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FEINTED FOH lOlfGlUK, OHlffi.BaoW^^ GREEN. & I.OHGiKNS, Pim-JOTOSTIU, BOW, Jj-SD JOHlir 1,333,011, -OypEB GOWER STREET, 1840.
CONTENTS.
PART T.
A GENERAL SURVEY OF THE TESTACEOUS MOLLUSCA.
CHAP. I.
Introductory Observations. — The Mollusca in general. — The Characters and Analogies of the three primary Divisions or Classes ; namely, the Acrita, the Radiata, and the Testacea — Notes on the Bibliography and the existing Classifications of the latter - - - Page 1
CHAP. II.
On the Testaceous Mollusca in general, the primary Divisions, and their Analogies to the Vertebrata and Annulosa - - - 26
CHAP. III.
On the Order of Gasteropoda, its primary Divisions, and the Characters and Analogies of the Muricidce and the Turbinellids - - 53
CHAP. IV.
The Zoophaga, or Predaceous Shell-fish, continued. — The Family of Volutida;, or Volutes - - - - - 97
CHAP. V.
The Predaceous Gastropods continued — The Strombidce, or Wing- Shells - - - - - - -136
CHAP. VI.
On the Phytophagous Tribe of Shell-fish The primary Divisions or
Families — The Helicidffi, or Land and Freshwater Snails - 158
Vlll CONTENTS.
CHAP. VII.
The Phytophagous Gastropods continued. — The TurbidaD, or Marine Snails - - - ... Page 1V.'>
CHAP. VIII.
The Phytophagous' Gastropods concluded. — The Haliotidae, or Ear-Shells, and the Naticidie, or Nerits - - . . £28
CHAP. IX.
On the Aberrant Tribes of the Gasteropoda, — namely, the .Scutibranchia, or Limpets; the Cyclobranchia, or Chitons; and the Pteropoda, or Crystal Shells - - - - - - 241
CHAP. X.
On the Order Dithyra, or Bivalve Shells — The Affinities and Analogies of the Unionidas, or River Unios - _ . . 253
PART II.
A NATURAL ARRANGEMENT OF THE UNIVALVE AND BI- VALVE SHELL-FISH COMPOSING THE ORDERS GASTERO- PODA AND DITHYRA OF THE CLASS TKSTACEA - 29^
EXPLANATION OF TERMS USED IN DESCRIBING THE SHELLS OF TESTACEOUS MOLLUSCA - - - 391
APPENDIX - - - - 405
A TREATISE
ON
MALACOLOGY;
OR
SHFTT.S AMD SHFT.T.FTSH
ERRATA.
Page 192. line 3. from bottom, for "LucideUa" read " Lucidula." 193. lines 19. and 36. for " Heraicycla" read " Polygyra."
CHAPTER I.
INTRODUCTORY OBSERVATIONS. THE MOLF.USCA IN GENERAL.
THE CHARACTERS AND ANALOGIES OF THE THREE PRI- MARY DIVISIONS OR classes; NAMELY, THE ACRITA, THE
RADIATA, AND THE TESTACEA. NOTES ON THE BIBLIOGRAFHY
AND THE EXISTING CLASSIFICATIONS OF THE LATTER.
(l.) In our last volume^ we completed the survey of those great divisions of animals which, from possessing a bony skeleton, are called the Vertebrata. Our pre- sent treatise will he devoted to a far more numerous, hut less interesting, assemblage, — namely, the Mollusca, or soft animals. These, with few exceptions, are either inhabitants of the ocean or of fresh waters. The majority are little known even to naturalists ; and
B
f
^ SHELLS AND SHELL-FISH. PART I.
hundreds of our readers may pass their lives without seeing one, save the slugs in their gardens, or the empty shells they once inhabited. Their aspect to the ordinary observer is strange and unprepossessing, with- out either the gracefulness of form, the activity of motion, or the richness of colouring which ornaments insects and vertebrated animals. Their manners and economy scarcely come within our cognisance, for their actions are carried on in an element we do not in- habit ; hence they are rarely witnessed, and a few partial details is all that has yet been gathered to eluci- date their history. Their soft and slimy bodies cannot be preserved so as to interest us even by their appear- ance, or to become objects of beauty or of popular interest ; they are, in short, almost passed, '' unheeded and unknown," except by the eye of Science.
(2.) The object of the series of volumes we are now producing, is, to give to the world what has never yet been attempted, — a philosophic survey of the works of nature, based upon the harmonious relations which every part bears to the whole. Partial systems, ap- plicable to one branch only, and a crowd of anatomical facts, have been either omitted, or but slightly touched upon, as mere accessory helps to the paramount object of our labours, ^^e have, indeed, got through the almost herculean task of arranging the whole of the Vertehrata according to their natural affinities and rela- tions, even down to the sub-genera ; but to follow up this plan with the annulose and the molluscous animals, would not only swell the Cabinet of Natural History to three times it prescribed limits, but would demand a knowledge which, individually, would be superhuman. The great truths, or, rather, the leading one, which the enlightened reader should have constantly brought before him is, the unity of plan in the creation : this might be lost sight of, if the attention was long withdrawn from such enlarged concei>tions, and occupied by a mul- tiplicity of small details, fit only for the technical de- scriber and the anatomical demonstrator.
CHAP. I. PLAN OF THE WORK. S
(3.) Under all these circumstances, we must therefore treat the molluscous groups with great brevity : the lead- ing divisions, indeed, of the whole will be briefly stated, sufficient to guide the researches of those who may be disposed to adopt our views of natural arrangement, and to analyse their contents ; but this will be entirely subordinate to the primary intention of this volume, which, it will be seen, is almost exclusively confined to the Testacea. Limited as is our space, we shall endeavour to fill it in that way which promises to be of the greatest permanent, as well as practical, advantage to science. The arrangement of one class of the Mol. lusca, founded upon analysis, is obviously more valu- able than a theoretical digest of the w'hole. We are seeking to place zoology upon a new basis. To discover and develope, as far as in us lies, the fundamental prin- ciples of the natural system ; and to exhibit its compo- nent parts — not as detached portions, as if each had its own set of laws and its own little system of arrange- ment, but — as a vast and connected whole, throughout which the utmost harmony and the most perfect unity of plan pervades. To do this, how^ever, with any degree of success, requires a fulness of detail, insepa- rably connected with the comprehensiveness of the subject, and the novelty of the design. It is due, not only to the scientific public, but to the labours of those great men whose opinions now reign paramount, that the systems now in use should not be lightly set aside. Hence a variety of details, unnecessary under other circumstances, becomes absolutely essential in these. Now, of the three classes of molluscous animals, the Testacea, or shell-fish, is that which possesses the greatest degree of popular, and even of scientific, in- terest. Their beautiful shelly habitations form some of the most interesting objects in our public museums and private collections. And although we should not consider ourselves bound to make this the only reason for a neglect of the other classes of the MoUusca, yet, nnder existing circumstances, we shall so far concede to
B 2
4 SHELLS AXD SllKLL-FISH. PART I.
popular taste^ as to devote our present volume almost entirely to so favourite a branch. This plan will enable us to submit nearly the whole of our investigations to the public ; while we trust to do the same hereafter in re- gard to the remaining classes in a separate publication.
(4.) The innumerable groups of beings which we comprehend under the general name of Mollusca, are at once distinguishable from all other animals^ by having no internal bones^ like the Vertehrata ; or no joints to their body and limbs^ like the Annulosa, or insect tribes. In the first, the skeleton is internal ; in the latter, it is ex- ternal ; but, in the Mollusca, it is entirely wanting. We might fill several pages on these anatomical dis- tinctions ; but simplicity is the soul of instruction ; and we feel assured, that in following this rule, in the pre- sent instance, we are saving the unscientific reader a world of perplexing circumlocution.
(5.) We shall first glance at those characters drawn from the nervous system, which, it is thought, sepa- rate the Mollusca irora the Vertehrata and the Annulosa. On a former occasion *, we have stated that their nerv- ous system is variable,- and that this variation pointed out the secondary divisions or classes, under which the leading zoologists of the age have, almost unanimously, arranged them. Thus, in the Acrita, or polypes, the nervous system has been called granular ; these granules, innumerable and minute, being generally dispersed over the bodies of these animals, which resemble " masses of transparent, homogeneous, mobile, and sensible pulp, and thus impregnating the whole with sensibility ."t In
* Classification of Quadrupeds, p. 37.
f Such, at least, is the definition of the Acrita of MacLeay; but our recent researches among the Mollusca induce us strongly to doubt the propriety of placing therein thegreater part of thoseminute animals wJiich that celebrated naturalist has arranged with the corals. Our present im- pression is, that the whole, or nearly so, of the true Acrita, are com- pound zo<)()hytes, or, in other words, plant-like animals; that the Ro. tifern and Infusoria are only prototypes of the Acrita in the circle of the lladiatn ; and that theaimulose intestinal worms are the same among the Annulosa. As for the Parcncliipnnta, it will be seen we have had no hesitation in placing them as the representatives of this class in the most aberrant order of the testaceous Mollusca. We feel, in short, more and more persuaded that the real contents of the order Ct/clobrancli/n cainiot be determined until the entire class of Acrita has been sufficiently ana-
CHAP. I. PRI3IARY DIVISIONS OF MOLLUSKS. 5
the second class, or the Rauiata, the nerves are ar- ranged in a radiated or star- like manner ; while in the testaceous Mollusca, or Testacea, the nervous system resides in four ganglions, either united in pairs, or altogether, which are embraced by a medullary collar.
(6.) It would thus appear that the three great divisions of Mollusca are as much distinguished by their ana- tomical peculiarities, drawn from their nervous system, as they are by their external and more obvious cha- racters. It is by these latter, however, that they are made intelligible to the generality of readers. Every one, therefore, will be at no loss to understand the ex- ternal distinctions of these primary divisions : 1. The Testacea, or shell mollusks ; 2. The Raihata, or radiated mollusks ; and, 3. The Acrita, or polypes. The first being represented by shell-fish ; the second, by starfish, sea eggs, and medusas ; and the third, by corals, polypes, and other plant-like animals. We shall now, in the first place, point out the manner of their con- nection to the higher classes of animals, with the object of showing that they form an integral part of that vast circle which comprehends the whole of the animal world.
(7.) The primary distinction of vertebrated animals is, their being possessed both of an internal column, or back-bone, and of legs or other members which give them the power of locomotion : it follows, therefore, that if we found among the soft Mollusca any animals which really possessed these characters, however slightly de- veloped, we should consider them as forming the pas- sage from one class to the other ; that is, from the Ver- tehrata to the Mollusca. Now, there is a whole tribe of animals which really present us with such a struc- ture, and yet, in all other respects, they are so unlike the Fertehrata, that every writer places them with the
lysed. Between the Doridee and the Branchiopoda, there must be, or have been, very many intervening forms : and we begin to think th;it Ciivier may not be very wrong in placing many, if not all, of his nakiiA Acephala close to the Branchiopoda. But the analysis of the Acrita can alone de- termine this question.
B 3
6
SHELLS AND SIIELL-FISH. PART I.
Testacea. This tribe is the Cephalopoda, or cuttlefiph. It is among these only^ out of the whole class of Mol- lusca, that we find a distinct, and often rigid, back-bone, — not, indeed, jointed or articulated, but performing the same office as the vertebrated column of a quadruped or a bird : others of its class have no limbs whatever ; but the cuttlefish have immense arms, which are also used as legs ; by these they crawl with the greatest facility on the bottom of the sea, swim quickly in the water, and retain the most forcible hold of such ani- mals as they prey upon. The eyes of nearly all Mol- lusca are either small and indistinct, or are entirely wanting ; in these, however, the eye is large, and as fully developed as in any vertebrated animal. There cannot, therefore, be the least doubt of the close ap- proximation of the Cephalopoda to the Vertehrata ; and as a large proportion of the fossil species were fur- nished with spiral shells, it follows that the testaceous class comes immediately after the Vertehrata. This affinity being established, we are at no loss to discover the point of junction between this and the next class, or the Jcrita. The singular naked animals forming the Nudihranchia of Cuvier, have been very properly placed by many authors close to the tunicated polypes (^Tunicata). Again, on the other side of the circle of Acrita, we have the genus Zoanthus and the Poli/pes charnues of the French Avriters, closely connected to the Radiata by Friapulis and other kindred forms ; while the last vestige of the radiated structure is seen in the Cirripeda : these latter animals, however, by their arti- culated limbs, are yet removed out of the confines of the Radiata, although they become the first group in the Annulosa, — thus standing in precisely the same re- lation as the Cephalopoda do to the Vertehrata. ^Ve have now traced the chain of affinity into the annulose, or insect class ; and it only remains to inquire how these latter are connected to the Vertehrata, or, in other words, how the animal circle is made out and closed. On this point, again, the labours of our predecessors
CHAP. I. RANK OF THE TESTACEA. 7
have removed all difficulty^ and even doubt. The Anne- lides have the joints of their bodies, like the common earth-worm, disposed in rings, but yet they offer the extraordinary character of red instead of white blood : hence^ they are always called red-blooded w^orms. There is, to be sure, no vestige of any internal support to the body, such as we have seen in the Cephalopoda ; but every one must be struck with the resemblance which exists between a worm and an eel, — the one being, in form, almost the miniature of the other. This re- semblance, moreover, is carried much further by certain eel-shaped fishes, which are destitute, not only of fins, but of eyes ; while in others^ as the genus Myxine, the vertebral column, or back-bone, is hardly to be dis- tinguished. It is impossible, therefore, for this grad- ation to be more perfect. Every naturalist of the least repute has viewed the connection of the Anne- lides to' the fishes in this light ; and thus are all the classes of the animal kingdom united into one vast circle.
(8.) Of the three divisions of the Mollusca, — namely, the Testacea, the Radiata, and the Acrita, — it is obvious that the latter are the lowest in the scale of animal life; the superiority of the Testacea to the Radiata must also be admitted, when we come to compare the or- ganisation of one with the other. The shells of the Echinid(B, the most typical group of the radiated animals, are certainly as beautiful and complicated in their con- struction— although not, perhaps, in outward appear- ance — as those of the Testacea ; but we must look to the animals themselves. The EchinidcE show not the least indication of that form which belongs to verte- brated animals : although provided with short tentacula, which are supposed to assist them in removing from place to place, they yet move so slowly, that a snail, in comparison, may be said to run : thus the Echinus, al- though with tentacula, — which are supposed to perform the office of feet, — can scarcely remove itself a few inches; the snail, which has no foot or similar processes,
B 4
8
SHELLS AND SHELL-FISH. PART I.
crawls on its belly, at what, in comparison, is a good round pace. The typical Testacea are all provided with eyes, however small, and with feelers ; but the Echinidce have none, properly so called ; they are, in fact, de- cidedly lower in the scale of creation than the shell- fish ; for, while the whole of the Radiata are destitute of eyes, those of the Testacea, in the pre-eminently typical division (the Zoophaga), and of the Cephalopoda, are generally very perfect, and always present. This accords exactly with what, from theory, we should have supposed : that the Testacea, being nearest allied to the typical Vertehrata, would consequently be more perfectly organised ; while the Radiata, being cut off, as it were, from the Vertehrata, by the intervention of the Arinu' losa, become further removed from the great types of animal perfection, and, consequently, exhibit an inferior developement. The Testacea are, therefore, the most perfect of all the Mollusca.
(9-) Having now indicated, although with more brevity that we could have wished, the relative station of the testaceous Mollusca, both in regard to other animals and their own class, we shall direct our chief attention to the exposition of their natural and circular arrangement. Although we so far concede to the popular taste for conchology (as the '' art " of arranging shells and other testaceous Ijodies is called) as to devote this volume exclusively to the testaceous Mollusca, we can- not sacrifice our conviction on the principles upon which tliese animals should be studied, or fall into the common method now in use of writing upon shells, independent of all consideration for the animals by which they are inhabited. To dignify any pursuit of this kind by the name of Science, seems to us quite misplaced ; since it would be hardly more absurd to classify birds by the colour of their eggs, or beetles by the shape of their wings, than to projjound an arrangement of shells, with- out a paramount regard to the animals which they cover. It is quite right that collectors of these elegant objectSj who mix up with them shelly cases of insects
CHAP. I. IIEMARKS ON CONCIIOLOGY. y
(Cirripedes) fragments of worms (Annelides), hack- bones of cuttlefish^ gill covers of sea hares (Aplysia), Sec, should arrange them in their cabinets upon some plan_, and give them names ; but no one will maintain that this amusement deserves to be called science.
(10.) One of the first zoologists of this country, in speaking of the utter ignorance which exists on the natural arrangement of the Testacea, and the high importance that belongs to the inquiry, makes the fol- lowing remarks : — " At all events, it is not to those collectors who are solely intent on the external form of a shell, or the streaks of colour w^hich ornament it, that the hope of discovering the true arrangement of the Mol- lusca can be held forth. The study of shells appears, indeed, to be indispensably necessary to the geologist ; and, no doubt, the testaceous covering of an animal is always so intimately connected with its structure, that it would be unpardonable in the naturalist, who ought to leave nothing without investigation, to forget shells. But, on the other hand, when we call to our recollection the lamentable error committed by Linnaeus and his disciples, in not following the example of our celebrated Lister in the arrangement of the Mollusca, we be- come convinced there was about as much hope of their ever arriving at the truth by the means they chose to adopt, as that a collection of the wings of different in- sects should ever instruct us fully in the natural history of the animals to which they belong. It is said that Klein formed an ornithological cabinet, in which the feet and beaks of birds were only to be seen ; because, according to his notions, they were all the parts re- quisite for the proper arrangement of the feathered creation. He thought that it was possible to be a good ornithologist, without knowing the least of a bird but its beak and claw. We may, indeed, laugh at this ; but, at the same time, we ought to inquire whether similar ridicule may not, with justice, be extended to those conchologists, who, having procured a shell, describe and classify it without deigning to bestow a single thought
10 SHELLS AND SHELL-FISH. PART J.
on the nature of the poor animal which constructed it for its habitation.* A curious arrangement, as might have been expected, has come of this method of pro- ceeding; for we have annulose animals i' (or insects) united to true Mollusca, merely because they have shells; and true Mollusca separated from this division, merely because they have no shells. In some cases, even, as in the genus Limax, it is sufficient for the shell to be small, in order to set it wide asunder from animals of the same family : but it would be endless, as well as useless, to detail the violations of natural order mani- fested by Linnaeus in his systematic arrangement of the mollusks, which have so truly constituted .his stum- bling block. It cannot, however, be denied, that, could we adopt his notion as to the nature of the animals, the principles upon which he arranged their testaceous co- verings are excellent. To those who admire the splen- dour of the pencilling, the beauty of the enamel, and the variety of sculpture, which exist in shells, it might be depriving them of an innocent amusement, to object the trivial nature of their study as leading to no general results ; but it may be as well to remind them, that, unless they add to their satisfaction and to their know- ledge by studying the structure of the animals them- selves, there is no more science in the disposition of their cabinets, than may appear in the tasteful arrange-
* A modern compiler, who has been at some pains to draw up what he considers some general observations on the " Principles of Conchology," very properly refrains from bestowing upon it the name of a science. " Conchology," as he observes, " is the art of arranging the protecting bodies of testaceous " (and he might have added of annulose) " animals, so as to enal)le us to recognise them promptly and certainly, without giving any attention to the animals which they have contained, or contain, or, at least, regarding this part a< a matter of very minor imiiortaiice." Inde- pendent of the assistance this '' art " bestows to the studies of the geologist, he further observes, " it may almost be regarded as a study nearly idle and useless by all true zoologists." Nay, he continues, "it is really to this cause that conchology, properly so called, owes both the continuance of its existence, and the daily increasing efforts of enlightened naturalists, who endeavour to give it sure priMcii)les and rules." He omits to inform us, however, how these sure principles and rules can be attained in an " art " which absolutely rejects that solid foundation for them, upon which their true knowledge depends, — that is, a primary regard to the principles of the variation in these animals.
f The CirripedeSy or barnacles.
