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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. <A single branch of each of the great vessels, accompanied by a branch of nerve, runs through a small foramen near the centre of this body, but there is no vestige of either muscle or tendon, the attachments of which are at each extremity. In fact, this body is perfectly defined, and can be turned out of the shell without being much injured.
“When the limb is thrown off, the blood-vessels and nerve retract, thus leaving a small cavity in the new-made surface. It is from this cavity that the germ of the future leg springs, and is at first seen as a nucleated cell. A cicatrix forms over the raw surface caused by the separa-
tion, which afterwards forms a sheath for the young leg.”
METAMORPHOSIS.
One of the most marked characters by which this class was long considered as distinguished from that of insects, was the supposed absence of any such change of form, during the progress of development after exclusion from the egg, as is ordinarily understood by the term metamor- phosis; and Dr. Leach, in his definition of the class,* formally adopts this character, which has been repeatedly recognised by others.
* Encycl. Brit., Art. Crustacea.
INTRODUCTION. XXX1X
It was in the year 1823 that Mr. Vaughan Thompson, whose name is now identified with the discovery, follow- ing up an observation made by Slabber, a Dutch natu- ralist, as long ago as 1768, and published ten years after- wards, established the remarkable fact that those ano- malous forms which constituted the genus Zoea of Bosc, are nothing more than the early or larva condition of the higher Crustacea. It will readily be imagined that no small excitement was produced in the scientific world by the announcement of a discovery which, followed up, as it afterwards was, with equal intelligence and perseverance, and with corresponding success, may claim for its author a place amongst the few observers who, from a single phenomenon, have been led to the establishment of gene- ralisations and laws of the highest importance.
Notwithstanding, however, the credit is due to Mr. Thompson of having carried out the suggestion to its full development, it was undoubtedly to the Dutch naturalist that he was indebted for the ascertained fact that the anomalous creatures on which Bose afterwards founded his genus Zoea pass by metamorphosis into a different and a higher form.
Before I proceed with the further history of this dis- covery, I think it right to show the grounds of Slabber’s claim, which had been wholly overlooked as to its results, and which, in consequence of an error arising from de- ficient information, Mr.'Thompson himself, in the first place, much depreciated, without, as far as I am aware, having afterwards taken any opportunity of correcting the misapprehension. It was, then, in the year 1778 that Slabber published a small work, in which occurs
a description with figures of a new crustacean animal
INTRODUCTION.
(fig. @,) to which the name of Zoea Taurus was afterwards given. Having taken at sea several spe- cimens of this singular creature, he placed one of them (a) in sea water, which he constantly re- newed, for the purpose of observation, and, ‘‘ on the third day, finding its
movement become slower
and its colour paler, he subjected it to the microscope,
and found to his surprise that the anterior part of the animal had changed its form, and on the fourth day it had acquired the appearance represented in fig. b, so that, together with the other individuals he had taken, it seemed to have experienced a complete metamorphosis ; under this new form the dorsal spine had disap- peared, the front spine had become compara- tively small, the antennz were rendered conspi- cuous, the feet and eyes
were apparently more de-
INTRODUCTION. xh
veloped, and the tail had changed from forked to spatu- late, fringed by arow of thirteen short spines.” It would certainly seem that this plain and simple statement, sup- ported as it was in many respects by Mr. Thompson’s own subsequent observations, can scarcely justify the conclusion to which that gentleman is led,* “that Slabber lost his Zoea, in changing the sea water, and that the new form came from the added portion.” But the truth of Slabber’s statement, and, consequently, the evidence of the correctness and originality of his discovery, are very strongly proved by the almost absolute identity of the second form of his animal with that of several species subsequently observed; and particularly of the ditch- prawn, Palemon varians, as figured by Capt. Du Cane.+ It was, however, from this observation of Slabber that Mr. Thompson, in the year 1823, was induced to carry out the investigation. In the spring of the previous year, as he informs us, in the harbour of Cove, he first met with Zoeas, and that in considerable abundance; and “in the year following, at the same season, one of considerable size occurred, amongst a number of smaller ones, and, judging it full grown, he considered it a fit subject to keep for the purpose of witnessing the metamorphosis observed by Slabber,” &c. The metamorphosis was interrupted by the death of the animal when in the act of undergoing it; but it had advanced sufficiently to show that the animal belonged to the Brachyura, and the portion which was observed, contained all the five feet on one side, the anterior foot being furnished with a perfect claw; and it appears now more than probable that the form into
* Zool. Researches, p. 8. + Ann. Nat. Hist. vol. ii. pl. 6.
xlii INTRODUCTION.
which it was passing was that of Megalopa, to which further reference will be presently made.
Here, then, was the first decided demonstration ; but any doubt which might be supposed to appertain to an incomplete fact, was shortly removed by Mr. Thompson’s success in hatching the ova of the common crab, Cancer Pagurus, the product of which were true Zoeas.
Subsequent observations by Mr. Thompson confirmed his new views, and he established the truth of a metamor- photic change in several genera; the results of his re- searches being given to the world in a subsequent portion of his Zoological Researches, in the “ Entomological Ma- gazine,”* in “ Jameson’s Journal,” + and particularly in a paper read before the Royal Society in 1835, and pub- lished in the “ Philosophical Transactions,’ in which details are given of the complete changes in Carcinus Menas, the common shore crab, which establish the fur- ther interesting and important fact, that while the animal appears under the aspect of a Zoea on its first exclusion from the egg, it undergoes a further change into a true Megalopa before its final assumption of the perfect form: showing that this supposed genus also, which was formed by Leach, is, like Zoea, only a phase of a higher type. Thus, in its progress from the egg to its final development, the brachyurous crustacean was proved to pass through two temporary conditions, which had previously been regarded as types, not of genera only, but of different families ; and both strikingly dissimilar from the group to which, in its perfect state, it really belongs.
The new doctrine was not received at once with im- plicit assent. Mr. Westwood, in a paper read before the
* Vol. iii. pp. 85, 275, 370, 452. + For 1846. PPO,
INTRODUCTION. xlii
Royal Society in June, 1835,* not only contests the uni- versality of the law, which Mr. Thompson had somewhat too hastily, perhaps, deduced from his facts, but concludes that that gentleman’s views are erroneous, and that “no exception occurs to the general law of development in the Crustacea—namely, that they undergo no change of form sufficiently marked to warrant the application to them of the term metamorphosis.”
This hasty, and, as the result has proved, very pre- mature condemnation, derived some primd facie supports from the elaborate investigations of Rathke on the deve- lopment of the embryo in the ova of the river cray-fish, Astacus fluviatilis, and the subsequent observations of Mr. Brightwell on that of the lobster, which latter, how- ever, have since been only partially verified by Rathke, and are, indeed, modified in some particulars by Mr. R. Couch. ‘To these I shall have occasion to refer more particularly hereafter ; it is sufficient now to observe, that in both instances the animal was stated to be perfected by gradual development, and not by any sudden change of form. ‘These, if even the statements were fully borne out, have since been proved to be merely exceptional cases; and not only is Mr. Rathke’s assumed general support of Mr. Westwood’s objections completely re- moved, but that distinguished physiologist himself volun- teers his strong testimony in favour of the opposite views in a subsequent paper, in which he says that he hastens the publication of these new researches respecting the development of several other forms of Crustacea, one of which is the lobster, “ in order, as soon as possible, to record a testimony to the correctness of Thompson’s dis-
* Phil. Trans. 1835, p. 311.
xliv INTRODUCTION.
covery, that even the Decapods, after they have already quitted the egg, undergo a very considerable metamor- phosis ;” and, in conclusion, he adds, “ from the notices which I have here briefly communicated respecting the development of some Decapods, it results that several of these animals, as first discovered and described by Thomp- son, undergo a very considerable and highly remarkable metamorphosis. . . . . I, therefore, confess that I have done Thompson injustice in not putting faith in that discovery.” And he then states his intention “ next spring, partially to subject bis researches on the cray-fish to revision.”* There is one apparent anomaly, however, on which Mr. Westwood dwells with some plausible show of reason, and on which it may be well to offer a few remarks.
