the Decapods, and co-extensive with the gastric region of the carapace, already described. It is pretty distinctly divided into two portions, a cardiac and a pyloric, the former occupying the greater portion of the cavity, the latter of small dimensions. The means of comminuting the food are not restricted to the complicated machinery above referred to, for the INTRODUCTION. XXV stomach itself contains a very remarkable apparatus, con- sisting of several hard calcareous pieces, which may be termed gastric teeth. These are attached to horny or calcareous levers fixed in the parietes of the stomach ; they are moved by a complicated system of muscles, and are admirably adapted to complete the thorough breaking down of the aliment, which had already been to a con- siderable extent effected by the buccal appendages. These gastric teeth may be readily seen and examined in the larger species of the Decapoda, as in the large eatable crab and the lobster; and it will be readily perceived how perfectly the different pieces are made to act upon each other, and to grind the food interposed between them. Analogous structures, but of less complexity, are found in the Edriophthalma. The single and simple intestine extends in a direct line from the stomach, and terminates at the last segment of the abdomen. Immediately from its origin at the pyloric opening of the stomach, a notable enlargement is observed, but the rest of the canal is of uniform size. The enlarged portion is, in some cases, very short; in others, it occupies the larger portion of the total length. The liver is of considerable volume in most of the families of Crustacea, and occupies in the Decapoda the ereater portion of the visceral cavity. It consists of a mass of cecal vesicles, ordinarily more or less elongated, and pouring the secretion into a system of membranous canals, the union of which forms ultimately a large trunk on each side, which opens into the pyloric portion of the stomach, Such is the structure of this important gland in the highest forms; but in the larger Stomapoda its structure is apparently granular, and it forms two series XXVl INTRODUCTION. of lobes extending the whole length of the intestine,— and in the Edriophthalma, according to Prof. M. Kd- wards, it is reduced to “three pairs of biliary vessels, running alongside the intestine, the whole length of the body.” There are other tubular appendages connected with the pyloric portion of the stomach, which are of considerable size in certain of the larger Decapoda, and which, from analogy, may with some probability be con- sidered as pancreatic. The respiration in this class is, with very few excep- tions amongst the Isopoda, aquatic. In some of the lower forms, it would appear that there are no special organs devoted to this function, but in the higher these are very varied, and in many cases of a complicated character. ‘The typical form of Crustacean respiratory organs may be considered that of lamellar branchie ; and this form is found in the Decapoda, and particularly in the Brachyura; in the crab it is seen in its most complete development. The branchie are placed within a distinct cavity on each side, protected above by the carapace, and lying upon the upper surface of the thorax. They con- sist of a series of elongated pyramidal bodies, each com- posed of a vast number of plates or lamelle, which are closely packed, but still admit of the free circulation of the water between them. ‘The respiratory cavity has an afferent and an efferent opening, through which the water is propelled by a mechanism differing in the different groups. The former opening, through which the water has access to the cavity, is a long lateral slit, between the cephalo-thorax and the side of the thorax; and the latter is near the buccal cavity, and is covered by the INTRODUCTION. XXVli last or flabelliform appendage of the second pair of the true jaws, which is developed into a broad horny plate, fixed by a sort of pivot, on which it continually turns, and thus regulates the efflux of the water. Prof. Milne Edwards observes, that this action is proved to be es- sential to the renewal of the water which bathes the branchie, as, if its movements be stopped, the animal becomes soon asphyxiated. The whole of the apparatus belonging to this function in the higher Crustacea is exceedingly curious and interesting, but it would be out of place to enter into the detail in this work. The branchiz are very differently formed in the dif- ferent orders of the class, and even vary considerably in some genera of the same family. In some cases the abdominal appendages support these organs; in others they are attached to the basal joint of the thoracic legs; in some genera, as in Mysis, their distinct existence has not as yet been demonstrated, although, as I have ob- served in speaking of that genus in the body of the work, there appears little doubt that a special organ exercises their function. In the terrestrial Isopoda, or the common Millipedes, as they are termed, the respiration is exclusively atmo- spheric. The respiration of the land crabs, which must neces- sarily be, during the greater part of their lives, atmo- spheric, is one of the most remarkable phenomena connected with this subject, and has occupied the atten- tion of Mons. Audouin and Dr. Milne Edwards, who have given a most elaborate and interesting memoir on this subject,* to which the reader is referred. It is well * Annales des Sciences Naturelles, t. vy. p. 85. XXVill INTRODUCTION. known that the lobster will live for a long time out of water, provided the branchiz are occasionally bathed, so as to keep them in a humid condition, whilst it will die very soon on being confined in a small quantity of water, without access to air. There has been considerable discrepancy in the state- ments of different anatomists respecting the circulation in the Crustacea. Messrs. Audouin and Milne Edwards * have considered that ‘no other than the two great bran- chial veins terminate in the heart, and, consequently, only pure aérated or arterial blood is propelled by it over the general system ; the circulation is, in fact, the same as in the Gasteropodous Mollusca; the ventricle is exclusively systemic, and is provided with only two venous aper- tures.” Such is a summary of their opinion. The fact, however, that the circulation is of a mixed kind was evi- dently known to Hunter, and has been elaborately demon- strated by Professor Owen in his more recent researches.t A reference to the engravings from the Hunterian draw- ings in the collection of the Royal College of Surgeons,{ to that of the heart of the lobster by Professor Owen in his lectures above referred to, and to the respective de- scriptions of these figures, will show “ that the heart, instead of being purely systemic, is partly branchial, and impels the blood, not through the body only, but also to the respiratory organs.” * Recherches Anatomiques et Physiologiques sur la Circulation dans les Crustacés. Ann. des Sc. Nat. t. ii. + Lectures on the Comparative Anatomy and Physiology of the Invertebr. ~ Catalogue of the Physiological Series of Comparative Anatomy contained in the Museum of the Royal College of Surgeons, vol. ii, Copied in Professor Rymer Jones’s “ Animal Kingdom,” pp. 333-336. INTRODUCTION. TXLX “We may trace,” says Professor Owen,* ‘in the heart of the Crustacea, a gradational series of forms, from the elongated, median, dorsal vessel, to the short, broad and compact muscular ventricle in the lobster and the crab. In all the Crustacea, as in all the other articulate animals, the heart is situated immediately beneath the skin of the back, above the intestinal tube, and is retained in situ by lateral pyramidal muscles. In the lower, elongated, many- jointed species of the Edriophthalmous Crustacea the heart presents its vasiform character: it is broadest and most compact in the crab. In this series we may trace a general correspondence in the progressive development of the vascular as of the nervous system, concomitant with the concentration of the external segments, and the progressive compactness in the form of the entire body.” Corresponding with the view which has been taken of the gradual condensation of the segments of the body and the centralization of the viscera, is that of the nervous system as seen in the various forms of Crustacea as they rise in the scale of organization. An elaborate detailed description of all the gradations formed the substance of an admirable essay t+ by the distinguished naturalists so often quoted, of whose labours an excellent abstract is given by my friend Professor Rymer Jones, in his “ Ani- mal Kingdom.” f¢ In Talitrus, where the insectiform arrangement is the most obvious, and where every pair of ganglia consists of elie. pe lo: + Messrs. Audouin et Milne Edwards, “ Recherches Anatomiques sur le Systeme Nerveux des Crustacés.” Ann, des Sc. Nat. t. xiv. Dec. ps do. XXX INTRODUCTION. two separate nuclei of nervous substance, united by a transverse band, with an anterior and posterior nervous filament uniting each to the antecedent and succeeding pairs, the number of ganglia (thirteen) coincides with that of the segments of the body. Proceeding upwards, a condensation, both lateral and longitudinal, of certain of the ganglia is found to be coincident with the concentra- tion of the rings, until in the crab the whole of the abdo- minal and thoracic ganglia become concentrated into one mass, from which the nerves radiate in a most beautiful manner to the parts about the mouth, the limbs, &c. The conclusions to which their elaborate researches have conducted Messrs. Audouin and Milne Edwards are thus given :— “Le systéme nerveux des Crustacés se compose tou- jours de noyaux médullaires dont le nombre normal est égal a celui des membres, et toutes les modifications qu’on y rencontre dépendent principalement de rapprochemens plus ou moins complets de ces noyaux, agglomeration qui s’opére des cotés vers la ligne médiane en méme temps que dans la direction longitudinale, mais peuvent tenir aussi en partie a un arrét de développement dans un certain nombre de ces noyaux.” * The organ of hearing is found only in the higher forms of this class. In the larger Decapoda, and particularly in the brachyurous group, it is very easily seen, on re- moving a little crustaceous plate in the basal joint of the second antenne, and thus exposing a small cavity. This operculum is pierced by a small oval opening, covered with a membrane ; and in the Macroura, the whole closure * Hist. Nat. des Crustacés, t. i. p. 147. INTRODUCTION. XXXl1 is membranous. Within the cavity and immediately be- hind the little opening before mentioned, is a minute vesicle filled with fluid, which conveys the vibrations to a branch of the antennal nerve, which is expanded upon the vesicle. This is the simple apparatus; but it is sufficient to receive and convey to the sensorium the imperfect sonorous vibrations to which they are subject. The visual organ is essentially similar to that of in- sects. ‘The eyes are compound in all the higher forms, and those of the Edriophthalma do not differ essentially from those of the Podophthalma, excepting in the ab- sence of those movable peduncles by which the eyes of the latter are distinguished. The optic nerve, the lenses, the facets of the cornea, the pigment, are alike in all, and in all resemble generally the same organs in insects. There is one peculiarity, however, which is found in certain species which live in such places as are inacces- sible to light, or to such degrees of it as would render eyes in any way useful. In Culocaris, for instance, a little prawn-like animal, inhabiting very deep water, and ordinarily immersed in mud, the eyes and their peduncles do not differ in form from those of the other Palemo- pid; but the vision is wanting. ‘There is no pigment, there are no corneal facets; the organ is evidently rudi- mentary and merely formal. Mr. Westwood has recently made known through the Linnean Society a form of Edriophthalma, inhabiting a deep well, a species in which there is no external appearance of eyes whatever; Mr. Newport has, however, by his accustomed accuracy of dissection, shewn that in this case also, a rudimentary visual organ exists underneath the cephalic crust. XXXil INTRODUCTION. The propagation of the Crustacea proper is invariably oviparous, and the sexes are distinct. The reproductive organs in either sex are double, the two elements being perfectly similar, and occupying a corresponding position on each side of the median line. The two are wholly independent of each other, having no communication even to the efferent opening, there being one of them to each. Dr. Milne Edwards mentions the following curious fact:—“ Cette indépendance des deux moitiés de l’appareil de génération est si compléte qu’on a vu un cas, ot l'un des cétés était male et lautre femelle, sans que cette monstruosité ett entrainé aucune autre perturbation sen- sible dans la conformation de ces organes.”* They are very similar in arrangement, position, and general relation to the other organs in the two sexes. In most cases the eggs are carried by the female until they are hatched; but in some they are previously de- posited in the sand. In different families the eggs are carried by the mother attached to different parts of the body. In the Decapoda they are borne on the under side of the abdomen, attached to the abdominal false feet. In the genus Mysis, a pouch is formed at the base of the posterior thoracic legs, in which the eggs remain until the young are excluded. In Thysanopoda, another genus of the Mysidx, they are contained in two oval purses, depending from the same part.{ * Hist. des Crust. t. i. p. 165. + See p. 336. See p. 346. INTRODUCTION. XXXill ON EXUVIATION AND THE RESTORATION OF LOST LIMBS. The fact that the throwing off of the old integument and its replacement by a new one during the growth of the animal, takes place in all the Crustacea as necessarily and as constantly as in insects during their larva condi- tion, has long been known, and as long has excited the admiration of all who take any interest in natural phe- nomena. That an animal covered by integument of the hard, solid, almost stony consistence as that of the lobster and the crab, for example, should have the power of with- drawing itself from its shell, leaving it, to all appearance, as perfect as before, with the carapace, the abdomen, the limbs, the eyes, the antenna, and even the stomachal teeth, and other internal shelly organs, whole and entire, and in their former relative situation and condition, is one of the most interesting, and, at first sight, one of the most perplexing and inexplicable, of all the phenomena of voluntary action. The first clear and satisfactory observations on this subject were made by Réaumur,* whose unexampled accuracy and truthfulness is attested by the fact that of all the observations made by himself alone, far exceeding those of any other naturalist of past or present times, and occupying, in their published form, numerous large quarto volumes, scarcely one has ever been contravened by subsequent credible observers, whilst they have formed the substance of half the numerous compilations on in- sect life, acknowledged or otherwise, which have appeared since his time. * Mem. de lAcad. des Se. 1712, p. 226, and 1718, p. 263. Cc XXXIV INTRODUCTION. The necessity for the process in question is so evident, seeing that, without it, there would be no possible means of allowing the gradual growth of the animal, that it is matter of surprise that it should have ever been doubted, as it appears to have been by a distinguished entomologist, more especially of late years, when so many conclusive observations have been made of the fact. There is no doubt that in many of the higher forms it takes place annually, with great regularity,* until the growth is com- pleted, which in many species is not the case before the animal is many years old. This is proved by the extent to which the size increases by each moult, compared with the difference between the young and the old ani- mal; and it is evident that after the growth has reached its maximum the crust ceases to be changed, from the fact which I have seen in several instances, as in the common crab, the lobster, and some others, where the carapace of the still living creature was the seat of bar- nacles so large, that several years must probably have been required for attaining their existing size. The observations of Réaumur to which I have alluded, and those of subsequent naturalists, and especially of Mr. Couch, furnish us with the following history of this curious process. When the animal by gradual internal increase has become too large for its existing covering, it ceases for a time to feed, and retires to a secret and undisturbed situa- tion, where it may undergo the process in security. If it be examined at this time, an evident loosening of the * Some recent observations by Mr. Warrington shew that in the common prawn, the moult is much more frequent; he has noticed its occurrence with much regularity, every twelve days, in the summer. INTRODUCTION. XXXV crust may be perceived, upon pressing it gently in dif- ferent parts. Shortly afterwards,—and this description belongs particularly to the river cray-fish,—it appears uneasy and restless, rubbing its limbs against each other, and moving the segments of the body in various direc- tions. It throws itself on its back, and, swelling out its body, ruptures the membrane which connects the cara- pace with the abdomen, and raises the former, so as to loosen it from its attachments. Resting from time to time after its laborious efforts, it finally detaches the whole thoraco-abdominal portion, from which it withdraws itself, having, with much apparent difficulty and pain, disengaged the legs, and then the antenne, the eyes, and other appendages. It is impossible to imagine that the crust of the legs, and especially of the great claws of the larger species, could be cast off unless it were susceptible of being longitudinally split; and Reaumur states that such is actually the case; each of the segments being composed of two longitudinal pieces, which, after sepa- rating to allow of the passage of the soft limb, close again so accurately that it is very difficult, in the cast crust, to discover the line of division. When the animal has disembarrassed itself of the crust, the latter is found abso- lutely entire, and has exactly the form which it possessed previous to the operation. In a recent interesting ac- count of the exuviation of a Maia,* Mr. Gosse has, how- ever, shewn that in this brachyurous form, no such split- ting of the legs takes place, but that “the animal pulled first at one and then at another, until they were quite out, as if from boots. The joints as they came out were a great deal larger than the cases from which they proceeded. It * Annals of Nat. Hist. 2nd Ser. vol. x. p. 210. XXXV1 INTRODUCTION. was evident that, in this instance, neither were the shells split to afford a lateral passage for the limbs, nor were the limbs reduced to tenuity by emaciation.” The new in- tegument is at first soft and membranous, but speedily becomes encrusted with calcareous matter, and as hard as the former. The additional size which is gained by each moult is very striking, and I have often felt, on seeing a newly-emancipated crab by the side of the shell which it had just shed, that, were not the fact absolutely ascertained by observation, it would appear physically im- possible that the larger body could have so recently been contained within so small a case. Réaumur supposed that even the hairs with which the surface is in many species furnished, were contained within the cast crust; but Dr. Milne Edwards asserts that such is not the case ; stating that they are not at first obvious on the surface of the new shell, but “sont rentrés a Vintérieur, comme le doigt @un gant qui serait retourné sur lui-méme!” If we open, says this author, a Maia a short time before the commencement of the moult, we find between the exist- ing shell and the “ chorion” a membranous layer, which resembles condensed cellular tissue, and which becomes thicker and more solid, as the period of moult approaches ; it is evidently secreted by the chorion, and is moulded upon the shell which covers it. In the common crab (Cancer Pagurus), and some others of similar form, it would appear that the carapace, instead of being cast entire, divides at the junction of the epimera with the dorsal piece or tergum ; a fact which I have often seen in many species, particularly in the larger Grapsid, which, from their form, could not possibly withdraw the body without such a separation. INTRODUCTION. XXXV11 In the account of the great crab, p. 62, I have stated that the male lies in wait for the female previous to and during her moult, and seizes her as soon as this is ac- complished, whilst she is still weak and enfeebled by the process; and I have so commonly seen the male and female shore-crab (Carcinus Menas) in conjunction when the latter is still soft, that there can be no doubt that this is a general, although certainly not a constant habit. A no less curious and interesting process than that above described, is the voluntary casting of the limbs, and the restoration of such as have been thus lost by the animal’s will, or by accident. Réaumur in this case also was the first to make any correct and scientific researches on the subject, and his statements, full of interest, will be found in the earlier of the two memoirs already quoted. My friend Mr. Couch has subsequently extended these observations, which will be found embodied in my account of the habits of the lobster at page 245. On this subject an interesting paper was read before the Wernerian Society of Edinburgh by Mr. H. Goodsir, in December, 1843 ; and to the details which I have given in the place above mentioned, I would merely add a short abstract of Mr. H. Goodsir’s paper :* “ It has long been known that the animals belonging to this class have the power of reproducing parts of their body which have been accidentally lost. If one of the more distant phalanges of a limb be torn off, the animal has the power of throwing the remaining part of the limb off altogether. ‘This separation is found to take place always at one spot only, near the basal extremity of the first * Annals of Nat. Hist. vol. xiii. p. 67. XXXVill INTRODUCTION. phalanx. The author has found that a small glandular- like body exists at this spot in each of the limbs, which supplies the germs for future legs. This body completely fills up the cavity of the shell for the extent of about half aninchin length. The microscopic structure of this glan- dular-like body is very peculiar, consisting of a great number of large nucleated cells, which are interspersed throughout a fibro-gelatinous mass. . =o ar) INTRODUCTION. lxi tail in the history of the discovery, in order to do justice to those whose original and independent observa- tions led them to break through the trammels of precon- ceived notions, and, notwithstanding much opposition and some misrepresentation, persevered in prosecuting the investigation until the truth of the doctrine has been universally received.