CHAP. I. REMARKS ON CONCIIOLOGY. 11
ment of porcelain on a mantelpiece. Separate the shell from the animal, and much less acquaintance with the natural system is to he derived from their inorganic covering, than Klein obtained of his birds_, by seeing only their beaks and claws." *
(11.) The above sentiments on the insufficiency of the shell, in all cases, to determine its place in the natural system, we are free to confess, were held by us for many years. But the results of that analysis now given to the public, have materially modified, if not altered, this opinion. It is needless, perhaps, to repeat, that a primary regard must always be had to the nature of the mollusk itself ; and that, without this knowledge, there are certain forms of Testacea, of which neither their natural tribes nor families can be conjectured, and which, for this reason, should always be kept apart. There are others, again, belonging to totally different families, or even orders, which are so alike in their shells, that conchologists place them in juxta-position.f But yet, on the other hand, there are numerous other families, where the modifications in the form of the shell are just as im- portant, and even more so, than those of the animal. The molluscous system of Poll fully establishes this proposition, even though the innumerable proofs in its support, hereafter detailed, were rejected. The truth appears to be, that Nature, on the whole, has diversified the external aspect of these singular animals, — that is, their shells, — much more than she has their soft or more unsightly parts. If, therefore, she has thus bestowed all her beautiful embellishment upon the habitation rather than upon the inhabitant, we may at least con- clude that the one is as essential to develope the plan she has pursued in her own system, as is the other. The diversity she has created on the shelly coverings of the typical Testacea is, beyond all comparison, greater
* Hor. Entom. p 240—244.
f Particularly the prototypes of the Planariilar, as Vitrina, Sigarelus,, Chcelinotus, &c.
12 SHELLS AND SHELL-FISII. PART I.
than is to be found among their animals ; but these latter must be well studied, before we can comprehend the leading types of form prevalent among the former. When this last discovery, if only in part, has been made, we shall find that the slightest modification in the shell is not without its meaning; and that, in nine instances out of ten, we may pronounce with as much confidence on its natural station in the scale of nature, as if we had actually dissected its animal.
(12.) A singular idea appears to be entertained by some writers, that the "^art" of conchology, popularly so called, is only really serviceable to science, when viewed in connection with geology. But it may fairly be asked, how geology or any other branch of knowledge can be benefited by any aid which is not, in itself, built on sound and philosophic principles, which this '^'^art" confessedly is not. It would be difficult to answer the question why one branch of zoology is to be separated from the others, and degraded into the hand- maiden of another science, — and that, too, of such very recent formation, that the most opposite opinions as to its very first principles are continually issuing from the press. It is not a little singular, also, that, while geologists appear to attach so much importance to mineral conchology, as it is termed, no author, as yet, has specifically written on the subject. In such a state of things, the attempts that are made to identify certain strata by the nature of the shells they may contain, should be ventured upon, in most cases, with very great cau- tion. We are fully persuaded that many of those fossil shells termed by conchologists fluviatile, are decidedly marine ; that the nature of others, from ignorance of their animals, can never be understood ; and that a great number, now considered identical with existing genera, belong to groups altogether extinct. Until, therefore, all these suspicious points are cleared u}), geologists will derive but very little comparative benefit by our modern systems of conchology, and will be fre- quently led to most erroneous conclusions. The " art,"
CHAP. I. BIBLIOGRAPHY OF MALACOLOGY. 13
in fact^ must merge into the science of Malacology, in which equal regard is paid both to the animal and the shell. It is then alone that geology will be really benefited. Our science will then repose upon a proper and philosophic basis^ and in that capacity will be ready to aid those of her sisters who may solicit her services. (13.) Our notices on the Bibliography of the tes- taceous Mollusca, must be very brief, and chiefly con- fined to such as have a practical influence on the present state of science. This brevity will be the less regretted, since the subject has been so ably and fully gone into by Maton and Racket, in the seventh volume of the Linncean Transactions. The foundation of this and every branch of zoological science was laid by the im- mortal Aristotle, who well discriminated all the leading groups of the typical Testacea, and was not inattentive to the habits and localities of the animal inhabitants. He separated the spiral univalves by the name of Mo- nothyra, while he applied the term of Dithyra to the bi- valves. It would have been as well if the moderns, in their multifarious and complicated nomenclature, had shown some little respect to the designations imposed by this commanding genius on the leading groups of Xhe Mol- lusca ; such defence would, at all events, have brought his name more frequently before us, and reminded the world how infinitely science was indebted to his labours. How much superior, also, is the simplicity of genuine classic names over those compounded in modern times, will be best seen by comparing those bestowed upon the bivalves, which are the Dithyra of Aristotle, and the Malacozoaria Acephalophora of M. de Blainville. It is too late, perhaps, to restore the entire nomen- clature of the illustrious Stagyrite ; but in this single instance we shall certainly prefer his designation of the bivalve Mollusca in preference to those of the moderns.*
* The term of Acephcila, given by Cuvier, would be by no means objec- tionable, but that it sets aside the name of antiquity, and include?, more- over, numerous groups which have nothing in common with the Dithyra of Aristotle, except the want of a distinct head. To judge, indeed, from the writings and nomenclature of the French school, it would hardly be conjectured that such a man as Aristotle had ever existed.
14j shells and shell-fish. part 1.
(14.) Our celebrated countryman. Lister *, was the first naturalist, after the revival of learning, who made any decided improvement in this science, since he re- garded both the animals and the shells ; and his noble volume will be an imperishable record, both of his talents and his industry. The excellent figures of Rumphiust;, published in 1711:> are still valuable, as are likewise those of Gualtieri :|:, but neither of these writers can scarcely be said to have benefited the subject in any other way. D'Argenville's plates, although more elaborately finished, are very inferior to those of the last-named works ; and it has been truly said, that what is really valuable in his book has been taken from Lister. The conchological labours of Klein, who was perpetually writing upon every branch of natural his- tory, partake of the character which belongs to all, — a total want of genius. It was, in fact, reserved for Adanson§, the celebrated French traveller and naturalist, once more to revive malacology from the frivolous state into which it had been gradually sinking since the days of Lister : by studying both the animal and its shell, he prosecuted his researches on sound and philosophic principles ; and hence it is, that his volume, although published in 1757:, is highly valuable, while the '^ tes- taceous " arrangement of Linnaeus is as if it had never been written, — or it is consulted only, at rare intervals, to determine a specific name. But Adanson confined himself to the shell-fish of Senegal ; and it was not sur- prising that the scientific world, captivated by the sim- plicity of the Linngean nomenclature, still continued attached to the plan of considering the Testacea merely in regard to their shells, of which innumerable species now began to pour in on the European cabinets. This,
* Lister. Historia, sive Synopsis Metliodica Conchyliorum. London, one volume, folio ; of which there are two editions, the last in two volumes. See Prcl. Discourse, p. 24.
t Ku.MPHius, G. E. 'J'hesaurus Imaginum Piscium, Testaceoriim, &c. Haga; Comilum, 17;)9, folio.
: Nico. GuALTiiRi. Index Testatum Conchyliorum. Flor. 1742, royal folio. The figures are the most artisticai of any that we remember: the rotundity of the spiral shells is admirably represented.
\ Hist. Nat. des Coquillages du Senegal. Tans, 1757, 4to.
CHAP. I. BIBLIOGRAPHY OF MALACOLOGY. 15
doubtless, gave rise to the voluminous work of Martini and Chemnitz, which, although published between 1769 and 1788, and with figures exceedingly ill drawn, is, nevertheless, the most valuable, as a general work, we yet possess. It was soon after this time, however, that George Humphrey*, F.L.S., the chief commercial conchologist then living, gave to the w-orld a small pamphlet, wherein he arranged the Testacea upon an entirely novel and very remarkable plan. As a system of conchology, this w^as both a sudden and a most extensive improvement upon everything of the kind which had hitherto been done. The arrangement, which wdll be subsequently adverted to^ as far excels that of Linnaeus, as Lister's exceeds that of Klein. There can be no doubt, in fact, that this little unpre- tending pamphlet, published in this country merely as an exhibition catalogue^ found its way to France, and served as the main foundation, although unacknow- ledged, for the subsequent system of Bruguiere, if not of Lamarck and Cuvier. It was, to write colloquially_, the first quiet but thorough breaking of the ice, in which conchologists were bound up by the Linnfean system ; and those w^ho followed up the reformation, however justly we may praise them as improvers, can- not be invested with the more honourable distinction of leaders. It was, therefore, not in France, but in England, that the revolution against the meagre concho- logical school of Linnaus first originated. But, having said this, w^e can put forth no claims for our countrymen_, on this head, during a subsequent period of nearly forty years. Montagu, indeed, must be named with honour, and Pennant's writings aided much to spread a taste for collecting shells ; but beyond these, we recollect no others deserving special record. Meantime, a more correct knowledge of the molluscous animals was making rapid progress on the Continent. Those illustrious and ad- mirable anatomists. Poll in Italy, and Cuvier in France^
* Museum Calonnianum. — Specification of the variouo Articles which compose the magnificent Museum of Natural History, collected by M. de Calonne in France. Anonymous. London, May 1. 1797.
10 SHELLS AND SHELL-FISH. PART I.
were prosecuting their researches with indefatigable industry ; while Bruguiere, and subsequently Lamarck, were no less occupied in describing and arranging the Testacea; meantime^ faint attempts, in the shape of In- troductionSj to keep alive Linnaean conchology, were all that appeared in England on this subject. The labours of Bruguiere were unfortunately terminated prematurely by deaths but those of his illustrious friend Lamarck were continued up to within these few years. His masterly and incomparable work, wherein aU his labours on the invertebrated animals are concentrated, are too well known to be expatiated upon in this place, since it is in the hands, or should be, of almost every zoologist who studies those classes. The investigations of Poli, even more elaborate than those of Cuvier, have been given to the world more slowly, and in such an expen- sive form, as to deprive them of half their utility.* Not so with those of the celebrated Cuvier. The Regne Animal, a book accessible to all purchasers, con- tains the essence of all his labours on the Mollusca, but, unfortunately, so much abridged, that the student is frequently more perplexed, than satisfied, on the point he is searching for. His more detailed memoirs are scattered through innumerable volumes of foreign transactions, where they lie completely hidden from every-day reference, although their intrinsic and per- manent value would fully warrant their being collected and printed in a cheap volume.f In estimating the merits of these three great men, — Poli, Cuvier, and La- marck,— in regard to their arrangement of the testaceous Mollusca, it may be stated, that the first confined his system entirely to the animal, giving to it a difi^erent name to that of the shell ; so that, if the animals of two conchological genera (as Avicula and Lima^ were nearly
* Poll Testacea Utriusque Sicilia', eorumque Historia et Anatomia, 2 vols, royal folio. Parma', 1790 — 5.
A Supplement, by Stephaiius della Chiaje, forming another volume, was published at Naples in 1S.')3.
f A few copies of these 3/e?«o»rs, with their plates, were struck ofT se- parately, and published in one 4to. volume, Paris, 1817 ; but this is now become so rare as to be unprocurable, excepting hy chance.
CHAP. I. RECENT WORKS. 17
alike, they were placed, in his system, in one and the same genus. Cuvier has altogether avoided this strange mode of procedure ; but an inspection of his system will bear us out, we think, in our opinion that he has placed far too great a stress on the modes of respiration, and paid too little attention to the shell, no less than to the animal ; while the great error of Lamarck appears to have been that of giving to the shell, and more espe- cially the hinge of bivalves, a greater regard than he bestows upon the animal. The system of M. de Blain- ville, indeed, professes to remedy these defects ; but we can discern in it little that is new, beyond innumerable compound Greek names, proposed for groups already established by his predecessors, and which are only calculated to overturn all existing nomenclature, with- out adding anything practical to the advance of science. (15.) Whatever may be the cause, certain it is that nearly all that is now valuable in malacology has emanated from the Continental naturalists. Besides those just enumerated, the unwearied zeal of the French circumnavigating naturalists,, more especially M. Quoy, has added to this science not merely a host of new shells, but — what is far more valuable — innumerable facts, of the highest importance, regarding their animals. We only regret that the price of these splendid publica- tions, and the few copies of them yet in this country, have prevented us, in all instances, from profiting from these most valuable materials. The only one of our country- men who has pursued the same path of inquiry, and on the same philosophic principles, was our late friend, the Reverend Lansdown Guilding, who, from his official residence in the West Indies, had the enviable opportunity of examining, and the rarely united talents of drawing, dissecting, and describing, the soft MoUusca of the Caribbean seas. To him is science indebted for a knowledge of the animals of numerous terrestrial and many marine shells ; and the institution, on the most solid basis, of several natural genera. These invaluable researches, too little appreciated by our conchologists,
G
18 SHELLS AND SHELL-FISII. PART I.
in their zeal for describing new species, and too little known to the scientific world, from being scattered in detached papers, or unpublished, are all incorporated and acknowledged in this volume.* To this accom- plished zoologist and exquisite artist are we indebted, among many other things, for the discovery of the extraordinary genus Herpa ; and for drawings of the animals of Oliva, Volutella, Marginella, Triton, and Trochella; as also of several other groups, originally characterised from the shells alone, but now confinued by the difference of their animals. The name of Mr. Lowe, the natural historian of Madeira, deserves honourable mention in this place, as connected with the illustration of many interesting facts on the Mollusca of that island. A most magnificent, but extravagantly expensive, work on the land and freshwater shells, was commenced, several years ago, by the late baron de Ferussac.t As it was patronised by Royalty, some hopes were entertained of its completion, notwithstanding the grand scale it set out upon ; but the undertaking was evidently too vast for the very moderate abilities of its projector ; the parts came out less and less regularly, until, after it had cost the subscribers near 50/., it was (virtually) given up, and the author died. This striking example is surely sufficient to convince any sober judging person of the utter impracticability of completing a General Conchology, or of carrying it on beyond a few numbers. It is, in fact, a physical impossibility for any one or five men to accomplish such a work in the ordinary term of human life ; and even if brought to a termination, unless conducted on the most economic scale, would involve an outlay to the projectors, and an expense to the public, which the latter, at least, would never incur. We are, in truth, heartily set against all these magnificent under- takings : they are absolutely detrimental to science ;
* A large collection of highly finished drawings, and several MSS., are now in the possession of Mr. Guilding's late widow.
t I'ERUssAc Hist. Nat. gC'ntralc et particulierc dcs MoUusques Ter- restres et Fluviatiles, 27 parts, published, Paris, 1819 — 3J.
CHAP. I. SYSTEMS AND ARRANGEMENTS. I9
for they confine the materials of knowledge and of study within the narrow limits of the select few (gene- rally wealthy amateurs)^ to the exclusion of all who cannot expend 400/. or 500/. upon a zoological library. We cannot but admire the zeal of their projectors_, — for such works never produce profit, and generally bring a heavy loss, — but we think it a zeal misplaced. What is now most wanted, is a collection of plates of shells, to supply the deficiencies of the series in the Tableau Encyclopedique et Metliodique *, and printed uniformly. The series in question contains nearly 300 plates, and is the very best which the naturalist can possess. We have constantly referred to it, as being more within the pecuniary reach of the student, and as being far more accurate in the figures, although uncoloured, than that of Martini and Chemnitz ; and these latter are there- fore only quoted for species not contained in the other. The figures in Wood's Catalogue are often very good ; but the arrangement is so confused, and often so erro- neous, that the nomenclature, in its present state, can seldom be quoted as an authority.
(l6.) In regard to systems and arrangejients of the testaceous animals, the only attempt that has ever yet been made towards the natural disposition of this extensive class, is that indicated in the Horce Ento- mologies. The ingenious author, however, candidly acknowledges his inability even to point out the primary divisions; although he has ventured, and, as we think, has partially succeeded, in tracing the links of affinity by which the testaceous Mollusca are connected, on one side, to the Aerita, or polypes, and, on the other, to the vertebrated animals, by means of the Cephalopoda. Of arrangements made without any ulterior object of illustrating the general harmonies of nature, and there- fore artificial t, there are several ; the best being those
* With these plates, and Lamarck's volumes of the Hist. Nat. des Ant- maux sans Vertibres, the conchologist will be at no loss to arrange an ordinary collection of shells, and name by far the greater portion of the species. The excellent Manuel de I'Hist. Nat. des Moliusques of M. Sander Rang should also be procured, on account of the valuable notices it con- tains on the structure of the animals.
t See Geography and Classification of Animals, p. 125.
c 2
20
SHELLS AND SHELL-FISH.