Amongst the specimens of Crustacea, preserved in spirits, which formed part of the collection of the late Rev. Lansdown Guilding, and which came into my pos- session after his death, was one of the abdomen of a female land crab, Gecarcinus, to which were attached numerous young, in their perfect form, and very similar, excepting in size, to the parent. Here, then, was a case in which, it may at once be granted, no external and independent metamorphosis, at least, had taken place ; and on this, with the other instances above alluded to, Mr. Westwood founds his principal argument against the doctrine enunciated by Mr. Thompson. But may not this probably be an analogous phenomenon to that of the land salamanders amongst the amphibia? And, as in
that instance, where the parent has no opportunity
* Wiegmann’s Archiv, part iii. 1840. Translated in Ann. Nat, Hist. vol, vi. pp- 263-268,
INTRODUCTION. xlv
of depositing her eggs in the water, where, in the more typical forms, the young undergo the transformations essential to the whole group, the changes take place in the oviduct; so may not the young of the land crab, whose habits require them to be speedily in a condition to leave the coast where they are hatched, formally un- dergo the metamorphosis within the egg? This being granted, it would be as reasonable to deny the pheno- menon of transformation in the amphibia generally, be- cause the young of the salamander are brought forth in the perfect state, as to deny its occurrence in the Crusta- cea, on the analogous exceptional case of the terrestrial Gecarcinus.*
I do not consider it necessary to examine at any detail the “ six arguments” which Mr.Westwood adduces “against the metamorphosis into crabs which the Zoes are stated to undergo,” since the facts, exactly as related by Mr. Thompson, have been so fully confirmed by subsequent observers. Indeed, I prefer referring to the whole of Mr. Westwood’s elaborate examination of the question, for the information of those who may have the curiosity to see how much may plausibly be urged against the truth of a theory, so irrefragably supported by facts. It is sufficient to say that Mr. Westwood does not attempt to bring forward a single investigation or observation of his own in support of his views, with the exception of that of the land crab, already mentioned.+
* Mr. Thompson, in the case of Gecarcinus, as in that of some other West- Indian species, depended for his information upon some specimens of female crabs with matured ova being sent to him in spirits. The ambiguous character of such observations may warrant us in eliminating them at once from the
question.
+ I haye thought it necessary to examine Mr. Westwood’s objections at
xlvi INTRODUCTION.
But Mr. Westwood was not the only one who demurred to the correctness of Mr. Thompson’s conclusion, In the first volume of Milne Edwards’s admirable “ History of Crus- tacea,”* this author says, “ Les Decapodes paraissent tous naitre avec la série compléte de leurs anneaux et leurs
’
membres ;” and in a note occurs the following opinion on the earliest researches of Mr. Thompson. “ Suivant M. Thompson, les Decapodes éprouveraient de véritable mé- tamorphoses, car ce naturaliste regarde Vanimal connu sous le nom de Zoé comme étant le jeune du crabe commun de nos cotes. Mais cette opinion n’est pas étayée d’observations assez précises pour entrainer la conviction.”
It is remarkable that this distinguished naturalist’s ulti- mate convictions were derived from his own observation ; and it is difficult to account for such a discrepancy when we consider the high character of the dissentient, and the means which were placed in his hands for determining the question ; for in consequence of the interest which it ex- cited amongst the scientific men of France, Dr. Milne Kdwards was deputed with another naturalist, to repair to the Isle de Rhé for the express purpose of settling the disputed point, and he arrived, as we learn, at the conclu- sion above stated. some length, on account of that gentleman’s deserved eminence as a profound entomologist, and because I believe that he has never published any recantation of the opinions stated in his paper. I have, howeyer, before me, a letter from him to myself, dated Sept., 1844, in which the following passage occurs, showing that his convictions on this subject had undergone a material change :—“ I be- lieve it will turn out, following the normal rule of development of the embryo, that at a certain period all the Decapods are Zoe, and that some are born (i.e. escape from the egg) in that state, but that others are not born until a late
pericd of development, that is, when the true legs and claws are disengaged.” Pe 198:
INTRODUCTION. xlvii
Subsequently to the researches above-mentioned, the late Capt. Du Cane investigated the development of the shore crab, Carcinus Menas, and of the Ditch Prawn, Palemon varians, with complete success ; establishing in each of these forms the truth of Mr. Thompson’s position. Mr. H. Goodsir also examined, with similar results, the former species. But by far the most complete illustration of the subject and the most extensive proofs of the general law, are afforded by the researches of my friend, Mr. Richard Q. Couch, of Penzance, who, dissatisfied with the uncertainty and contradiction of former testimony, resolved to investigate the matter for himself; and this he effected with a degree of acumen and perseverance which characterise all his researches, and by which the truth of the doctrine is fully established, as regards the genera Cancer, Zantho, Pilumnus, Carecinus, Por- tunus, Polybius, Maia, Galathea, Homarus, and Pali- nurus —a goodly number to have been investigated by one observer—and of some of these he watched every change. These results were published in two Memoirs, read to the Cornwall Polytechnic Society in 1843; in which the author takes a clear and fair view of the whole subject, and comes to his decision with a host of evidence sufficient to set the substantive question entirely at rest. Unfortunately, the useful local publication in which these memoirs appeared, is so much confined in its circulation that it has probably fallen into the hands of but few naturalists.
I have felt it desirable to give a more extended history of the discovery, as, with the exception of Mr. R. Couch’s first memoir just referred to, no such digest has ever been
placed at one view before the world. I now proceed to
xlviii INTRODUCTION.
examine the actual results, and to endeavour to reduce the facts already known to some order.
It will be inferred from the previous account, that there are considerable variations in the character of the meta- morphosis of different families, and that in the case of Astacus fluviatilis, there appears at present to exist even an abrupt and isolated exception to the general law. As this is the only case at present in which such exception has been established, I refer my readers for further in- formation on this subject to the work of Mr. Rathke himself,* which constitutes one of the most complete and elaborate monographs in existence, illustrated in the most beautiful and perfect manner; and to the full and satisfactory analysis of the work by Milne Edwards in the first volume of his “ History of the Crustacea.”
Eliminating, therefore, this exceptional case, it will be found that the fact of a metamorphosis has been demon- strated with more or less success in no less than seven- teen genera of the Brachyurous order of the Decapoda —in which order the phenomenon is most decided and obvious—belonging to the families Leptopodiade, Maiade, Canceride, Portunide, Pinnotheride, Grapsida, and Ge- carcinide. Inthe Anomourous order, it has been shown in the genera Pagurus, Porcellana, and Galathea, and amongst the Macroura in Homarus, Palinurus, Palemon, and Crangon.
The facilities which everywhere exist for procuring
the common shore crab, Carcinus Meenas, have occa-
* Untersuchengen neber die Bildung und Entwickeberg des Flusskrebses, von
Heinrich Rathke. Folio. Leipzig. 1829.