* It has not been my object, in the present Introduction, to enter into the details of the anatomy and physiology of the class of animals of which it treats. It has been con- sidered sufficient for my present purpose to offer a very slight sketch of the principal organs and their functions, * During the passage of part of this introduction through the press, I received a communication from my friend Mr. Couch, containing some new observations on the development of the lobster. From these observations, and others made on Caprella and other forms, Mr. Couch comes to the following conclusions, which are strongly confirmatory of the doctrine of arrested development, and are, in that point of view, very interesting. The original paper was read at the Royal Cornwall Polytechnic Society. “*So far as my observation has extended, it appears probable that the meta- morphosis of the young in their progress to adult growth is not universal in all Crustaceans ; but, on the contrary, that the families in which the eyes are always sessile in their adult growth, and which do not exuyiate or voluntarily throw off their limbs, are in the habit of producing their young perfectly formed ; and an opportuyity that has occurred to me of observing the process of early develop- ment in the common lobster will tend to establish the existence of a law of Nature as applicable not only to it, but probably also to all the genera of this extensive family or class—that is, the long-tailed crustacea—which law is, that the greatest extent of metamorphosis is in those genera which are of the highest rank in the series—that is, the short-tailed, or crabs—that, even at their birth, the long-tailed genera—as the lobster—approach more closely to the ultimate form of the parent ; and-—what is still more extraordinary than all beside—that so long as the lobster in particular, retains the eyes sessile, the progress of develop- ment and growth is conformed to what is the perpetual mode of growth of the permanently sessile-eyed races; and it is only when the crust has become fully extended and hardened, and thus the exuviation is rendered necessary, that the eyes become elevated on footstalks, and the adult form and habit are completely established.” lxii INTRODUCTION. with reference, on the one hand, to the characters which are given of the different genera and species, in the body of the work, and, on the other, to their habits and mode of life. For those who seek for further information, I beg to refer to the excellent digest contained in Pro- fessor Rymer Jones’s “ Outline of the Animal Kingdom,” to Professor Owen’s admirable lectures on the Inver- tebrata, to Dr, Milne Edwards’s article CRUSTACEA in Dr. Todd’s “ Cyclopedia of Anatomy and Physiology,” and above all, to the great general work of the same author on the natural history of this class of animals.* In the introductory portion of that invaluable book, and in the general description of the different groups contained in the body of the work, will be found an immense fund of information, great part of which is original and based upon the actual dissection and observation of that distin- guished naturalist, and of his no less talented friend and coadjutor, Mons. Audouin. My obligations to this un- rivalled monograph will appear in every page of this little work, and demand my warmest acknowledgments. * Histoire Naturelle des Crustacés, tom. iii. Paris, 1834. [ The systematic names, including the Latin synonyms, are printed in J¢alics.] A. Acheus Cranchii, 10. Alauna rostrata, 330. Albunea dentata, 159. Alpheus Caramote, 318. aan Tubers Dil. » stvado, 312. » Spinus, 284. Astacus Bamfficus, 208 » Bernhardus, 171. » Crangon, 256. » fluviatilis, 237. > Homarus, 213. 5 marinus, 242. 5 nitescens, 261. » Norvegicus, 251. » serratus, 302. 5, squamifer, 197. » Squilla, 305. » strigosus, 200. » stellatus, 223. subtewraneus, 217. Atelecyclus heterodon, 153. os septemdentatus, 153. A thanas nitescens, 261. Awxius stirynchus, 226. B. Blastus tetraodon, 22. Bodotria arenosa, 333. C. Callianassa subterranea, 217. Calocaris Macandree, 533, Cancellus marinus, 135. Cancer angulatus, 130. >» araneus, 31. » casper, 46. » Astacus, 237. » Bamfficus, 208. » Bernhardus, 171. » biaculeatus, 2 BB UjO. 3)l\< > Cassivelaunus, 159. » corrugatus, 94, INDEX. Cancer denticulatus, 72. » Depurator, 101, » digitatus, 351. » LDorsettensis, 13. » Dromia, 369. » jloridus, 51. » fluviatilis, 237. » Gammarus, 242, » irtellus, 68. horridus, 165. » hydrophilus, 54. » netso-serratus, 59. 5 meisus, 51. » latipes, 85. » longicornis, 193. » Maia, 39, 165. 5 minutus, 135. 9 Menas, 76. » Norvegicus, 251. » Pagurus, 59. » Phalangium, 2. » Lisum, 121. » Platycheles, 190. » puber, 90. » rostratus, 2. » Scorpio, 13. » Spinus, 284. » Squilla, 202, 305. » Squinado, 39. » strigosus, 200. » tetraodon, 22. » tuberosus, 141. » tumefactus, 145. » velutinus, 90. Carcinus Meenas, 76. Corystes Cassivelaunus, 159. » dentatus, 159. Crab, angular, 130. a ecincilarse lose 5 floating, 135. » great, 59. » harbour, 77. 5 masked, 159. shore, ae. C; vate yon bispinosus, 268. » CEU Ee 261, » fasciatus, 259. 35 se ulptus, 263. lxiv Crangon spinosus, 261. » trispinosus, 265, » vulgaris, 256. Cray-fish, common, 237. Cuma Audouinii, 328. » Edwardsii, 326. » trispinosa, 329. Cynthia Flemingii, 379. D. Dromia Rumphii, 369. » vulgaris, 369. EK. Ebalia Bryerii, 145. > Cranchit, 148. » Pennantii, 141. Eurynome aspera, 46. >» Spinosa, 46. G. Galathea Bamffia, 208. Galathea, Embleton’s, 204. Galathea neaa, 204. ax rugosa, 208. Galathea, scaly, 197. Galathea spinigera, 200. Galathea, spinous, 200. Galathea squamifera, 197. 5 strigosa, 200, » adeltura, 225. Gebia stellata, 223. Gelasimus Bellii, 130. Gonoplax angulatus, 120. is bispinosus, 130. “a rhomboides, 130. Grapsus cinereus, 135. 3 minutus, 135. » Lestudinum, 135. H. Hermit-crab, blue-banded, 375. ss common, 17]. ‘a Prideaux’s, 175. os rough-clawed, 186. ‘a smooth, 184. Hippa septemdentata, 153. Hippolyte Cranchit, 288. Hippolyte, Cranch’s, 288. Hippolyte Moorii, 292. » Pandaliformis, 294. p Prideauxiana, 292. Hippolyte, Prideaux’s, 292. Fippolyte Sowerbai, 284, Hippolyte, Sowerby’s, 284, Hippolyte Spinus, 284. . Thompsont, 290. Hippolyte, Thompson’s, 290. INDEX. Hippolyte varians, 286. Hippolyte, varying, 286. Homarus vulgaris, 242. Hyas araneus, 31. 5, coarctatus, 35. Inachus araneus, 31. » Dorsettensis, 13. > Dorynchus, 16. » leptochirus, 18. >» Phalangium, 2. » Scorpio, 13. L. Leptopodia tenuirosiris, 6. Lithodes Maia, 165. Lobster, common, 242. » Norway, 251. M. Macropodia longirostris, 6. fo Phalangium, 2. & Scorpio, 13. os tenuirostris, 6. Macropus longirostris, 6. 3 Phalangium, 2. Maia aranea, 31. 5 Sguinado, 39. » tetraodon, 22. Mantis digitatus, 351. Munida, long-armed, 208. Munida Rondeletii, 208. » rugosa, 208. Mysis Chameleon, 336. » Griffithsie, 342. » Leachii, 336. » rostratus, 342. > spinulosus, 336. » vulgaris, 339. N. Nautilograpsus minutus, 135. Nephrops Norvegicus, 251. Nika eanaliculata, 275. Couchii, 278. edulis, 275. ted ”° O. Ocypoda angulata, 130. IE Pagurus Bernhardus, 171. 4» Cuanensis, 178. | | Pagurus Dillwynit, 377. » fusciatus, 375. » orbesii, 186. e Hyndmanni, 182. » levis, 184. » Prideauwii, 175. » streblonyx, 171. »5 Thompsoni, 372. ulidianus, 180. Palen Leachi, 307. i; nitescens, 261. 95 serratus, 302. 5 Squilla, 302, 305. VATLANS, 309. Polinurus Homarus, 213. a quadricornis, 213. 5 vulgaris, 213. Pandalus annulicornis, 297. Pasiphea brevirostris, 312. eS Savignii, 312. -p Sivado, 312. Pea-crab, Pinna, 126. +» common, 121]. Peneus Caramote, 318. » trisulcatus, 318. Planes Linneana, 135. Platycarcinus Pagurus, 159. Pilumnus hirtellus, 68. Pinnotheres Cranchit, 121. i Latreillii, 121. os Montagui, 126. os Pinne, 126. os Pisum, 121. . varians, 121. 9 Veterum, 126. Pirimela denticulata, 72. Pisa biaculeata, 27. 9 Gibbsii, 27. » tetraodon, 22. Pisidia longicornis, 193. Platyonicus latipes, 85. Polybius Henslowii, 116. Pontophilus bispinosus, 268. 5 spinosus, 261. - trispinosus, 205. Porcelain-crab, hairy, 190. 9 minute, 193. Porcelluna Leachii, 193. oS longicornis, 193. a platycheles, 190. Portumnus variegatus, 85. Portunus arcuatus, 97. a5 corrugatus, 94. 5 Dalyell, 361. 3 Depurator, 101. Sy emarginatus, 97, ~ holsatus, 109. 9 infractus, 361. oF lividus, 109. INDEX. Ixv Portunus, longipes, 361. 5 maculatus, 112. os marmoreus, 105. - Menas, 76. » Pplicatus, 101. » puber, 90. » pusillus, 112. Rondeletii, 97. Prawn, 303. Processa canaliculata, 275. 3 edulis, 275. Ss. Shrimp, banded, 259 3 common, 256. 5 sculptured, 263. » spinous, 261. >» three- Pete en two-spined, 2 Spider- -crab, Cranch’s, a a four-horned, 22. es Gibbs's, 27. 3 long-legged, 2. - Scorpion, 13. - slender, 6. 55 slender-legged, 19. spinous, 39. Spiny- “lobster, common, 213. Squilla Desmarestit, 354. » Mantis, 351. Stenorynchus longirostris, 6. 7) Phalangium, 2. a tenuirostris, 6. Stone-crab, northern, 165. Swimming-crab, arched, 97. PS cleanser, 101. p dwarf, 112. = Henslow’s, 116. = livid, 109. long-legged, 361, 5 marbled, 105. e velvet, 90. > wrinkled, 94. T. Themisto brevispinosa, 364. » longispinosa, 381, Thia polita, 365. Thysanopoda Couchii, 346. Kk Xantho florida, bills inciso-serrati, 51. ? », revulosa, 54, » tuberculata, 359. BRITISH CRUSTACEA. DECAPODA. LEPTOPODIAD. BRACHYURA, GENUS STENORYNCHUS, Lamarcr. CANCER, Linn. Penn. Herbet. INACHUS, Fabr. Mara, Bose. Macropus, Latr. Macropopia, Leach. STENORYNCHUS, Lamk. Edwards. Generic character. External antenne setaceous, the basal joint narrow, the second * inserted close to the side of the rostrum, very short ; the third, three times as long as the former. Earterna/ pedipalps narrow, the second joint considerably produced internally at its apex; the third jomt oval. Anterior Jeet shorter, and much larger (in the male) than the succeeding ones; equal; the hand somewhat ventricose ; the fingers slightly inflected. The remaining pairs very long and slender, diminishing in length from the second to the fifth ; the nails of the second and third pairs long, slender, and curved only at the apex; those of the fourth and fifth shorter, curved at the base and somewhat faiciform. Hyves not retractile, larger than their peduncles, oval, pointed at the apex and setiger- ous. Carapace triangular; rostrum taper and bifid. Abdomen six-jointed, the terminal portion being formed by the union of the sixth and seventh joints. * Leach calls this the first joint of the antenna, as he does not reckon the basal joint, which is fixed, and, as it were, soldered to the parts contiguous, as in most of the higher forms of Crustacea. B 2, LEPTOPODIADA. DECAPODA. LEPTOPODIAD. BRACHYURA. LONG-LEGGED SPIDER-CRAB. Stenorynchus Phalangium. Specific character.—Rostrum shorter than the peduncle of the antenne ; a single minute spine on the epistome, close to the auditory cavity ; no spine behind the base of the antenn ; arms slightly scabrous, without spines. Cancer rostratus, Lin. Faun. Suec. Hergsst. t. xvi. f. 90. 5 Phalangium, PEnn. IV. t. ix. f. xvii. Inachus 5 Fapr. Supp. p. 358. Macropus i Latr. Hist. Nat. Crust. VI., p. 110. Macropodia ,, Lxacu, Tr. Linn. Soc., XI., p. 33], Malac. Brit. Uh 2o-obie 15 (ip Stenorynchus 4, Epw. Hist. Crust. I. p. 279. Tue general form of the carapace in this species is that of an acute angled triangle, rounded at the posterior angles. It has several rather prominent spines; one on each he- LONG-LEGGED SPIDER-CRAB, 3 patic region, forming, with one on the gastric region, an equilateral triangle; there are two small ones on each branchial region, and one, the largest of all, on the cardiac ; there are also one or two smaller ones near the latero- anterior margm. The rostrum is of moderate length, scarcely reaching to the middle of the third joint of the peduncle of the antenne; it has a groove through its whole length, reaching to the back of the orbit. The ex- ternal antennz are long and setaceous, and furnished with several long hairs; the basal jomt is narrow, entirely im- moveable, and continuous with the epistome; the move- able part of the peduncle consists of two joints, of which the second is three times as long as the first. The internal antennz are lodged in fosse, which are separated from each other by a ridge, which is incomplete at the middle. The eyes are oval, larger than their peduncles, and pointed at the apex, where there is a small bristle.* The orbits are round, and there is a prominent ridge over the upper margin. The epistome, or that portion of the shell be- tween the mouth and the base of the antenne, has a very minute tubercle, just in front of the organ of hearing, but none at the base of the antenne, as in S¢. tenuirostris.+ The first pair of legs in the male are about twice as long as the body; the arm has a line of minute tubercles on the outer, and another on the inferior surface, which parts are also hairy; but there are no spines on its inner margin, as in St. tenwirostris: the wrist is similarly furnished : the hand is somewhat ventricose ; it is hairy both on the outer and inner margin ; the fingers are slightly inflected ; the moveable one is furnished with a tubercle near its base, * This curious appendage I have never seen mentioned as appertaining to this genus. + This second tubercle is also found in a Mediterranean species S#. Afgyptius. B 2 4. LEPTOPODIAD &. and there is a corresponding excavation in the other. In the female these feet are altogether much smaller than in the male. The remaining pairs are very slender and fili- form; the second pair is three times and a half the length of the post-rostral part of the body, and they diminish regularly to the last pair: the claws of the second and third pairs are slender, and slightly curved towards the extremity; those of the fourth and fifth are shorter, and somewhat faleate, being curved more abruptly near the base. The abdomen in both sexes has six joints, the sixth and seventh being united into one piece. That of the male is broadest at the base, and again at the union of the third and fourth joints, and terminates in an obtuse triangle : each Joint is furnished with a tubercle. The abdomen of the female is very broad, and much curved: the tubercles pass into a continuous obtuse carina on the three or four last joints. These characters belong for the most part to both the species, excepting where the contrary has been stated ; the specific difference with those exceptions being rather in the degree of development than in the existence, or non- existence of parts. This is one of the most common species of the Trian- gular Crabs, bemg found in considerable numbers on most parts of the coast. I have obtained it from Wales, the coast of Cornwall, Devonshire, Dorsetshire, and Sussex, from Scarborough, and from Orkney. It is also not un- common on the coast of Ireland. Dr. Leach mentions its being particularly common at the mouths of rivers, and in estuaries ; but I have found it in very different localities, having often dredged it in deep water, and taken it in crab and lobster pots. Mr. Hailstone states that ‘it is very common at Hastings, both among the rocks on the LONG-LEGGED SPIDER-CRAB., 5 shore, and in deep water, and is occasionally caught in the trawl-net in vast numbers. Of sixty-eight specimens brought up at once, the proportion of males to females was as two to one.” Like all the species of the family it is slow, sluggish, and timid. It generally has small fuci growing on it, especially on the legs; and I have some- times seen the body completely covered and concealed by amass of sponge. When taken it moves with very little energy, and speedily dies after bemg taken out of the water. Its slow and sluggish habits render it an easy prey to many fishes; Mr. W. Thompson says, ‘* On opening a thornback, Raia clavata, about twenty inches in length, [ found the stomach entirely filled with Macropodia Pha- langium.” It deposits its spawn during the early spring months. oO 6 LEPTOPODIAD&. DECAPODA. LEPTOPODIAD. BRACHYURA. SLENDER SPIDER-CRAB. Stenorynchus tenuirostris. Specific character.—Rostrum longer than the peduncle of the external antenna, its two portions being in contact throughout their whole length ; two minute spines on the epistome, one close to the organ of hearing and another at the base of the external antennz ; arms spinulose at the inner margin. Leptopodia tenuirostris, Leacu, Edinb. Enc. VII., p. 43]. Macropus longirostris ? Latr. Hist. Nat. des Crust. VIII., p. 110. Macropodia ,, Risso. Hist. Nat. de l’Eur. Merid. V., p. 27. 