PART I.
of Humphrey, Lamarck, and Cuvier. The two first of these will therefore be exhibited in their details ; the latter having already been placed before the reader in a former volume. Although that of Lamarck, by common consent, has been preferred by nearly all zoo- logists, it is but justice to the distinguished author of the Regne Animal, to designate his early Memoires upon these animals as fully entitling him to the high reputation his anatomical talents have so justly acquired for him in other departments. They are materials upon which all true knowledge of the Testacea must repose. (17-) The conchological arrangement of Humphrey, already spoken of, will now be detailed, so far, at least, as regards the names of the genera ; since their de- finitions were never published. To show how intimately very many of these accord with those of Lamarck, we have, in almost every instance, added the corresponding genus of the latter. The ingenious author had such a conviction that the fluviatileand terrestrial genera should be kept distinct from the marine, that he places them in separate divisions.*
Class TESTACEA. Order I. MARINE.
|
Division |
I. Univalves. |
Conus L. |
|
|
Serpula Linn. |
Melo. |
Broderip. |
|
|
Dentalium L. |
Valuta L. |
||
|
Patella L. |
Musica. |
Voluta Lam. |
|
|
Larva. |
Fissurella Lam. |
Harpa. |
La 771. |
|
Crypta. |
Crepidula Lain. |
Dolium. |
La7n. |
|
Calyptra. |
Idem Lam. |
Casida. |
Lam. |
|
Galerus. |
Calyptrffia Lam. |
Haliotis L. |
|
|
Pedum. |
Spirula Lant. |
Haliotoidea. |
Stomatia Lam. |
|
Nautilus L. |
Auris Veneris. |
Sigaretus Lam. |
|
|
Argonauta L. Bulla L. |
Neritoidea. |
i; lanthina, &c. (. Lam. • |
|
|
Licium. |
Ovula Lam. |
Uber. ; Lunatus. ',\ |
Natica Lam. |
|
Cypraea L. |
|||
|
Dactylus. |
Marginella Lam. |
Nerita L. |
|
|
Oliva L. |
Auris Mustela;. |
Tornatella La7H. |
* The author, with that modesty which was his peculiar characteristic, thus expresses himself: — " I'he editor hopes that his confession of being but little acquainted with the learned languages will be received as an apology for such improprieties in the generic orspecific names as he fears will be found."— Museum Calon/ieanum, pref. p. v.
|
CfHAP. I. |
SYSTEM OF HUMPHREY. |
21 |
|
|
Turbo L. |
Strombus. |
Pterocera. Lam. |
|
|
Eutropia. |
PhasianellaLflw. |
Triplex. ' > Purpura..' |
|
|
Scala. |
Scalaria Lam. |
Mtirex Lmn. |
|
|
Terebra. |
Lam. |
Rheda. |
Hyalia Lam. |
|
Obeliscus. |
Trochus Linn. |
||
|
Cochlus. |
■ Cidaris Sw. I Marmarostoma. |
Div. IL |
Bivalves. |
|
Pinna L. |
|||
|
€enectus. |
SV3. |
Mytilus L. |
|
|
Blench us. |
Sw. |
Solen L, |
|
|
Physeter. |
Solarium Lam. |
Margaritifera. |
Avicula Lam, |
|
Apiculum. |
Trochus Lam. |
Vulsella. |
Lam. |
|
Trochulus. 7 Trochus- 3 |
Placuna. |
Lam. |
|
|
Monodon Lam. |
^ M «-• ^.z v« ■ m b4 ^ Cepa. |
Anomia Linn. |
|
|
Sol. |
Tubicanthus Sw. |
Lampus. |
Terebratula Lam |
|
Onustus. |
Sw. |
Mactra L. 7 Trigonella.3 |
|
|
PygmEea. |
Columbella Lam. |
Mactra Linn, |
|
|
Pyrum. |
Pyrula Lam. |
Tellina L. |
|
|
Haustrum. |
Purpura Lam. |
Cuneus. |
Donax Linn. |
|
Hystrlx. |
Ricinula Lam. |
Pectunculus. |
Venus Linn. |
|
Bulbus. |
Rapella Stv. |
Cardium L. |
|
|
Acus. |
Terebra Lam. |
Trapezium. |
Chama Lhtn. |
|
Clava. |
Cerithium Lam. |
Tridacna. |
Lam. |
|
Cassidula. ' ' Ficus. |
Pyrula Lam. |
Glycymeris. Area L. |
Lam. |
|
Rhombus. |
Fusus, &c. Lam. |
Pecten. |
Lam. |
|
Rana. |
Ranella Lam. |
Ostrea L. |
|
|
Buccinum. |
Triton, &c. Lam. |
Lacinia. |
Chama Lam, |
|
Turris. |
Turritella Lam. |
Spondylus L. |
|
|
Colus. 7 Fusus. 3 |
|||
|
Fusus Lam. |
Div. III. MuLTivALVEs. |
||
|
Cuma. |
'Fusus Lam. ( . Fasciolaria lb. |
Pholas L. |
|
|
Lepas L. |
|||
|
Mitra. |
Lam. |
Cornucopia. |
Lepas Linn. |
|
Murex. |
Scolymus Sw. |
Balanus. |
|
|
Rapum. |
Turbinella La7n. |
Chiton L. |
|
|
Alatus. |
Strombus Linn. |
Order II. FLUVIATILE.
|
Div. T. |
Univalves. |
Div. |
II. |
Bivalves. |
|
Catillus. ■ Neritella. , |
Barbata. |
Unio Lam. |
||
|
Neritella Lam. |
Scapha. |
Iridina? Lam. |
||
|
Pomus. |
Ampullaria Lam,. |
Mya. |
Unio Lam. |
|
|
Vesica. |
'Lymnia. '. Melania Lam. |
Nux. Capsa. |
Cyclas Lam. ? |
|
|
Ligula. 7 Turricula. 3 |
Melania Lam. |
|||
|
Order IIL T |
ERRESTRIAL. |
|||
|
Sylvicola. |
Cyclostoma Lam. |
Otis. |
Auricula Lam |
|
|
Helix L. |
Chersina. |
Achatina Lam |
||
|
Lituus. Cistula. |
Cyclostoma?Za7«. Cyclostoma. |
Lendix. ' Pupa. J' |
Pupa Lam. |
|
|
,Bombyx. |
? |
22
SHELLS AND SHELL-FISH. PARTI.
(18.) As a purely conchological system, this was un- questionably the best and the most original of any that had appeared since the revival of learning. It was pub- lished in 1797, nearly twenty years before the first of Lamarck's volumes appeared. * That it was well known to the latter can hardly be doubted, when we see no less than ten genera similarly named by both ; and that almost every genus of Lamarck's univalves are found in this list, under different, but less classical, names. Of univalves, Humphrey has 87, contained in the single collection of which his book is a catalogue. How many more he had determined to name, does not, of course, appear ; but the total number of Lamarck's is but Q6, for the whole of the testaceous gastropods.
(19.) Lamarck's system, so far as regards the animals now before us, may be thus briefly stated. He arranges the whole group under the two classes of — I. Con- chifera; and, IL Mollusca. The first contains the bivalve shell-fish, and is again divided into two orders : one of these is called Conchiferes dimyaires, the in- terior of the shells presenting two muscular impressions, separated and lateral ; while in those of the second order, or ConcJuferes monompaires, there is but one muscular impression, placed nearly in the centre, — the muscle itself being single, and which appears to run through the body of the animal. Each of these great divisions of bivalves contains several others, denominated sections, chiefly differing in the structure of their feet.
Order I. CONCHIFITRES DIMYAIRES.
|
Section 1. |
Mya. |
Amphidesma. |
|
|
Aspergiliuin. |
Anatina. |
Corbula. |
|
|
Clavagella. |
Pandora. |
||
|
Fistularia. |
Sect. |
TI. |
Saxicava. |
|
Septaria. |
Conch, tenuipedes. |
Petricola. |
|
|
Teredina. |
Lutraria. |
Venerirupis. |
|
|
Pholas. |
Mactra. |
Sanguinolaria. |
|
|
Gastrochaena. |
Crassalella. |
Psammobia. |
|
|
Solen. |
Erycina. |
Psammota;a. |
|
|
Panopa?a. |
Ungulina. |
Tellina. |
|
|
Glycimeris. |
Solenimya. |
Tellinides. |
* The first volume of the Hist. Nat. des Animaux sans Verthbres bears the date of March, 1815.
|
CHAP. I. |
■ |
SYSTE3I OF |
LA3IARCK. ^ |
|
|
Corbis. |
Cytberea. |
Trigonia. |
||
|
Lucina. |
Venus. |
Castalia. |
||
|
Donax. |
Venericardia |
Unio. |
||
|
Capsa. |
Cardium. |
Hyria. |
||
|
Crassina, |
Cardita. Cypricardia. |
Anodon. Iridina. |
||
|
Sect. |
III. |
Hiatella. |
||
|
Conch, lamellipedes. |
Isocardia. |
Sect. IV. |
||
|
Cyclas. |
Cuculzea. |
Conch, ambigus. |
||
|
Cyrena. |
Area. |
Diceras. |
||
|
Galathea. |
Pectunculus. |
■ Chama. |
||
|
Cyprina. |
Nucula. • |
Etheria. |
||
|
Order II. CONCH. |
MONOMYAIRES. |
|||
|
Section I. |
Sect. |
II. |
Sect. III. |
|
|
Tridacna. |
Pedum. |
Branchiopoda Cuv, |
||
|
Hippopus. |
Lima. |
Sphserulites. |
||
|
Modiola. |
Plagiostoma. |
Radiolites. |
||
|
Mytilis. |
Pecten. |
Calceola. |
||
|
Pinna. |
Plicatula. |
Birostrites. |
||
|
Crenatula. |
Spondylus. |
Discina. |
||
|
Perna. |
Podopsis. |
Crania. |
||
|
Malleus. |
Grypheea. |
Orbicula. |
||
|
Avicula. |
Ostrea. |
n^prphratula. |
||
|
Meleagrina. |
Vulsella. Placuna. Anonica. |
Lingula. |
23
(20.) To his second great division^ Lamarck restricts the title oi Mollusca : these he again subdivides into the five following orders : — 1 . The Pteropoda, which forms a part of our Cephalopoda. 2. The Hydrohranchia^ which includes the JVudibranchia, Scutihranchia, and Tectibranchia of Cuvier ; together with the genera On- chidium, ParmaceUa, Limax, Testacellus, and Vitrina : these genera he places in his section Pneumobranchia, and makes them the passage to his tlm^d order, or the Trachelipodes, in which all the univalve shells are placed. The foiu'th order is composed of the Cephalopoda, or cuttlefish ; and the fifth contains the Heteropoda. The genera belonging to each of these orders are as follows : —
Order I. PTEROPODA.
Hyalaea. Ciio.
Cleodora. Limacina.
4
Cymbulia. Pneuraodermon.
|
5J* |
SHELLS AND SHELL- |
-FISH. PART I |
|
Order H. GASTEROPODES. |
||
|
Section I. |
Pleurobranchus. |
Bulla. |
|
Glaucus. |
Umbrella. |
Aplysia. |
|
Eolis. |
Parmophora. |
Dolabella. |
|
Tritonia. |
Emarginula. |
|
|
Scyllaea. |
Fissurella. |
Sect. II. |
|
Tethys. |
Pileopsis. |
Onchidium. |
|
Doris. |
Calyptraa. |
Parmacella. |
|
Phyllidia. |
Crepidula. |
Limax. |
|
Chitonellus. |
Ancylus. |
Testacella. |
|
Chiton. |
Acera. |
Vithna. |
|
Patella. |
BuUaea. |
|
|
Order HI. TRACHELIPODES. |
||
|
Section I. |
Haliotis. |
Triton. |
|
Les Phytiphages. Tornatella. |
Rostellaria. |
|
|
Helix. |
Pyramidella. |
Pteroceras. |
|
Carocolla. |
"Vermetus. ^ |
Strombus. |
|
Anastoma. |
Scalaria. |
Cassidaria. |
|
Helicina. |
Delphinula. |
Cassis. |
|
Pupa. |
Solarium. |
Ricinula. |
|
Clausilia. |
Rotella. |
Purpura. |
|
Bulimus. |
Trochus. |
Monoceros. |
|
Achatina. |
Moiiodonta. |
Concholepas. |
|
Cyclostoma. |
Turbo. |
Harpa. |
|
Planorbis. |
Planaxis. |
Dolium. |
|
Physa. |
Phasianella. |
Buccinum. |
|
Lymneea. |
Turritella. |
Eburna. |
|
Melania. |
Terebra. |
|
|
Melanopsis. |
SECT.:n. |
Columbella. |
|
Pirena. |
L.es Zoophages. |
Mitra. |
|
Valvata. |
Cerithium. |
Voluta. |
|
Paludina. |
Pleurotoma. |
Marginella. |
|
Ampullaria. |
Turbinella. |
Volvaria. |
|
Navicella. |
Cancellaria. |
Ovula. |
|
Neritina |
Fasciolaria. |
Cypraea. |
|
Natica. |
Fusus. |
Terebellum. ; |
|
lanthina. |
Pyrula. |
Ancillaria. |
|
Sigeretus. |
Struthiolaria. |
Oliva. |
|
Stomatella. |
Ranella. |
Conus. |
|
Stomatia. |
Murex. |
|
|
Order IV. CEPHALOPODES. |
||
|
Section I. |
Spirula. |
Melania. |
|
Testaceous Cephalo- Spirolina. |
Rotelia. |
|
|
poda. |
Lituola. |
Lenticulina. |
|
* Belemnites. |
Renulina. |
Placentula. |
|
Orthocera. |
Christcllaria. |
Discorbis. |
|
Nodosaria. |
Orbiculina. |
Siderolites. |
|
Hippiirites. Conilites. |
Miliola. Gyrogona. |
Polystomella. Vorticialis. |
CHAP. I. SYSTEM OF CUVIER. 25
NummuUtes. Baculites. Sect. III. Nautilus. (^epf^- Cepiaria.
Ammonites. Sect. II. Octopus.
Orbiculites. Ceph. Monothalama. Loligopsis.
Ammonoceras. Argonauta. Loligo.
Turrilites. Sepia.
; Order V. HETEROPODA.
Carinaria. Pterotrachia. Phylliroe.
(21.) The system of M. Cuvier difFers, in many re- spects^ from the above. The Mollusca form the second great division into which this admirable anatomist divides the animal kingdom. These he distributes under six principal classes : 1 . Cephalopoda, or cuttlefish ; 2. Pteropoda, or clios ; 3. Gasteropoda, an immense and heterogeneous assemblage, which we shall presently notice in detail ; 4. Acephala, or bivalve Testacea, at the end of which he introduces the tunicated Mollusca {Tanicata Sav.) ; 5. Branchiopoda, or anomian shells ; 6. Cirripedes, or barnacles. The great variety of ani- mals brought together in the third order, Gasteropoda, obhges our author to divide it into others, the names and contents of which are as follows : — 1. Pulmonia, con- tains the slugs and snails, both terrestrial and fluviatile.
2. NuDiBRANCHiA, iucludes all the naked marine Tes- tacea without shells, — as Triton, Doris, Thethys, &c.
3. Inferobranchia, consists but of two genera, Phyl- lidia and Diphyllidia. 4. Tectibranchia, compre- hends the Bulla family and the Aphjsia. 5. Hetero- PODA, embraces the Firoles and the CariiiaricE. 6. Pec- TiNiBRANCHiA : Under this order, arranged in sections, are placed the whole of the Trochus and Turbo families, together with the greatest part of the marine univalve Testacea. 7- Tubulibranchta, is limited to the genera Vermetus, Magilis, and Siliquaria. 8. Scutibranchia, contains Haliotis, Fissurella, and Emarginula : while the 9th and last order, Cyclobranchia, consists but of Patella and Chiton. To go into further detail will be needless, since the student will at once arrive at a general idea on the contents of these groups, by the indi- cations already given.
26
SHELLS AND SHELL-FISH. PART I.
(22.) In both these latter methods of classifymg the Testacea, there is much to approve and much to dissent from. It is clear that neither of these naturalists^ how- ever great their merits undoubtedly are in other respects, have paid any attention to the difference between analogy and affinity : nor have they aimed at anything beyond producing a simple scale or line of connection from one group to another. Now, as no such simple series exists in nature, — whose relations of affinity are always double, and generally treble, and whose analogies are interminable, — it follows, as a matter of course, that both have completely failed in laying down a simple graduated scale of the objects before them. Hence, as the groundwork of both systems is founded in error, no apology is necessary for rejecting them, particularly when the object sought for is the discovery of the na- tural arrangement. It is time, however, to leave the systems of others, and to lay before the naturalist some details of that here proposed.
CHAP. II.
ON THE TESTACEOUS MOLLUSCA IN GENERAL, THE PRIMARY DIVISIONS, AND THEIR ANALOGIES TO THE VERTEBRATA AND ANNULOSA.
(23.) The testaceous mollusks, or shell-fish, with few exceptions *, are all marine, or, at least, aquatic animals, soft and slimy in their nature, and without articulated limbs, so that such as can move about, crawl upon their belly, or swim in the water by means of the fin- shaped lobes of their mantle. Independent of their peculiar anatomical structure, and merely looking to external characters, the most perfect of the testaceous
* Some of the parasitic groups, and the land shells, or slugs.
CHAP. ir. TESTACEOUS MOLLUSKS GENERALLY. 27
tribes are at once known^ either by being covered with a hard shelly or^ if without this protection, by having white blood, and being destitute of any processes which perform the office of feet. Many, indeed, are fixed to the surface of rocks, and other substances, where they remain during life ; while others bore for themselves internal cavities, or cells, in which they take up their per- manent habitation; while the least organised are parasitic. The similarity of some of the naked Testacea to XheAnne- lides, or sea-worms, is so great, that the older naturalists classed them together ; and even to this day we find a whole division mixed up with the annulose Vermes, or true intestinal worms. Let the student, however, bear in mind that the animals of which we are now speaking have neither joints to their bodies or limbs, nor any pro- cesses, by which they can crawl ; and that their blood is white, and not, as in the Annelides, red. Further- more, the testaceous Mollusca never assume the shape of the polypes ; nor do they possess that radiated form and arrangement of filaments, which give such a pecu- liar aspect to the Radiata. By these circumstances, therefore, the observer may discriminate, in ordinary cases, the characteristic marks of even the aberrant or less perfect Testacea ; while he can be in no doubt as to those which constitute the types. The perfection of the class is seen in those animals whose body is pro- tected by a hard calcareous covering, or shell, either in the form of a twisted or convoluted cone, variously modified, or composed of two principal valves or pieces, more or less flattened, and united by a cartila- ginous hinge. These shells are generally ornamented with a variety of colours, and are frequently polished, on their external surface, in the most beautiful and perfect manner, by the animals themselves. The single shells are called Univalves, and such is the periwinkle and snail ; while the double are termed Bivalves, and are exemplified in the oyster and the cockle. As nature, however, proceeds from one to the other of these groups by gradations of structure, we consequently
28 SHELLS AND SHELL-FISH. PART I.
find a few bivalves which assume the appearance of univalves ; and others which, from the valves being more than two, were called by Linnaeus Multivalve shells. This term the great Swede applied not only to those animals which really belonged to the Testacea, but to the Cirripedes, or barnacles, which have nothing to do with shells, properly so called. The term, there- fore, is altogether objectionable, and will not here be employed.