INTRODUCTION. xlix
sioned it to be more fully investigated than any other; and it may, therefore, be taken as the type of the process amongst the Brachyura. Thus it was the first form in which the Megalopoid period was observed by Mr. Thompson ;* it was four years afterwards described in its zoeform state by Capt. du Cane, who, it appears, was not acquainted with Mr. Thompson’s paper; it has occupied the attention of Mr. H. Goodsir; and it forms the subject of Mr. R. Couch’s elaborate and very complete re- searches. To the latter of these, as embodying all that is at present known on the subject, and as being the result of the personal observation of so intelligent and acute an observer, I shall have recourse for the general description of this process in the Brachyura. In the first place it appears that Mr. Couch met with the young Zoes already hatched; and even then he had the satisfaction of finding them pass into the Megalopoid condition described by Thompson. Afterwards, however, he procured some specimens of the crab itself laden with ripe ova, just ready for shedding; and he then proceeds with the account of his observations :—
“These were transferred to captivity, placed in sepa- rate basins, and supplied with sea water, and in about sixteen hours I had the gratification of finding large numbers of the creatures alluded to above, swimming about with all the activity of young life. There could be but little doubt that these creatures were the young of the captive crabs. In order, however, to secure accuracy of result, one of the crabs was removed to another vessel, and supplied with filtered water, that all insects might be removed; but in about an hour the same crea-
* Phil. Trans. ut supra.
] INTRODUCTION.
tures were observed swimming about as before. To render the matter, if possible, still more certain, some of the ova were opened, and the embryos extracted; but shortly afterwards I had the pleasure of witnessing, be- neath the microscope, the natural bursting and escape of one precisely similar in form to those found so abun-
Fig. ¢. ' dantly in the water. Thus, then, there is no doubt that these grotesque- looking creatures are the young of the Carcinus Menas; but how diffe- rent they are from the adult need hardly be pointed out any further than by referring to the fig. (c). When they first escape they rarely exceed
half a line in length. The body is ovoid, the dorsal shield large and inflated, on its upper edge and about the middle is a long spine, curved posteriorly and rather longer than the diameter of the body, though it varies in length in different specimens ; it is hollow, and the blood may be seen circulating through it. The upper portion of the body is sap- ereen, and the lower semi-transparent. The eyes are large, sessile, and situated in front, and the circum- ference of the pupil marked with radiating lines. ‘The lower margin of the shield is waved, and at its posterior and lateral margin, is a pair of natatory feet. The tail is extended, longer than the diameter of the shield,
and is composed of five equal annulations, beside the
INTRODUCTION. hi
terminal one; its extremity is forked, and the external angles long, slender, pointed, and attached to the last annulation by joints. Between the external angles, and on each side of the median line, are three lesser spines, also attached to the last ring by joints. Between the eyes, and from near the edge of the shield, hangs a long, stout, and somewhat compressed appendage, which, as the animal moves, is reflexed posteriorly between the claws. Under each eye there is also another appendage, shorter, and slightly more compressed. The claws are in three pairs ; each is composed of three joints, and terminates in four long, slender, hair-like appendages. These claws are generally bent on the body, but stand in relief from it. If the animal be viewed in front, the lower margin of the dorsal shield will be found to be waved into three semi- circular festoons, the two external of which are occupied by the eyes, and between which the middle one inter- venes ; the general direction of the claws will be seen to be at right angles to the body. As the young lies en- closed within the membranes of the egg, the claws are folded on each other, and the tail is flexed on them so far as the margin of the shield, and, if long enough, is re- flected over the front of the shield between the eyes. The dorsal spine is bent backwards, and lies in contact with the dorsal shield; for the young, when it escapes from the egg, is quite soft, but it rapidly hardens and solidifies by the deposition of calcareous matter, in what may be called its skin. The progress of this solidifica- tion may be very beautifully observed by watching the circulation in the dorsal spine. When the creature has just effected its liberation from the egg, the blood glo- bules may be seen ascending to the apex; but as the
d 2
hi INTRODUCTION.
consolidation advances, the circulation becomes more and more limited in its extent, and is finally confined to the base. These minute creatures, in this early state of their existence, are natatory, and wonderfully active. They are continually swimming from one part of the vessel to the other, and when observed free in their native pools, if possible even more active than when in confine- ment. Their swimming is produced by continued flexions and extensions of the tail, and by repeated beating mo- tions of their claws ; this, together with their grotesque- looking forms, gives them a most extraordinary appear- ance when under examination. As the shell becomes
more solid they get less active, and retire to the sand
INTRODUCTION. lini
at the bottom of the vessel, to cast their shells, and acquire a new form. They are exceedingly delicate, and require great care and attention to convey them through the first stage; for unless the water be supplied very frequently and in great abundance, they soon die. The second form of transmutation is equally as remarkable as the first, and quite as distinct from the adult animal (d). In the species now under consideration this second trans- formation is marked by the disappearance of the dorsal spine; the shield becomes flatter and more depressed, the anterior portion more horizontal and pointed, the three festoons having disappeared. The eyes, from being sessile, are now elevated on footstalks ; the infra-orbital appendages become apparently converted into antenne. The claws undergo an entire revolution; the first pair become stouter than the others, and are armed with a pair of nippers,” the others being simple; “ but the posterior pair are branched near the base, and one of the branches ends in a bushy tuft. The tail is greatly diminished in its relative size and proportions, and is sometimes partially bent under the body, but is more commonly extended. This form is as natatory as the first. They are frequently found congregating around floating sea- weed, the buoys and strings of the crab pot marks, and other floating substances, both near the shore and in deep water. Their general form somewhat resembles a Galathea.”
Every one will immediately recognise in this descrip- tion, and in the figure which accompanies it, the creature typifying the genus Megalopa of Dr. Leach. Here, then, is the second form of a brachyurous type, and its final
change is seen in the accompanying figure (e). It is
liv INTRODUCTION.
Fig. Ce
unnecessary to follow out the minor distinctions in the various brachyurous genera. It is sufficient to state that the investigations of Mr. Couch confirm fully the views of Thompson, by the establishment of a metamorphosis of similar character, as regards the first change, in the large edible crab, Cancer Pagurus, in Portunus, and in several of the Maiade and Leptopodiade. There are some minor differences in the structure and form of the first stage of these as compared with that of Carcinus, but they do not involve any important consideration. ‘The curious little larva of Pinnotheres I have figured at p. 125, after Thompson, and as [ have myself seen it.
Amongst the oxyrhynchous forms there are some rather curious deviations from the type above described, par- ticularly in the absence, according to Mr. Couch’s figures in the genus Maia, of the dorsal and frontal spines; but these, as I understand Rathke’s description, are found in the corresponding stage of the neighbouring genus Ayas; if this be so, it shows that the existence or absence of these spines is of little importance.
In the Anomoura we have elaborate descriptions of the young stage of Pagurus, in the paper by Rathke already
referred to, and in one by Dr. Philippi, with a figure.*
* Ann. of Nat. Hist. vol. vi. p. 92, pl. iii. f. 7, 8.
INTRODUCTION. lv
If this figure be correct, we have a remarkable approach in the general form of this species to that of some of the smaller Macroura, as observed by Mr. Thompson and Capt. Du Cane; but the details scarcely agree with the full and doubtless correct description of the former author. The researches of Mr. Rathke * are, in fact, of great value, as affording the only clue we have yet seen, to the homologies of the members which exist in this early condition of the animal. It appears from this account, that the true feet are not represented by the three pairs of locomotive organs which are observed in the early stage, but that these are in fact developed into the foot- jaws of the adult. ‘ Embryos about to escape have only three pairs of members that can serve for locomotion. All these six members are not, as might be expected, true feet in a lower state of development, but the foot- jaws. Of true legs, and also of branchie, there does not yet exist a trace.” It is not until a subsequent period that these organs are formed, and, in fact, the whole account of the development of the young Paguri, as given by M. Rathke, is highly interesting, and would be particularly useful as a guide to those observers who might have the opportunity of watching the whole pro- gress of any of these animals from the egg to maturity.