2 tenuirostris, Leacu, Trans. Linn. Soc. XI. p. 331. Malac. Brit. t. XXIII. f. 1-5. Stenorynchus longirostris ? Epw. Hist. Crust. I. p. 280. Covucn, Cornish Fauna, p. 64. Tuts elegant species may be readily distinguished from the former by the long attenuated rostrum, by the existence of a small spine on the epistome, immediately behind the SLENDER SPIDER-CRAB. i basal joint of the external antenne, and by a series of minute spines on the inner part of the arm. The body is altogether more elongated, and the spines more acute ; but, in other respects, the characters are nearly the same, “T first observed this species,” says Dr. Leach, “ amongst some Crustacea collected at Torquay, in Southern Devon, by Hooker; and have since found it a very common inhabi- tant of all the deep water off the coast of that country, especially in the Sound of Plymouth.” Mr. Couch states it to be very common in Cornwall, at the depth of from two to twenty fathoms ; and Mr. Embleton includes it in his list of the Crustacea of Berwickshire and North Durham. It does not appear to have been taken in Ireland. I have taken it in prawn pots at Bognor, and by dredging in Studland Bay in Dorsetshire. I have appended a note of doubt to the synonyms of the Mediterranean species, Macropus longirostris, Latr., hitherto considered as identical with this, as I am much inclined to believe they may be distinct. I am led to this supposition by a careful examination of specimens of my own collection on our coast, with some which I had received from Sicily, and from the Bay of Naples, and I find that on all those brought from the Mediterranean, the body is proportionally longer ; the rostrum also longer and more slender, reaching very much beyond the peduncle of the antenne. By measurement I find that, in the Mediter- ranean specimens, the length of the carapace, including the rostrum, is to its breadth, at the widest part, as five to two ; whereas, inthe British, it is not quite twice as long as broad. The two portions of the rostrum in the former are a little separated throughout almost their whole length, and each is perfectly round ; whereas, in the British specimens, they 8 LEPTOPODIAD &. are entirely in contact, and flattened above and beneath. There are a few other differences principally proportional, but these are the most considerable. These may be mere accidental variations, but I think it not improbable that they indicate a specific distinction. DECAPODA. LEPTOPODIA Di, BRACHYURA. GENUS ACHZEUS, Leacn. ACH&US, Leach, Latr. Edwards. Generic character. External antenne remote, setaceous, the first articulation united to the front, and extending beyond the inner canthus of the orbits ; the second articulation inserted at the side of the rostrum, and entirely exposed from above, and, with the third, much thicker than the subsequent ones. Eaternal pedi- palps, with the second articulation much longer than broad, and produced at the interior and anterior angles, the third subtriangular with the angles rounded. The first pair of feet (in the female) short, rather slender; the second and third pairs having the ter- minal joint long and styliform ; that of the fourth and fifth com- pressed, abruptly curved, and falciform. Carapace somewhat. tri- angular, slightly spinous, the branchial regions elevated and swollen. Rostrum extremely small, bifid. Eyes not retractile, placed on long footstalks of equal size, and furnished with a single tubercle on the fore-part. Abdomen six-jointed in both sexes. This genus, of which one species only is at present known, is considered by Dr. Leach as intermediate between Inachus and Leptopodia | Macropodia], and by Milne Ed- wards it is placed between Stenorynchus (Macropodia Le.) and Camposcia. Its relation to Hurypodius is also pro- bable from the character of the feet, whilst the structure of the eyes and some other points appear to indicate an ap- proach to some of the Maiade. 10 LEPTOPODIAD A. DECAPODA. LEPTOPODIAD. BRACHYURA. CRANCH’S SPIDER-CRAB. Achaus Cranchii. each. Specific character—* Carapace, with two tubercles in the median line, and } pace, with two elevated lines between the eyes.”—LEACH. Acheus Cranchii, Leacu, Malac. Brit. XXII. C. Ed. 2. Larr. Reg. Anim. IV. p. 64. Epw. Hist. Crust. I. p. 281. Tue carapace of this interesting species, is triangular, contracted behind the orbits, then enlarged into a promi- nent point or tubercle, then again contracted, and finally enlarged and rounded at the sides of the branchial regions. Two conspicuous elevations, or tubercles, occur on the median line, with an inconspicuous one between them ; and the branchial regions are elevated and rounded. The ros- trum is extremely small and bifid, as broad as it is long. The orbits are small and open above, and the eyes exposed almost to the insertion of the peduncles, which are long, cylindrical, furnished with a small rounded tubercle on the anterior part, about the middle of its length, and standing directly outwards ; not retractile. The antenne and the ee ee ee ee ee CRANCH’S SPIDER CRAB. 11 feet are very hairy. The hands are carmated longitudinally. The epistome is quadrate. The abdomen in the female (and, according to Dr. Milne Edwards, in the male also,) is six- jointed. In the former it is oval, expanded towards the posterior part, and carinated through its whole length. The carapace is about six lines in length. Colour, pale reddish brown. Of the occurrence of this beautiful little species on our coasts, we have, I believe, only two recorded instances. In the “ Malacostraca Podophthalma Britanniz,” Dr. Leach first made it known as haying been discovered by Mr. Cranch in dredging off Falmouth. This single specimen, a female, is now in the British Museum. The second ex- ample is thus stated by Mr. W. Thompson in his catalogue of the Crustacea of Ireland. ‘“ In the collection of Crustacea formed by Mr. J. V. Thompson, and now in the possession of the Royal College of Surgeons, Dublin, is a native speci- men of this crab, which we may presume was obtained on the Southern coast.” This is the sum of the information we have respecting this species as indigenous to this country. Dr. Milne Edwards gives as its habitat on the French coast, ‘“‘l’embouchure de la Rance, prés Saint-Malo.” Of its habits nothing whatever is recorded, beyond the remark of Dr. Edwards, that it lives amongst sea-weeds and on oyster-beds. DECAPODA. LEPTOPODIADA. BRACHYURA. GENUS INACHUS, Fanr. CANCER, Pennant, Herbst. INACHUS, Fabr. Leach, Latr. Edw. Macrorus, Latr. Malia, Bose. Generic character. — External antenne not more than one-fifth of the length of the body; the basal joint forming the inferior margin of the orbit ; the second inserted by the side of the rostrum. External pedipalps with the second joint much produced internally ; the third joint elongate, somewhat triangular, the anterior and inner angle truncate at the insertion of the palp, which is three- jointed. The anterior legs, in the male, twice as long as the body, the arms and the hands subovate, the fingers inflected. The re- maining pairs very long, diminishing in length from the second to the fifth ; second pair larger than the succeeding ones; the terminal joint long and slightly curved. Cavapace subtriangular, nearly as broad as long, the rostrum short and bifid. Eyes on short foot- stalks, retractile or capable of being bent backwards and lodged in the posterior part of the orbit. Addomen in both sexes, six-jointed and carinated. ae SCORPION SPIDER-CRAB. DECAPODA. 15 BRACHYURA. LEPTOPODIADé. SCORPION SPIDER-CRAB. Inachus Dorsettensis. Leach. Specific character.— Rostrum very short, emarginate: the gastric region fur- nished with four small tubercles ranged in a line transversely, and a larger one behind them. Cancer Dorsettensis, Penn. Brit. Zool. IV. t. x. f. 1. p. 12. » Scorpio, Fasr. Ent. Syst. Il. p. 462. Huresr. I. p. 237. No 130. Macropus ,, Larr. Hist. Nat. Crust. VI. p. 109. Tnachus 55 Fase. Suppl. 358. Dersm. Cons. t. xxiv. f. 1. Epw Hist. Crust. I. p. 288. p: 65. 5 Dorsettensis, Coucu, Cornish Fauna, Leacu, Edinb. Encycl. Malac. Brit. t. xxii. f. 1-6. I nave found it necessary to restore to this species the original specific name given to it by Pennant, who first described it from specimens in the Portland Cabinet, taken 14 LEPTOPODIAD&. at Weymouth, from which locality he designated it Cancer Dorsettensis. His work was published in 1777; and the Entomologia Systematica of Fabricius, in which it first re- ceived the name of C. Scorpio, not until 1793. The Fab- rician name has recently been adopted by Dr. Milne Edwards, as it had previously been by Desmarest, probably from some objection to the local origin of the former name ; this, however, is quite admissible in the present instance, as indicating the locality in which it was first discovered. At all events, it is not more objectionable than the other. The carapace of this species is triangular, rounded poste- riorly, and yentricose. The rostrum is very short and bifid ; the orbits oval, so that the eyes, which are attached by their peduncles to the anterior portion of the orbit, can be laid backwards into the posterior portion of that cavity ; a character which belongs to most of the genera of the triangular or oxyrynchian families. The eyes are protected by a spine on the anterior, and a stronger one on the posterior margin of the orbits, of which the upper margin is also raised, and the inferior, formed by the basal joint of the antennee, slightly tuberculated. The external antenne are short ; the moveable portion not much exceeding twice the length of the rostrum. There are four small tubercles on the anterior part of the carapace arranged transversely, and one much larger behind them, on the centre of the gastric region; there are two tubercles on each branchial region, one at the anterior part and another rather larger on the centre; there is also a conspicuous one on the cardiac region. The external pedipalps are elongate, the second joint being much produced anteriorly at the inner angle; and the third, which is somewhat triangular, has the inner and anterior angle truncated, for the articulation of the terminal portion, which consists of three joints. The anterior pair of legs in SCORPION SPIDER-CRAB. 15 the male are thick and long, the Joints of a somewhat oval form, and the fingers considerably incurved. Those of the female are very small. The remaining feet are very long and slender, the second pair being considerably more than three times the length of the body, including the rostrum. They are also much larger than the succeeding one, which diminish in length and thickness to the last. The abdomen of the male is rather short and broad, the widest part being at the union of the third and fourth jomts; that of the female is remarkably broad. In both sexes it is tuberculo- carinated. It would appear that this species is more widely distri- buted than had been supposed. Dr. Leach states that it is very plentiful on the coast of Devon; we have seen that Pennant’s specimens were from Weymouth; and I ob- tained it in Studland Bay, Dorsetshire, and at Hastings. Mr. Couch states that in Cornwall it is commonly taken in crab pots, within a few miles of the shore, at all depths; and Mr. Eyton informs me that it is found on the oyster- beds at Rhoscolyn, near Holyhead. In Ireland it has been found in many places; in the Harbour of Cove, by Mr. J. V. Thompson. “It is pretty commonly taken,” says Mr. W. Thompson, “in the loughs of Strangford and Belfast, and on the western coast.—Mr. Ball,” adds Mr. 5 Thompson, “finds it in Dublin Bay.” It is also recorded that Captain Beechey, R.N., brought up a specimen of this species alive in the dredge from a depth of one hundred and forty fathoms, in the Mull of Galloway. Its habitat extends far north, Fabricius having found it in the Nor- wegian Seas. — 16 LEPTOPODIAD. DECAPODA, LEPTOPODIADA. BRACHYURA. Inachus Dorynchus. each. Specific character.— Rostrum bifid, extending beyond the third joint of the pedun- cle of the antennze ; gastrie region with three spines, two anterior, and the third much longer, forming a triangle. Second pair of legs not more than three times the total length of the body. Inachus Dorynchus, Leacu, Edinb. Ene. art. Crust. p. 431. Id. Malac. Brit. t. xxii, f. 7-8. Epw. Hist. Crust. p. 288. Coucn, Cornish Fauna, p. 65. Tue general form of this species is very similar to the former, but it is less globose. The carapace is triangular, longer than it is broad. The rostrum is short, some- what hastiform, and in most slightly bifid; although in some specimens the division is more considerable. The antenne, the eyes, and orbits, as well as the external — ea INACHUS DORYNCHUS. J fi pedipalps, are very similar to those of the former species. The gastric region of the carapace has three spines, two small ones distant, and another much stronger placed far- ther back on the median line, and, with the others, forming a triangle. There are two tubercles on each hepatic region, placed as in the former species; and the cardiac region, instead of a spme, has only an elevation, on which are three very small tubercles. The sides of the shell are destitute of tubercles. The hands are smooth. In other respects this species resembles the former. The present species of Jnachus was discovered by Dr. Leach, as he informs us, “ whilst cleanig a parcel of J. Dorsettensis from the Salcombe estuary for examination.” Mr. Couch states that it is commonly found m crab-pots in Cornwall. Mr. Hailstone found it at Hastings, where I have also obtained it. I have taken it by the dredge in Studland Bay, Dorsetshire, and at Bognor I found several small specimens amongst the refuse of prawn and lobster pots. These were of a lighter colour than most which I have observed from other localities, but this may have arisen from their bemg young. In Mr. Embleton’s list of the Crustacea of Berwickshire and North Durham, it is stated to occur not uncommonly in Berwick and Embleton Bays. It is found on the coast of Ireland, though rarely, having been taken by Dr. Drummond in Belfast Bay. This species, like all the others of the family, is very liable to be covered with small fuci and sponges ; hence, as Dr. Leach has observed, im all probability arose its having been for so long a time undiscovered, having doubtless been passed over as J. Dorsettensis; it does not, however, at present appear to be so generally distributed as that species. 18 LEPTOPODIADE. DECAPODA. LEPTOPODIAD.. BRACHYURA. Y Y SLENDER-LEGGED SPIDER-CRAB. Inachus leptochirus. Leach. Specific character.—Feet slender, anterior pair in the male extending beyond the penultimate joint of the second pair. Rostrum hastiform. Sternum in the male with a round polished tubercle. Inachus leptochirus, Leacu, Malac. Brit. t. xxii. B. (errore leptorinchus) Epw. Hist. Crust. I, p. 289. Tue carapace in this species considerably resembles that of I. Dorynchus. It is triangular, considerably longer than it is broad, much narrowed forwards; the rostrum hasti- form, bifid at the extremity, and with a slight groove ex- tending from thence backwards between the eyes. There is a strong spine on the gastric region, a very small tuber- cle on each hepatic, a spine on the latero-anterior margin, SLENDER-LEGGED SPIDER-CRAB. 19 two on each branchial region, the posterior beimg the larger, and one on the genital region in a straight line between the two larger ones on the branchial. The feet are all very long and slender. The hands in the adult male are considerably longer than the carapace; the fingers curved. The second pair of feet are three times the length of the carapace. On the sternum, immediately in front of the apex of the abdomen, when in its usual position applied against the thorax, is a round or oval prominent and po- lished tubercle, of a greyish-white colour. In the adult state this is considerably the largest of the British species of Znachus. It is also then readily distin- guished from the others, by the general form, as well as by the extraordinary length of all the legs, and especially by the form and length of the first pair. But in the younger state all these characters are much less conspi- cuous, and it might almost be mistaken for J. Dorynchus, but for the remarkable character of the round polished tubercle on the thorax, which somewhat resembles the half of a pearl. This is peculiar to the male, and cannot fail to strike us as offering a very obvious mark of relation to the Mediterranean species J. Thora- cicus, on the thorax of which there is a very curious development of a similar hard shelly substance, in the form of a broad, three-lobed plate. This formation is peculiar to the genus Jnachus, and, as far as it is at present known, to the two species in question. The Znachus leptochirus is extremely rare. It was dis- covered by the ill-fated Mr. Cranch on the western coast of Devon, or Cornwall, and was afterwards taken by Mr. Prideaux from a crab-pot in Bigbury Bay. In Mr. W. Thompson’s ‘‘ Additions to the Fauna of Ireland,” is men- co 2 +“ 20 LEPTOPODIAD 4. tioned ‘‘a specimen dredged in Clifton Bay, Connemara, by Mr. Forbes and Mr. Hall, and another in Belfast Bay by Mr. Patterson.” The latter specimen, through the kindness of Mr. Thompson, I have now before me. It isa young male. The same gentleman subsequently states that he had seen specimens from Belfast Bay “in the Ordnance collection.” This is the extent of our knowledge of this curious species. Dr. Milne Edwards has misquoted Leach’s specific name as ‘¢ Leptorinchus,” and this error has been copied by Mr. Couch in his ** Cornish Fauna.” DECAPODA, MAIAD 48, BRACHYURA. GENUS PISA. Cancer, Penn. Herbst, Montagu, Inacnus, Fabr. Risso. Mata, Latr. Bose. Pisa, Leach, Desmar, Edwards. Generic character.—External antenne beset with club-shaped nairs; the basal joint longer than broad, extending beyond the inner canthus of the orbit ; but concealed above by the strong spine which proceeds from the upper margin of the orbit: second joint of the antenne rather slender, inserted a little behind and on the outer side of the rostrum. L2ternal pedipalps very broad, the second jomt produced at the imner and anterior angle ; the third triangular, very broad at the outer margin; the anterior and inner angle truncate or emarginate. Fst pair of feet in the adult male very large, longer than the second pair; the hand thick and the fingers meeting only at the outer margin of the points which are toothed ; those of the female much smaller, the fingers meeting throughout nearly their whole length; shorter than the second pair. The remaining feet moderately long, diminishing regularly from the second to the fifth, cylindrical, the terminal jomt curved, pectinato-denticulated beneath, naked at the extremity. yes searcely thicker than their peduncles, capable of being reflected in the orbits. The orbits oval, directed outwards and downwards ; their upper margin with a strong triangular spine directed forwards. Carapace triangular, terminating in a strong bifid rostrum, divari- cating at the extremity. dddomen seven-jointed in both sexes, ——— 2») MAIAD&. DECAPODA. MAIADE., BRACHYURA. FOUR-HORNED SPIDER-CRAB. Pisa tetraodon. Leach. Speerfie character.