(24.) Such are the leading external distinctions of the class of animals now before us. Their typical characters are three ; two positive, the other negative. The first is that of crawling upon their belly, yet without feet; the second is their being covered with a beautiful calca- reous shell, which is their constant habitation, and which they have the power of enlarging, to suit the progressive growth of their soft bodies ; the third is, that, if deprived of this covering, they have not the least vestige of rings or joints on their bodies : the mouth, indeed, may be circular, and even the branchia, but this is the only analogy they have to the Radiata. In proportion as nature recedes from this typical eminence, the structure of the shell becomes imperfect, until, in the aberrant groups, the animal is either naked, or is but partially protected by such a covering.
(25.) The Testacea, considered anatomically, may be described as soft inarticulate animals, almost always breathing by branchia, or lungs, which vary, however, in the most singular diversity of ways both as to form and situation ; this variation, moreover, takes place in groups so closely related to each other in all other re- spects, that it is perfectly clear no natural arrangement can be founded upon the organs of respiration. The least organised, in fact, such as the PlanaricB, &c., have no branchia whatever ; so that they only possess two of the characters of the class, — namely, a flattened disk or disks, which act as a foot, and a total absence of joints in their body. Their blood is white, and its circulation, observes Cuvier, is always double ; that is, their pul-
CHAP. IT. TESTACEOUS MOLLUSKS GENERALLY. 2Q
monary circulation describes a separate and distinct circle. As for their manner of reproduction, it is even more variable and diversified than their mode of re- spiration. In some, as with Gasteropoda, there is a head with tentacula and eyes, either slightly or very fully developed ; while in the Dithyra, or bivalves, all these parts are wanting. Nearly all, however, have a developement of the skin which covers their body, which bears more or less resemblance to a mantle : but even this assumes innumerable shapes; — sometimes it is di- lated in the form of wing-like fins ; in others, as the car- nivorous Gasteropoda, it becomes a syphon by which the animal breathes. In the naked Testacea, the mantle is simply membranaceous, coriaceous, or fleshy. It is, in fact, utterly impossible to give such a general detail of this diversified class, either in respect to external or internal anatomy, as will not be subject to innumerable exceptions at every step. All the modes of mastication and deglutition, as Cuvier says, are found among these animals ; their stomachs are sometimes simple, some- times multiple. They also present examples of all the modes of generation ; and the same learned anatomist confesses that " these varieties of the digestive and ge- nerative processes are found in the same order, and sometimes in the same family." * Hence it inevi- tably follows, that any system founded solely on any one or more of these anatomical considerations, is sure to be not only unnatural, but perfectly unintelligible to the great bulk of naturalists, who are referred to the soft parts of an animal which they never saw, and cannot procure. In regard to the nervous system, Mr. MacLeay has well observed, that " the most ge- neral notion we can form, at present, of the nervous system of the Molhisca, is, that the medullary collar, in the more typical groups, must always, in its circum- ference, contain four ganglions, which may either be united two and two, as it is probable they are in the
* Griff. Cuv. p. 4.
30 SHELLS AND SHELL-FISH. PART I.
AcephaJa (Dithyra), or all four together, as in Tritonia. The brain is always composed of two of these lobes, which are generally connected, as in Aplysia, or some- times separate, as in Haliotis and Patella : the remaining two ganglions of the collar send off nerves to the or- gans of respiration, &c., and are either united together, as in the common slug and Patella, or are separate, as in Aplysia." It is time, however, to quit these ge- neralities, and enter into more definite details.
(26.) A rapid survey of the general peculiarities of the class will not, how^ever, be here misplaced. We have said that these animals have no distinct feet, or any organs which, by forming appendages to their body, supply their want. It is, however, customary — although the appella- tion is certainly incorrect — to call that part of the body which is next to the ground, and which is generally smooth and flattened, the foot, when, in fact, it is merely the belly, assuming only the office of a foot, and the shape of a sucker : by alternately contracting and extending this part, the animal moves forward, — slowly, indeed, but very surely. The aquatic species are able to crawl on marine rocks, even when the sea is greatly agitated ; and every one knows the tenacity with ^vhich a slug will adhere to the substance from wdiich we attempt to remove it. This is at once explained by the smooth disc of the belly acting as a sucker, like the tail of the leech. This mode of progression is almost universal among the Gasteropoda, or univalve shell-fish ; but, in the bivalves, the body of the animal is frequently length- ened behind, so as to assume a much more analogous appearance of a foot than what we find in others. The common cockle is one of the best, as it is one of the most familiar, instances of this structure. Those who have watched these animals at the ebb of tide, know that they leap very frequently ; but on their method of doing this two opinions have been given : some main- tain that the foot, which, when protruded, forms a sharp angle, is the chief organ made use of; while others assert that this motion is caused by the sudden
CHAP. ir. TESTACEOUS MOLLUSKS GENERALLY. 31
shutting of the shelly valves, which produces a jerk. In some very few instances among the typical Testacea, as in the genus lanthina, or oceanic snail;, the animal has a cellular organ attached to the belly, by which it floats on the surface of the ocean, or sinks to the bottom, at its own pleasm-e. The power of swimming, how- ever, is chiefly found among the aberrant groups, such as the cuttlefish (^Cephalopoda), the tritons {JVudi- hranchia), and the Tectibranchia : the first of these may really be said to possess Jins ; while the naked tri- tons, no doubt, use the appendages of the body for the same purpose. The power of adhesion is also diflferently bestowed : in the cuttlefish and Planar ice, it resides in the innumerable suckers which terminate the arms of one, and are placed on the under side of the other. In the limpet {Patella), the ear-shell (Haliotis), and the chiton, it originates in the excessive breadth of the disk upon the belly, which covers a surface equal to that of the whole animal and its shell : so firmly, indeed, do these genera adhere to the rocks or other substances upon which they are found, that they can only be sepa- rated by great force. It is among the limpets that we find the power of locomotion at its lowest ebb ; for they seldom remove far from the spot on which they were born ; and many, from the shape of the shell corre- sponding to the surface of the rock, appear never to have done this : finally, in the genus Hipponix, we arrive at a positive certainty that the animal is fixed, because it adheres by a separate distinct plate, which thus, in point of fact, renders it a bivalve shell. At- tachment, however, is much more prevalent among the bivalves, where we have entire families fixed to marine substances, either by one of these valves, as the oysters, or by a packet of strong fibrous threads. The attached genera are much less numerous than the others, and are affixed in different ways. Some, like the muscles {My- tilus), are merely connected into little bunches or fa- milies, by slender and scattered threads, strong enough to keep them together ; others, as the Pinna', or wing-
32 SHELLS AND SHELL-FISH. PART I.
shells, are provided with a thick tuft of silky hairs, called a byssus, which issues from one side only of the shell, the other end being firmly attached to m.arine bodies. In both these families, however, there is still some slight locomotive power left; for, although the animal does not, and probably cannot, quit the spot by disengaging its byssus, and mooring itself to another station, still it is not rendered absolutely motionless : the waves can move the shell backwards and forwards, and the fish may be compared to a horse or other animal fastened by a very short rope, which, neverthe- less, permits him to move his body and limbs. In the Pholas, we have the next step towards an absolute ex- tinction of the power of moving. These shell-fish have no byssus, nor are they affixed by any other method ; yet, soon after birth, they perforate the substance upon which they have been deposited by the parent, and ex- cavate for themselves deep burrows, or caves, exactly of the circumference of their own shells ; and in these hollows they take up their permanent residence. It is not absolutely ascertained, indeed, that these boring Testacea cannot quit their first habitation for another ; but there are many reasons to authorise the supposition that they live and die in the same which they excavated when young, and which they have the power of en- larging as they increase in size. A\^ithin such a narrow compass, it is obvious that the Pholas is more a prisoner than the Pinna or the Terehratula, because the walls of its habitation keep it immoveable, so that even the agitation of the waves cannot give it that undulating motion enjoyed by the byssiferous families. Finally, we come to such as are absolutely cemented by one of their valves to rocks or stones^ or to each other : many of the oysters are of this description ; but the most con- spicuous are the different species of Chama and spon- dyles ; several of which have the entire surface of one valve fastened by a calcareous deposition to rocks, pieces of floating timber, and to the bottoms of ships. It is, consequently, in these families, and in the worm-shells.
CHAP. II. TESTACEOUS ANIMALS IN GENERAL. 33
that we have the most perfect examples of the sedentary Testacea.
(27.) Although the head, where it exists, of the Tes- tacea, is very different from that of vertebrated and annulose animals, — inasmuch as it is not separated, from the body by a neck, — it is yet to be distinguished, in many groups, by the presence of tentacula, or feelers, and by two or four black dots, which are generally con- sidered to be the organs of sight : in proportion as we advance from the PlanaricE on one side, and from the chitons on the other, towards the cuttlefish, we find the head and the eyes gradually assuming that definite shape and structure which are so characteristic of the vertebrated animals. Some of the tritons (^Nudi- branchia), and all the bivalve shell-fish (^Dithyra), have no indication of eyes, nor have the latter any obvious head ; but in the Gasteropoda, or univalves, both begin to appear. We see this in the garden snail, and in all the freshwater and marine animals of this tribe. In the StromhidcB and the Volutidcp, the eye is nearly as perfect as that of the cuttlefish. From this group, however, nature again recedes ; and in the Pteropoda, although the general form is preserved, the head is once more confounded with the body, and the eyes disap- pear.
(28.) On the habits, food, and geographic distribu- tion of the Testacea we can say but little w^hich is applicable to all. The great majority are aquatic and marine ; but two or three extensive families are found only in fresh water. The land shells are exceed- ingly abundant in species, and the gastropod worms are parasitic in or upon other animals. It may be here remarked, that all the bivalves (Dithyra) are aquatic, but that the univalves inhabit the different situations just enumerated. The food of all these creatures varies according to their own particular races. A large num- ber (forming the phytophagous gastropods) feed almost only upon living vegetables, either terrestrial or aquatic, — as the snail of our gardens, and the periwinkle of our
D
34 SHELLS AND SHELL-FISH. PART I.
coasts ; but a still greater assemblage are carnivorous, — devouring not only living, but dead, animals, and even attacking other tribes of their own class. It Avould be interesting to know in what manner nature has pro- vided for the sustenance of such as are permanently affixed to one spot. Some of these have divers me- thods of exciting little currents in the water, by Avhicli means fresh portions of it are brought to the mouth, along with which such minute animals or fragments of vegetables as are adapted for food are secured. The branchipodous bivalves, like the TerehratulcB, although sedentary, are provided with long fringed processes, which are, no doubt, employed to capture their prey, in a similar manner to the arms of the Cirripedes, or barnacles; while the cuttlefish (C6';^//«/o/)06?a) and the Tritonia swim about in search of marine animals weaker than themselves. In regard to their geographic distribution, much might be said, did we not fear being drawn into longer details than our space would permit. It will be only necessary to observe in this place, that the geographic range of the Testacea is not so wide or uncircumscribed as the generality of authors assert. Tropical latitudes, as usual, display a greater variety of species, and a larger number of individuals, than those seas which lie under temperate or frigid skies. The Testacea of Europe are as distinct from those of America, as the latter are from those of Aus- tralia, Africa, or Asia. We have already illustrated this fact in that part of our series devoted to the geo- graphic distribution of animals ; and it may be safely asserted that the grand features of zoological geography are as conspicuous in this class of animals, as in any other.
(29.) The great natural divisions of the testaceous Mollusca appear to us to be these : — The first, or pre-eminently typical, are unquestionably the Gastero- poda, or spiral univalves, whether we consider the comparative perfection of their internal or their external structure. The second, or sub-typical class, is com-
CHAP. II. PRIMARY DIVISIONS OF TESTACEA. 35
posed of the Dithyra of Aristotle^ or the bivalves_, whose structure is less perfect^ but which are in like manner protected by a regularly formed, and often richly coloured, bivalve shell. The third, or aberrant group, as usual, comprehends three : 1 . The Nudibran- CHiA of jVI. Cuvier, or the naked Gasteropoda ; 2. The Pa renchymata, or intestinal Testacea; and, S.TheCE- PHALOPODA, or cuttlefish. We shall first slightly glance at the leading characters of each of these classes, and then endeavour to trace their analogies to other animals. (30.) Under the name of Gasteropoda, we retain the greater number of Cuvier's divisions*; but the most typical consists of the univalve or spiral Testacea, whose body is protected and generally coveredt by a calcareous shell : the head, although not assuming a very decided shape, is always present, and is, in almost all instances, at once distinguished by having two or more tentacula, assuming the appearance of the antennse and the palpi of insects. All the true Gasteropoda possess the rudi- ments of eyes ; in the generality, these organs appear in the form of black specks, either at the tips of the longest pair of tentacula, as in the common snail, or at their base. "We thus find that the true Gasteropoda possess four primary characters, — the power of crawling upon their belly, the possession of a head and eyes, and, finally, the protection of a shell. Those which are most remote from the point of perfection, and which form the links of connection to other classes (as the Tectihranchia on one side, and the Nudihranchia on the other), have some one, or, perhaps, two, of these characters either lost, or but very imperfectly developed; these, in short, are the aberrant groups, and must never be looked to for the right understanding of the class to which they belong. The slug, for instance, has no shell, or merely the rudiments of one ; yet it crawls upon its belly, it is furnished with a distinct head and even jaws, it has four tentacula, and a pair of rudi-
* As the Heteropoda, Cydobranchia, Scutibranchia, and Pulsnonaria. t Except in Limax, Sec.
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36 SHELLS AND SHELL-FISH. PART I.
mentary eyes ; it presents us, in fact, with all the cha- racters of a testaceous gastropod, except one, — that of being covered by a shell. In the Tectihrunchia, again, v/e have a group still more remote from the typical structure ; for many of these have the mere rudiments of a shell covering a small part of their body, and they swim as much as they crawl. Yet their evident connection to the VolutidcB (by means of the Cyprcfidcp) on one side, and to the chitons on the other, points them out as truly belonging to this order.
(31.) The DiTHYRA of Aristotle, or bivalve shells, form the next, or sub-typical division. This comprises animals destitute of an apparent head, but still inclosed in a shell, and still moving on the belly. There is not, however, in this latter part, any flattened disk ; and the shell, instead of being spiral, is generally composed of • two pieces, or valves, joined together by a horny liga- ment. The Dithyra, moreover, are further distin- guished by having neither tentacula, nor the least vestige of eyes. We meet with some, indeed, as the Chelisom(jP, which have no external shelly covering ; and others, where the bivalve shell is inclosed in a tube, as the family of TuhuUhranchia, — thus assuming the disguise of a univalve. But these remarkable de- viations are few, and point out, as we have just men- tioned, the extreme limits of the tribe.
(32.) The NuDiBRANCHiA, or tritons (part of the naked Gasteropoda of i\I. Cuvier), form the third of our principal divisions, and are all no less strongly cha- racterised. Destitute of any covering, and presenting a marked peculiarity in their external branchia, their appearance is so very different, that every unprejudiced observer cannot but wonder they should, up to this day, have been mixed up with the true gastropod shell-fish. These animals, in fact, are entirely flattened, naked, soft, and gt^nerally ornamented with beautiful colours ; they move about by means of their foot, or concave imderside of their beUy, in the depths of the ocean ; on the sides, and often on the upper part of their
CHAP. II. PRIMARY DIVISIONS OF TESTACEA. S/
bodies, they are provided with processes like filaments ; and there are generally two very short tentacula, at the teimination of which are two black dots, representing the eyes ; in this respect they certainly show a relation to the Gasteropoda, but then their respiratory organs are totally different. The Nudihranchia, in short, as their name implies, have these organs arranged on the upper part of their body, in the form of a rosette, so as exactly to resemble a bunch of vine leaves, whose stalks form a common centre. One, out of the three great characters of the typical Testacea, is yet retained, — for the animal crawls upon its belly; but has lost the other two, — since they have neither a distinct head nor shell. The tritons and^ dories have the additional power of swimming and crawling on the surface of the sea, with their foot uppermost : in the former case, they are pro- pelled both by their branchia and the thin sides of their body, which act in the manner of fins.
(SS.^ Our next group is composed of those simply constructed Testacea, which represent the Acrita in this class, and which have hitherto been arranged among that heterogeneous assemblage of animals, named Intes- tina by Cuvier. Having now arrived at the most re- mote limits of the Testacea, we find, in the order before us, nothing more than faint indications, or, in other words, the elements, of that organisation which belongs to the typical tribes. The flattened disk-like form, indeed, of the dories and the tritons is fully preserved in the Planarice, and even in some of the Fasciolce ; but the branchia, hitherto so variable, now become less and less apparent, and finally disappear. Some of these animals inhabit the water, but others are internal or external parasites ; and this change of habit takes place in groups so intimately connected in all other respects, that we become convinced of the propriety of retaining them in one and the same assemblage. Hence, without venturing to determine the precise limits of the animals which really belong to this class, we feel no hesitation in considering a large portion of Cuvier's Parexchymata,
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38 SHELLS AXD SHELL-FISH. PART I.
or intestinal worms, as truly belonging to this class. Our reasons for this will be again adverted to. At present, it will be sufficient to state, that these animals are totally distinct from the true Vermes, where the body is composed of articulations more or less developed, and which consequently form the corresponding group in the annulose circle. Nearly all of these imperfect and obscurely known animals, however, partake of the general character of the Testacea, in crawling or adhering by their belly, beneath which, — as in the Fasciolce, — there are cup-shaped disks, or suckers. Analogous, in every respect, to these, are the arms of the next tribe.