The most remarkable form of the larva amongst the Anomoura hitherto observed, and, indeed, one of the most anomalous in the whole Decapod group, is that of Porcellana platycheles, as described and figured by Mr. R. Couch, in his second Memoir. There is no appear- ance of either dorsal or frontal spines, in which respect
it agrees with the Macroura, as it does also in the com-
* Ann, of Nat. Hist. vol. vi. p. 263.
\ " %
lvi
INTRODUCTION.
pressed corselet, and the large, sessile eyes. On its
Fig.
first escape from the egg (fig. f), the feet are in two pairs, dichotomously branched and destitute of hairs ; the tail comparatively short, the terminal flap somewhat lozenge- shaped, and armed with long, slen- der, bristle-like appendages. From
the anterior partof the carapace hang
two long, slender filaments which turn under the thorax.
In a few hours the first exuviation takes place, and the
animal appears under a different aspect (fig. g). The
branchial members are converted into two pairs of simple
Fig. h.
three - jointed tufted feet. The hairy tufts are appended only to the last joint. The terminal seg- ment of the six-jointed tail (fig. /) is expanded into a large ,quadran- gular surface, the inferior mar- gin of which is fringed with six
pairs of long slender filaments.
INTRODUCTION. lvii
But one of the most remarkable peculiarities of this state of the animal is the existence of an _ exces- sively long filament extending from above the eyes and in front of the corselet: this is rough with minute spines, and appears, as Mr. Couch says, to be hollow. Two similar filaments, equally long, are attached to the posterior part of the corselet above the _ tail. From the repeated and careful observations of Mr. Couch there can be no doubt of their correctness, for he not only bred them repeatedly in filtered water, but succeeded in artificially extracting some from the ova.*
The metamorphosis in the Macroura generally is less strongly marked than in those forms to which we have hitherto referred. Of these, the lobster, Homarus, the spiny lobster, Palinurus, the prawn, Palemon, and the shrimp, Crangon, have been more or less fully observed. Mr. Brightwell did not consider the changes which he observed in the lobster such as to warrant the application of the term metamorphosis ; but even Mr. Rathke him- self, whose researches in the river species have offered the strongest Fig. ¢. arguments to the opponents of this view, in his subsequent Memoir, adduces this, amongst other spe- cies, as an attestation of the truth of Mr. Thompson’s theory. Mr. R. Couch’s figure (fig. 2) of the young
lobster on its exit from the egg
does not differ materially from that
* The larva of Gadathea is figured at p. 203, in illustration of Mr. R. Couch’s description at the previous page.
lviti INTRODUCTION.
of Galathea and Palinurus, excepting that on the superior rings of the tail in the latter are situated four pairs of appendages (fig. 7). Upon this point Mr. Couch has the
mA following sensible remarks. “ There is not certainly the same difference of configura- tion between the young and adult condition of these (the Macroura), as is found to be
the case with the short-tailed crabs, simply from the circumstance of the tail being extended in both states, and the claws also show a nearer approach to each other. But this similarity is more apparent than real, for the physiological difference is nearly as wide in one case as in the other. The form of the shield and the body generally, the sessile character of the eyes, and the long and slender filaments on the tail in Palinurus, undergo an entire change in the transformation. The shield and body become more depressed and elongated, the eyes be- come elevated on stout footstalks,’ &c. The sessile character of the eyes in the early stage of all the Po- dophthalma hitherto examined is a very remarkable and important character.
The changes in the smaller decapod Macroura, repre- sented by the genus Palemon, were first examined by Mr. Thompson, and formed the subject of a second paper read before the Royal Society in 1836. This paper, as well as that on Carcinus before referred to, appears not to have been known to the late Capt. du Cane, who having amused the hours of a long illness by a number
of interesting investigations on subjects of Natural His-
INTRODUCTION. lix
tory, communicated two papers to the Annals of Natural History, on the Metamorphosis of Crustacea. To one of these, on Carcinus Menas, I have already alluded ; the other * contains a brief account of the transformation and development of the ditch prawn, Palemon varians, in four stages, accompanied by excellent figures; and a still more slight one of the common shrimp, Crangon vul- garis, in its first stage only. I give that author’s figure of the first stage of the prawn (fig. 4), in which the locomotive organs are pro- Fig. k.
bably the homologues of the foot-jaws, and the rudiments of some of the true feet ap- pear under the cephalo-tho- rax. The eyes are wholly sessile; there is not the slightest appearance of ab-
dominal members; and the
simple spatulate form of the tail is remarkably dif- ferent from the highly de- veloped and complicated structure of that organ in the adult.
The two following figures
exhibit two successive states
of the young animal, gra-
dually approaching more and more to the adult con-
dition. In Fig /, is seen one of the serratures of the
* Ann. Nat. Hist. vol. ii. p. 178, pl. vi. and vii.
Ix INTRODUCTION.
carapace, the rostrum is produced, the important change nee in the eyes from the sessile to the pedun- culate form has now taken place, the true feet have become evolved, developed, and rudimentary ab- dominal members are perceived, and in fig. m, all these develop- ments are far more ad- vanced, and the animal has nearly approached its final state. Such is, as far as it appeared to me neces- sary to detail it, the
state of our present
knowledge of this very Ae interesting phase in the f \Y—s ae i I\ WS economy of this class | . WON of animals. I have
entered more into de-
>.
=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. <A full-sized male is more than an inch and a half long, and nearly two inches and a half broad; and the anterior legs of such an individual are nearly four inches long, and the hand is three-quarters of an inch broad.
This species formed the type of a new genus established by Dr. Leach, and was at that time the only one known to him. Since that time, however, many others, some before known and placed in other genera, and some since discovered, have been ascertained to belong to it, so that it now consists of between twenty and thirty species, inhabit- ing every quarter of the world. Until lately, however, it has been considered our only indigenous species. It was first described by Montagu in the ‘‘ Transactions of the Linnean Society,” under the name of Cancer floridus ; but, as Dr. Leach very truly says, he must have been misled in supposing it to be identical with Linnzus’s species of the
same name. The Cancer foridus of Herbst, which Mon-
XANTHO FLORIDA. 53
tagu quotes also as a synonyme of this species, is a charac- teristic figure of Zozymus ancus.
It is found in considerable numbers on the coast of Corn- wall and Devonshire, and also in Dorsetshire. It has been ‘observed on several parts of the coast of Ireland. The female produces a large quantity of eggs, which are of a reddish brown colour. Of its peculiar habits nothing is known.
54: CANCERID&.
ding tal g: the
DECAPODA. CANCERID. BRACHYURA.
es
NXantho rivulosa.
Specific character.—Carapace nearly horizontal ; latero-anterior margin with four triangular teeth ; fingers brown, the moveable one grooved above ; the second to the fifth pairs of legs with all the joints ciliated on the upper edge.
Cancer hydrophilus, Hersst, I. t. xxi. f. 124. p. 266. Xantho florida, var. B, Leacu, Trans. Linn. Soc. XI. p. 320. » rivulosus, Epwarps, Hist. Crust. I. p. 394. Roux, Crust.
Mediterr. t. xxxvy. Coucn, Cornish Fauna.
‘Tus species exceedingly resembles . florida, and has been doubtless often confounded with it. There are, how- ever, numerous well marked distinctive characters, as the following description will show on a comparison with that of the former.