—Lateral margin with four spines, (exclusive of those aboye and behind the orbit.) Posterior portion of the carapace rounded, without spines ; a small tubercle near the posterior margin. Cancer tetraodon, Penn, Brit. Zool. IV. t. viii. f. 2. p. 11. Maia A Bosc, Hist. Crust. I. 254. Leacu, Edinb. Encycl. VII. p. 395. Blastus x Leacu, l.c. p. 431. Pisa 5 Leacu, Trans. Linn. Soc. XI. p. 328. Id. Encycl. Brit. Supp. I. p. 415. Id. Malac. Brit. t. xx. f. 1-4, Epw. Hist. Crust. I. p. 805. Coucu, Cornish Fauna. p. 65. Tue general form of the body of this species is trian- gular, produced anteriorly, and with the posterior angles much rounded. The rostrum is large, strong, and promi- nent, about one-third as long as the remainder of the cara- ae a ee EE ee i FOUR-HORNED SPIDER-CRAB. 23 pace ; it is formed of two strong horns, diverging for about one-third of their length, and slightly deflexed ; the lateral margin has four spines, exclusive of a very strong one above the orbit, and a smaller one behind that cavity. There are numerous tubercles on the carapace, several small ones on the gastric region, disposed transversely ; one on the centre of the carapace; two considerable ones on each branchial region, one on the centre of the cardiac, and a small one near the posterior margin. The spines above the orbit are triangular, very strong and prominent; di- rected forwards and a little outwards, and so formed that the eyes can be deflexed within them, so as to be quite concealed from above. The external antenne are beset at their base with long club-shaped hairs. The anterior pair of feet in the male are exceedingly strong and thick, the hands especially are nearly as broad as they are long. The fingers meet at the points; the outer edge of each being denticulated, and the moveable one has a small round tooth. The arms and wrists have several round tubercles. In the female these feet are very small, and shorter than the second pair, and in the immature male they are very similar to those of the female. The remaining feet are of moderate size and length, the second pair being but little longer than the carapace, and the fifth pair shorter than its breadth. There are a few tubercles, and a few small spines upon the legs, and the nail is furnished beneath with a regular row of sharp spines arranged like the teeth of a comb. The abdomen has seven distinct joints in each sex; that of the male being broadest at the third joint; the sixth is broader than the fifth, and the seventh is trian- gular. Each joint has a central tubercle. The abdomen of the female is very large and broad, and has a broad carina. The whole surface of the shell, and oo ae ee oe ——— i ae 24 MAIAD&. the greater part of the limbs, is covered with a close, short, villous coat ; and the antenns, rostrum, and all the tu- bercles are furnished with tufts of long, curved, club- shaped hairs. Underneath this covering the shell is po- lished, and minutely punctured. The colour is a dull red- dish-brown, becoming bright red by boiling, or by the action of spirit. The general length of the carapace in a full-grown male is two inches three lines, breadth one inch six lines. The habits of this species, as far as I have had an op- portunity of observing them, are curious. They are found concealed under the long hanging fuci which clothe the rocks at some distance from the shore, in which situation I have taken them amongst the Bognor rocks. They con- gregate in vast numbers at the place I have just mentioned, in the prawn and lobster pots. I have seen, probably, thirty amongst the refuse of one of these, attracted no doubt by the garbage which is placed in them as bait. These were much larger and finer than any I have seen elsewhere. Contrary to the comparative sizes of the two sexes, as figured by Dr. Leach, I found the males larger than the females, exceeding. them in length by about half an inch. Thus, Leach’s figure of the male is not at all equal in size or apparent strength to those which I found at Bognor, but that of the female is about the ordinary size of that sex. Like all the slow moving Crustacea, they are very liable to be covered with small fuci, so that they are sometimes completely concealed by a mass of these marine plants growing upon their surface, where their roots find a secure hold amongst the villous coat of the shell and limbs.* This is especially the case with the * Say supposes that the fuci, which are found covering certain Crustacea, are merely entangled mechanically in the hooked hairs by which they are covered ; FOUR-HORNED SPIDER-CRAB, 25 females, which in this, as in many other species, are less active than the males. Their movements are extremely slow and measured, and they are very timid, concealing themselves under the fuci, and remaining for a time almost motionless. But notwithstanding their timid and lazy character, they seize the object of their anger by a sudden and unexpected snap, and nip with great force, holding on with extraordinary firmness and tenacity, although unable, from the bluntness of their pincers, to inflict a wound. The manner of their seizing any object, when from their slow motion it is least expected, reminded me of the mode in which I have seen the Ofolicnus tardigradus seize a bird, or other small living animal; and any one who has seen both, must, I think, be struck with the similarity. This species of Pisa formed the type of the genus Blas- tus of Leach, who, however, afterwards reunited the two forms, which certainly are not sufficiently distinct to war- rant their separation. It would appear from the paucity of observations which I have found of the occurrence of this species, that it is not a common one; or at least that it is very local. Mr. Couch says in his “ Cornish Fauna” that it is not common in that county. Dr. Leach gives, as its localities, ‘‘ The Isle of Wight, Teignmouth, and Brighton.” It is not mentioned by Mr. Hailstone in his MS. Catalogue of Hastings Crustacea, which he obligingly sent me, nor do I remember to have found it there. I have taken many small specimens on the Dorsetshire Coast by dredging, and, as I before observed, in very large num- bers at Bognor. The only account of its occurrence as an Irish species is, that “two examples exist in Mr. Ball’s but there is no doubt that they actually grow upon them, and are attached by roots. This is evident from the healthy state of the little plants, as well as from the direction of their branches. 26 MAIAD&. collection which were obtained at Roundstone, Conne- mara.” It inhabits, also, the Mediterranean; and I have observed a remarkable peculiarity in some of the specimens from that locality. The anterior pair of legs, as I have before mentioned, do not assume their full size and development until the animal is quite adult; but I have seen Mediter- ranean specimens of a very small size comparatively, with the full adult development of the feet. In such cases we might expect to find the reproductive organs fully per- fected, from some local circumstances favourable to their development, whilst the general growth of the animal had been retarded, probably by deficiency of nourishment. GIBBS’S SPIDER-CRAB. pif DECAPODA, MAIADA. BRACHYURA. GIBBS’S SPIDER-CRAB. Pisa Gibbsit. Leach. Specific character.—No spines on the lateral margin. A strong spine on each branchial region, and a large prominent tubercle just above the posterior margin of the carapace. ‘ancer biaculeatus, Monracu, Linn. Trans. XI. t. i. f. 2. p. 2. Pisa oH Leracu, Edinb. Encycl. VII. p. 431. » Gibbsit, Id. Trans. Linn. Soc. XI. p. 327. Malac. Brit. t. xix. Epw. Hist. Crust. I. p. 307. Coucu, Cornish Fauna, p. 65, Tue general form of the carapace in Pisa Gibbsii is very different from that of P. tetraodon. The rostrum is much longer, being not less than half the length of the rest of the shell, and its two horns, in the male, are parallel throughout almost their whole length; but in the female 28 MAIADA. they are shorter, and divergent for about one-third of their length, as in the former species. The lateral margin of the carapace is without spines,—excepting, in some speci- mens, a very small one on the hepatic region. The supra- orbitar spine is smaller than in the other species, not ex- ceeding one-third the length of the rostrum in the male ; it is directed outwards and forwards; the post-orbitar spine is very small. The regions of the carapace are very strongly marked and gibbous, particularly the genital and intestinal, and they are separated by deep furrows. There is on each branchial region a strong prominent spme which, with a large round tubercle just above the middle of the posterior margin, on the intestinal region, form an obtuse triangle. The antennz, the pedipalps, and the abdomen, are very similar to those of P. tetraodon. The anterior pair of feet are of moderate size, not nearly so broad and massive as those of the other species, and the hands com- pressed. The remaining feet are tuberculated, excepting the penultimate joint of the second pair, which is without tubercles or spines. The whole surface is covered with a very dense villous coat, much thicker than in P. tetraodon, and there are a few tufts of longer club-shaped hairs inter- spersed, with which also the base of the rostrum and that of the antennz are furnished. This species is exceedingly liable to the growth of foreign substances upon the surface, to which the dense villous covering affords a very ready and firm attachment. I have a specimen in my collection the form of which is almost completely concealed by a mass of sponge which has grown on its back. Dr. Leach states that it was first noticed by Mr. Gibbs, who was employed as a collector by Montagu. It was described and figured by the latter indefatigable naturalist, ee GIBBS S SPIDER-CRAB. 29 in the eleventh volume of the “Transactions of the Linnean Society,” under the name of Cancer biaculeatus; and Dr. Leach afterwards assigned to it its present name after the discoverer. According to the same authority it is not an uncommon species on the southern coast of Devon and Cornwall. In the latter county Mr. Couch says it is not uncommon, oc- curring at various depths, from two to twenty fathoms. I have obtained it at Hastings; where Mr. Hailstone also mentions its frequent occurrence ; and Dr. Milne Edwards mentions it as an inhabitant of the French coast. It is generally found in deep water, and is taken either by the trawl net, or by dredging. It spawns in December, according to the observation of Mr. Hailstone. DECAPODA. MAIADE. BRACHYURA. GENUS HYAS, Liacn. CANCER, Herbst. Mara, Bose. INACHUS, Fabricius. PIsA, Latr. Hyas, Leach, Edwards. Generic character.—External antenne with the basal portion slightly narrowed forwards, and separated from the outer portion of the orbit by a notch ; the second joint dilated externally, longer than the third. Lzternal pedipalps with the third joint notched at the internal apex. The first pair of legs thicker than the rest, shorter than the second pair, and equal; the fingers tapering to the point, and when closed, meeting throughout nearly their whole length. The remaining pairs of legs simple, slender, long, almost cylindrical ; the terminal joint without spines beneath. Carapace tuberculous, elongate-subtriangular, much rounder at the posterior margin ; rostrum of moderate length, triangular, depressed ; the lacinia somewhat converging. The lateral margin with a strong spear-shaped process immediately behind the orbit. Eyes capable of being deflexed within the orbits. Abdomen seven-jointed in both sexes; the terminal joint in the male is transversely oval, and the corresponding margin of the penultimate joint is broadly emarginate to receive it. This genus bears considerable relation to Pisa, from which it differs, amongst other characters, in the dilated form of the second joint of the antenne, and the absence of spines beneath the last joint of the legs. —_ HYAS ARANEUS. 31 DECAPODA. MATAD A. BRACHYURA. yas araneus. Specific character.—Carapace not contracted behind the post-orbitar hastiform process. Cancer arancus, Linn. Syst. Nat. I. 1044. SoU; Os Hersst, I. t. xvii. f. 59. p. 342. Inachus araneus, Fapr. Ent. Syst. Suppl. 356. Maia ~ Leacu, Edinb. Encycl. VII. 394. Hyas 55 Id. l.c. p.431. Id. Malac. Brit. t. xxi. A. Epw. Hist. Crust. I. p. 812. Coucu, Cornish Fauna, p. 66. Tus is the largest British species of the family with the exception of Maia Squinado. The carapace is of an elongate- triangular form, the posterior margin very much rounded, and the anterior portion considerably narrowed. The ros- trum is triangular, its two lacinie nearly parallel at their 32 MATADA. inner edge, converging at the points, somewhat flattened above, and slightly hollowed beneath. The external an- tenne are remarkable in this, as in the other species of the genus, for the dilated form of the external margin of the second joint, which is also considerably longer than the succeeding one; the peduncle is nearly as long as the ros- trum. The eyes are but little larger than the footstalk, and capable of being retracted within the orbit, which is large and open, arched above, and protected posteriorly by a strong hastate process. There are no spines on any part of the body or limbs; but the carapace is covered with low tubercles of various sizes. Of the external pedipalps the second joint is quadrate, slightly produced at the an- terior and inner angle; the third joint of an irregular form, and somewhat notched at the imner apex for the articulation of the terminal portion. The abdomen of the male is of a very peculiar form. he third joint is the broadest, the fifth and sixth nearly equal, and the latter excavated in its distal margin to receive the seventh joint, which is transversely oval, or rather reniform, being broad- ly emarginate at the terminal margin. The abdomen of the female is broadly oval, and has a broad tuberculated carina, which is also the case with that of the male. The body and limbs are partially covered with a villous coat. The dimensions of a fine male are as follows : In. Lines. Length of the carapace. : : . 3 6 Breadth of do. . : : : 2 6 Length of the anterior legs : ; a 3 3 “This species,” says Dr. Leach, “is very common on the coasts of Scotland and Kent. On the shores of Devon- shire it is of rare occurrence.” I have received it from HYAS ARANEUS. 33 Worthing in Sussex, and from the coast of North Wales, through the kindness, respectively, of my friends Mr. Dick- son and Mr. Kyton. I have obtained it at Hastings, where it occurs in considerable abundance ; and dredged it on oyster-beds at Sandgate, of large size, at from ten to twelve fathoms. The following particulars respecting the occurrence of this species on different parts of the coast of Ireland, are very imteresting, and are taken from the Catalogue of Irish Crustacea, by my friend Mr. W. Thompson. ‘““Mr. Templeton has noticed this species as taken at Carrickfergus ; and native specimens are in Mr. J. V. Thompson’s collection. It has been obtained at Youghall and Dublin by Mr. R. Ball. We take it by dredging in the loughs of Strangford and Belfast, where, too, it is com- monly thrown ashore. In the estuary, at little more than half a mile from Belfast, a number of large specimens of this crab were captured in the month of October 1839, on the hooks attached to hand lines, much to the surprise of the fishermen, who had never met with them so near the town before, or in brackish water. The lug-worm (Lum- bricus marinus,) was the bait attacked in this instance by the crabs. Hyas araneus was taken in the dredge at Bun- doran, on the western coast, by our party in July 1840, and very small living specimens were found under stones, between tide-marks at Lahinch, on the coast of Clare. In Mr. Hyndman’s cabinet are two crabs of this species, with oysters attached to their backs. The oyster (Ostrea edulis,) on the larger crab is three mches in length, and five or six years old, and is covered with many large Balani. The ‘shell, or carapace of the crab is but two inches and a quarter in length, and hence it must, A tlas- like, have borne a world of weight upon its shoulders. D 34 MAIADA. The presence of this oyster affords interesting evidence that the Hyas lived several years after attaining its full growth. Both crabs and oysters, though dead, were brought to Mr. Hyndman in a fresh state. The hairs on the body and legs of specimens in my collection are longer in the small than in the large individual. On the north-east coast of Ireland, the H. araneus is very much preyed on by the codfish. “In January 1840, I saw specimens of this crab of very large size on the coast near Edinburgh; the carapace of one which I measured was three inches in length, and the extent from the extremities of the first pair of legs eleven inches.” Mr. Hailstone states that this crab spawns in February ; this, however, cannot be universally the case, as I took several females at Sandgate early in May, in the year 1845, every one of which was carrying her load of spawn, which is of a rich deep orange colour. HYAS COARCTATUS. 35 DECAPODA. MATIADE, BRACHYURA. Hyas coarctatus. Leach. Specific character.—Carapace distinctly contracted immediately behind the post- orbitar process. yas coarctatus, Leacu, Trans. Linn. Soc. XI, p. 8329. Id. Malac. Brit. t. xxi. B. Epw. Hist. Crust. I. p. 312. Coucu, Cornish Fauna, p. 66. Turs is a small and elegant species, differing so much in the contour of the shell from Hyas araneus, as to be dis- tinguished at a glance from that species, although agreeing with it in almost all the essential characters. The carapace is very broad anteriorly, and suddenly contracted at the sides, both of which characters arise from the extraordinary breadth of the post-orbitar processes, which are half lyre- shaped and lamelliform. The rostrum is bifid, triangular, and each lacinia has a series of minute tubercles along the middle. The whole carapace is tuberculated. The an- tenn, the eyes, the orbits, and the pedipalps, are very Die 36 MAIADAR. similar to those of the former species. The first pair of legs in the male are fully half as long again as the body ; those of the female, which are slender, about the length of the body; the arms, wrists, and hands are tuberculo- carinated. The remaining legs are slender, shorter and smaller in proportion, than in H. araneus; the third joint with a line of small tubercles above. The abdomen re- sembles in each sex that of the former species. The colour of the carapace and legs above is reddish-white, the tu- bercles a beautiful pink or rose-colour; the under parts dirty white. The dimensions of a fine male taken at Sand- gate by myself, are as follows : In. Lines. Length of Carapace : F é 1 3 Breadth of do. : 5 . 5 9 Length of first pair of legs . : : 1 9 It is remarkable that in Dr. Leach’s plate of this species, the figure of the male is very much smaller than that of the female. In the specimens which I have taken, the contrary has been generally the rule, and the males have been much larger than those figured by him. This species was discovered by Dr. Leach in the Frith of Forth, and afterwards found by him on the southern coast of Devon. I procured it at Hastings. Mr. Eyton sent it to me from the coast of North Wales; Mr. Couch from Cornwall, and Mr. Dixon from Worthing. Dr. Leach mentions Sandgate as a particular habitat, where I also obtained several specimens by dredging, in May. I have received it through the kindness of Mrs. Tate from Zetland, and from Orkney by Dr. Pollexfen and Dr. Du- guid. As an Irish species, it has occurred at Youghall, in Dalkey Sound near Dublin ; in the loughs of Strangford and Belfast, and at the Giant's Causeway. “ Thus,’* says HYAS COARCTATUS. Si Mr. Thompson, “from the North to the South of Ireland this species prevails.” This extensive range authorises me to consider it as even more generally distributed on our coasts than H. araneus. In the young state it is very difficult to distinguish the two species, as the former has, in its early age, the spreading form of the post-orbitar pro- cesses which distinguishes the present species in its perfect adult condition, and which is gradually lost by the other. It is said by Mr. Hailstone to spawn in January. Amongst those which I obtained at Sandgate in the month of May, were several females, all without spawn. Mr. Hailstone described in the eighth volume of Lou- don’s Magazine of Natural History, what he considered to be a distinct species, under the name of Hyas serratus. There can be no doubt that these were very young speci- mens of the present species, as was suggested by Mr. Westwood in some observations on Mr. Hailstone’s com- munication. There were three specimens, which Mr. H. states were all males; but as the largest was only a quar- ter of an inch long, it would be impossible at so early a period to distinguish the male from the female by the abdomen. DECAPODA. MATIADE. BRACHYURA. GENUS MAIA, Lam. CANCER, Herbst. INACHUS, Fabr. Mata, Lam. Leach, Edwards. Generic character—External antenncee with the basal portion very broad, forming a considerable part of the inferior boundary of the orbit, fwmnished with two strong spines, the outer one directed outwards and forwards, the inner curved downwards ; the move- able portion inserted at the outer and upper angle of the basal por- tion, where it fills the inner canthus of the orbit. Internal an- tennee placed in triangular fossee, between the anterior extremity of which is a strong spine, exactly similar to the inferior spine of the basal joint of the external antennz and ranging with them. Eyes not thicker than their peduncles, which are elongated and slightly curved. Orbits deep, oval; their upper boundary, which is arched, having two fissures. Casapace ovate-subtriangular, convex, cover- ed with numerous spines or tubercles. Rostrwm very strong, bifur- cate, the horns somewhat divaricate. Anterior legs elongated, thicker than the others in the adult male, but much smaller in younger age, and in the female; the hands and wnists long, the fingers tapering and pointed, and scarcely toothed. Legs of the remaining pairs elongate, cylindrical, the terminal joint naked at the extremity, and without spines beneath. Abdomen seven- jointed in both sexes. SPINOUS SPIDER-CRAB. 39 DECAPODA. MATADE. BRACHYURA. SPINOUS SPIDER-CRAB. CORWICH. Maia squinado. Specific character.