(34.) In this manner, then, are we conducted to the fifth and last tribe of the testaceous Mollusca, — namely, the Cephalopoda, or cuttlefish. But this is done by the intervention of a group of ani- mals, almost as simple in their organisation as the intestinal tribe last mentioned. Some of the Ptero- poda, in fact, like the Parenchymata, are without head, branchia, eyes, or any external members ; even the fin, so universal among the Firolce, is wanting in such genera as Timorenia and Monojjliora : but these, or any of the Hetei'opoda, are not the animals to which we must look for the typical characters of the group before us. The types of the Cephalopoda, in fact, are the most highly organised, and, therefore, the most perfect, of all the Testacea. The appearance of these animals is strange and grotesque in the extreme. Their body is soft and pulpy, having the limbs ar- ranged in a circle round the mouth ; these limbs per- form all the offices of feet, arms, and tentacula, and, in many genera, they are used also as fins. The head, which, in all the other Testacea, is either wanting or but slightly developed, is here large and conspicuous ; while the eyes are so clear and distinct, that they re- semble those of a vertebrated animal ; the mouth, from the arrangement of the limbs, or, as we shall term them, the arms, is consequently in the centre, like that
CHAP. II. THE CEPHALOPODA. 3Q
of a radiated animal ; and the sides of the body are either slightly dilated into a distinct fin-shaped mem- brane, or are so thin that it can be vised for the same purpose. In size, the cuttlefish are by far the largest of all the testaceous Mollusca ; they are, indeed, the giants of invertebrated animals ; for, if the accounts of the old Indian voyagers are true, there are some of such enormous dimensions, that they seize upon the divers, entangle them in the folds of their serpent-like arms, and finally devour them. These stories are, no doubt, exaggerated ; but we have, ourselves, seen many of such a size, caught on the shores of Sicily, that two would be a good load, — their arms being as thick as those of a man. Most of these animals now in exist- ence are naked; but in the former aeras of the world, there appears, unquestionably, to have been a most numerous and gigantic race, which had a part of their body protected by a spiral shell, rolled in the form of a disk. Ancient revolutions of our globe, however, have swept away nearly the whole of these testaceous monsters, leaving in the Nautilus almost the only genus hitherto found in a recent state. It is among the existing genera that we find a horny or calcareous plate, which supports the body, and is altogether in- ternal. This, as before remarked, is the first indication of the vertebrated structure among molluscous animals ; and hence, nearly all zoologists place these animals immediately in junction with the Vertehrata : or what is the same thing, consider them the last in the series of the Mollusca. It thus appears, on a general view of the whole of the testaceous Mollusca, that they may be thus concisely described : — The typical and sub-typical divisions crawl, and are covered with calcareous shells ; of which the first is univalve, and generally spiral, while that of the other is bivalve and simple. The aberrant group, on the contrary, have no calcareous covering, but are externally naked, and they have the faculty of swimming added to that of crawling. Thus, we cannot but adm.ire the simplicity and beauty of the
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40 SHELLS AND SHELL-FISH. PART I.
distinctions which nature has thus stamped upon the primary groups^ infinitely diversified as they are in all other respects.
(35.) Our next object is, to show upon what grounds our conviction rests, that these orders form a circular group, more or less perfect. It is hardly necessary to apprise the zoologist, that in this class of animals, above all others, the effects of those revolutions in our globe, which have nearly exterminated so many races of animals, are most apparent. It appears, at first, difficult to say whether this destruction has been most extensive among those whose hard vestiges yet remain in a fossil state, or among such as, being entirely soft, have alto- gether disappeared, and " left not a wreck behind." Our own opinion, however, is decidedly in favour of the latter supposition. Four fifths of the testaceous Cephalopoda have certainly disappeared ; yet their shelly portions, abounding in incalculable quantities in all the older formations, are yet sufficient, with the aid of the few species now existing, to give us some general idea of the chain of continuity : but, among the Nudihran- chia and the Branchiopoda, whole families seem to have disappeared : such of the latter, indeed, as possessed a hard covering may be judged of by their shells; but in what way their union was effected with the existing races of Dithyra it is altogether impossible to judge. The Nndibranchia, again, are allowed by all naturalists to constitute a distinct tribe ; and yet it does not con- tain more individuals, or a greater diversity of structure, than may be met with in any one of the numerous families of the gastropod Testacea. Now, it must be remembered that these are all soft, and often sub- gelatinous, animals, without any hard or durable parts whatsoever ; so that all that have only existed in former periods of our globe, have been exterminated both in life and substance, no indication whatever remaining that they ever had existence. Upon what ground, then, it may be asked, do we take for granted that they have ever been among the things that were ? and what
CHAP. II. ON EXTINCT ANIMALS. 41
reason is there to suppose any one has heen abstracted from the living races ? To this we would simply re- ply^ that such a conclusion is home out by every prin- ciple of analogical reasoning. Throughout the whole of the vertebrated classes^ it is solely in groups where congenial forms have been found in a fossil state that we find the gradations in the living series broken and interrupted. Very few such interruptions^ for instance, occur in the class of birds, and they are so slight as hardly to merit such a term : this fact, in our esti- mation, at once accounts for the extreme rarity of the remains of birds in a fossil state; scarcely any having been exterminated. The living series is, consequently, almost perfect. Not so, however, among the reptiles. In that class there is an entire order (the Elaniosaures) which has been so absolutely exterminated that .not a living example remains ; hence, but for the fossil bones of the Ichthyosaurus, Plesiosaurus, &c., there would not merely be a wide and violent disruption of the reptile series, but an absolute impossibility of forming even a rational conjecture as to its course ; at least, in that dissevered portion which these extinct reptiles actually fill up. But we will bring this theory more home to our present purpose. There is no circular series of living Testacea, wherein is found every modification of form necessary for unquestionable connection, more perfect than that of the predaceous shell-fish {^Gasteropoda Zoophaga): hence the extinct fossil species are not only rare, but they nearly all belong to genera now living, and therefore termed recent. Any one family in this group, in short, contains more species and genera than are now known in. the entire tribe of Nudihranchia, or in the family of Branchiopoda. What, then, are the legitimate deductions from these facts ? We must take our choice of these two : — Either we are to suppose that Nature at first made these latter groups as imperfect as they now are, while all others, abundant in recent species and forms, are perfect ; or that she has removed from the creation most of those links which would fill up the
42 SHELLS AND SHELL-FISH. PART I.
intervals between the existing races^ and which^ were they now living, would render all her groups equally perfect. All analogy, drawn from theory or from facts, compels us to embrace this latter conclusion. Perfec- tion in all His works is one of the attributes of the Creator; it is therefore clear that nothing imperfect could have entered into the plan of the creation.
{36.) An attentive consideration of the vertebrated classes of animals, both collectively and separately, will convince the philosophic inquirer, that in every instance nature begins, as it were, from a small rudimentary group, — a point, so to speak, in existence, — which seems to contain such animals as have the very least affinity to those which, standing at the head, exhibit the typical structure ; they possess only the rudiments of the perfection to which they gradually, but ulti- mately, lead ; and their structure is often so exceed- ingly simple, that, in such as may be termed the germ, even these rudiments are scarcely perceptible. One such, or at most two, are all we can expect to find. Hence it follows, that such imperfectly formed beings, although found in every large division of animals, must neces- sarily possess a strong resemblance to each other ; al- though, in reality, they belong to classes widely distinct, when we trace them up to their full developement. This theory, although in some respects not new, — for it has been tacitly or indirectly admitted in a general way, — has never received that attention it deserves. It has consequently resulted, that nearly all those authors who overlook the important differences between analogy and affinity, have naturally supposed these rudimentary animals, as they may be called, were closely connected to each other hy affinity, and have accordingly classed them as such. This seems to be the true cause why we have such a heterogeneous assemblage of animals under Cuvier's class of Intcstina, and even in those of Mac- Leay's Acrita and Vermes. They agree, indeed, in one respect, — that is, of being the most simple of all others in structure ; but this is altogether more a negative
CHAP. II. OX RUDIMENTARY TYPES. 4S
than a positive character, and altogether fails of that accuracy, to he desired. Besides, it is quite evident, that, if the several threads of affinity — collected together in the above-mentioned groups — had been followed up, each would have been found leading to totally dif- ferent divisions of the animal kingdom. The Acrita, in fact, as at present constructed, is such an ill-defined group, that some writers think they are bound to bring "within its limits the Medusas, and many of the most perfect radiated animals ; so that, if this is allowable, there is no reason whatever for excluding the annulose Vermes, the cephalopodous Foraminata, and the mol- luscous Parenchymata. It may be thought somewhat premature to state these objections, seeing that we have not yet attempted to substitute any other arrangement of the Acrita * for that which we hold to be a false one, although proposed by the very founder of the class. But we are all aware, that the perception of an error, and the power of rectifying it, are not inseparable. Our researches may have proceeded quite far enough to satisfy us on the former, and yet may not have extended, or have been sufficiently matured, to accomplish the latter. It is precisely in this predicament that we now stand. Our researches in the true Acrita, the Radiata, and the Annulosa, — have advanced sufficiently far to convince us of the fundamental truth of what we have just advanced. The subject, however, is of such vast importance to the first principles of natural arrange- ment, that we may well devote to it a few additional remarks.
(37.) If we look to the vertebrated circle of animals, ■we find that many of the amphibians are the most simply constructed of all the Vertehrata ; the Amphiuma are worm-like salamanders, having the body excessively
* We trust this investigation may be taken up by the only naturalist of this country who has devoted himself to the study of the soft Mollusca, and from whose talents, experience, and zeal, we may expect so much — Dr. Johnson. It is a serious loss and inconvenience to science, that the numerous and truly valuable memoirs of this accomplished malacologist are now scattered in periodicals and magazines, almost hid in a mass of temporary and trivial articles.
4-4 SHELLS AND SHELL-FISH. PART I.
lengthened, and the legs and feet so small as to be rudi- mentary ; while the Ccecilia have neither feet nor bran- chia, and sometimes are without eyes. This group, therefore, among the Vertebrata, is precisely the sort of point or nucleus from which diverge two distinct series of animals : the one leads to the serpents, or reptiles ; the other branches out, in an opposite direction, to the fishes ; but both these ultimately meet in the ostrich, which exhibits a union of the bird and the quadruped.' Each of the five divisions of the vertebrated circle afford parallel instances ; so that we invariably find the most aberrant group is always that which is the least or- ganised ; just as is the class ^cnto in the whole animal kingdom. The annulose Vermes, as the tape-worms, and other intestinal creatures stiU more simple, forming the Tcenioides of Cuvier, are, in the annulose circle, precisely what the amphibians become in the Vertebrata, They exhibit the first simple outlines /3f that structure which terminates in the painted butterfly and the sa- gacious bee ; and, when nature has reached these points of perfection, she returns, by slow degrees, through the Annelides, or red-blooded worms, to the same point, although by a different route. Such, also, will be found her course in the testaceous class. The Paren- chymata, or parasitic Mollusca, may be considered the first indistinct and incipient developement of the Tes- tacea, — the point from which nature diverges towards the phytophagous gastropods on one side, and to the car- nivorous gastropods on the other, until both these series meet together, and form a perfect circle in the family of Turhklce. It will subsequently appear that this re- markable principle of variation is not merely confined to the first great circle formed by the Testacea ; it is abundantly evident in its primary divisions — nay, in some instances, even in its families. Among the Ce- phalopoda it is particularly strong. All waiters who have mentioned the Foraminifera, so admirably and beautifully investigated by D'Orbigny, hesitate not to place these microscopic atoms in that order, although it
CHAP. II. ON THE TYPES OF ACRITA. 45
contains the most perfect Mollusca in existence. And yet the organisation of these beings is so very simple, that, if no regard be paid to the difference of analogy and affinity, they might be placed next to the animalcule? in the class Acrita. The chitons among our Gasteropoda, and the genus Chelisoma in the circle of the Dithyra, are further instances : both are the most simple and slightly organised of their separate groups ; and both, in this respect, as well as in the shape of their bodies, are prototypes of the PlanaridcB and Fasciolce, among the parasitic Testacea. But the universally confessed affinities of the naked slugs to the testaceous snails brings this theory home to the personal cognisance of every naturalist. Some of these creatures are so small, ge- latinous, and so little organised, that, but for their in- disputable and immediate affinity with the beautiful land shells of the Helix race, no one would think of placing them in the same order, much less in the same family ; and yet every zoologist sees that such is their natural situation. Hence these naked slugs become nothing more than prototypes of the PlanaricB and Fascioltp ; related, ilideed, to them by analogy, but without any connection whatever in regard to affinity. The extraordinary genus Herpa, one of the splendid discoveries of Guilding (which will be subsequently noticed), carries this analogical resemblance to the highest pitch ; so that, but for the discriminating acumen of that profound observer, we should have been tempted, without seeing the animal, to consider it was an actual type of Planaria, in the disguise, only, of a Limax. On these, and numerous other similar facts resulting from the analysis of this class, we hesitate not to place a por- tion of Cuvier's intestinal worms as the most aberrant order of the testaceous Mollusca. We wish to follow nature, and nature only ; perfectly satisfied, from past experience, that, however various and conflicting may be the comments of her interpreters, she has pursued but one course, and but one plan, in her system of animal variation.
46 SHELLS AND SHELL-FISH. PART I.
(38.) We may noAv'^ commence a rapid survey of the course by which the class before us resolves itself into one great circle, the furtner details of which will be noticed under the several chapters devoted to the chief divisions. We have already expressed our con- viction that the germs of the Testacea exist among the various discordant animals comprising Cuvier's Paren- chymata, but it is by no means clear which is the pre- cise point where the very first indication of this struc- ture is seen ; this cannot be cleared up until the Acrita and the Radiata, not to mention the annulose Vermes, have been sufficiently analysed. Without speculating, therefore, on the probability or possibility of such genera as Echinorynchus and Herula being the rudi- mentary type, we may safely point to the Tremadotes of Rudolphi, and the, whole of the second family of Cuvier's Parenchymata, as containing the vermiform or most aberrant types of the class before us. These, in fact, are nothing more, in one sense, than naked gas- teropod Mollusca, crawling upon their bellies, or ad- hering by means of cup-shaped suckers, which are analogous to, and perform the same office as, the single disk of the more perfect testaceous gastropods. Some of these, like the FasciolcB of Linnaeus, are feeders on the internal parts of animals, and adhere, by means of these suckers, to the viscera of quadrupeds, birds, and fish ; others, as Cyclocotyles of Otto, are external para- sites ; while the true PlanaridcE are entirely free^ and swim about in the water. Now, it is from these animals that nature throws out, as it were, two lateral branches. One of these, emanating from the Planaridce, conducts us, in the most beautiful and graduated man- ner, to the NudibranchUi ; the other, departing from the Fasciola, leads us, by means of such genera as Menostoma of Blainville, and Hectocotylcs of Cuvier, to the no less vermiform animals among the Ftrolcp and other finless Hetcropoda. This latter branch, however, we shall leave after this indioation, and pursue the for- mer. Commencing, then, with the Planarida', we see a
CHAP. II. GREAT CIRCLE OF THE TESTACEA. 47
family as much diversified as any of the naked Testacea, but which, at present, remains almost as a genus. In it are found representations of nearly all the onisciform Molluscttj as Sigaretus, Chelisoma, Chelinotus, Chiton, and numerous others : the interesting genus Tristorna of Cuvier, contains the first rudiments of branchia, — for such do we consider that ^' ramified circular vessel in the parenchyma of the body/' the nature of which, as that learned anatomist conceives, " it is difficult to determine." * This, together with the many beautiful and interesting forms discovered and figured by Riip- pell, establishes the union of the PlanaridcB and the DoridcE — in other words, the two orders of Parenchy- wm^a and Nudihranclua — in the most perfect manner. ^Ve pass, then, from these latter, to the Branchiopoda, the first tribe in the order of bivalves. From this point our course is plain : Anomia connects them with the Ostrcea and other Dithyra without siphons ; while these latter are connected to the more typical bivalves, where these organs are fully developed, by means of Chama and Hippopus. We quit the perfect bivalves for such as are tubular, and hence almost univalve shells, through the Myadce and Solenidcp, and thus reach the Teredince. By this latter family, the path is smoothed to the terminal series of the Dithyi'a, — namely, the Tuhiili- hranchia of Cuvier, — where we have the singular union of a gastropod mollusk inhabiting a tubular shell. The two typical orders being thus united, we enter^ at once, among the spiral or testaceous Ga^Ye/'opocfa, — that group, in short, which stands at the head of the entire class. Beginning with the Scutihranchia or Patellides, as the least organised of these univalve animals, we see a gradual developementof the spire take place in the Halio- tidce, Trochidce, and HelicidcB ; until, in the Tiirhidce, we have a union of the phytophagous and the zoophagous gastropods. The old genera of Melania in one, and Cerithium in the other, effects this union, and conducts us at once to the StromhidcFy MuricidcB, and, finally, to
* Griff. Cuv. xii. 473.
48 SHELLS AND SHELL-FISH. PART I.
the Volutida. The transition from these to the CyprmdcB is no less clear than that from the Cyprceidce to the BuUcBj — the latter being the most perfect of the TectihruncMa. In some of these half naked gastropods, the foot-like disk of the belly is reduced to very small dimensions, while the two lobes of the mantle become so dilated that they are used as fins. In this manner does nature leave the Gasteropoda, and unites them to the swim- ming order of Cephalopoda, — the first tribe of which is the Pteropoda. The straight cylindrical case of some of these singular animals, few in number, but highly in- teresting, prepares us for that extinct tribe of cuttle- fish of which the fossil Belemnites, in all probability, formed the type : from these to the spiral Cephalopoda, the passage is so easy, that it can be traced by the shells alone; and then, with the assistance of Argonauta and C{irinaria, we at once reach the Heteropoda. The affinity between some of these simply constructed animals and the aberrant Parenchymata has already been intimated. Thus we find that the two lateral series which branch off from the Planaridce meet toge- ther in the Turhidce, and complete the circle of the whole class.
{39-^ Ii'i thus tracing the course of the circle of the Testacea, the zoologist, versed in the circular theory, will perceive we have taken no notice of the most aber- rant groups in each order, — and this, because it would have incumbered, without necessity, the simple ex- position of the union of the orders themselves. He will also be aware that it is by these particular groups that each order forms a circle of itself. This important pro- perty will, of course, be adverted to when we come to treat of each order separately. In the mean time, we shall now compare the orders of the Testacea with such other groups of the animal kingdom as appear calculated to render their analogies more comprehensible to the ordinary reader. Our first comparison will consequently be with the vertebrated anhnals.
CHAP. II. ANALOGIES OF THE TESTACEA. 49
Analogies of the Testacea to the Vertebrata.
:^ Orders of the Testacea. Circ\e oC the rerfebrata.
Gasteropoda. Qiiaorupeus.
DiTllYRi. JilRDS.
NlJDlBRANCHIA. REPTILES.
Parenchvmata. A:mphibians.
Cephalopoda. Fishes.