The carapace is nearly horizontal, the anterior portion
bs ie
XANTHO RIVULOSA. 55
being very slightly deflexed ; the front nearly straight, projecting, the margin minutely beaded. The latero- anterior margin with four triangular teeth, the posterior of which reaches scarcely beyond the line of the posterior edge of the gastric region; the imequalities of the surface and the intervening grooves, are not very strongly marked. The anterior legs are large and strong, the wrist bituber- culated ; the moveable finger has a distinct groove on the outer side of the upper surface, extending from the joint nearly to the extremity. The remaining pairs of legs are compressed, and the upper edge of all the joints ciliated.
The general colour is yellowish, with red markings; the fingers brown, sometimes but little darker than the rest of the shell. The specimens which I have seen have all been smaller than the full size of . florida.
It appears, then, that the present species differs from the former in the following particulars :—the carapace is much more horizontal, the inequalities of the surface less con- spicuous, the lateral teeth more angular, the front less de- flexed, its margin short and prettily beaded, which is not the case with those specimens of \. florida which I have examined, But besides these comparative characters by which the two species may be distinguished, when ex- amined together, there are others of a positive kind by which the present animal may be readily detected. The moveable finger is grooved ; the whole of the joints of the legs are ciliated on the upper edge, whereas in 1. florida this is the case only with the third jomt. The colour of the pincers in this species is brown, in the other it is quite black.
There can be no doubt that this is the Cancer hydrophilus of Herbst. It is figured also by Savigny in the “ Crustacea
of Egypt ;” it occurs in Risso’s ‘‘ Crustacea of the Neigh-
56 CANCERID®.
bourhood of Nice ;” and Edwards says that it inhabits the western coast of France. In all probability it is identical with XY. florida, “var. 8 digitis concoloribus” of Leach; but Mr. Couch of Polperro was the first to detect it as an English species, and to refer it to its proper name; and it was also detected by Captain Portlock as an Irish species, a specimen haying been obtained at Portruch, in the coun- ty of Antrim. I have been favoured by Mr. Couch with specimens from Cornwall; I have also received it from North Wales, through the kindness of my friend Mr. Ey- ton. Mr. Couch, writing from Polperro says, ‘“ XYantho rivulosa is common with us, rather more so than 1. florida. It is found concealed under stones at low-water mark ; is of rather slow habits, and exuviates much in the same manner as the common crab.” There is indeed but little difference in this respect amongst all the true brachyurous
forms.
DECAPODA. CANCERID. BRACHYURA.
GENUS CANCER.
CANCER, Linn. Leach, Bell. PLatycarcinus, Latr. Edwards.
Generic Character. — External antenne with the basal joint very long and thick, filling the hiatus between the inner canthus of the orbit and the front, and terminating forwards in a strong, angular, tooth-like projection, directed forwards and slightly in- wards, reaching a little beyond the frontal line ; the terminal por- tion is very short and slender, and arises from the internal part of the basal joint, nearer to the cell of the internal antenne than to the orbit. Internal antenne directed forwards, placed in longi- tudinal cells. External pedipalps with the third joint excavated at the anterior and inner margin. Anterior feet nearly equal, robust ; the others, more or less hairy, but without spines. Cara- pace transversely elliptic, sormewhat elevated, with the regions obviously marked; front trifid ; orbits with a strong tooth over the inner canthus; and with two fissures above, and one bhe- neath: the latero-anterior margin on each side extends back to the centre of the cardiac region, and passes off into a sinuous, granulated ridge, which rises over the latero-posterior margin ; it is divided into ten lobes, of which the last is very small, and often obsolete. Eyes placed on short peduncles. Addomen, in the male, five-jointed ; in the female, seven-jointed.
This genus is readily distinguished from its immediate congeners by the form of the basal portion of the external antenne, by the direction of the internal antenne, and by the form of the latero-anterior margin of the carapace,
which is, in this genus, uniformly ten-toothed. There is
58 CANCERID.
but one species of this genus, as now restricted, native of the shores of this country, or indeed of Europe, all the others bemg South American.
The generic name Cancer was applied by Dr. Leach to this, the present genus, as restricted by him; and I have elsewhere* stated my reasons for restoring it, after La- treille had, in the French Museum, assigned to it the name of Platycarcinus, i which he had been followed by Dr. Milne Edwards. When the characters of the present genus were first defined, the only known species was the common large eatable crab of our coasts, the Cancer Pa- gurus of Linneus. Subsequently another species was added by Say, and since that three others by myself, from the South American collection of Mr. Cuming. The whole of these are described in a monograph of the genus just
referred to.
* “ Transactions of the Zoological Society,” vol. i. p. 335.
GREAT CRAB. 59
DECAPODA. CANCERID. BRACHYURA.
GREAT CRAB.
Cancer Pagurus. Auct.
Specifie character.—Shell granulated ; latero-anterior margin ten-lobed, the lobes contiguous, quadrate, entire ; hands smooth.
Cancer Pagurus, Linn. Syst. Nat. XIT. i. 1044. HeEresr, Krab. ti 1xe 59. PENN. Brit. Zool. LV. it. als tere Leacu, Malac. Brit. t. x. Bret, Trans. Zool. Soc. I. p. 341.
Platycarcinus Pagurus, Epwarps, Hist. Crust. i. p. 413
Jun. Cancer inciso-crenatus, Coucu, Cornish Fauna, p. 70.
Tue carapace is transversely oblong, flattened, slightly elevated in the middle, somewhat rounded before and be- hind; the surface minutely granulated, smooth, with the regions but slightly marked. The latero-anterior margin is slightly recurved, divided into ten quadrate lobes, the
sides of which are contiguous, and the margins entire ;
60 CANCERID&.
the last lobe inconspicuous, and passing into the posterior marginal line, which terminates immediately anterior to the posterior marginal ridge. The front trifid, the teeth nearly equal. The orbits are round, with a strong trian- gular tooth over the inner canthus, which does not project as far as the front, and a smaller one between the two superior fissures. The external antenne have the basal joint much elongated, and terminating forwards in an ob- tuse tooth; the first jomt of the moveable portion club- shaped, the second cylindrical. The internal antenne stand forwards, the anterior half beimg folded directly backwards when at rest. The sternum minutely punc- tated, and furnished with small patches and lines of short scanty hair. The abdomen in the male, has the margin fringed with short hair, and the surface with numerous small tufts of short stiff hair; the last jot forming an equilateral triangle: in the female the sixth joint is very large, the terminal one triangular, the sides slightly sinu- ated. The anterior pair of feet large, robust, smooth, without spines or tubercles, minutely granulated ; the hand rounded, without any ridge; the fingers with strong round- ed teeth. The remaining feet slightly compressed, irre- gularly angular, and furnished with numerous bundles of stiff hairs.
The colour above reddish brown, in younger individuals with a purplish tint ; the legs more red; the claws black ; beneath nearly white.
There can be little doubt that this species was the one known to the Romans by the name of carabus, from whence our common name crab.* Pliny, in enumerating
* The common name of the wild apple has probably no reference to the animal ;
it is, doubtless, as Skinner has it, from schrabben, A. S., to scrape, to bite, from the harsh, rough taste of the fruit.
GREAT CRAB. 61
the different kinds of ‘‘ cancer” says,—‘“* Cancrorum genera carabi, astaci, mai, paguri, heracleotici, icones et alia ig- nobiliora.” It would appear by this passage that the term Cancer was applied to the whole of the Malacostracous Crustacea; for not only are the drachyura and some of the larger macroura evidently here designated, but the “alia ignobiliora,” in all probability, indicated all the smaller and less important forms.