—Carapace conyex, covered with sharp spines. Cancer Squinado, Hersst, I. t. xiv. f. 84-85, (jun.) Id. III. t. lvi. (adult. ) » Maia, Sowers. Brit. Misc. t. xxxix. Maia Squinado, Later. Hist. Nat. des Crust. VI. p. 93. Bosc, Hist. Nat. des Crust. I. p. 257. Luacu, Trans. Linn. Soe, XI. p. 326. Id. Malac. Brit. t. xviii Epw. Hist. Crust. I. p. 327. Tue carapace of this species of Maia is considerably con- vex, of an ovoid form, but becoming more triangular in adult age, by the increased narrowing of its anterior por- tion. The rostrum is strong and prominent, its two horns 40 MATADA. somewhat diverging, so as to leave a triangular space be- tween them. The orbit has a strong spine above its outer angle, and a smaller one at the base of the former; its superior boundary is arched and rounded. The lateral margin has five or six very strong sharp spines, the an- terior of which bounds the outer angle of the orbit. The upper surface of the carapace is covered with innumerable spines and tubercles. The under surface of the anterior portion is furnished with five strong spines, two on each side on the basal joint of the external antenne, the outer one directed forwards and outwards, the other curved downwards, and a single one at the root of the rostrum, likewise curved downwards. The second and third joints of the antenne of nearly equal length, and inserted at the outer angle of the basal joint. Anterior pair of legs in the adult male nearly twice as long as the carapace, much larger than the succeeding ones; the arm and wrist tuberculated ; the hand scabrous; the fingers very taper, pointed, the moveable one slightly curved, scarcely denticulated. The remaining legs cylindrical, without spines or tubercles; the second pair nearly half as long again as the carapace, the rest diminishing regularly to the fifth; the last jomt very slightly curved, its extremity naked, abruptly smaller, and pointed. The abdomen is in each sex seven-jomted. In the male, the second joint is very narrow at the insertion of the last pair of legs, the anterior part of it becoming abruptly much wider; the sides of the remainder are nearly parallel, becommg, however, a little narrower, and the terminal margin is rounded. It has a broad carina occupying one-third of its breadth. In the female it is oval. There are few species of Crustacea in the form of which age produces so great a change as in this. The younger in- SPINOUS SPIDER-CRAB. 41 dividuals not only exhibit the more slender and shorter dimensions of the anterior legs, but the anterior part of the carapace is much broader in proportion ; a character which permanently belongs to the Mediterranean species, J/. ver- rUucosa. Pennant’s figure of what he terms Cancer maia, belongs to Lithodes arctica, and it is very probable that he, as well as others, has confounded these two species, before the true characters of Crustacea were understood, and indeed before naturalists in general were aware of the value of specific characters. There is a species found in the Mediterranean very nearly allied to this, and which has been supposed to in- habit our southern coast. It is the Maia verrucosa of Kdwards already alluded to: it is readily distinguished from this by the absence of spines on the surface, which are replaced by tubercles; by the greater extent and de- velopment of the supra-orbitar arch; by the breadth of the anterior portion of the carapace, which remains to the adult age as broad as in the younger state; and by the depressed form of the carapace. I believe MZ. verrucosa has not been taken on our shores; those found in Cornwall, and considered as such by Mr. Couch, being undoubtedly the present species. This Crab is found in great abundance on almost all parts of our southern and western coast. In Ireland it occurs also on the southern coast. It is by far the largest species of the family, and with the exception of the great Crab, Cancer pagurus, the largest of the British Brachyura. I have a specimen taken in Plymouth Sound, the carapace of which is eight inches m length, and nearly six in breadth, and the length of the anterior feet is fifteen inches. 42 MAIAD®. It is eaten by the poorer classes, though I understand it is but indifferent food. Like all the other triangular Crus- tacea, the fishermen inveterately term it ‘‘ spider ;” and they appear to have very little idea of any affinity between these forms, and the Crabs properly so called. I remem- ber some years since seeing in one of the back streets of Poole, near the water-side, a little girl standing by a small table, on which was a plate contaming two of these Crabs, of moderate size, cooked and for sale. On my accosting her with “‘ Pray do they eat these crabs here?” She re- plied with a look of great surprise at my ignorance, “ They ben’t crabs, sir, them’s spiders !” Mr. Richard Couch informs me that in Cornwall several dozens of “the Corwich” are sold for sixpence, but that they are more frequently given away to those who ask for them. Mr. Couch adds, that he never saw a soft one, or one soon after casting its shell, although they are often taken ‘‘ peel,” or ready to cast it. This, doubtless, arises from the extreme secrecy of their retreats when undergoing this process. The following account, for which I am indebted to the gentleman just mentioned, is very interesting, and it affords another opportunity of confirming the true metamorphosis of the decapodous Crustacea. ‘‘ This is the most abundant of all the Crabs found on our coast, but it does not make its appearance so early in the season as the Common Crab, the Lobster, or indeed any other ; it is rarely found earlier than May, but from that time till the end of the fishery in August or September, these Crabs make thei appear- ance in vast numbers, to the great vexation of the fisher- men; for it is found that from the time these begin to enter the pots, the more valuable kinds considerably de- crease in nuinber ; and this is supposed to arise from their SPINOUS SPIDER-CRAB. 43 restless activity. No sooner are they in the crab-pot, than they are continually in motion, scrambling from one part to another, and in this way frighten the Crab and Lobster, and prevent them from entering. In the spring and early part of the summer they lie concealed beneath the sand, in deep water. About May they leave their places of con- cealment, but never come into shallow water, as does the common crab; the latter is often found in crevices of rock, or beneath stones left by the receding tide; but this is never the case with the Corwich. They shed their spawn about August or September, at some short distance from the shore, most probably in the sands. In this, too, they differ from the Common Crab, for even when the spawn is quite mature for “casting,” they enter the pots as readily as at any other time; whilst on the other hand it is a very rare occurrence to catch the Common Crab with spawn, unless it be with a dredge-net. It would seem either that they grow very fast, or that the young differ considerably in their habits from the larger ones; for whilst it is very common to find specimens measuring nine or ten inches in the length of the carapace, it is very rare indeed to get one less than three inches; and a fisherman tells me that after many years fishing he caught one about the size of a half- crown, which was the smallest he ever saw. “'The ova, when quite ready for shedding, (fig. 1,) are about the size of a very small mustard-seed, and of a reddish-brown colour, besprinkled with small dark spots. After keeping them suspended in sea-water for twenty-four hours, some of the ova dropped from their attachments, and soon after the young escaped, and this evidently by their own exertions, as distinct motions were easily ob- servable under the microscope while they were yet en- closed. When they first escape, they are, as it were, rolled 44, MAIAD A. on themselves, (fig. 2,) the caudal extremity being bent on the body; but this is soon changed for the position re- presented in fig. 3. I could detect no spine on the anterior part of the carapace, which was quite smooth, but marked with dots. The eyes are sessile and large; the claws, particularly towards the extremity, covered with minute hairs.” These interesting observations of Mr. Richard Couch af- ford a fresh confirmation of the truth of the metamorphosis of the brachyurous Crustacea, and it is to be hoped that whenever an opportunity occurs to any observer to pre- serve and examine the embryo, and the subsequent pro- gress towards the perfect state of any other species, similar notes may be made, and thus we shall hereafter arrive at a knowledge of this curious process in most of our native species. An ordinary sized Corwich, as Mr. Couch informs me, bears at one time upwards of seventy-six thousand eggs. JF S a) 0 < thecal fi" ce of Ee RC, DECAPODA. PARTHENOPID EE. BRACHYURA. GENUS EURYNOME, Leacu. CANCER, Pennant. EURYNOME, Leach, Risso, Edwards. Generic character.—External antennee scarcely longer than the rostrum ; the basal joint triangular, and perfectly united to the surrounding parts ; the second inserted at its apex, at the inner canthus of the orbit, and beneath the rostrum ; second joint larger, but shorter than the third. External pedipalps with the third joint dilated at the outer and emarginate at the inner angle. dzn- terior pair of legs in the male, larger and much longer than the succeeding ones ; hands long, linear; fingers inflected. The second to the fifth pairs of legs linear, diminishing regularly in length. Carapace irregularly rhomboidal, produced anteriorly, and much rounded behind, verrucose. Rostrwm bifid, the lacinize triangular, flattened, slightly divaricate. Orbits deep, above strongly arched, with a single fissure near the external angle. yes retractile, globular, larger than the peduncles, which are short. Abdomen seven-jointed in both sexes. This genus is the only British representative of a highly interesting and curious, as well as natural family, agreeing nearly with the genus Parthenope of Fabricius, and com- prising a number of bizarre forms, which have for the most part very long arms and rough, rocky-looking bodies. They form upon the whole, as Milne Edwards has observed, a passage from the triangular families, to the more typical Cancerip#; and, like many other small osculant or inter- mediate groups, exhibit many diverse and somewhat isolat- ed forms. Of these the present genus, Murynome, may be considered as the most nearly related to the Marana, with which family it agrees in the union of the basal joint of the external antennee with the parts surrounding it, as well as in the general form of the body. 46 PARTHENOPID Ab. DECAPODA. PARTHENOPID. BRACHYURA. Eurynome aspera. each. Specific character.—Rostrum less than one fourth the total length of the body. Carapace covered with numerous small warty tubercles, regularly disposed. Cancer asper, PENNANT, Brit. Zool. IV. t. x. f. 3. p. 13. Eurynome aspera, Leacu, Malac. Brit. t. xvii. Epw. Hist. Crust. I. p. Bolle as spinosa, Hatisrone in Mag. Nat. Hist. VIII. p-. 549. Tue carapace of this very pretty crab is irregularly rhom- boidal, the anterior triangle being longer than the posterior, which latter is somewhat rounded; the rostrum is less than one-fourth the whole length of the carapace, bifurcate, the lacinix somewhat divergent, acute, and flattened. There is a large triangular laminar tooth at the outer angle of the orbit, and there are three smaller ones at the lateral mar- gin of the branchial region. The carapace is covered with numerous small, round, warty tubercles, which, on a close examination, are found to be distributed with perfect regu- larity. The most conspicuous of these are two on each EURYNOME ASPERA. 47 branchial region, and one on the centre of the cardiac. The latter, which is smooth and polished, is surrounded by ten others, which are warty, arranged in an oval form, five on each side. The external antenne are not longer than the rostrum. The basal joint, as in the Maiade, is sol- dered to the surrounding parts; in which respect it differs from that of some other genera of the family in which it is detached ; it is triangular, and the moveable portion is inserted at its apex, and does not extend beyond the ros- trum. The second and third joints are oval, and nearly equal. The external pedipalps have the second joint oblong-quadrate ; the third has the outer angle produced, and the inner angle truncate and emarginate. The an- terior legs in the male are nearly twice as long as the body, and much larger than the succeeding ones, the arms and hands long, the wrists short, the fingers long and inflected. In the female they are but little larger, and scarcely longer than the second pair. The whole are covered with tubercles. The abdomen in the male is tubercu- lated and carinated; the terminal joint triangular. In the female it is oval, carmated, and the margin broadly ciliated. The length of a very fine male specimen is about nine lines, and its breadth seven lines. Its colour is a light rose, intermixed with a slight tint of blueish-grey. The Hurynome aspera, which is one of the rarer of the British Crustacea, inhabits deep water, having been dredged in seventy fathoms. It has been taken by dredging, or by the trawl on the coasts of Cornwall, Devonshire, Dorsetshire, and Sussex. I find by my own notes that I took a speci- men in Swanage Bay, in Dorsetshire, some years since, but it has been lost. It has also been dredged off the Isle of Man, and in Loch Fyne, by Mr. McAndrew, to whom I 48 PARTHENOPID-%. am indebted for specimens from both localities. I have been favoured with another specimen, also a female, and loaded with spawn, by Mrs. Griffiths, who took it at Tor- quay. I cannot doubt that Lu. spinosa of Mr. Hailstone, described in the eighth volume of the Magazine of Natural History, is the young of the present species ; it was taken at Hastings “in a mass of Pilipora filigrana.” The following account of its occurrence as an Irish spe- cies, is taken from Mr. W. Thompson’s Catalogue of the Crustacea of Ireland. ‘* Marked as Irish in Mr. J. V. Thompson’s collection. It is rather a rare species, and an inhabitant of deep water.” In Strangford Lough several specimens were taken by Mr. Thompson and Mr. Hynd- man. It has occurred in Belfast Bay, on the Dublin coast, and at Roundstone on the western coast. It was obtained also by Captain Beechey off the Mull of Galloway, at seventy fathoms. It is found on the coast of France, from whence I have received specimens through the kindness of my friend Dr. Milne Edwards. Being found only in deep water, but little is known of its habits. The eggs are of a beautiful orange colour; they are deposited in June, or the early part of July, as I have a female specimen taken at the latter end of June, in which the eggs are so fully developed, that the embryo can be seen through the investing membranes. When Dr. Leach established this genus, the present was the only species known. Risso has, however, since that, described another species, to which he gave the name Hw. scutellata,* but so imperfect is the description, that Dr. Milne Edwards found it impossible to judge, with any degree of certainty, whether it belonged to this genus or not; and if so, whether it might not be identical with the present. I * Risso, Hist. Nat. de Eur. Merid., IV. p. 21. EURYNOME ASPERA. 49 possess, however, a pair of this beautiful little species from the Bay of Naples, and find it to be very distinct from ours in several points, yet bearing a near affinity to it. As a sufficient distinctive character of it has not yet been given, for that of Risso is altogether useless, I thought it desirable to notice it on the present occasion. It differs from the English species by its longer rostrum, which equals one- third of the total length, and by the absence of the scat- tered tubercles by which that is distinguished, instead of which there are several broad, flat, shield-like elevations. Risso had not seen the female, of which sex I have a specimen loaded with eggs of a deep amber colour. My friend Professor Forbes dredged Hw. aspera at a depth of thirty fathoms off the Isle of Man, and at seventy fathoms in the A®gean. This evidently shows that the genus belongs to deep water, an observation which holds good of all the family of the Parthenopide. DECAPODA, CANCERID. BRACHYURA, GENUS XANTHO, Leacn. CANCER, Montagu, Herbst. XANTHO, Leach, Edwards. Generic Character.—External antenne very short, the basal joint longer than it is broad, in contact with the front only at its anterior internal angle; the moveable portion inserted at the inner canthus of the orbit ; the second joint considerably larger than the succeeding ones. Internal antenne placed obliquely immediately under the front. LHaternal pedipalps with the third joint quad- rate, the inner anterior angle truncate and slightly emarginate. Carapace very broad, slightly convex from before backwards ; the latero-anterior margins with the front forming a semi-ellipsis ; the latero-posterior margin nearly straight ; front projecting, divided by a slight fissure ; orbits, with a fissure beneath, at the external angle. Anterior legs very large, nearly equal, the fingers pointed. The posterior pairs short, compressed; the terminal joint very short. Abdomen, in the male, five-jointed ; in the female, seven- jointed. XANTHO FLORIDA. 5l DECAPODA. CANCERID, BRACHYURA, Nantho florida. Leach. Specific character.—Carapace deflexed anteriorly ; latero-anterior margin with four strong obtusely triangular teeth ; fingers black, without grooves ; the second to the fifth pairs of legs with the third joint only ciliated on the upper edge. Cancer floridus, Montagu, Trans. Linn. Soc. IX. t. ii. f. 1. p. 85. + ncisus, Leacu, Edinb. Encycl. VII. p. 391. Xantho incisa, Id. 1. c. p. 480. » florida, Id. Trans. Linn. Soc. XI. p. 320. Malac. Brit. t. xi. » floridus, Epwarps, Hist. Crust. I. p, 394. Tue carapace of Vantho florida is about two-thirds as long as it is broad; the anterior portion somewhat de- flexed; the latero-anterior margin with four strong ob- tusely triangular teeth, and reaching nearly as far back as E 2 52 CANCERID2&. the anterior part of the cardiac region. The surface of the anterior portion has several broad flattened elevations, which are separated by grooves, the principal of which are continuous with the intervals between the lateral teeth ; the posterior portion nearly smooth. The front is very slightly waved, and sub-emarginate. Orbit with a fissure at the inner angle beneath. The anterior legs very large and strong; the wrist with a double tubercle above ; the hand rugous, the fingers without grooves. The remaining legs short, slightly compressed, the third joint only hairy on the upper edge, the fourth and fifth joints grooved. Abdomen in the male five jointed, in the female seven jointed ; oval, ciliated with long hairs. The colour of this species is a reddish brown, the claws black. The male is much larger than the female, and his claws are very large in proportion to the size of the body. » lividus, Leacu, Malac. Brit. pl. ix. figs. 3. 