(40.) The reader will bear in mind that, hitherto, we have spoken of relations of affinity ; but our present business is with analogies, or mutual representations. Setting aside, therefore, all we have already advanced, we accordingly find that the best modern zoologists place the Dithgra, or bivalve shell-fish, close to the Gaste- ropoda, or univalves, upon the same principle as the birds, in the other column, follow the quadrupeds. This arrangement, at the very first, seems to carry with it an appearance of being natural, because we thus find that both the Dithgra and the Ai'es are the sub- typical divisions of their own circles. But this parallelism, although highly satisfactory, is not of itself sufficient ; we must look further, and inquire whether these groups actually agree in any particular circumstance of struc- ture, common to both. Now, every one knows that, among the many things in which quadrupeds differ from birds, their mode of feeding is altogether dissi- milar. Quadrupeds are provided with jaws bearing teeth, with which the food is masticated before it enters the stomach : birds, on the contrary, have the jaws dilated into a snout-shaped bill, and teeth are alto- gether wanting. The rapacious birds (Raptores), in- deed, which typify the quadrupeds, may be said, in some degree, to masticate their food ; but by all others it is sucked into the mouth, the effects of mastication being supplied by the stomach. If we inquire into the modes in which the typical Gasteropoda and the Dithyra take their food, we find that it is precisely conformable to the above variation. The most typical of the spiral shell- fish (^Gasteropoda), like quadrupeds, are provided with fleshy lips and corneous jaws, varied, as M. Cuvier truly observes, into numerous modifications ; while in many genera (on the same authority), the inside of the cheeks
E
50 SHELLS AND SHELL-FISH. PART 1.
are provided with reflected teeth^ to aid deglutition. On turning to the Dithyra, however^ we find a totally different structure : the mouth has neither lips^ jaws^ nor teeth, but is " a simple aperture" entering into the stomach ; the food, in short, is sucked in, and is swallowed entire, as it is by birds : so that, strange as it may appear, the two most perfect groups of the testaceous Mollusca exhibit, generally speaking, the same mode of feeding as the two most perfect groups of vertebrated animals. It seems hardly necessary to strengthen analogies so beautiful ; yet we cannot omit, in this place, that there are not wanting indications, even in the structure of the bivalve shell-fish, to remind us of the peculiar, character of birds : in these latter, the sides of the body are enveloped by two broad and expansive wings ; in like manner is the body of an acephalous bivalve enveloped on its sides by the ample folds of its cloak or mantle. Yet neither of these appendages occur among the typical quadrupeds and the typical gastro- pods.* But it is time to pass on to the Nudibranchia and the reptiles. Do these represent each other .f* and in what manner ? We will set aside that forbidding appearance which these reptile-looking Mollusca possess ; and which indicates, at first sight, some analogy to the true reptiles, because this is a mere m.atter of opinion : not so, however, is the circumstance that both these classes crawl upon their belly, and are destitute of any limbs. The tritons, in fact, have no real feet ; and the serpents, standing at the head of the ReptUia, are eminently distinguished in the very same way. The analogies of the Parenchymata, in general, have been sufficiently explained ; it is, therefore, only necessary to observe in this place, that the Amphibia are the most imperfect of the vertebrated animals, just as the Paren- chymata are the most simply constructed, and the fur- thest removed from the typical Testacea. Their short, thick, and broad form reminds us again of the onisci- form type of annulose animals. We have now only to
[* Except in such as are aberrant in their ovv-n circles, as the Volutidce, &c.
CHAP. II. THE TESTACEA AND ANNULOSA. 5\
compare the two last groups in our table^ — namely^ the Cephalopoda and the true fishes. These agree in con- taining the largest individuals of their respective circles,
— except, indeed, the fish-quadrupeds, or whales. Both swim by means of their fins, which in both groups represent the arms and feet of other animals : the eyes of both are almost perfectly the same : the old natu- ralists, indeed, who were more led by general appear- ance than by anatomical peculiarities, considered the cuttlefish and Loligo as true fishes. It may, therefore, safely be said, that, if we are to decide which division of the Testacea bears the greatest resemblance to fishes,
— whether as regarding outward form or internal or- ganisation,— no one would hesitate to name the Cepha- lopoda as that group.
(41.) In further confirmation of this arrangement, we will take a slight glance at the classes of annulose animals (which are to form the next volume of our series), and compare them with those of the Testacea. It is scarcely necessary to dwell upon the two typical groups of each, — the Gasteropoda and the Ptilota, which stand as the pre-eminent ; and the Aptera and Dlthyra, as the suh-typical classes : when, however, we proceed to the aberrant groups, we find the analogies, as in all other instances, much stronger. How beauti- ful, for instance, do the Annelides, or red-blooded worms, put on the very aspect and form of the Nudibranchia ; a naturalist, looking to the outward appearance of these creatures, — their naked body, often covered with tufts of plumed or ramose appendages, assuming sometimes the likeness of horns, filaments, or tentacula, — would even entertain a suspicion that they really belonged to the same class of animals. No wonder, therefore, that the older naturalists, and even Linnaeus, mixed them together ; since the circumstance of one having red, and the other white, blood, was not, in those days, considered a matter of much importance. Now, this analogy, which is perhaps one of the most striking in the whole of the animal creation, is highly important
E 2
52 SHELLS AND SHELL-FISH. PART I.
when viewed in reference to any doubts which may hang over this group^ from its isolated situation on one side of its own circle. The strong analogy between the Parenchymata and the annulose Vermes has induced all writers to blend them together^ even up to this day ; the one being the most imperfect of all the Tes- tacea, as the other is of the Annulosa. Passing on to the relationship between the cuttlefish {Cephalopoda) and the barnacles {Cin'ipeda), we are struck with a resemblance much stronger than would be supposed to result from a mere relation of analogy. In both these tribes, the mouth is surrounded by long slender arms, employed to catch their prey : both contain ani- mals whose softer parts are protected by shells. Never- theless the Cirripedeshsive no more to do with MoUusca, than the latter have with those crabs, which, like the genus Cyclops, are naturally enveloped in bivalve shells. To the Radiata, again, the analogy of these tribes is no less apparent ; for, as both have the organs of motion arranged around, or rather radiating from, their mouth, which thus becomes the common centre, they have, to all outward appearance, the essential characters of ra- diated mollusks.
(42.) Assembling all the groups thus brought into comparison in the following table, we shall see, at one glance, the mutual relations they present in their com- ponent parts.
Analogies of the Test acrovs Mollusca to the Annulosa.
Analogical Characters. "Typical, the most hif;hly organised;'
Tribes of ,« 7 • ? /-.i j Classes of the
-r „/^^,^ Analogical Characters. j., ,. ; ^
festacea. ^ Annulosa.
rTypical, the most hif;hly organised ;T Gasteropoda. < head distinct, with long antennae or >Ptilota. t tentacula. j
rHead indistinct, confounded with theT DiTHYRA. -j thorax, or altogether wanting; no>APTERA.
C antennte or tentacula. J
M.Tn,T,DAi«r'«ii yCiskof the belly flattened, and often 7 4^,„^,,„^, NUDIBRANCHIA. ^ performing the olhcc of a foot. j Annelides.
TThe most simple in their organisation, 1 Parenchymata. •< naked, and crawl upon tiieir belly ;> Vermes.
C no perceptible branchia. j
f Mouth surrounded by long tentacula,^ Cbphalopoda. < or arms ; soft parts of the body ge- ^Cirripeoa.
C. ncrally protected by a shell. j
CHAP. 111. THE ORDER GASTEROPODA. $3
So singularly do the Aptera represent the Dithyra by the head (as in spiders and scorpions) being con- founded with the trunk, that they might even, without any violation of propriety, be termed acephalous in- sects. But we presume enough has now been said on this set of analogies, to satisfy the unprejudiced reader. And having now sufficiently dwelt upon our arrange- ment of the Testacea as a class, we may at once pro- ceed to the details of the tribes in which the whole are here arranged.
CHAP. III.
ON THE ORDER OF GASTEROPODA, ITS PRIMARY DIVISIONS, AND THE CHARACTERS AND ANALOGIES OF THE MlIRICIDjE AND THE TURBINELLID^.
(43.) The gastropod shell-fish, as we have already shown in the preceding pages, stand at the head of the testaceous Mollusca, — a station which both Cuvier and Lamarck have also assigned to them. This has now been confirmed by the theoretical and analogical tests with which our last chapter was concluded. Bnt as our ar- rangement of these aninials will be in many respects very different from that of preceding writers, it will be proper, before submitting its details to the reader, that we should take a short review of the group as it at pre- sent stands in existing systems.
(44.) On referring to the definitions given in the Itegne Animal of the order Gasteropoda*, and to the animals composing it, we find it embraces more than nine tenths of the whole of the Mollusca inhabiting univalve shells, and by far the greater part of such as are naked. The inevitable consequence of thus includ- ing a multitude of groups, differing from each other in
* Griffith's Cuvier, xii. 21. E 3
54' SHELLS AND SHELL-FISH. FART I.
almost every thing, has been this_, — that the reader is at a loss to know by what other principle they are united, even according to the system of the learned au- thor. Some crawl on their belly, others do not ; some have shells, others none ; many have a distinct head, but many have not ; the eyes are present, or they are wanting : all the organs, in short, of respiration, deglu- tition, and reproduction, are admitted to vary ; and this, in such an extraordinary manner, and in species so ob- viously allied to each other, that they have no claim to a primary consideration. True it is, that all these ani- mals possess an aortic heart ; but this, properly speak- ing, is more the universal character of the testaceous Mollusca as a class, than one by which such an immense number of animals, totally different in all other respects, can be distinguished. The order, as it noAv stands, may be said to embrace the whole of the Mollusca, except the Dithyra, or bivalves, and the Cephalopoda, or cuttlefish. " There is. no doubt, some great error," observes jNJr. MacLeay, " yet undetected in the principles upon which we are accustomed to arrange the 3Iollusca, and that we shall never arrive at the truth, by looking, like M. de Blainville, solely to the position and structure of the organs of respiration ; or, like M. Cuvier, to the method of reproduction, as when he unites the Cyclohranches to the Acpphala or Dithyra.
(45.) Rejecting, therefore, all those animals from the true gastropods, which have neither a distinct head, as the Tubulibranchia, or whose branchia are naked, as in Doris, we shall retain an assemblage of mollusks, nearly all of which are furnished with univalve shells*; and whose head, distinguished from their body, is provided with tentacula and eyes ; the flattened part of the belly serving them as a foot. Thus restricted, we shall find that nearly all the remaining divisions of M. Cuvier, under certain modifications, indicate so many natural groups. It is clear, however, that when M. Cuvier
* Excppt in Chiton, where the valves are separate and dorsal only, and some of the Tectibrancliia.
CHAP. III. TRIBES OF THE GASTEROPODA. 55
places such genera as Planorhis and Ampullaria in two different orders, merely on account of a difference in their organs of respiration, he falls into as great an error as that he has elsewhere committed in uniting the Cyclo- .hranchia to his Acephala. The order Piihnonaria, there- fore, must be clearly abolished. This, indeed, has been already done by Lamarck, whose authority on all ques- tions of natural affinity must, in general, be regarded as superior to that of Cuvier.
(46.) ^\^ith the foregoing restrictions, the primary divisions of the order before us wuU be found to consist of the five following tribes: — 1. The Zoophaga of Lamarck, or the carnivorous shell-fish (corresponding to the Pectinibranchia Cuv.); 2. The Phytophaga of the same author, which live chiefly on vegetables, as the snails and slugs; 3. The Scutibranchia Cuv., or lim- pets ; 4. The Cyclobranchia Cuv., or chitons ; and, 5. The Tectibranchia Cuv., or buUas, whose univalve shells, where they exist, are all hid in the flesh of the animal, while their mantle is dilated into two fin-Hke lobes, with which they can swim. We shall now state a few general particulars of these tribes, and then proceed to determine their analogies.
(47.) The Zoophaga are the most pre-eminently typical of the whole of the testaceous Mollusca ; and this holds good, whether we regard the organisation of the animal, or the symmetry and beauty of their ex- ternal shell, wdth which, in every instance, they are provided. They have only two tentacula ; and the eyes, which are always conspicuous, are sometimes (as in the Stromhid(E) highly developed- The edge of the mantle is almost always provided with a siphon, or tube for respiration, and by which the animal can breathe without protruding its head and foot from the aperture of its shell : this siphon is protected by a corresponding canal, either long or short, at the base of its habitation ; and its presence, in all these Mollusca, constitutes one of their most essential characters. The mouth, also, is very re- markable, — resembling more or less, as Cuvier well
E 4
56
SHELI.S AND SHKLIi-FISIl. PARTI.
observes, "an elongated proboscis. Their tongue/' he continues, " is armed with little hooks, which, by slow and repeated rubbings, act upon the hardest bodies/' It is by this process that they perforate, with the smoothness and precision of an auger, the shells of. other animals, which they then destroy and suck the juices of. The sexes are always separate; and the aperture of the shell, in most instances, is closed by an operculum. The various modern genera formed out of the Linna^an Murex, Biiccinum, Conns, Voluta, &c., are included in this tribe, the shells of which are always spiral, and furnished with a notch or emargin- ation at the base.
(48.) The Phytophaga, as the name implies, are feeders upon plants ; for although several, like the slugs, will devour animal substances, they more habitu- ally live upon vegetables. They are, besides, eminently distinguished from the carnivorous race by two cha- racters : their mouth does not form a proboscis ; and the aperture of their shell is entire, — in other words, without the notch or canal for the passage of the siphon (when it exists), so universal in the last group. In all but one or two genera, as the slugs and the marine Onchid^B, they are more or less covered with shells, which, in however small a degree, are always spiral. By far the greater part of them have the sexes separate ; but in regard to all the other organs connected with respiration, they may be said to vary in every possible way, — a clear proof that such variations, in groups naturally and closely allied, cannot be taken in an arbitrary sense. Many of these animals have their branchia as in the Zoophaya; some few, as Cyclostoma and Helicina, even according to M. Cuvier's admission (who places them, nevertheless, with his Pectin ibrajichia), '' have instead of gills, a vascular network covering the top of a cavity that is otherwise similar ; and they respire, like the Limax, the natural air." The whole of the terrestrial slugs and snails, again, breathe through an open perfo- ration under the edge of the reflected mantle, which
CHAP. III. TRIBES OF THE GASTEROPODA. 57
they can dilate or contract at pleasure : hence they have no gills, " but merely a network of pulmonary vessels, which spread over the parietes and the roof of their respiratory cavity." The tentacula, in such as inhabit fresh water, are generally only two ; but in the land and amphibious groups, as Helijo, Ampidlaria, Pla- norbis, &c., they are four. Their food, notwithstand- ing all these variations, is always essentially vegetable. Their mouth is uniformly the same, and their shell is always spiral ; this latter circumstance, it should be remembered, carries with it an important character in the form of their body, which is of much consequence, and separates them from the next tribe. The whole of the land shells, as well as the marine families of Neritinw, Turbidce, TrochidcE, &c., are comprised in this division ; the HaUotidcp, or ear-shells, being the connecting link to the next.
(49.) The ScuTiBRANciiiA have the same system of respiration, according to Cuvier, as hh PectinibrancMa ; but they differ not only in their mode of reproduction, but most remarkably in the form of their body. They are all attached to their shelly covering by an amazing strong muscle, which fills the centre, and gives them such an adhesive power, that they affix themselves im- moveably to other substances, from which they can only be separated by the sudden insertion of some sharp instrument. They are, in fact, affixed Testacea ; for although the animals can move about, they cannot live but upon a substance where they can instantaneously fix themselves. In their internal structure, we find the heart, according to Cuvier, " traversed by the rectum, and receiving the blood from two auricles, as is the case in the greater number of bivalves." * The form of the shell is no less peculiar ; its general shape is that of a low, broad-based pyramid, or, if viewed inside, of a very wide but shallow funnel. The common limpet, in short, appears to us the most typical of the whole ;
* It is by this group, in fact, as will subsequently be shown, tliat we consider the Gasteropoda and the Di(/ii/ia are united.
58 SHELLS AND SHELL-PISH. PART 1.
for although this genus has heen excluded by some writers, and separated from Fissurella, Sec, in a dis- tinct tribe, yet this is evidently doing a violation to nature. None of the genera in our present group pos- sess spiral shells ; for although Haliotis is obviously intermediate between the Phytophaga and the Scuti- hranchia, its preponderating character, both as regards the animal and the shell, appears to us in favour of its being placed as the last of the turbinated families, rather than as the first of the present group. Thus restricted, the Scutihranchia will contain Patella, Siphonaria, Fissurella, E7nargmula, Parmophorus, Capulis, Sec, together with the singular genus Hijiponyi-, of which we shall have occasion to speak hereafter. Magilis and Siliqiiaria evidently disturb this series, yet open a direct path to the Dithyra, or bivalves.
(50.) The Cyclobranchia, according to Cuvier, '^'have the branchia resembling small lamella, or little pyra- mids, forming a cordon more or less complete under the borders of the mantle, very nearly the same as the In- ferohranchia," from which, however, he separates them on account of their different system of reproduction : " the heart," he continues, " does not embrace the rectum, but its situation varies ; the stomach is mem- branaceous, and the intestines very long." The only genera placed by Cuvier in this group, are Patella and Chiton. The first, however, is so evidently connected to the Scutihranchia in all other points of organisation, setting aside the shell, that we have no hesitation in adopting the theory of Lamarck, who unites the genera Phyllidia and Diphyllidia to Chiton, particularly as this arrangement at once opens a direct passage to the Tcc- tihranchia. The shells of the chitons, which thus become the types of the Cyclobranchia, are boat-shaped and multivalve, the valves being disposed transversely upon the back of the animal, and folding over each other like a coat of mail.
(51.) TheTECTiBRANCHrA,to which we are conducted by Lamarck, form a most natural group. It is peculiarly
CHAP. III. TRIBES OF THE GASTEROPODA. 59
interesting^ because it contains those diverging genera which connect it not only with the chitons^ but with the Gasteropoda on one side, and the Cephalopoda, on the other. They may be described as thick, fleshy, soft mollusks, generally possessing a distinct head furnished with a pair of ear-shaped tentacula, and with the mantle usually dilated into two lobes resembling fins : the branchia are folliculated on the right side or on the back, and are generally covered by a small bulla-shaped shell concealed in the folds of the body. They have the power both of crawling by means of a narrow disk on their belly, and of swimming by their fins. JNIany of the species are very large, and when taken out of the water they appear like great oval masses of flesh. They are the only swimming gas- tropods possessed of a univalve shell, and are con- nected to the Cephalopoda by the singular genus Gas- teropteron Meek., which thus brings us at once to the Pteropoda ; while the connection of the Bullce to the CypraidcR is obvious to every one.