The habits of this species have been perhaps more thoroughly investigated, and are better understood than those of most other species. Its large size, and the ex- cellence of its flavour, occasion it to be more sought after as an article of food than any other of the brachyurous species; and hence its habits and the places of its resort have been necessarily much observed by those whose occu- pation it is to procure it for the market; whilst the natu- ralist has found it a convenient species for his more scien- tific investigations, whether as it regards its history or its structure.
It inhabits the whole of our coasts, preferring those parts which are rocky ; and its usual retreats are amongst the holes in the rocks, where it generally retires when not engaged in seeking its food. It is often seen in such situations, even when the tide has retreated sufficiently to render the rocks accessible, as, for instance, among those on the shore at Hastings, where I have often seen them in the pools and caverns, left by the receding tide. These are, however, always small individuals, rarely more than three inches in breadth; the larger ones remain farther at sea amongst the rocks in deep water; and they also bury themselves in the sand, but always in the immediate neigh- bourhood of the rocks. The food of this species, like that
of most others, consists principally of animal matter, such
62 CANCERID A.
as dead fish, and the like; and it is exceedingly probable that the crabs discover their food rather by the smell than by sight, or, at least, by an impression made by the dif- fusion of odorous particles emanating from it, and diffused through the water. Thus they detect the bait which is often placed in such situations that it cannot be seen by them at any distance, and which consists generally of pieces of fish, in which decomposition has already commenced. Mr. Couch, indeed, states in his ‘‘Cornish Fauna,” that ‘ It is found that the freshest (bait) only will attract the crab, whilst for the lobster it is best when hung for several days to become tainted.” And this may doubtless be true to a certain extent; but I have often seen crabs taken with lobsters in pots in which the bait was far from being sweet. The period of life at which the ‘“ Bon crab,” as the female of this species is termed along the western coast, begins to breed is, according to Mr. Couch, when the carapace is about three inches across. The male seeks the female at various seasons; but it would appear that in this, as in the case of the Carcinus manas, this often takes place im- mediately after her exuviation, and that the male watches for the completion of this process, when the female is in a soft and unprotected state. My friend Mr. Richard Couch, thus writes to me on this subject. ‘* When the female retires for exuviation, she is generally accompanied by a male; and when the shell is removed impregnation takes place. If the male be discovered and removed, an- other will be found to have taken his place after the following tide, and this will be repeated for many times in succession.” The spawn is carried by the parent for a considerable period, and is deposited “at all seasons of the year,” according to Mr, Couch; Mr. Hailstone says in March; but it is most probable that it occurs during
GREAT CRAB. 63
the spring and summer, as is the case with so many other species.
It was in the month:of June, 1826, that Mr. J. V. Thompson* “had the good fortune to succeed in hatching the ova of the common crab,” and thus, by perfect and satisfactory observation, demonstrated the theory which his imvestigation of Zoea had already suggested to his mind, of the true metamorphosis of the crustacea; a dis- covery which may rank amongst the most interesting and important that have been made within the sphere of the sciences of observation, not only in the present, but in any previous age. The extreme difficulty of preserving these little animals alive, and ensuring them a supply of their proper food, has prevented the observations of their subse- quent growth from being so satisfactorily carried out as could have been wished; but the doctrine thus established has been confirmed in so many instances by observations on other species of crustacea, that the metamorphosis of these animals may now be considered as a fixed and incontrovertible truth.
The fishery for these crabs constitutes an important trade on many parts of the coast. The numbers which are annually taken are immense; and as the occupation of procuring them is principally carried on by persons who are past the more laborious and dangerous pursuits of general fishing, it affords a means of subsistence to many a poor man who, from age or infirmity, would be unable without it to keep himself and his family from the work- house. They are taken in what are termed ‘“ crab-pots ;” a sort of wicker trap, made, by preference, of the twigs of the golden willow, (Salix vitellina,) at least, in many parts of the coast, on account, as they say, of its great
* See his “ Zoological Researches,” No. I. p. 9.
64 CANCERID&.
durability and toughness. These pots are formed on the principle of a common wire mouse-trap, but with the en- trance at the top; they are baited with pieces of fish, generally of some otherwise useless kind, and these are fixed into the pots by means of a skewer. The pots are sunk by stones attached to the bottom, and the situation where they are dropped is indicated, and the means of rais- ing them provided, by a long line fixed to the creel, or pot, having a piece of cork attached to the free end of the line: these float the line, and at the same time serve to designate the owners of the different pots; one perhaps having three corks near together, towards the extremity of the line, and two distant ones; another may have one cork fastened cross-wise ; another two fastened together, and so on. _ It is of course for their mutual security that the fishermen abstain from any poaching on their neighbour’s property ; and hence we find that stealing from each other's pots is a crime almost wholly unknown amongst them. It is at Bognor, and Hastings, and in Studland and Swanage Bays in Dorsetshire, that I have principally had opportunities of personal observation on these points; and I am also in- debted to my friend Mr. Richard Couch for some interest- ing observations on this subject ; in addition to which I would refer to an excellent account of the crab and lobster fishery, in the 6th volume of the Penny Magazine.
Mr. Richard Couch informs me that on the coast of Cornwall ‘most of these crabs are sold to the lobster smacks; but, that when brought on shore for sale, those measuring six inches across the carapace are sold for two- pence each; those of eight or ten inches, threepence, and the largest from sixpence to eightpence!” If the crabs are not immediately wanted on being taken out of the
pots, they are placed in store pots, which are of the same
GREAT CRAB. 65
form and materials as the others, but considerably larger. They are conveyed to great distances, as far, for instance, as from the coast of Norway to the Billingsgate Market, in well boxes, which are of wood, very strongly construct- ed, and with holes in all the sides to admit of continual change of water, as the boxes are drawn through the sea, attached to the vessel.
The male Crabs are esteemed the best for the table; they are generally larger than the females, and the claws are much heavier. They often weigh eight or nine pounds, and sometimes as much as twelve pounds.
Examples are not few of the occurrence of different spe- cies of Crustacea in armorial bearings. Prawns, Crayfish, Lobsters, and Crabs, are occasionally found, and these, not only as “canting” bearings, or puns upon the name of the bearers, but often as examples of that emblematical allu- sion in which the heralds of former times so much delight- ed. This is not, perhaps, the place to enter into much serious disquisition on the utility of such a custom; and yet one can scarcely read the quaint, but wholesome mo- ralities, of good old Guillim, and other professors of the gentle science, without some misgivings that the matter-of- fact and prosaic scorn of such emblems, which has suc- ceeded to the more poetical
may we not also say the happier credulity of olden time, may have given us no equivalent advantage for the loss of those striking and epigrammatic maxims. I shall venture, therefore, to in- dulge an old fondness for this ancient, and really not un- interesting “science,” (I do not use the term in its modern and critical sense,) by giving some occasional examples of Crustacean Heratpry. And in doing this I cannot but refer to Mr. Moule’s “ Heraldry of Fish,” as a work not less interesting in its historical and technical details, than
F
66 CANCERID®.
tasteful and elegant in its illustration. We will presume, and it appears extremely probable, that the Heraldic Crab is the present universally known and useful spe- cies. Mr. Moule observes, ‘“‘The Crab, the emblem of inconstancy, appears on a shield of Francis I., one of the finest specimens of art in the collection of armour at Goodrich Court ; and, according to Sir Samuel Mer- rick, the Crab was intended as an allusion to the ad- vancing and retrograde movements of the English army at Boulogne, under the celebrated Charles Brandon, Duke of Suffolk, in 1523.” A golden Crab, according to the same authority, was one of the cognizances of the Scrope family, and is found on the portrait of Henry, Lord Scrope. ‘The Crab also appears as a crest on the seals of several mem- bers of this noble family.” *
The families of Bridger of Sussex, Crab of Scotland, Bythesea of Kent, and some others, also bear this ani-
mal in their coat-armour.