4. Ir is extremely difficult to assign any very satisfac- tory distinctive character to this species. Its great resem- blance to P. marmoreus,—at least to all the specimens which I have in my possession, fully justify the belief 110 PORTUNIDA. that they may be merely varieties; although there are certain comparative characters which, as they are pretty constant, render it necessary that further investigations should be made before their identity can be fully es- tablished. Then the whole contour of the animal is more strongly marked in the present species; the mar- ginal teeth are more prominent; the margins of the orbit more distinctly granulated; the latero-posterior mar- gin much more contracted and more deeply emarginate at the angles; the outer carina of the hand, more strongly denticulate; and the terminal joint of the posterior feet rounder and broader in proportion to its length. In other respects the similarity is so great in the form of all the parts, as fully to justify Dr. Milne Edwards’s remark of their “extreme resemblance.” It is matter of surprise that Dr. Leach should not have observed this close relation of these two species; but that he should, on the contrary, have stated that P. lividus |[holsatus|] most nearly resembles P. depurator, a species from which, in fact, it differs most ob- viously. It is remarkable that the specimens of P. mar- moreus in the British Museum, which were collected by Dr. Leach, differ much more from holsatus, than those which I have myself procured ; the hand having in all those unarmed carine, and the upper margin of the orbit without granula- tions. The figures in Dr. Leach’s beautiful work, also magnify the distinctions far beyond the truth. The occurrence of this Crab is extremely rare on our coasts; Dr. Leach mentions his having found a single spe- cimen amongst a number of P. depurator that were taken in the Frith of Forth at Newhaven, and that he observed another in the collection of Montagu; but there is a fine series in the British collection of the British Museum, which must have been procured after the ‘ Malacostraca LIVID SWIMMING-CRAB. aL Britanniz” was published. It is not mentioned by Mr. H. Goodsir as occurring within his notice on the Scottish coast; nor does Mr. Couch give any account of its oc- currence in Cornwall. In Ireland, however, according to Mr. W. Thompson’s statement, it has occurred repeatedly ; but as it appears to me that faded specimens of P. marmoreus might be easily mistaken for this species, it is always desirable that they should be compared with those well distinguished specimens which exist in the British Museum. The followmg is Mr. Thompson’s notice to which I have referred. ‘‘ Templeton mentions it as found by him ‘on the shore at Dunfanaghy. We have dredged it on more than one occasion in Belfast Bay, and have obtained it on the beach of Carnlough, county of Antrim. In Mr. R. Ball’s collection, are several specimens which were dredged in Dublin Bay.” It is mentioned by Milne Edwards as occurring on the French coast. 1 BY PORTUNID®. DECAPODA. PORTUNID. BRACHYURA. DWARF SWIMMING-CRAB. Portunus pusillus. Specific character.—Carapace considerably raised, rugose ; front three-lobed, much advanced ; latero-anterior margin with five teeth. Portunus pusillus, Leacu, Malac. Brit. t. ix. f. 5—8. Epwarps, Nat. Hist. Crust. I. p. 444. = maculatus, Risso, Hist. Nat. Eu. Mérid. v. p. 5. Roux, Crust. Mediter. t. xxxi. Tue carapace of this species is broader than it is long, considerably elevated, and with the regions remarkably distinct ; the surface is rugose, and irregularly granulated. The front is advanced much beyond the orbits, flattened, and three-lobed, the middle lobe being longer than the others: the latero-anterior margin has five teeth, (including the outer angle of the orbit,) of which the posterior one is the most acute, and the most curved. The posterior margin is almost straight. The first pair of legs are large and robust ; the wrist is armed with a very strong spine on the imner and anterior angle; the hand has a double DWARF SWIMMING-CRAB. Nels carina above; the fingers are strongly tuberculated, and the moveable one has a shallow longitudinal groove on the upper and outer margin. The second, third, and fourth pairs are slightly compressed and grooved. The fifth pair has the penultimate joint grooved, and the terminal joint is oval; they are both ciliated all round. The abdomen in the male is broadest at the base of the third joint, the remainder forming a regular acute angled triangle; that of the female is ovate-lanceolate and ciliated at the margin. The colour is reddish-brown, often with red spots on the back. In some specimens the colour is lighter, bemg of a pale red with darker spots. The legs are usually annulated with similar colours. This very pretty species was first described by Dr. Leach in the eleventh volume of the Transactions of the Linnean Society, under its present name. Subsequently to this, Risso described it in his Natural History of South- ern Europe, giving it the name of P. maculatus, which Roux very improperly retained m his Crustacés de la Méditerranée, notwithstanding he was aware of the pri- ority of Leach’s name. It mhabits deep water, and is common on the coast of Devonshire and Cornwall; it occurs all along the southern coast, and is also found in the Frith of Forth, and I have specimens taken by Mr. McAndrew off the Isle of Man. On its oc- currence as an Irish species, Mr. Thompson has the fol- lowing remarks, ‘‘ It is ordinarily taken by us when dredg- ing in the loughs of Strangford and Belfast. At the Killeries in Connemara, it has similarly occurred, as well as in Dublin Bay. In the South, too, it has been taken in the harbour of Cove. I have several times taken it in the stomach of fishes; in one instance, in a 7 rigla I 114 PORTUNIDA. Gurnardus, taken in the open sea off Dover.” It is found also in the Mediterranean, and off the coast of France. It spawns in June, and the eggs are of a reddish orange colour. Its ordinary size is about four lines in length; this is the size of the figures of Roux, and of those of Leach ; but it occasionally grows much larger, as one of the specimens, a male, taken by Mr. Me Andrew off the Isle of Man, is fully an inch in breadth, by eight-tenths in length. DECAPODA. PORTUNIDE. BRACHYURA, GENUS POLYBIUS. Weacu. PoLyBIvs. Leach, Edwards. PLaTyONIcHus. Latr. Generic character. — External antennce with the basal joint round, detached, moveable, with the remaining portion lodged in a hiatus at the inner canthus of the orbit, which it does not fill. Internal antennce in fossee, which are entirely open forwards. Eyes larger than their peduncles, which are short. E2ternal pedipalps with the third joint subquadrate, longer than broad, and slightly notched at its inner margin, near the anterior angle. Carapace nearly orbicular, slightly contracted posteriorly. An- terior pair of legs equal, the pincers curved. Second, third, and fourth pairs compressed, the terminal joint flattened, thin, broad, and lanceolate. The fifth pair with the penultimate jot much flattened ; the terminal one very large, oval, foliaceous. Cara- pace much depressed, the anterior margin semicircular. Orbits with two fissures in the superior, and one in the inferior margin ; a hiatus at the inner angle, and a small tooth at the outer. Abdomen of the male, five-jointed, the first, second, and third joints very short and broad, and transversely carinated ; of the female, seven-jointed, the sides nearly parallel as far as the middle of the sixth joint. The structure of this genus, of which a single species only is known, is of a more decidedly natatory character than any other brachyurous form found on our shores. It is on this account that it has been with great propriety con- sidered as generically distinct from Portwmnus, with which, however, it stands in very near relation. 116 PORTUNIDA. DECAPODA. PORTUNID. BRACHYURA. HENSLOW’S SWIMMING-CRAB. Polybius Henslowii. Leach. Polybius Henslowti, | Leacu, Malac. Brit. t. ix. B. Epwarps. Crust. I. p. 439. Tuts species, the only one of the genus at present known, exhibits the natatory structure to the greatest ex- tent of any of the British examples of this family. The carapace is remarkably flat, even in the female, and the regions are very indistinctly marked ; it is all over minutely granulated. Its form is nearly orbicular ; the latero-anterior margins, with the orbits and front, forming a semicircle, and the latero-posterior margins being but little contracted : the front is flat, and has five teeth, the external of which on each side belongs to the orbit: the latero-anterior margin has five flat teeth, the points directed somewhat forwards. HENSLOW’S SWIMMING-CRAB. 11 if The first pair of legs are nearly equal: the wrist has two sharp teeth on the anterior margin, of which the inner is much the more prominent, and a third tooth is found at the outer and anterior angle, which forms the commencement of a carina, which extends the whole length of the wrist. The hand is compressed, and has three low but sharp longitudinal carine, the spaces between them being slightly hollowed: the fingers are much compressed, somewhat incurved, as long as the hand. The three fol- lowing pairs are much compressed, particularly the last two joints; the terminal one being very thin and _ lan- ceolate. The last four joints are ciliated on the inferior margin. The fifth pair have the last two joints very broad and flat; the penultimate being irregularly quadrate, and the terminal one broadly oval, slightly acuminated at the apex. The abdomen in the male consists of five joints, of which the first, second, and the base of the third are transversely carinated ; the third joint is broadest at the base, and becomes moderately contracted with a_ slight notch ; the fifth is rather acutely triangular. In the fe- male, the abdomen is seven-jointed; the first three joints transversely carinated ; the fifth joint suddenly smaller than the preceding one, and obtusely triangular. The colour is a rich reddish-brown, which becomes a pale salmon-colour in drying. The under parts are pale. Of this species, which is very local in its distribution, and probably nowhere existing in great numbers, there is a specimen in the Banksian collection in the Linnean Society, which was taken on the coast of Spain. It was first disco- vered on our shores by Professor Henslow in a herring-net, on the north coast of Devon, in 1817, and by him com- municated to Dr. Leach, who named the species after its discoverer, assigning to it also a new generic appellation. It was afterwards found by Mr. Prideaux on the south- 118 PORTUNID ©. western coast of Devon; also in herring-nets on the Dorset- shire coast, amongst the refuse of the nets of fishermen, by the late Rev. Dr. Goodall. I have also obtained it at Hastings, and received it, by the kindness of Mr. Couch, from Cornwall, and by my friend Mr. Dixon, from Worthing. The following observations on the habits of this species are from the Cornish Fauna of Mr. Couch; and as this gentleman appears to be the only one who has ever ob- served its habits, I make no apology for quoting his ac- count entire. “This is, more than any others, a swimming- crab; for whilst the other British species of this family are only able to shoot themselves from one low prominence to another, the Nipper Crab, as our fishermen term it, mounts to the surface over the deepest water, in pursuit of its prey ; among which are numbered the most active fishes, as the Mackerel and the running Pollock; the skin of which it pierces with its sharp pincers, keeping its hold until its terrified victim becomes exhausted. We are witnesses of this curious method of obtaining food in the summer only, at which time the fishermen’s nets intercept them and their prey together; and it is probable, that in colder weather, they keep at the bottom in deep water, from which, however, I have never seen them brought in the stomachs of fishes. So faras my observation extends, it is chiefly or only the male that pursues this actively preda- ceous existence; but that for a time they also remain quiet, as appears from the fact that while for the most part the smooth and flattened carapace is clean, I have seen it covered with small corallines.” * This interesting narrative is perfectly consistent with the remarkable natatory structure of the species, evinced in the form of the carapace and the structure of the legs, and with the sharpness and strength of the claws. * Couch’s Cornish Fauna, p. 71. DECAPODA. PINNOTHERID&, BRACHYURA. GENUS PINNOTHERES, Larr. CANCER, Linn, Fabr. Herbst, Penn. PINNOTHERES, Latr. Leach, Edwards. Generic character.—External antenne very short, occupying the inner canthus of the orbit. External pedipalps oblique ; the se- cond articulation rudimentary, the third large, and forming the whole valvular portion; the fourth inserted at the extremity of the previous one; and the fifth giving attachment to the sixth at the middle of its anterior margin, resembling the thumb of a didactyle hand. Anterior legs equal, the remaining pairs some- what compressed ; the terminal joint acute, curved, and strong. Eyes inserted on very short peduncles, distant. Orbits nearly circular. Carapace nearly circular, rounded at the anterior mar- gin. Front not united to the epistome. Addomen seven-jointed in both sexes; that of the male small, of the female extremely broad, round, and prominent. Tue species of this genus are very remarkable from the peculiarity of their being indebted to animals of a very different class for protection, although not truly parasitic. They are found always to inhabit the shells of the Bivalve Mollusca, principally of the genera Mytilus, Modiolus, and Pinna, and occasionally also of Ostrea, Cardium, and other genera; and this habit, which was well known to the ancients, gave rise to some interesting and curious hypo- theses and fables, which will be alluded to hereafter. The males are always very much smaller than the females, and 120 PINNOTHERID-E. the crust of the former is as hard as in other brachyurous forms ; but the female is comparatively very large, almost globular, and remarkably soft ; the latter character being doubtless the cause of its requiring the efficient protection of the shells of Mollusca. In other allied forms a some- what analogous habit is observed; the soft body of Hla- mene and Hymenosoma demanding extrinsic protection, which they obtain by appropriating to themselves small single shells of dead acephalous Mollusca, as I have my- self seen in several instances,—a fact which affords a col- lateral argument in favour of Milne Edwards’s association of these different genera in one family. The species of the present genus even yet require careful revision ; and I have found it necessary to comprehend the whole of Dr. Leach’s six species in two,—which, how- ever, I have not done without the most deliberate con- sideration. COMMON PEA-CRAB. 121 DECAPODA. PINNOTHERID&. BRACHYURA. 1 Pinnotheres Latreillii, Leach. 2 Pinnotheres varians. Leach. 3 Pinnotheres Pisum. Leach. 4 Pinnotheres Cranchii. Leach. COMMON PEA-CRAB. Pinnotheres Pisum. Specific character.—Front of the male projecting ; carapace of the female uni- formly rounded at the anterior margin ; abdomen in the latter sex broader than it is long. Cancer Pisum, PENNANT, Brit. Zool. IV. t. i. f. i. p. i. Heresr, I. p. 95, t. 2,f.21. Fasr. Suppl. Ent. 343. Pinnotheres Pisum, Latr. Hist. Nat. des Crust. VI. p. 83. Leacu, Mal. Brit. t. xiv. f. 2, 3, (fem.)° Epwarps, Hist. Nat. des Crust. II. p. 31. » Cranchii, Leracug, |. ¢. fig. 4, 5, (fem.) » Latreillii, Leach, l. c. f. 6, 7, 8, (mas immat. ?) 3 «varians, Lracu, l.c. f. 9, 10, 11. (mas.) Tne sexes in all the species of this genus differ so re- markably, that a separate description is necessary. Mate. (Figs. 1 and 2.) The carapace is nearly orbicu- J At 129 PINNOTHERID®. lar, very slightly narrowed forwards, convex, glabrous, and solid; the front projecting, arched, and entire; the latero- posterior margin slightly hollowed. The eyes small, round, and filling the orbits. Sternum large and orbicular, An- terior feet robust, the hands large, ovate, with two lines of hairs beneath; the fingers much enrved, the moveable one with a single tooth. The remaining pairs of legs fringed with hair both above and below, terminating in a hooked claw. The abdomen is broadest at the third joint, be- comes narrower from this to the fifth, the sixth is a very little broader, and the last abruptly narrower. Femate. (Figs. 3 and 4.) The carapace in this sex is nearly orbicular, rather broader than it is long, without any projecting front, or hollows at the latero-posterior margin, soft and glabrous. The hands are oblong, weak, and fur- nished beneath with a single line of hairs. The remaining legs slender, the thighs fringed with a line of hairs on the upper side only. Abdomen very large, broader than it 1s long, almost evenly rounded. The colour of the male varies; it is usually of a pale yellowish grey, with rather darker symmetrical markings. The female is ordinarily slightly transparent, brown above, a yellow spot over the front, and an iregular one on each branchial region; the abdomen yellow, with a central large triangular brown spot extending from the base nearly to the extremity. In accordance with the opinion of Mr. W. Thompson, I cannot but believe that the individual figured by Leach under the name of P. Latreillii, which he considered as an immature female, in which he is followed by Milne Ed- wards, is in fact a young male. The form and apparent consistence of the carapace, the form of the hands, and the colour, are all in favour of such an opinion. The form a COMMON PEA-CRAB. 28 of the abdomen is not at all at variance with it, as in many species this part is very similar in the young of the two sexes. It is very remarkable that Leach should have failed to detect the male and female of this very common species as being specifically identical. They are frequently found together, and yet he describes the female as one species, P. Pisum, avowing his ignorance of the male, and the male as another, P. varians, acknowledging himself similarly unacquainted with the female, “unless she be P. Pisum.” After a careful examination of the subject, I have come to the conclusion that the first four species of Leach are all to be referred to one; an opinion in conformation with that of Dr. Edwards. This species of Pinnotheres is very commonly found in the common mussel, M/ytilus edulis, on many parts of our coast ; and especially in those which are found in rather deep water. On one occasion I dredged great numbers of these Mollusca on the coast of Dorset, and found by far the greater number of them with one or two of these little soft-bodied crabs within their shells ; for the females are much more common than the males. The latter sex I have occasionally taken apart from the mussel- shells, the former never. They also inhabit the shells of Modiolus vulgaris, and occasionally also the common cockle, Cardium edule, in which I have now and then found them, as well as very rarely in the oyster, in which Mr. Ball also states that he has taken them. The following account of some circumstances respecting this crab is extracted from my friend Mr. W. Thompson’s observations on the Crus- tacea of Ireland,* and is too interesting to admit of being curtailed. * « Ann. and Mag. Nat. Hist.” vol. x. p. 284. 124 PINNOTHERID-%. “The smallest Pinnotheres I have seen was found by Mr. Hyndman, in a living Cardium exiquum, dredged by us in Strangford Lough in October, 1834. It is a male ; the carapace is under a line in length ; the entire breadth of the crab from the extremities of the outstretched legs is three lines. The cardium is under three lines in length, and barely exceeds that admeasurement in breadth ; so that the crab when in the position just mentioned must have, on both sides, touched the walls of its chosen prison. The Pinnotheres likewise inhabits the Cardium edule. Be- fore me is one of these crabs, of which the carapace is two lines in breadth, obtained by Mr. Hyndman in a full grown C. edule from Strangford Lough; but from the Sligo coast, where this crab attains an extraordinary large size, a crab with a carapace four lines in breadth, and with outstretched legs seven lines across, was once kindly brought to me by Lord Enniskillen. Mr. R. Ball informs me that on two occasions he obtained a great number of the Pinnotheres, and which were all males, from the Cardium edule taken at Youghal,—about nine out of every ten cockles contained a crab. On opening oysters in Tenby, in Wales, he has likewise procured the Pinnotheres. This crab, like the Pagurus, occupies different species of shells according to its size, and at every age generally selects such as with outstretched legs it would fill from side to side.” It is a point of considerable interest as connected with this species, that it formed one of the subjects of Mr. Vaughan Thompson’s investigations on the transformations of Crustacea, and the description with figures of the Zoéa of Pinnotheres as given in a paper by that gentleman in the ‘* Entomological Magazine.”