(52.) The union of the Phytophaga and the Zoophaga, or the typical divisions, is so perfect, that the only ap- parent difliculty seems to be where one terminates and the other begins : thus, if we look to the possession of a siphon as a primary distinction of the Zoophaga, we find this organ fully developed in the sub-aquatic genus Ampullaria, which is nevertheless so closely united in its other characters to the Phytophaga, that we cannot separate it from its obvious allies : the mouth of the shell, in fact, is as entire, or rather as destitute of any notch or canal, as that of the garden snail ; while PlO' naxis and Melanopsis, both of which are most inti- mately related to Melania, have a deeply notched aperture. If we look to the relations afforded by the animals themselves, the same interchange of characters takes place. As these two groups follow each other in afl5nity, we may pass on to the HelicidcE, or land snails, and the marine Trochidce, until we reach the Scuti- hranchia by means of such genera as Trochella, which
60
SHELLS AND SHELL-FISII. PART I.
unites the essential character of a turbinated Trochus with those of the patelliform Calyptrtra, Capulis, &c. By following this clue, we arrive at once among the limpets, while the NaticidcB branch off and unite again with the TurhidcB. It is quite indifferent to our present purpose_, whether Haliotis is retained in the Scutibranchia, or within the confines of the Phytophoga ; but we may here anticipate our subsequent analysis, by stating that it truly belongs to the latter, where it forms a particular family, representing the limpets. Having arrived, therefore, among these latter shells, the most simple of all the univalve Testacea, nature returns to the carnivorous gastropods through the Cyclohranchia and the Tectibranchia ; so that the junction of the latter with the CyprcBidce, as before remarked, completes as perfect a circle as any, perhaps, in the entire animal kingdom. From this disposition of the groups results the following table of analogies : —
Analogies of the Ti'ibes of Gasteropoda to the Orders
of the Testacea.
Tribes of t , ■ , nu u Orders of the
/^„ /,,. «„^« Analogical Characters. T^.y,, .^,
Gasteropoda. ° lestacea.
r Pre-eminently typical; mantle^ ZoopHAGA. ■< formed into one or two long tu- > Gasteropoda,
C bular siphons. j
Phytophaga. Siphons entirely wanting. Dithyra.*
'Animal oval, greatly depressed;' o 1 thebranchia, in the typical di- 1 x-
SCUTIBRANCHIA. < „;„:„„. f.. :„„,') „.,,, .■:iL.„,, >- N UniBRANCHIA.
Lnimal oval, greatly depressed ; '\ thebranchia, in the typical di- f^ visions fringed, and placed on i the back. J
^ ("Tentacula none; body broad, 7 r>.
Cyclobranchia. J oval, onisciform. ' j Parenchymata.
Sliell, when present, protecting') only a part of the body, con- f . cealed ; mantle dilated into fin- 1' like lobes. J
Tectibranchia. ■{ ^^J^^ ; mantle dilate.l into fin' ^ Cephalopoda
It is not a little extraordinary that these two series of animals, which in their external aspect are so very dis- similar, should yet present such strong analogies to each other ; the Scutibranchia, in fact, may be called A''i(di- branchia provided with shells _; and, in the same way,
* The sub-typical group, of course, is the one here compared, and there the animals have no siphon.
CHAP. III. THE CARNIVOROUS TRIBE. , 6l
the PlanaridcE among the Parenchymata are naked chitons (^Cijclohranchia). The Cephalopoda, in hke manner, are as perfectly represented by the swimming tribe of the Tectihranchia ; and like them, also, have their shell internal. Adverting, again, to the two first analogies, we find the primary types, the Zoophaga and the Dithyra, furnished with long siphons^ or tubes, which are totally wanting in the secondary types. To this table^ however, w^e may hereafter return ; and, in the mean time^ w^e shall enter at once on the most typical families of the entire class.
\5S.^ The tribe of the Zoophaga, or rapacious shell- fish, is distinguished by a tubular or proboscis-like mouth, a respiratory siphon, and two tentacula, upon the sides or near the base of which are the eyes. In some few, as in the cowries (^Cypr(Ea\ the mantle is ex- ternal, and almost envelopes the shell ; and this, we sus- pect, is likewise the case in some of the Volutidcs, or volutes ; but in general it is internal, and of ordinary dimensions. Nearly all are provided with a horny oper- culum for closing the aperture of their shell ; but in the Cones and ColumheUirKe this is reduced to a mere vestige ; while in the Cypraidce, and such as have the lobes of the mantle very much developed, it is unneces- sary, and therefore does not exist. All these variations, however, in the operculum are slight and trivial, in com- parison to those exhibited in the form of the animal and the construction of the shell. Here the greatest variety, and the most regular constancy in the variation of natural groups, is everywhere discernible. Hence it is, that while our primary attention must be directed to the variation of the animal, we must still have a suf- ficient regard to its testaceous covering. It is the abuse, and not the judicious use, of a regard to the shell, which is to be condemned. A system built only on the vari- ation of the animal, would be as useless and insufficient for all practical or philosophic purposes, as another would be detrimental to sound principles of classifi- cation, if it w^as framed entirely on the form of the
62 SHELLS AND SHELL-FISH. PART I.
shell. The first would include^ like the old systems, all manner of spiral shells,, under the generic name of Buccinum ; while the other would p^ace Parmophorus, Fissurella, and Umbrella in the same group as the limpet, merely because they had similar shaped shells. "While, therefore, we make this and all our other chief divisions to repose on a primary consideration of the soft parts of the body, we regard the construction of the shell as much a part and parcel of the animal itself, as are the wings of an insect or the hard covering of the chelonian reptiles. The shell of testaceous animals, in fact, is precisely analogous to the covering of the tortoises, and are to be considered in the same light, • — that is, furnishing a secondary, although a very im- portant, set of characters for the determination of the minor groups. It is not a little remarkable that, as the tribe before us is the most completely organised, and therefore the most typical of the whole of the Testacea, so do we find their testaceous coverings are the most complicated, and by far the most beautiful of all the spiral univalves. The gradual transitions of form which they present, even when there is little or no variation in the animal, or, at least, none that has yet been detected, is a clear proof, if any other was wanting, that all our secondary characters taken from the shell, are those which nature herself has employed to designate the sub- ordinate groups. The definitions, therefore, of the families in which we shall now arrange this tribe, will be mainly taken from the shell, at the same time intro- ducing all such information regarding the soft parts of the inhabitant as appear of primary consequence.
(54.) The five leading divisions of the Zoophaga may be thus named and defined: — 1. The MuRiciDiE, or murexes, having the respiratory siphon in general very much developed, and its corresponding canal at the base of the shell always straight. 2. The Turbinellid^, or turnip -shells, where the base of the shell is straight and lengthened, and the pillar strongly plaited. In both these, the mantle of the animal is never dilated, but is
CHAP. III. FAMILIES OF THE ZOOPHAGA. 63
of ordinary dimensions, and drawn back into the shell with the animal. 3. The Volutid.^, or volutes, having the mantle much developed in the typical species : the column of the shell is always marked by regular and well-defined plaits, nearly the same as in the last; but the base of the aperture is obtuse, truncate, and notched. 4. The Cypr^id^, or cowries, whose shells are without any spire ; the last whorl enveloping all the others, as in the bullas. 5. The Strombid^e, or wing-shells ; the only division where the outer side or lip of the aperture is considerably dilated. The two first of these are the typical and sub-typical groups ; the three latter form- ing the aberrant circle. The whole are marine.
{55.) The MuRiciDiE, or whelks, are resolvable again into the following sub-families, each of which contains genera and sub-genera : ] . The Muricince, or murexes * ; 2. The Cassinw, or helmets ; 3. The Buccinincp, or whelks ; 4. The PurpurincE, or purpuras ; and, 5. The NassincB. These we shall now enter upon in the above order of arrangement.
(56.) The MuRiciN^ is a very diversified and (from* the little yet knowni of the animals) a very difficult group to arrange. Generally speaking, they are strong shells, of a rough exterior, without any plaits or teeth either upon the pillar or outer lip : the different periods of their growth, or rather of their enlargement by the anim.al, are marked by thickened transverse ribs called varices, which are differently disposed in the genera : the canal is generally short, or of moderate length, but always present, and usually a little bent on one side. The aper- ture is oval; and the spire nearly as long as the body- whorl. They chiefly abound in the shallow waters of temperate seas; and are either covered with an epidermis of their owai, or by extraneous marine substances. The typical genus is MureJc, where we find some of the most beau- tifully coloured shells, and certainly the most elaborate in structure, among the whole of the spiral univalves.
* Sometimes called rock-shells, from the roughness and irregularity of their surface.
64
SHELLS AND SHELL-FISH.
PART I.
This and Ranella appear to be the two typical genera ; but of the three aberrant divisions^ Triton is the only one that has been yet named or defined. The foliated varices of Ranella, and the sharp tubercles on the whole shell, joined to the additional canal at the upper part of the aperture, indicate that this group is naturally con- nected to Miirex ; but the species are very few, and , present no very marked deviation from the typical form. In Triton, however, the case is far otherwise. The species are not only more numerous, but exhibit in their structure so many different modifications, that there is no one generic character to which there are not exceptions in some of the species. The most usual is that of having but few varices, and these placed alternately ; whereas in Ranella they are so united as to form a continuous ridge on each side the shell, when it is placed with the aperture downwards. But this character is by no means constant. The animal {fig. 1.) is here represented from
an unpublished drawing by Guilding ; the tentacula are short, and the eyes at their base. This remarkable diversity in the genus Triton is easily accounted for, on the ground that this group contains representations of all others in the family, besides aberrant forms leading to the more proximate genera. The two other aber- rant types, which we consider as completing the circle of the Muricince, we name Vitulina and Muricidea. The first is advancing towards Murex, and is repre- sented by the Mureoc Vitulinus of authors, and is dis- tinguished by having the varices nearly obsolete, and the piJlar smooth, broad, and flattened, like a purpura.
CHAP. III. THE GASSING, OR HELMETS. 65
The type of Muricidea, is the harp-like Mureoc Magel- lanicus* Where, as in very many other of the small murexes, the progressive growth of the shell is marked by longitudinal ridges, either foliated or spined, some- times as close together, and nearly as regular, as those upon the harp-shells. The outer lip is quite smooth, and the inner Hp thin : there is no internal groove ; and the basal canal is almost always closed over, so as to form an internal tube, open only at the two ends. The connection of this group of Murices to the true genus Murex is so close, that they have never, until now, been separated ; so that, being connected to Triton by means of Vitulina, also a Lamarckian murex, we find the whole forming a circular group of themselves.
(57.) Ill the Cassin.e, or helmet-shells, the first cha- racter which strikes us is their large and often gigantic size : the spire is remarkably short; and the base, instead of being prolonged, as in the Muricince, is either truncated so as merely to present a wide notch, or is very short, and turned back on the body-whorl. These are the typical characters of the sub- family, but much remains to designate the genera. Our attention has been more especially called to this group, not merely from^ the size and beauty of the shells, but from the great reluctance some conchologists have manifested to adopt the genus CyprcEcassis, proposed by j\Ir. Stuchbury, whose valuable Essay upon the growth of corals has rendered his name familiar to naturalists. That Cyprcecassis pos- sessed a decided relation, either by affinity or analogy, to Cyprcea, we had long been persuaded. But vre freely confess, that previous to, and even for some time after, its being proposed as a genus, we looked upon it only as a subordinate type of Cassis. Anxious, never- theless, to arrive at some definite conclusion on this point, we were induced to re-examine the whole of the Lamarckian genus Cassis; the result of which has con- vinced us that our first impression was erroneous, and that Cyprcecassis is as truly a natural genus as any in
* Ency. Method, pi. 414. fig. 4. a, b. F
66
SHELLS AND SIIELL-FISH.
PART I.
the whole circle of the Testacea. It will be needless in this place to enter into the definitions of this and the other four genera^ since they will be found in our sys- tematic arrangement ; but they may shortly be cha- racterised in the folio-wing manner : — In Cassidea and Dolium, the aperture of the shell is always wdde, rarely with distinct varices^ and the outer lip never dilated into a marginal rim over the body- whorl; but in the first, the inner lip is reflected, thickly marginated, and generally toothed, while in the last it is always thin : these will be found, upon analysis, to be the two typical genera. In the harps {Harpa), which obviously follow the tuns (^Doliimi), the whole shell is marked by varices, which assume the form of ribs. Now, the ample information given by M. Quoy on the animal of this genus, not only fixes its station in the present circle, but demon- strates it to be a representation of the volutes, with •which that admirable malacologist compares it. This im- portant point being determined upon such high authority and unpremeditated testimony, we arrive, by induction, at the station of the two remaining types. Cyprce- cassis, consequently, intervenes between Harpa and Cassis; and this latter fills up the interval between Cy- prcEcassis and Cassidea. Thus, the Cassince, like the MuricincB, form a circle of affinity among themselves, and present one of the most beautiful set of analogies to be found among the families of Testacea.
Analogies oftheCASSiyiM to theFamiUes q/* Gasteropoda.
Genera of the
CASSINiB.
Cassidea.
DOLIliM.
Harpa.
CyPRj1?CASSIS.
CTypical ; X straight.
Analogies.
basal cliannel never '
{
Cassis.
Sub-typical.
Font of the animal enormously
large ; mantle dilated ; tcnta-
cula short.
r Aperture of the shell linear ; both") lips regularly toothed, the in- | ner spreading, but never pro- )■ minent ; aperture with a ciian- | L nel at each extremity. J
Outer lip gibbous or angulated ^ above, considerably dilated on f ts margin ; eyes of the animal T ghly developed. j
rOutc 3 ab( 1 its C hit
Families of Gasteropoda.
muricidj!.
TuUBINELLIDiE. VOLUTIDJE.
CVPR.EID.C
STROMBID.E.
CHAP. III. ANALOGIES OF THE MVRICIN^, Gj
As no very tangible analogies exist between the shells of the two first groups in each column^ we may fairly presume that they exist only in these hitherto not well defined animals^ particularly as it is only by this means that the resemblance of Harpa to the ]\Ielons^ or typical volutes^ has been established ; and yet, when we look at a harp-shelly we cannot assimilate it to any other than a coronated volute. The analogy between Cypr(Ecassis and the cowries is too strong to be insisted upon ; and in this view it is quite unimportant whether the former has or has not an operculum^ for the relation, in either case, is clearly one of analogy, and not of affinity : we are disposed to consider the common C. testiculus as the type, simply because it puts on more the aspect of a cowry than any other species we have seen ; it is less nodulous, and its slender longitudinal ribs accord more with those of Oniscia and other cyprseform types. Cassis, itself, is indubitably a prototype not only of the Sti'omhidcE, but of the NassincE, to which it at once leads through the intervention of Cassidaria.
(58.) It is not a little remarkable that while the genera of the Cassince represent the families of the car- nivorous gastropods, those of the pre-eminently typical Muricince have a more especial reference to the sub- families, as will be seen by the following exposition : —
Analogies of the Muricin^ to the Sub-families.
Genera of j^^;„„-^<. Sub-families of
MuRiciN^. Analogies. Muricid^.
Murex. Typicalofthtir respective groups. Cassincz.
Ranella. Sub-typical. Muricin<s.
r Spire generally longer than the"! Triton. \ aperture ; base short, nearly > Buccinince.
C truncate, straight. j
r-., ,. „ ■ f Inner lip broad, smooth, and flat- 7 „
Jduhna. ^ tened ; basal channel narrow, j Purpurm<e.
Muricidea. Base of the shell slightly produced. 'Nassimc.
Here, again, insufficient acquaintance with the animals very much lessens the interest of these comparisons : and yet there can be no doubt that Murex vitiilinus of
F 2
6s SHELLS AND SHELL-FISH. PART I.
authors is more a miirex than a purpura, — that Triton passes into Bnccinuni, and therefore represents it, — and that, of all the carnivorous gastropods out of the CassincF, Murex JMagellanicus and its alUes have the greatest similarity to the harp-shells. This is all we would maintain. For the rest, there is such an extreme regu- larity in all the existing species of Harpa, that we may fairly conclude the aberrant examples have become extinct, or have possibly not been discovered. One species, however, of Muricidea, with the ridges of 31. Magellanka, but with a truncated base, would con- nect the two groups ; and when we consider that, in Triton, the comparative length of the channel is only used to designate the species, we may fairly conclude there is no violation of nature in supposing that Harpa and 3Iuric'idea pass into each other. As for the analogy between the latter and yassa, we have at this moment a species of Muricidea before us, whose canal is reflected backwards precisely as in the common ^'i. ar- cularia.
(59.) The typical distinction of the Nassje lies in a very thick deposition of enamel which encircles the aperture, and not only spreads far beyond the inner lip, but forms a vitreous mass all over the under part of the body-whorl. The only other genus of predaceous Testacea having a shell thus constructed, is Cassis, and a few tritons, w^hich are probably its representatives. Nevertheless, there are many Kassce which have this peculiarity but slightly developed, and others in which it is not at all apparent ; in all, however, there is a pro- minent internal ridge at the base of the pillar, and a small transverse tooth on the upper part of the inner lip. These shells are all of a small size, and abound in the shallow waters of Southern Europe and the East. Among the unpublished researches of Guilding*, is a highly finished drawing of a species from St. Vincent's {fiy.2.), which throws an important light on the animal :
* Now in the possession of his widow.
CHAP. III.
Tin: NASSIXiE.
69
from this, it does not appear to have a probosciform mouth ; but the anterior part of the foot is prolonged into a subulate point on each side, and the hinder jmrt termi- nates in two little tail-like appendages. Now this has much of the character of our genus Leiodo- nius *, figured by Quoy and Gaimard ; and, although both they and their shells are too dissimilar to be placed in the same group, they may be considered analogous.
(60.) The broad, spreading, and dilated inner lip of Cassis prepares us at once for the sub-family of Nassin^e, which is entered by the genus Cassidaria of Lamarck. These shells differ from all those we have just left, by having the basal canal considerably more lengthened, and only slightly turned backv/ards, without reposing on the shell itself : they are of an intermediate size be- tween the largest Nassce and the smaller helmets ; and thus the gradation even of size is preserved. The typi- cal genus Nassa then succeeds : the species, although all of them small, are much varied in shape, and in the degree in which the inner lip is developed; but the twisted ridge at the base of the pillar, the striated aper- ture, and the tuberculated tooth at the top of the aper- ture, are so constant, that they must remain as they now are in our systems, until their sub-genera are worked out. There is one form, however, so very remarkable, that we have placed it as the genus Cyclonassa *: it is the only snail-shaped flattened shell in this tribe ; and the animal, when known, will no doubt be very curious. Our next genus, Vexilla, opens the passage to the Pm'purbife, which it perfectly resembles in general form, and in its broad depressed inner lip ; but the outer
* Bucc. agath^ Quoy, Voy. Astrol. pi. 31. fig. 17.
+ Cyclops of Montford ; but this is a long established genus of crabs.
F 3
70
SHELLS AND SHELL-FISH.