* Moule’s “ Heraldry of Fish,” p. 231.
DECAPOD4A. CANCERIDE. BRACHYURA.
GENUS PILUMNUS
CANCER, Linn., Pennant, Herbst. PILUMNUs, Leach, Edwards,
Generic Character.—External antenne long and setaceous ; the basal joint not continuous with the surrounding parts, but sepa- rated by a distinct line, and filling the inner canthus of the orbit ; second joint nearly as broad as it is long, and moveable with the remaining portion; third joint longer than the second. Jnternal antenne with the last point of the peduncle club-shaped. Exter- nal pedipalps with the third joint transversely quadrate, the antero-internal angle emarginate. Azterior pair of feet unequal, robust, rounded ; the remaining pairs rounded above, flattened beneath ; the second pair not longer than the third or fourth. Carapace convex, the anterior part much curved from before backwards ; the surface even; the latero-anterior margin extend- ing backwards as far as the posterior part of the gastric region ; JSront slightly prominent; orbits elliptical, the inferior margin spmulose. Abdomen, in each sex, seven-joited; in the male, the third joimt the broadest, the succeeding ones diminishing regu- larly to the apex ; in the female, all the joints sub-equal.
68 CANCERID#.
DECAPODA. CANCERID. BRACHYURA.
Pilumnus hirtellus. each.
Specific character.—Superior margin of the orbit not spinous, but, with the front, minutely denticulated ; latero-anterior margin armed with four spines (ex- clusive of the external angle of the orbit); hands slightly tuberculated.
Cancer hirtellus, Linn. Syst. Nat. I. 1045. Puzwn. IV. t. vi. f. 1. p. 9. Pilumnus 45 Leacu, Trans. Linn. Soc. XI. p. 321; Malac. Brit. t. xii. Epwarps, Hist. Crust. I, p. 417.
Tue carapace is smooth, anteriorly much incurved ; its length to its breadth, as seven to ten; the front broad, finely toothed, divided in the centre by a deep fissure ; the latero-anterior margin evenly arched, furnished, ex- clusive of the outer angle of the orbit, with four strong sharp spines, the anterior two being frequently bifid ; the hinder one the strongest, and in a line with the posterior part of the gastric region. The upper margin of the orbits very minutely toothed ; the lower margin spinous, and in
each a small fissure. The anterior pair of legs are remark-
Pee ee ee ee ee ee ey
PILUMNUS HIRTELLUS. 69
ably strong, thick, and rounded; they are somewhat un- equal, in some the right, in others the left being the larger; the wrist is tuberculated, and furnished with a single spine, and is slightly hairy; the smaller hand is tuberculated on its upper and outer surface, the larger one almost entirely smooth ; the moveable finger much curved, the fixed one triangular, and strongly toothed. The remaining legs are slightly rounded above, flattened beneath; they are covered with numerous hairs, and there are also a few on the wrist and on the anterior part of the carapace, which is also covered with short down. The abdomen in the male is breadest at the proximal margin of the third joint, thence diminishing regularly to the extremity, the third to the seventh, thus forming a long acute triangle. The abdomen of the female is of the form of a long ellipse, with the proximal portion truncate ; its margin is frimged with long hair. The colour of most individuals is brownish red, with obscure yellowish spots; the anterior legs brownish red, the fingers light brown; the remaining legs red, with ob- scure yellowish bands. In many the brownish red colour
is replaced by a dull purple.
In. Lines. Length of the carapace - : : , mG 7 Breadth of do, : : : : : ] 0
The present species is the only one of the genus found on our coast, and it may be readily distinguished from all the foreign species by the absence of spines on the superior margin of the orbit. The figures m Dr. Leach’s great work are very inferior, and would scarcely serve to dis- tinguish it, were any of the other species indigenous to this country with which it might be compared. They must have been taken from immature specimens; but even of
such they torm but very erroneous representations.
70 CANCERID 2.
It is a common species on all the western coast of England, having been taken in Cornwall, and along the coast of Devonshire, Dorsetshire, Hampshire, and Sussex. Dr. Leach mentions it being taken under stones at low tide, but those which I have obtained have been from deep water. I have dredged them in Swanage Bay, Dorset- shire ; but the finest specimens J ever saw, I procured from prawn and lobster pots at Bognor, in September, 1842. It is worthy of remark, that amongst twenty or thirty specimens, I found only one female, a dead and mutilated one. It would appear from Mr. Thompson’s Catalogue to be widely distributed on the coasts of Ireland, although occurring in small numbers.
The different species of this genus are very widely dis- tributed. They inhabit the Mediterranean, the Red Sea, the East Indies, and other parts of the coast of Asia, Australia, and both the eastern and western coasts of South
America.
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—_o oO Sc rc eee ee ee
DECAPODA. CANCERID “i. BRACHYURA.
GENUS PIRIMELA.
CANCER, Montagu. PrIRIMELA, Leach, Desmarert, Edwards.
Generic Character—External antenne nearly half the length of the carapace ; the basal joint short, filling a space at the inner angle of the orbit; the moveable portion inserted at its inner eanthus. Internal antenne lying somewhat obliquely in their cavities, which open immediately under the margin of the front. External pedipalps extending forwards beyond the oral cavity, and covering the epistome ; the third joint sub-quadrate, emargin- ate at the inner margin, about one third from the anterior angle, for the articulation of the palpes. Anterior legs small, compressed ; the remaining pairs of moderate length, much compressed ; the terminal joint nearly straight. Carapace nearly as long as it is broad, convex, with numerous strongly-marked elevations ; the anterior margin arched, the posterior much narrowed ; front tri- dentate, the middle tooth the longest. Ordits, with two fissures above. Eyes, not thicker than their peduncles, which are very thick at the base. Abdomen, in the male, five-jointed ; in the female, seven-jointed.
Of this genus one species only is at present known. It differs from all the other Cancerida, in the circumstance that the external pedipalps, instead of being confined to the opening of the oral cavity, are advanced over the epistome to the antennary cavities.
In its affinities this genus probably approaches the Por- tunida by the genus Carcinus ; possibly Panopeus may be
intermediate between them.
12 CANCERID#.
DECAPODA. CANCERID .
BRACHYURA.
Pirimela denticulata.
Cancer denticulatus, MonracGu, Trans. Linn. Soc. IX. p. 87. t. ii. f. 2. Pirimela denticulata, Leacu, Malac. Brit. t. ili. I. p. 424.
Epwarps, Hist. Crust.
Tue general form of this pretty Crab will at once strike us as differing very greatly from all those which have preceded it. The carapace is very little broader than it is long; the anterior margin is so much arched, as to form nearly a semicircle, whilst the posterior portion is regularly and greatly narrowed. The latero-anterior margin is armed with four prominent teeth, which are triangular, slightly curved forwards and upwards, and flattened. The front is tridentate; the two external teeth are triangular, flattened, curved a little upwards and inwards, and small ; I have seen specimens in which they are almost obsolete ; the middle tooth is spiniform, and considerably longer than the others. The orbit is also furnished with similar teeth, of which there are two above, the inner one being the
larger ; one beneath, and one at the external angle. The
PIRIMELA DENTICULATA. 73
surface of the carapace is convex, the regions distinctly marked, and the anterior half has several rounded eleva- tions, but the hepatic regions are excavated towards the margin. The anterior pair of legs are of moderate size, equal; the wrist has three carine, each of which termi- nates in a small tubercle near its articulation; the hand has four distinct carine, two on the upper, and two on the outer surface; the moveable finger has two longitu- dinal grooves; and both the fingers are moderately and evenly toothed. The remaining legs are compressed and ciliated at the edges, particularly the fifth pair. The ab- domen of the male has five joints, that of the female seven; the latter is of a lanceolate form, and furnished at the margin with numerous long hairs. The usual’ length of the carapace in English specimens, is not more than six lines, and its breadth nearly seven; but I have m my collection specimens from the Mediterranean, of which the carapace is nine-tenths of an inch in length, and an inch in breadth.