* = Vols isps.ops COMMON PEA-CRAB. 125 “As the females are found with an amazing group of ova under their abdominal plate,” says this author, “in spring, summer, and autumn, it is probable that they have several successive broods. This circumstance renders it no difficult matter to select a number of females with mature ova at any convenient time, and to preserve them alive in sea water for a few days, or until the ova should hatch. “« From several females selected and kept alive after the above manner, I had the satisfaction to see the ova hatch in great numbers, under the form of a new kind of Zoé, differing from all those previously discovered, with the front and lateral spines deflected, so as to resemble a tripod. In this stage the minute animals are all like the Zoea, purely natatory, disperse themselves abroad, probably un- dergo a further change, and may be supposed to gain an easy access within the bivalve shells, before they lose their power of swimming.” I add a copy of Mr. Thompson’s figures of this imterest- ing state of the animal, the accuracy of which I can attest from my own observation. ey, 5) “a Sy KGRSS 126 PINNOTHERID 2. DECAPODA. PINNOTHERID. BRACHYURA. Pinnotheres veterum. Leach. Male and Female. PINNA PEA-CRAB. Pinnotheres veterum. Specific character.— Male. Carapace subquadrate, rounded, the front slightly emarginate. Memale.—Carapace broader than it is long; abdomen broadly ovate, longer than it is broad. Pinnotheres veterum, Bosc, Hist. Nat. des Crust. I. 243. Leacu, Malac. Brit. t. xy. f. 1, 2, 3, 4, 5. Epw. Hist. des Crust. II. p. 32. ~ Pinna, Leacu, Edinb. Encycl. VII. p. 431. V. THomp- son, Ent. Mag. III. p. 89. op Montagui, Lracu, Malac. Brit. t. xv. f. 6. Epw.1.c. p. 32. Tue male of this species has the carapace less solid than P. Pisum, rather broader than it is long, rounded, slightly quadrate, with the front slightly emarginate ; the hands are ovate, with the fingers arched ; the remaining feet very similar to those of P. Pisum. The abdomen gradually and evenly decreasing towards the extremities, the last PINNA PEA-CRAB. i 7 joint evenly rounded, nearly semicircular. In the variety termed P. Montagui by Dr. Leach, this joint is abruptly broader. In the female the carapace is rounded, broader than it is long, very minutely punctulate ; the front trans- verse, slightly arched, scarcely emarginate at the middle. “The anterior feet with a small spine on the inferior ” margin of the hand.” The abdomen is evenly ovate, broadest at the fourth and fifth joints, broadly carinate along the middle, the last joint emarginate. Colour in both sexes almost uniformly brown. This species differs sufficiently from the former, in either sex, to be distinguished at the first glance. Its habits, however, are perfectly similar, as far as we have an oppor- tunity of knowing them, but it is much less common than the other on our coasts. It was first discovered to be an English species by the indefatigable Montagu, who found both sexes in Pinne from the Salcombe Estuary in Devon- shire; and it was subsequently taken by Cranch in the same locality. Vaughan Thompson records its being found on the Trish coast, ‘‘ both in Pinne and in Modioli.” It has not, as far as I am informed, been found on any other part of the English coast but that already mentioned, nor has it yet been taken in Scotland. Its favourite haunt justifies the name which Leach first assigned to it, P. Pinne; although he afterwards very properly adopted the name previously given to it by Bose. It is found in the Pinna ingens, both on our coast and in the Mediterranean ; it has also been taken in Modioli, and in the common oyster. There can be no doubt that it was of this species that the ancients, aware of its peculiar mode of existence, formed such absurd notions. It is not, in- deed, wonderful that with such imperfect ideas of the value and bearing of natural phenomena, and with a love of the 128 PINNOTHERID.E. marvellous, which no Baconian philosophy then existed to correct, the relations of these little interesting parasites to their gigantic hosts should have given rise to legends as amusing as they were false ; and we find that Cicero and Pliny and Oppian have, in various degrees, given currency to the most erroneous notions. Aristotle, indeed, with his accustomed accuracy, first, and alone amongst the ancients, offered any correct ideas of their habits; but even he states that the life of the protecting shell-fish de- pends for its continuance on that of its little guest. The absurdities of the other ancient authors whom I have named, are only worthy of recital as examples of the danger of trusting to the assertions and conclusions of those who have no general principles to guide them,—a danger not even in the present enlightened age, altogether to be neglected as chimerical. I have thought it necessary, on the most mature con- sideration, to merge Pinnotheres Montagui of Leach as a synonyme of this species,—a result to which I am led by a careful examination of the single specimen on which that species was founded, and which is in the British Museum. The sole appreciable distinction between them is the enlargement of the last joint of the abdomen in P. Montagui, a character which probably depends on age; the individual in question is a male, and is a little larger than the ordinary males of P. veterwm. Milne Edwards speaks of the ‘female of P. Montagui ;” bemg probably misled by a cursory observation of the enlarged view of the male in Leach’s plate. DECAPODA. GONOPLACID#. BRACHYURA. GENUS GONOPLAX, Leacu. CANCER, Fabr. Pennant. OcyPopa, Bose, Latr. GONOPLAX, Leach, Edwards. Generic character.—External antenne long, slender, setaceous, the basal joint not notably broader than the following. Internal antenne lying in transverse cells. External pedipalps with the third joint transversely subquadrate, the anterior inner angle trun- cate for the insertion of the palp. Anterior feet equal, extremely long in the male, nearly cylindrical ; the remaining pairs somewhat compressed, the fourth pair the longest, then the third, the fifth, and the second. Cavapace quadrate, much broader than it is long, narrowed behind ; the fronto-orbitar margin extending the whole breadth. Ordits long, transverse, open, terminating at the external angle of the carapace. Eyes small, with extremely long pedun- cles. Abdomen in both sexes seven-jointed. 130 GONOPLACID &. DECAPODA. GONOPLACIDE. BRACHYURA. ANGULAR CRAB. Gonoplax angulata. Cancer angulatus, Fasr. Suppl. p. 341. Prnn. Brit. VI. Zool. IV. p. 7. t- v. fig. 10. Hzersst, t. i. f. 13. Ocypoda angulata, Bosc. Hist. Nat. des Crust. I. p. 198. Larr. Hist. Nat. des Crust. &c., VI. p. 44. Gonoplax angulata, Leacu, Edinb. Encycl. VII. 480. Epwarps, Hist. Crust. II. p. 61. Covcn, Cornish Fauna, p. 72. » bispinosa, Leacu, Malac. Brit. t. xiii. ? Gelasimus Bellii, Coucu, Corn. Faun. p. 73. ? Gonoplax rhomboides, Roux, Epwarps, &c. Tue carapace is half as broad again as it is long, broader across the anterior margin than at the posterior, rounded from before backwards, nearly even from side to side; the anterior outer angle with a prominent and acute spine, ANGULAR CRAB. 131 and a smaller one behind it on the lateral margin. Front entire, imcurved, broad; orbits directly transverse, open directly forwards; eyes on long peduncles, and protected by the latero-anterior spines. The anterior legs in the male four times the length of the carapace ; those of the female much shorter, as are those of the young male. The arm cylindrical, curved, armed with a small spine near the middle of its upper side ; a still smaller spine on the inner margin of the wrist; the hand gradually increasing in size towards the extremity, rounded, somewhat flattened at the sides; fingers finely toothed, and with a few larger tubercles; in the older individuals separated for nearly half their length. The remaining feet long, slender ; the second and third pairs with the last three joints hairy on the edges. Abdomen of the male triangular from the third joint to the extremity, the last joint forming nearly an equilateral triangle; of the female broadly oval: both fringed with hair. Colour dull yellowish red. The moveable finger, in the male only, blackish. It was not until this species was obtamed by Montagu in the Estuary of Kingsbridge, Devon, that it was ascer- tained to be British. Since that period it has been re- peatedly taken on the southern parts of the coast. I have received it through the kindness of Mr. Couch from Corn- wall, and from the coast of Wales, where it was procured by Mr. Eyton; but I am not aware of its having been found on the eastern coast, nor have I heard of its having been taken in Scotland. In Ireland we have the following records of its occurrence from Mr. W. Thompson’s account of the Crustacea of that portion of the kingdom. “ Mr. J. V. Thompson’s collection contains an Irish specimen of this Crab, marked ‘rare Mr. R. Ball has found the K 2 P32 GONOPLACIDA, species in the stomachs of cod-fish, purchased in the mar- kets of Youghal and Dublin, and commonly in those brought to the former place: four of these Crabs is the greatest number he has obtained from the stomach of a single fish. In the Ordnance Collection is a fine example, labelled as procured at ‘ Bangor, January, 1836.” It is a Mediterranean species, and is found also on the north-west and southern coasts of France, according to the observation of Dr. Milne Edwards. I cannot but believe that the Gonaplax rhomboides of Roux and other authors, is merely a variety of this species, in which opinion I concur with Mr. W. Thompson. Should further observations, however, prove that it is distinct, it is probable that the Gelasimus Bellia of Couch’s Cornish Fauna will prove to be the female, or young male of that species. It is found in moderately deep water; and Leach re- cords on the authority of Cranch, that “they live in ex- cavations formed in the hardened mud, and that their habitations, at the extremities of which they live, are open at both ends.” They appear to constitute a favourite food of the cod and other fish, as, in addition to the observation of Mr. Ball quoted above, Mr. Couch states that it is often taken in their stomachs. DECAPODA. GRAPSID. BRACHYURA. GENUS PLANES, Leacn. CANCER, Herbst, Fabr. GRAPSUS, Latr. Roux, Leach. PLANES, Leach, Bowdich. Nauritograpsus, Edwards, Mac Leay, Goodsir. Generic character.— External antenne lying at the exterior of the antennary fosse, the basal articulation nearly horizontal, ex- tending obliquely forwards and outwards, the outer extremity the narrowest ; its moveable portion very short, setaceous, the joints rounded. Internal antenne folded transversely in the fosse, which are covered by the lamellar front, and separated by a broad process extending from the epistome to the front. External pedi- palps with the third joint broader than it is long, broadly and not deeply emarginate at the inner half of the anterior margin. Ante- rior legs robust, rounded, smooth, the hand inflated, the fingers somewhat inflected, slightly toothed ; the remaining pairs much compressed. Carapace depressed, convex, rounded, quadrato- orbicular. Font broad, lamellar, bent somewhat downwards. Orbits distant, open above. Abdomen seven-jointed in both sexes ; in the male acutely triangular ; in the female, nearly orbicular. Tus genus, the only representative of the family Grap- sip“ known to have been found on our coasts, has hitherto been but very imperfectly elaborated. The synonymy of the species is much involved, and it is almost impossible satisfactorily to disentangle it. I believe there are not less than three or four species, the whole of which are found floating about amongst the sargasso or gulf-weed 134 GENUS PLANES. Fucus vagans, or attached to the bodies of the large marine turtles. The figures of Linneus in his “ Iter Westrog.”—of Bowdich in the ‘ Excursions in Madeira and Porto Santo,” the descriptions of Say, of Edwards, of Mac Leay, and others, only tend to show that there are several species in existence, but do not diminish the diffi- culty of distinguishing them. It is not intended on this occasion to attempt their discrimination; but it would be very desirable that the task should be undertaken by some one having the means at hand of comparing a great number of specimens. There is a good collection of them in the British Museum, and I have little doubt that I possess three species in my own collection. I have thought it right to restore the generic name of Planes to these Grapsida, because it was not only applied to them by Leach in his MSS. in the British Museum, but adopted by Bowdich in his book above referred to. Whether Leach had ever published any account of the genus under the name Planes or not, I have not been able to ascertain; but it is highly probable that Bowdich quoted it from some such authority. FLOATING CRAB. 135 DECAPODA. GRAPSIDE. BRACHYURA. FLOATING CRAB. Planes Linneana, Leach. 2 Cancellus marinus minimus quadratus, SLOANE, Nat. Hist. Faun., II. p. 270. t. cexlv. fig. 1. ? Grapsus testudinum, Roux, Crust. Mediterr. t. vi. figs. 1—6. ? Cancer minutus, Fapr. Syst. Ent. XI. p. 443, ejusd. Suppl. 343. Heres, I. t. ii. fig. 32. ? Grapsus, 55 Latr. Hist. Nat. Crust. VI. p. 68. ? 9 «—(CiMeT EUS, Say, Journ. Acad. Sc. Phil. p. 99. ? Nautilograpsus minutus Epw. Hist. Crust. II. p. 90. Planes Linneana, Lracu, MSS. Brit. Mus. Tue carapace in this species is nearly quadrate, with the sides somewhat rounded, and slightly contracted posteri- orly: it is of a generally depressed form; the surface smooth but not polished; and there are on the posterior part of the branchial region several faint stria, occupying the place of those which are so conspicuous in the genus Grapsus, and some other forms of this family. The front 136 GRAPSID 2. is lamellar, broad, projecting, slightly inclining, and entire. The orbits open above, with a small tooth at the outer angle, forming the anterior angle of the lateral margin: immediately behind this tooth is a very slight depression. The margins are very entire. The external antenne are ex- tremely small. The antennary fosse are separated from the orbits only by the basal joint of the external antenne, which scarcely fills up the hiatus. The anterior legs are robust, and, ordinarily, nearly equal; the arm is distinctly denticu- late on the anterior and slightly so on the inner margin ; the wrist has a minute tooth on the anterior inner and outer angles ; the hand is smooth, very slightly granulated beneath, rounded and inflated ; the fingers somewhat in- curved, furnished with small tubercular teeth. The re- maining pair of legs are considerably compressed; the upper edge of the last three joints fringed with stiff hairs ; the inferior edge of the last joint, and the last but one, furnished with sharp spines, of which there are often two or three also on the upper edge of the last joint near the point, which terminates in a sharp spine. The abdomen in the male is triangular, formed of seven smooth joints, the first of which is transversely carinated ; that of the female is nearly orbicular and very slightly raised along the centre. The colour is very various in different individuals. In those which are marked in the British Museum as English, it is of an uniform brownish buff; in others grey, mottled with brown: but the most beautiful are those in which the upper parts are mottled with various shades of reddish brown and rich dark brown, with blotches of yellow or buff; the legs being marked with obscure bands of similar colours. These, however, doubtless belong to a distinct species. FLOATING CRAB. 137 The carapace in the largest specimens in my possession, which are from the gulf-weed floating in the Atlantic, is eight-tenths of an inch long, and the same broad: the females being smaller than the males. In the British specimens the length and breadth does not exceed four- tenths of an inch. The occasional occurrence of this erratic species on our southern coast enables me for the first time to give it a distmet place in our British Fauna. There are in the British collection of Crustacea, in the British Museum, three specimens, placed there by Dr. Leach, obtained, as I believe, from the coast of Devonshire ; and Mr. Couch, in his Cornish Fauna, has the following notice of another :— ‘“‘ A species of the genus Grapsus is in the Atheneum at Plymouth, under the name of G. pelagicus, by Mr. Prideaux, and known to Dr. Leach. It is understood that the collection in the Museum of that Institution is con- fined to specimens taken on the borders of Devon and Cornwall.” I have also received from this gentleman, whose diligence and tact in observing facts in Natural History is equalled by his kindness and liberality in im- parting his information, a very young specimen from the Cornish coast, which is extremely small, being not more than a line in breadth. It was sent to me with some other specimens of various very small Crustacea, apparently taken from sea-weed ; it is quite perfect, although so small, and is of avery pale grey colour, with small dark dots. Such is the amount of our knowledge of this species as an inhabitant of our coasts. The several species are found in great numbers on the sargasso or gulf-weed, amongst which they breed, live, and die. One species is particularly mentioned by Sloane in his Natural History of Jamaica, as being found on the Sargasso 138 GRAPSIDA. and other submarine plants growing on the north side of that island ; and adds that, ‘‘ Columbus, finding it alive on the sargasso floating in the sea, concluded himself not far from some land, in the first voyage he made, on the dis- covery of the West Indies.” They are, however, found wherever the gulf-weed floats; and it is doubtless from some accidental drifting of this plant towards our own coast, that we owe the addition of one species to the British Fauna. As has been already observed, there are, doubtless, at least three distinct species of the genus. As the British specimens have been named by Dr. Leach, and are cer- tainly distinct from that ordinarily found, I have thought it right to retain his name; and shall be glad to find that the investigation of the genus by some competent person has led to the adoption of sound specific characters by which the different species may be distinguished. DECAPODA. LEUCOSTAD /E. BRACHYURA, GENUS EBALIA, Leacu. CANCER, Pennant, Montagu. LEucosIA, Leach. EBALIA, Leach, Edwards, &e. Generie Character.—External antenne extremely minute, in- serted in the inner canthus of the orbit. Internal antenne lying in oblique fossee, which are entirely separated by a small process of the epistome, and concealed by the front. External pedipalps elongato-triangular, reaching forwards to the margin of the ep7- stome ; the internal footstalk gradually acuminated, the third joint internally palpigerous. Azterior legs large, equal, the hand in- flated, those of the male larger than those of the female ; the other legs shorter than the first pair, diminishing gradually in length, terminating in a slightly curved, rather strong claw. Abdomen seven-jointed, but with several of the middle joints confluent ; that of the male narrow, gradually diminishing from the third joint : of the female very broad, the last joint very small, abruptly narrower than the preceding. Carapace rhomboidal, with the angles more or less truncated or rounded ; front produced, ele- vated. Eyes very small. Orbits with two small fissures on the superior margin. Or this genus, which forms the English representative of the family Leucosiada, there are three distinct species found on our coasts. These are sufficiently distinct in several very tangible and essential characters; and I am surprised to find that Dr. Mine Edwards should con- sider them merely as varieties. The distinctions will be 140 GENUS EBALIA. particularly pointed out in the descriptions of the several species. At present I am not aware that either of them has been found in any other locality than on our own coasts; but Dr. Edwards describes a species existing in the French Museum, and I have specimens from Mr. Cuming’s collection from the western coast of America, which must be referred to this genus, but belonging to a new and very remarkable species. The genus was formed by Dr. Leach, who, with great propriety, separated it from his genus Leucosia, to which he had at first referred the species then known. The family of which this genus forms a part is perfectly natural and well defined, and contains many very inter- esting forms, all of them so characteristic as to exhibit at once their close relation to each other. PENNANTS EBALIA. 