The colour in some specimens is greenish, in others purplish and brown mottled.
This must be considered as one of the least common species belonging to our coasts. It was first described by the indefatigable Montagu, who states that it was sent to him by Mr. Boys, “as the produce of the coast of Sand- wich ;” and he adds, “I have seen a specimen in the cabinet of Mr. Donovan, which I am assured came from the coast of Scotland.” Leach mentions the latter specimen, and says that he obtained a fragment from the same locality ; two other places on the south coast of Devon, Bantham and Torquay, are also named by that celebrated naturalist as its habitats. Mr. W. Thompson found three specimens washed ashore at Compton, in the Isle of Wight. 'The
[ay |
poe)
74 CANCERID &.
same gentleman mentions two localities in Ireland where it has been found, namely, the coast of Antrim, and La- hinch on the coast of Clare. Of its habits nothing, I believe, is known. It would appear not to approach the shore, as the only living examples on record were obtained
from the refuse of trawl-fishers,
DECAPODA. PORTUNID. BRACHYURA.
GENUS CARCINUS, Leach.
CANCER, Auct. CaRcINUS, Leach, Edwards.
Generic Character. — External antenne \odged in the inner canthus of the orbit, the basal joint narrow and sub-cylindrical. Internal antenne lying obliquely in nearly circular cells. Ev- ternal pedipalps with the third joint excavated on the anterior half of the inner margin, and dilated at the outer side. First pair of feet somewhat unequal, the wrists with a strong spine on the inner side, standing forwards ; the hands glabrous on the outer surface ; second, third, and fourth pairs slightly compressed, with the terminal joint long, styliform, somewhat four-sided ; the ji/th pair more compressed, formed for swimming, the terminal joint lanceolate. Carapace slightly convex, rather broader than it is long ; the front somewhat projecting, and forming, with the orbits and the latero-anterior margin, a nearly regular curve, which ex- tends back to a lme drawn through the middle of the genital region ; latero-anterior margin strongly toothed. Orbits, oval, directed forwards, very open above, with a single fissure, both in the superior and inferior margins. Eyes, smaller than their peduncles. Abdomen, in the male, five-jomted ; in the female, seven-jointed.
This genus, of which one species only is at present known, constitutes the nearest approximation amongst the swimming Crabs, to the cancerida; the osculant genus in that family which bears a near affinity to this, is Pano-
peus.
76 PORTUNID&.
DECAPODA. PORTUNID.. BRACHYURA.
COMMON SHORE-CRAB. HARBOUR-CRAB. Carcinus Menas.
Cancer Menas, PENN. Brit. Zool. IV. p. 3. t. iii. f. 5.
Portunus 4, Leacu, Edinb. Encycl. VII. p. 390.
Carcinus 4 Leacu, Ib. p. 429. Trans. Linn. Soc. XI. p. 314. Malae. Podophth. Brit. t. v. f. 1—4. Epw. Hist. Crust. I. p. 434.
Tue carapace of this common species is rather broader than it is long, minutely tuberculated, the regions very distinct and rather prominent. The front is divided into three lobes, of which the middle one is rather longer than the others; they are distinctly margined and slightly turned upwards ; the orbits very open above, with a single fissure in the superior, and one in the inferior margin, and
a strong tooth at the outer, and a smaller one at the
COMMON SHORE-CRAB. 77
inner angle. The latero-anterior margin has four strong flattened triangular teeth, directed forwards; the second and fourth more acute than the others. The latero-pos- terior margin extends backwards in a straight line, and the posterior margin has a distinct elevated waved border. The external antenne are placed in a hiatus at the mner canthus of the orbit, which they do not entirely fill. The basal joint is rather narrow, and somewhat round. The internal antenne are lodged rather obliquely in large open fosse. The anterior pair of feet nearly equal, the wrist with a strong but not very prominent tooth at the upper and anterior angle; the hand smooth externally, the upper margin with a double longitudinal carina ; the fingers toothed. The second, third, and fourth pairs slightly compressed, the terminal joint very long, styliform, somewhat four-sided; the fifth pair more compressed, the terminal joint broader and flatter than in the others, form- ing an approximation to the more perfectly natatory form observed in the other genera of the family. The two last joints of the second pair, and the three last of the fifth pair, ciliated on the under edge, and the latter also on the upper edge of all the jomts. The abdomen, in the male, five-jomted, forming a slightly acute triangle from the base of the third joint ; in the female, it is seven-jointed, broad, with rounded and ciliated margins, the terminal joint rather abruptly smaller than the preceding.
The general colour of this species is a blackish green, darker anteriorly, and often dull red underneath; they vary, however, considerably, both in the hue and in the intensity of the colour. The young are often mottled with white, and sometimes almost wholly white, with perhaps a single black spot on the centre of the carapace.
This is the only known species of the genus, and is
78 PORTUNID&.
undoubtedly the most common Crab of our shores. On every part of the coast, it is found in numbers ; on sandy beaches it is constantly left by the receding tide, concealing itself under stones, and on being disturbed, either runs to regain its natural shelter in the retiring sea, or hastily buries itself completely in the soft sand. It is, however, by no means confined to the sandy shores; it is often dredged in rather deep water, though its favourite haunt is in the former situation. Such habits as these require a power of remaining for a considerable time out of water, and we find this to be remarkably the case with this species ; it cannot, it is true, like the land Crabs, live at a great distance from the sea, requiring only the moisture of a humid atmosphere, to preserve their branchiz in a state fit for respiration, but it will remain active for many hours, and probably for days together, if it have the opportunity of burying itself in sand which is wetted with sea-water : differing in this respect from the more typical forms of the family, which require constant immersion in deep water. It will even, as Mr. Couch informs me, survive its im- mersion in fresh water for several hours.
This Crab is much eaten by the poorer classes on the coast, and great numbers are also brought to the London markets, the flavour being very delicate and sweet. On some parts of the coast, a small black variety is found, which the fishermen consider as a distinct species, distin- gnishing them as the black and the green crab. This variety is found in deeper water, and is believed to interfere with the success of their prawning, by either destroying the prawns, or frightening them away from the pots. It is certainly merely a variety.
Its food consists principally of the fry of fish, of shrimps,
and other Crustacea, but it will also feed upon dead
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EE
site 4 7 COMMON SHORE-CRAB,. 19
fish, and almost any- other animal substance. Indeed, the most common method of taking these Crabs at Poole, where numbers are caught by the fishermen’s children, is by tying a mass of the intestines of either a fowl or of any fish to a line, and hanging it over the quay: the Crabs seize upon this bait, and are drawn up in considera- ble numbers. Mr. Hailstone states, that they attack mussels, and that he once saw one carrying about on its hand a mussel which had closed its shell upon it. They run with considerable rapidity, and with an awkward sidelong gait ; and they lurk in pools of water left by the tide, partially concealed in the sand, but with the anterior part of the carapace, including the eyes, exposed, so as to watch for the approach of their small living prey, on which they spring with great activity. They are, however, very timid and wary, and will not move if they discover that they are watched. ‘They simulate death, if disturbed, as completely as do many coleopterous insects.
The process of exuviation takes place at various parts of the year, from spring to autumn. I have found the fe- male carrying spawn as early as April, and as late as Sep- tember.
The