141 DECAPODA., LEUCOSIAD, BRACHYURA. PENNANT’S EBALIA. Leacu. Kbalia Pennantii. Specific character. Carapace granulated, with an obtuse elevated transverse and longitudinal ridge, forming a cross ; latero-anterior margin divided into two lobes by a fissure ; abdomen with the third to the sixth joints united. Cancer tuberosus, PENNANT, Brit. Zool. IV. t. ix. a, f, 19. Ebalia Pennantii, Leacu, Malac. Brit. t. xxv. f. 1—6. Zool. Miscell. Te palo: Tue carapace in Lbalia Pennantii is rhomboid, rather broader than it is long, the angles rounded, the latero- anterior margin slightly sinuous, and divided by a small fissure ; the posterior margin is rounded ; the front elevated and emarginate ; the orbits very small, and with two small fissures above ; the carapace has an elevated cross, formed by a rounded longitudinal ridge crossed by a transverse one; the whole posterior portion is elevated, and the anterior part slopes suddenly from the obliquely transverse 142 LEUCOSIAD.2. ridge on each side; the surface is everywhere distinctly granulated. The first pair of legs are the longest and are equal ; the arm is trihedrous, the wrist short and slightly inflated, the hand rounded, inflated, externally carinated, the fingers furnished with two very minute ridges on the outer surface ; the whole granulated. The remaining pairs of feet are slender, the joints rounded, the terminal one slightly curved. The whole of the parts about the mouth, particularly the foot-jaws, distinctly granulated, the granu- lation appearing almost like minute pearls. The abdomen in the male is triangular and more than twice as long as it is broad; the third to the sixth jomts united,—in the female it is much rounded, nearly as broad as it is long, the terminal articulation abruptly much smaller than the preceding, to which it is, as it were, a mere appendage. Colour reddish brown, paler beneath, the abdomen in either sex often symmetrically spotted with red. I have a specimen obtained by Mr. McAndrew, and to whom I am indebted for it, which is all over of a lovely bright rose colour. This species, which is the largest of the genus, is about five-eighths of an inch long, by two-thirds broad. These are the dimensions of the carapace of a female specimen in my cabinet from the coast of Devon; and Dr. Leach speaks of female specimens half as large again as his figure, which would correspond with mine, or perhaps rather ex- ceed it. It was first described by Pennant, from speci- mens in the Portland Cabinet, which were probably ob- tained at Weymouth, a locality in which another species, E.. Bryerii, was also first discovered. It was afterwards found on the coast of Devonshire, from whence I have obtained it, through the kindness of my friend Walter Buchanan, Esq., who procured it at Exmouth. It is men- PENNANTS EBALIA. 143 tioned in the following terms by Mr. Embleton, in his Catalogue of the Podophthalmous Crustacea of Berwick- shire and North Durham. ‘A single specimen, taken at Redhaugh, Berwickshire, in the collection of Dr. John- stone, and another in my own, taken in Embleton Bay, are the only ones which have fallen under my notice. In both, which are females, the abdominal covering is marked with two rows of bright scarlet spots, a character not noticed by Dr. Leach.” Its occurrence as an Irish species is thus detailed by Mr. W. Thompson.* “ Although this species must be considered rare, it is less so than HL. Bryerii and #. Cranchii. A specimen (from Cork?) is in Mr. J. V. Thompson’s collection. In September, 1836, one was dredged up from deep water in Belfast Bay, by Mr. Hynd- man, and subsequently another was similarly obtained there by Dr. Drummond. Several were procured in the same locality by the collectors attached to the Ordnance Survey, who likewise dredged a specimen in Larne Loch. To Mr. G. J. Allman I am indebted for one which he found in Dublin Bay. Three examples of the #. Pen- nantii were brought up alive in the dredge from a depth of fifty fathoms, off the Mull of Galloway, by Captain Beechey, R.N.” + Its occurrence on the eastern coast of Scotland is also well attested, and I have before me an immature female specimen,? obtained by Mr. H. Goodsir, who notices its being generally found on stony bottoms, and on fishing- * ¢ Ann. and Mag. Nat. Hist.’ vol. x. p. 286. + Ibid. vol. x. p. 21. { The specimen here alluded to was considered by Mr. Goodsir as belonging to a distinct species ; but from a careful examination of several specimens, I am satisfied that it is the present species at an immature age. The form of the ab- domen is the only character in which it differs, and this has the comparatively narrowed form which always belongs to this part in the young female in all the Brachyura, 144 LEUCOSIAD A. ’ banks. Professor Forbes informs me that he has repeated- ly procured it. The above account of the localities in which this species has been found, warrants us in believing that it is not so rare as has been imagined ; and that its unfrequent occur- rence is to be attributed to its deep-water habits, rather than to its actual scarcity. As far as I have had oppor- tunities of judging, females are much more numerous than males. EBALIA BRYERII. 145 DECAPODA. LEUCOSIAD. BRACHYURA. BRYER’S EBALIA. Ebalia Bryerii. Lracn. Specific character. Carapace slightly and minutely granulated ; lateral margin entire, somewhat revolute at the angles; two tubercles on the cardiac region, and one on each of the branchial in the male ; these parts very tumid in the female. Abdomen in the male with the third to the fifth joints united ; in the female, the fourth to the sixth. Arm not more than twice as long as it is broad. ‘ancer tumefuctus, Mont. Trans. Linn. Soc. IX. p. 86. t, ii. fig. 3. (fcem. auct.) Ebalia Bryerii, Leacu, Mal. Podoph. Brit. t. xxv. figs. 12, 13. Tue carapace in the male is somewhat flattened, de- pressed in the centre, and transversely hollowed imme- diately behind the front, which is considerably raised, and slightly emarginate. The branchial regions and the car- diac region are raised, the elevations in the male being distinct, in the female so tumid as to form a general eleva- tion of the whole of the posterior two-thirds of the cara- pace, abruptly sloping to the margin, which is turned up at the sides. The orbits are very small, and the fissures in their superior margin indistinct. The surface is minutely and almost obsoletely granulated. The arm in the male is less than twice as long as it is broad, with a projection on the mner side, and furnished on each edge with a few L 146 LEUCOSIAD&. minute but distinct tubercles; the hand is somewhat tumid, robust, and the fingers slightly grooved. The re- maining feet slender, and little different from those of the former species. The foot-jaws and other parts about the mouth, as well as the whole surface, are nearly smooth. The abdomen in the male is triangular, about twice as long as it is broad, obsoletely carinated, the third, fourth, and fifth joints united, the terminal one with a small promi- nent point directed backwards, In the female the general form of the abdomen much resembles that in #. Pennantii, but the fourth, fifth, and sixth joints are united ; it is distinctly carinated. Colour reddish white, the anterior margin and a few dots on the carapace red, with indistinct reddish bands across the abdomen in the female. Length half an inch; breadth very little exceeding the length. This species, which appears to be more rare than the former one, although perhaps less so than £. Cranchii, was first described and figured by Montagu, who at once ap- preciated the distinction between it and Pennant’s Cancer tuberosus, and gives those distinctions with great discrimi- nation. The carapace is more nearly rectangular; the whole surface nearly smooth, instead of being, as in the former case, covered with distinct pearly granulations ; the three distinct tuberosities of the carapace, so different from the cruciform elevation in H. Pennantii, the raised margin, together with the different form and composition of the abdomen, and the more swollen and uneven cha- racter of the hands, form altogether an accumulation of distinctive characters so obvious that it is impossible to account for the two species bemg for a moment considered as mere varicties, as they are by Dr. Milne Edwards. BRYER’S EBALIA. 147 The first occurrence of this species on record is that mentioned by Montagu, who received specimens from Weymouth, where it was discovered by Mr. Bryer, to whom Dr. Leach afterwards dedicated it. This distin- guished zoologist subsequently procured it through Mr. Prideaux from the Sound of Plymouth; it is mentioned by Mr. Couch in his Cornish Fauna as the only species he had himself taken. I have received both sexes from Ex- mouth, through the kindness of Mr. Buchanan; and I have a fine male specimen from Torquay, and a female from Tenby; for both of which I am indebted to Mr. Bowerbank, by whom they were procured by dredging. It occurs also in Mr. Bean’s collection at Scarborough. Mr. W. Thompson mentions its rare occurrence as an Irish species, the only locality in which it has been found there being Belfast Bay. Captain Beechey dredged it with the former off the Mull of Galloway, in fifty fathom water. Nothing is known of the habits of this species, nor in- deed of either of the others of the genus. Its occurrence, as far as we have any data, has always been in deep water. 148 LEUCOSIADA. DECAPODA. LEUCOSIAD A! BRACHYURA. CRANCH’S EBALIA. Ebalia Cranchii. each. Specific Chavacter.—Carapace distinetly granulated, carinated ; with five tuber- cles, two near together on the cardiac region, two distant on the branchial regions, and one on the intestinal region ; latero-anterior margin nearly entire ; arm linear, three times as long as it is broad, Ebalia Cranchit, Leacu, Zool. Misc. III. p. 20. Malac. Brit. t. xxv. f.7—ll. Epw. Hist. Nat. Crust. II. p. 129. Tue carapace in this species is more regularly rhombic than in either Lb. Pennantii or Bryer. ‘The surface is distinctly granulated; there isan obtuse longitudinal cara extending the whole length, and there are five distinct tubercles, of which two are very near each other on the cardiac region, one on each branchial, and a single one, larger than the others, on the intestinal. The latero- anterior nargin is almost entire, having only a slight sinu- ation; the front is emarginate, as is also the posterior angle. ‘The anterior pair of legs are equal, robust, and in CRANCH’S EBALIA. 149 the male nearly twice as long as the carapace; the arm is somewhat trihedrous, and three times as long as it is broad; the wrist ovate, the hand slightly tumid, the fingers shorter than the hand ; the remaining pairs of legs slender, the second and third pairs in the male one-third longer than the carapace. In the female the carapace is, in pro- portion, a little longer than in the male, and the legs con- siderably shorter. The abdomen in the male has the third, fourth, and fifth joints, and the female the fourth, fifth, and sixth, united; in the former the penultimate joint is emar- ginate in the anterior margin to receive an angular projec- tion in the posterior margin of the terminal joint. Length of the carapace half an inch. Colour yellowish red, the female paler. The male of this species so nearly resembles that of /. Bryerii, that without very careful examination they may very readily be mistaken for each other. The principal distinctive characters are to be found in the form and pro- portions of the arm, and the size of the granulations on the surface. The arm in #. Cranchii is three times as long as it is broad, and without any dilatation or protuberance on the inner side; in L. Bryerii the arm is scarcely twice as long as it is broad, and is furnished with a distinct pro- jection on the inner side. In /. Cranchit the granulations which cover the surface of the body and limbs are distinct and somewhat prominent; in 7. Bryerit they are very small, and depressed. The female in the present species very nearly resembles the male; in KL. Bryerit the sexes are very dissimilar. This is the most rare of the British species of Ebalia. It was discovered by the indefatigable and unfortunate Cranch, in Plymouth Sound, where it was afterwards ob- served, according to Dr. Leach, in considerable numbers ; 150 CORYSTID.E. it occurs in Mr. Bean’s collection at Scarborough. In the Frith of Forth it is mentioned by Mr. Goodsir as being very rare. Mr. Thompson records its occurrence as an Irish species in Roundstone Bay, Connemara; Mr. Ball found several on the beach at Portmarnoch after a storm ; and Captain Portlock obtained it “by deep dredging in Belfast Bay, in the course of the Ordnance Survey.” * The vignette is an illustration of the sign Cancer, from a thirteenth century drawing, contained in the Prayer- book of Queen Mary in the British Museum. * Thompson, Ann. and Mag. Nat. Hist. vol. x. p. 285. DECAPODA., CORYSTID&. BRACHYURA, GENUS ATELECYCLUS. Leacu. CANCER, Herbst. Cancer (Hira). Montagu. ATELECYCLUS, Leach, Edwards. Generic Character.—External antenne with the basal articu- lation very large, united to the floor of the orbit at the outer side, and to the front above, thus separating the orbit from the anten- nary fossa: the moveable portion inserted beneath the front, be- tween the orbit and the antennary fossa. Internal antenne lying longitudinally in the antennary fossa, which are, as it were, exca- vated in the front. LKaternal pedipalps completely closing the buccal opening, and advancing forwards to the base of the ex- ternal antennae; the third jot much longer than broad, ter- minating in an oblique line, and giving attachment to the terminal portion in a notch near the middle of its internal margin. Cara- pace more or less approaching a circular form, evenly convex ; the latero-anterior and lateral margins numerously toothed ; the front moderately projecting, quinquedentate, the exterior tooth forming the boundary of the orbit ; the hepatic regions small, the bran- chial very large. Orbits, directed forwards, with a single fissure beneath, and two above, which form a distinct tooth towards the outer angle. Anterior legs very large and strong, short, com- pressed, the hand carinated and ciliated above ; the fingers curved ; the remaining pairs of moderate length, compressed, the ter- minal joint long, acute, and nearly straight.- Aédomen in the male, five-jointed, in the female, seven-jointed. This genus was established by Leach for a species found by Montagu, and described by him in the eleventh volume of the Linnean Transactions, under the name of Cancer 152 GENUS ATELECYCLUS. (Tippa) septemdentatus. ‘There are now several other species known, one of which A. erucntatus, is found on the coast of France, and probably in the Mediterranean. — It appears very nearly to resemble our species, and may pos- sibly be a variety of it. The group is a very natural one, and its characters well defined, but its geographical distri- bution is so extensive as to set all ordinary laws at defi- ance; I have a well-marked species, hitherto undescribed, which was procured on the western coast of South America by Mr, Cuming. CIRCULAR CRAR. 158 DECAPODA. CORYSTID&. BRACHYURA. CIRCULAR CRAB. Atelecyclus heterodon. each. Specific Character.—Carapace nearly circular, the lateral margins with nine teeth, alternately larger and smaller; hairs of the legs very long. Cancer (hippa) septemdentatus, Montacu, Trans. Lin, Soc. XI. t. 1. f. 1. Atelecyclus op Leacu, Edin. Encycl. VII. p. 430. Trans, Lin, Soc. XI. p. 313. Px heterodon Leacu, Malac. Brit. t. ii. Tue general form of the carapace of this species is so nearly circular, as to distinguish it at first sight from all the other brachyurous Crabs of our coast. The lateral margins with the front form somewhat more than a semicircle, and the latero-posterior margins form three sides of a nearly regular octagon. The whole circumference is fringed with hair. The lateral margin on each side is furnished with nine teeth, which are alternately a little smaller and larger; the front is tridentate, the middle tooth being rather the 154 CORYSTID.®. longest ; the whole of the teeth are slightly denticulate. The carapace is granular, moderately elevated, and the regions not very distinct. The orbits are open forwards, and have two fissures in the upper and one in the lower margin, the two former being the boundaries of a small projecting tooth. The anterior pair of legs are large and strong, compressed, and, when at rest, closing accurately against the under part of the body. The outer and upper surface of the wrist is furnished with short lines and warts of minute raised points, and there is a spine on the inner and anterior angle. The hand, which, with the fingers, is incurved, has five longitudinal lines of small raised points, besides similar ones on the superior and inferior margins. The fingers are compressed, curved, slightly toothed, and meet only at the points. The remaining legs are slightly compressed, of moderate length, and the whole are fringed with long hair. The abdomen in the male is five-jointed, nearly linear, slightly hollowed on the sides, the terminal joint triangular: in the female it is seven-jointed, very slender, being three times as long as it is broad, the ter- minal joint elongate and somewhat cordate. The colour is reddish white, with red spots; the anterior feet red, the fingers black ; the hair light brown. The carapace of a full-sized male is about an inch and a quarter in diameter ; the female considerably smaller. The credit of the discovery of this species is due to Mon- tagu, who found it on the coast of Devonshire, where it has since been found, as Leach observes, in great plenty in deep water. Mr. Gouch, in his Cornish Fauna, observes that it is “‘common in the stomachs of fishes, chiefly cod- fish and rays, from the depth of twenty to fifty fathoms. They must abound at these depths, as I have found more than thirty in a single fish, and almost every ray opened CIRCULAR CRAB. 155 for several days in succession, was found to contain them.” I have obtained it from the Welch coast; and I find a very young specimen amongst some rare crustacea kindly forwarded to me from Scarborough by Mr. Bean. It has been found on the coast of Scotland, in the Frith of Forth, both by Mr. Stephenson of Edinburgh, as stated by Leach, and by my friend Mr. Harry Goodsir, who, however, states that it is rare. I have lately received a specimen which was taken from the stomach of a cod, off the coast of Zetland, by my friends Mr. M‘Andrew and _ Professor Forbes. The accuracy and detail which characterize all the observations of my friend Mr. W. Thompson of Belfast, induce me to quote at length his account of this species as belonging to the Fauna of Ireland. ‘ Mr. Tem- pleton notices a Crab of this species as found by him in the stomach of a codfish, Jan. 17, 1817. In Mr. J. V. Thompson’s collection is an Irish specimen, probably from Cork. In January 1839 I obtained a perfect adult male from the stomach of a brill, (Pleuronectes rhombus,) taken at Ardglass, County Down; it somewhat exceeds in size that figured by Leach, which again is larger than Montagu represents the species. The circumstance of the species being found in the stomachs of the cod and brill would in- dicate its being an inhabitant of deep water. In the Ordnance collection are examples of this Crab from Mo- ville (Co. Donegal), Portrush, near the Giant’s Causeway, and Carrickfergus. Mr. R. Ball has twice obtained it on the Dublin coast ; on one occasion many specimens were found by him on the beech at Portmarnoch after a great storm.” In confirmation of Montagu’s and Leach’s obser- vations of the great prevalence of male specimens—those observed by the former having been all of that sex, and the latter stating that two females only were found amongst 156 CORYSTID.®. several hundreds of males, Mr. Thompson informs us that the several Irish examples which he examined with refer- ence to their sex were all males. The testimony which I have given from these different authors prove that the south-western coast, that of Corn- wall and south Devon, is the locality in which this species is most abundant, although it occasionally occurs far to the North. That it is generally an inhabitant of deep water, is also evident ; yet an observation of Mr. Thomp- son’s would seem to show that the spawn is deposited, and that the young continue to reside, in shallower depths. ‘In the month of September 1835,” he observes, ‘“T obtained several small living specimens of