PART I.
one is slightly inflected, and distinctly toothed. There is still wanting another genus possessing some of the characters both of Vexilla and Cassidaria: this genus is Oniscia Sow., where the inner lip is still more in- flected and toothed, and the spire much shorter than in Vejcilla, but yet with something of the protruding basal channel and general aspect of Cassidaria. As INIr, Sowerby has judiciously alluded to this affinity, we need not defend its existence. The circle of the Nassince thus becomes closed ; since we have returned to Cas- sidaria, or to that genus with which we began.
(61.) We shall now see how beautifully this na- tural series coincides with that of the Cassince, and rightly estimate the additional value attached to the genus CyprcEcassiSy without which an important link would be altogether wanting.
Analogies of the NASsiNiE and the CASsiNiE.
Genera of
Nassa.
Cyclonassa. Vexilla.
Oniscia. Cassidaria.
Analogical Characters.
fTypical ; inner lip much develop-"] I ed ; spire not depressed ; base | <{ of the pillar internally cari- }> I nated ; the basal canal reflected | l_ backwards. j
Spire very short, more or less de- pressed ; the basal canal trun- cated.
5 Aperture very effuse; outer lip? X_ often crenated. 3
r Ovate; inner lip spreading, but" \ not margined ; outer lip thick, ( "i inflexed ; both lips striated and ( i, toothed.
Vciitricose ; generally tubercu- lated ; basal canal curvcdback- wards.
{
H
{
Genera of
CASSI.NiB.
Cassidea.
Dolium. Harpa.
Cyprcecassis. Cassis.
To dilate upon this table, would be almost implying that our conchological readers were purblind. And yet, for those who are not scientific, we may advert to the intimate resemblance which some species of N'assa bear to the small helmet-shells in Cassidea ; so that, but for their size, a superficial tyro would mistake one for the
CHAP. III. THE PURPURIN^. 71
Other. VexUla represents^ in outward form, and most perfectly in colour_, Harpula vexillum, just as Harpa typifies the crowned volutes. Oniscia and Cyprcecmsis are perfect counterparts of each other; while Cassidaria and Cassis complete this system of analogies. If any doubt existed as to the absolute union of Oniscia and Cassidaria in regard to affinity, it is set aside by a re- markable shell obligingly sent me by ^Irs. Stuchbury, where the characters of both are united. This is of much additional importance, because it shows that Cas- sidaria does not form one of the five types of the Cas- sirne, but merely leads to them from the Nas since. These, therefore, are the grounds upon which we have adopted ]\Ir. Stuchbury's genus Cyprcecassis. And while we return his opponents our best thanks for stimulating our attention to the subject, and thus detecting a mate- rial error of our ow^n, w'e sincerely trust that he himself will prosecute his researches with the same ability and w^th the same success ; to the true advancement of our favourite science of Malacology.*
(62.) The PuRPURix^E form the next sub-family in our arrangement. They include shells whose general form closely resembles the BucciniiKe, or whelks, but with this difference, — that the pillar, without being ele- vated round the margin, is very much thickened, yet always more or less flattened and depressed — not, as in the generality of shells, convex. This, in truth, is the only character seen in the shells, by which this assem- blage is in any way linked together. For the rest, the spire is almost always very short; the aperture large and wide; the inner lip not otherwise developed than by a transparent polish spread over it, wdiich is sometimes
* I cannot pass over this opportunity of publicly expressing my obliga- tions to his worthy brother, Mr. S. Stuchbury, of Theobald's Road, one of the tirst commercial naturalists in I.,ondon, for the free use he has always given me of any interesting shells in his collection, without the necessity of purchasing them ; a liberality not always met with. With him, I have named a series of types of the greater part of the new genera here defined, and 1 feel assured he will supply them to collectors on the most fair and moderate terms.
F 4
72 SHELLS AND SIIELL-FISH. PART 1.
thickened in the middle, so as to form a slight elevation; and in one genus (Rici)iula), both lips being toothed renders the aperture very narrow : they are all heavy, thick, and rough shells, often armed with tubercles and spines, but never with varices ; there is generally an in- ternal groove at the top of the aperture. The true type of the whole sub-family, which is a representation of the Cyclohranchia, is Concholepas, — a most singular-formed shell, which was long classed as Patella : next to this follows Monoceros, having a basal spine at the aperture much developed. Following these, we place certain shells where the basal notch is so small as to be nearly obsolete. Of all the different modifications in the genus Purpura, as it now stands, we think these point out the third sub-genus, since they are evident representations of Cerithuni, Melania, and other half-emarginate groups: the spire is very short, and the pillar curves inwards. Following these, which we distinguish by the name of Microtoma, come the ordinary PurpurcB; and these blend imperceptibly into Riciyiula, by means of P. coin- mellaris, and Ricinula aspera and morus.*
(QS.^ Ricinula is a most remarkable genus of small prickly shells, with a very short spire, and the mouth, in the typical species, so beset on both sides with tooth- like projections, that the aperture itself becomes remark- ably narrow ; but these teeth are only developed at the matured age of the animal, and even in some species they are very small ; nevertheless the pillar is almost always flattened. The gradual developement, and some- times the digitated outer margin, of the external lip, shows a strong analogy to the Stronibidte, while the toothed aperture instantly reminds us both of Cohunhella and Cassis : all these relations will be still more deter- minate, if the circle of the Purpiirince is tested on the same principles as those last examined. It is this group, in fact, which unites the Purpurince with the NassincSy by means of Vexilla, where we see in the toothed outer
* Ency. Meth. pi. 317. tig. 4. 6. t Ibid. pi. 317. fig. 5.
CHAP. III.
THE BUCCININ^ffi;.
73
lip the last indication of Ricinula. The connection^ again, of these singular shells to Concholepas seems to be effected by our Ricinula planospira\, which has the spire nearly obsolete. This, as we believe, is the true course of the circle, the contents of which find their re- presentatives in the sub-families. It really seems ad- visable that the sub-genera of Ricinula, Nassa, Triton, and such varied groups, should be characterised when the science is somewhat more advanced.
(64.) There is one set of analogies, however, result- ing from this disposition of the PurpuriniB, which we cannot omit, because it illustrates that sub-family by which they are represented in the circle of the Turhi- nellidcE, — namely, the PyruUncE. This will also save much useless repetition when we come to speak of the latter group.
Analogies of the PuRPURiNiE and the Pyrulin^.
Genera of the
PURPt'RlN.E.
Pillar flattened.
Concholepas.
Monoceros.
Microtoma.
Purpura. Ricinula.
Analogical Characters.
r Shell smooth; spire excessively T -5 small, scarcely projecting; aper- V c ture very efifuse. j
Spire more lengthened, conic, r Shell smooth ; spire small ; aper ■5 ture very effuse ; the basal ca C nal narrow and almost obsolete.
Shell ponderous, rough, often spired ; basal canal wide, and fully developed.
Pillar, or inner lip, toothed.
{
^
Genera of the
Pyrlltn^.. Pillar convex.
Ficula.
Pyrula.
Rapella.
Myristica. Cuma.
Considering that these sub-families belong to two supe- rior divisions, of which each is the most aberrant type, the coincidence of each agreeing in their details, is not a little remarkable.
{Q5.') The BucciNiN^, or whelks, form the fifth and last division of this family : they are known from the murexes by having no varices, and from the PurpurincB by the pillar not being flattened : they are generally re- cognised by the abrupt termination of the base, v^'hich is deeply notched. They are nearly all smooth shells,
74f SHELLS AND SHELL-FISH. PART I.
or at least without spines^ or very prominent nodules. The typical genus is Terebra, — the longest spired group of all the carnivorous gastropods^, but so closely resem- bling TurrUella, that the difference in their apertures alone distinguishes the shells. In the genus Bucciiium, the spire is much shorter^ and the body-whorl more ventricose. These seem to be the typical groups. The three aberrant will be now described. The first, which appears to us to make the nearest approximation to the wide-mouthed genus Microtoma, is Leiodomus, founded upon two shells, the animals of which have been beauti- fully figured* by M. Quoy. One of these is the Bucci- num Icevigatum of authors; the other, XheB.Achatinum.f Both these have the foot of an immense size, so that it spreads over a circumference near three times as large as the shell, and is sufficient to envelope it entirely. In other respects there are some slight points of variation between the two; but they do not strike us, at present, of sufficient moment to sanction the formation of sepa- rate genera. To these we add the Terebra vittata j, and three or four other species, apparently undescribed. The vittata, however, appears aberrant, and leads im- mediately to Terehra. We are disposed to consider, also, as the type of another genus ( Trochia), the species of Purpura of that name, — since its characters will not agree with those of Purpura, while the striated inner lip leads to the conjecture that it is a prototype or Oniscia and similar shells. Lastly, we have, in Tri- tonidea §, a remarkably varied group of small shells, some of which resemble Triton, and others Buccinum; the base, however, is always contracted, and even slightly produced ; the pillar marked at the base with elevated granulations, or short obsolete plaits ; and a distinct canal at the top of the aperture. The connection of this group to Buccinum is very obvious, while its union to Triton
* Encv. Mcth. j)l. 400. fig. 1.
f Ibid. pi. 400. tig. 4. J Ibid. pi. 402. fi?. 4.
^ I have since learned that this genus is the same as Po/li'n Gray. — a name 1 should gladly liave adopted, had it not previously been given to a genus of European Lcpidoptcra.
CHAP. III. THE TURBlNELLIDiE. 75
is even more so. Triton ckmdestinum has the obsolete plaits and the mternal channel of Tritonidea ; while its thickened outer lip and more produced channel is suffi- cient to give it a place within the limits of Triton. The circle of the MuricidcB is thus complete ; but whether Leiodomus is a sub-genus of Terebi-a, or really that type which passes into Microtoma, is a matter of doubt ; its analogy, however, to Harpa, as shown in the animal, is a weighty consideration, although we have no interme- diate links by which it is connected to Trochia.
(66.) The TuBBiNELLiDiE form our next great di- vision of the predatory sheU-fish. As the Muricidce are chiefly distinguished by the general shortness of the testaceous canal which receives the respiratory siphon, or by its total absence; so may the great majority of the TurhinellidcB be known by this canal being considerably lengthened.* The animals, unfortunately, of nearly all the typical genera are as yet quite unknown f; so that we have only a few detached land-marks, as it were, to assist us in the arrangement of their shells. Looking, therefore, to such characters, we observe that the Tiir- hinellida, as a whole, are remarkable for the length of the basal canal ; and that the two typical sub-families have the pillar plaited, — a character never met with in the Muricidce. The volutes, indeed, possess it ; but the total absence of a canal in those shells serves at once to distinguish them. We shall now arrange the whole under the following families: — 1. TuRBiNELLiNiB, having a large, very heavy, and smooth shell, the canal nmch lengthened, and the spire generally papillary. 2. ScoLYMiNiE, equally strong and ponderous with the last, but the shell is rough, with foliated spines or tubercles, as in Murex, and the canal short. These two are the typical groups ; the first representing the Cassintr, the second the Muricince of the last family ; and both are
* Except in the Eburnidce, and some of the aberrant ScohjmincE.
t Guilding has ascertained that oi Scolymus, and Quoy those oi Eburna and Strutheolaria : the former has not a probosci^brm mouth, but the two latter have this structure highly developed.
76 SHELLS AND SHELL-FISH. PART I.
furnished with distinct plaits on the pillar. 3. The Eburninje, where the base of the shell is truncate and notched^ the pillar smooth, and the inner lip considerably thickened and spreading. 4. The Pyrulin^e, or pear- shells, having the spire short, the pillar smooth and con- vex, and the canal moderate. 5. and lastly. The Fusin^e, or spindle-shells, slender and delicate, having the canal, as well as the spire, remarkably long, and generally of nearly equal length. As it will subsequently appear that these groups are of the same rank and value as those of the CassincB, we have given them the same termin- ation in ince, although their contents are by no means so numerous as their prototypes.
(67.) The TuRBiNELLiN^ are remarkable in their typical genus,— which is Turhmella, — for the excessive heaviness and even the size of their shells, for in this latter respect they almost equal any others of the family. Their surface, although usually smooth, is generally covered with an epidermis : the outer lip is rather thin and simple, but the inner is frequently thickened and margined at its basal half : there are three or four very strong transverse plaits on the pillar, placed nearer to the top than to the bottom of the aperture ; but the uppermost is always largest — not, as in the Volutidce, the smallest. Like these latter shells, also, the tip of the spire is almost always papillary ; but this part is small, and assumes a very different appearance to that of of the true volutes. The next genus we shall notice — (there being an hiatus in this part of the series, which we shall subsequently advert to) — is Fasciolaria, where the spire is so much lengthened, as to be longer than the canal, — thus reversing the proportion between these parts as seen in Turbinel/a. The plaits on the pillar are small, placed close to the bottom of the aperture, and generally not more than two ; the last being by far the largest. Some of these large shells are smooth, but a few are corrugated or wrinkled; thus preparing us for the ScolymincB, to which they directly lead. Two other genera, however, enter into this circle: one of
CHAP. III. THE TURBIXELLIN^. 77
these we designated^ on a former occasion*, as the Pyrella spinlla : it so completely represents Pyrula in this group, that no one can mistake the analogy ; while it differs from the old TurhinellcBi by having no other indication of teeth hut a sharp ridge along the bottom of the aperture. Following this, we assemble nearly all the fossil TiirhinellcB under the name of ClavaUthes: they form, in our estimation, one of the best defined and most natural groups in malacology ; and our only surprise is, that they never should have been so defined by Lamarck. The species, we believe, are all found in the plastic clay formations. They have hitherto been confounded with Fusus, but they clearly hold an in- termediate station between that genus, or rather sub- family, and the typical TurhineU(F, close to which we now arrange them. The ClavaUthes, in short, are Turhinellce, without plaits on their pillar, and with a more lengthened spire, but the tip of which is also pa- pillary : the smoothness of the inner lip, and the fusi- form shape of the shell, has probably induced authors to place them with Fusus ; but the great size of the body-whorl, the papillary spire, and the thickness and general habit of all these shells, bring them much nearer to Turh'melki. Several species occur among the fossils of the Paris basin; and one or two of gigantic size are found at Hordwell Cliff, in Hampshire. We have now indicated four of the types of form or ge- nera, Avhich compose the natural series of the Turbi- NELLiN^ : but there is a hiatus between Turhinella and FascioJaria ; and this cannot be filled up by any shells which, so far as we are aware, have yet been published. As this form, according to our theory, should represent Scoli/mus and Murex, we should expect it would have the general shape, and plaits on the pillars, of Turhinella, but with the rugosity and perhaps the spines of a Scolymus or Murex, Now, such a recent shell we have a distinct recollection of see- ing, many years ago, in the hands of a dealer ; and we
* Zool. 111. series i.
78 SHELLS AND SHELL- FISH. PART I.
remember, at the time^ being completely puzzled as to what genus it should be placed in. This, of course, was when we were entirely ignorant of those prin- ciples of variation in the MoUusca here developed ; but we made a memorandum of the occurrence at the time, conjecturing that it might hereafter be useful. Such we now think it, inasmuch as it realises the very form which is requisite to complete the circle we are now upon. Finally, the long spire of Clavalithes is continued to TurbineUa Scolymus*, which differs only in this respect from T. rapa.f
(68.) The ScolymincB, as already remarked, are rough, blunt-spined shells, having the aspect of many of the Linnsean murexes : but the canal, although short, is straight; the pillar is furnished with distinct plaits, generally central ; while the spire is always pointed. The animal we can fortunately describe from the un- published drawings of our late friend Guilding : the foot of Scolymus is a little longer than the aperture, the the breadth measuring one half the length ; the oper- culum semicircular, and tolerably large, as in Fascio- laria; the peduncles of the eyes very long, the eyes themselves being placed more than half way from the base to the tip ; the anterior part of the foot is truncate, with the angles rounded ; the hinder part is also rounded ; the mouth is not probosciform ; and the respiratory siphon is rather short. We cannot make use of this information to the extent that could be wished ; but it will become doubly valuable for comparison, so soon as the animals of TurbineUa and of the neighbouring genera are made known. The first form which pre- sents itself in this division, after leaving Fasciolaria, is our genus FlicatcUa, — an extensive group of small shells hitherto confounded with Fasciolaria and Sco/i/nins. From the first, they are known by the little plaits upon the pillar being almost transverse (as in Scoli/miis), and not oblique, as in Fasciolaria; these plaits are likewise
* Ency. Mcth. pi. 431. bis, fig. 2. + Ibul. fig. 1.
CHAP. III. THE SCOLYMIN^. 79
much less distinct, and of the same thickness, without the last being manifestly larger; they are always situated across that part of the pillar which forms the lowest part of the aperture, and not, as in Scolymus, higher up towards the middle ; the situation of these plaits, in short, removes the genus from Scolymus, while their form and direction separate it from Fasciolaria. The variation in the shape of the shells is precisely what may be expected from this intermediate position. In such as approximate to Fasciolaria, the canal is nearly as long as the spire; while in those wliich lead to Scoly- mus, it is shorter : many of the species, again, put on the aspect of the spindle-shells (Fusus), and hence have been arranged among them"; while others have the exte- rior aspect of Murex. They are all of a m.oderate or small size; and may be known from the Muricidtp by the distinctness of their transverse plaits, the absence of internal tubercular teeth on the inner lip, and their longer channel : they are united to the next genus by Scolymus (or Plicatelki) capitellum, — a shell which may be placed in either group without any violation of na- ture : its predominant characters, however, appear to us to be those of the last, inasmuch as the three plates are nearly of equal thickness; whereas, in Scolymus, the lower are generally much smaller than the upper, and their situation is much higher. This last-named genus is a very striking one, and, being now disencumbered of Plicatella, admits of a much more precise definition than we originally gave it*: the shells are short, excessively heavy; the spire acute, and almost turbinate: the pillar short; the canal straight, and longer than the spire; while the whorls are rugged, and beset with blunt, simply folliculated, or plaited spines. All the species are from warm countries.
(69-) There is strong evidence to believe that the natural situation of Cancellaria is immediately after that of Scolymus; for, although the two genera, in their typical chaiacters, are very different, v^^e once possessed
* Elements of Conchology, p. 21,
80 SHELLS AND SIIELL-FISH. PART I.
certain species which exhibited so many intermediate characters, that, but for the pecuHarly small and incurved channel of Cancellaria, we should have been at a loss where to place them : one, we more particularly remem- ber, had an exceedingly wide umbilicus, nearly as large as the Scolymus iimbilicaris* , with a very simi- lar shaped shell; and it is not a little remarkable that, in the figure of this very Scolymus, the base of the pillar, instead of being straight, as in all the other species, is represented as curved inwards, and with an exceedingly small notch, — two characters which are absolutely peculiar, in this group, to Cancellaria.
(70.) The fourth genus, Rhinedomus, is typically represented by the Cancellaria senticosus of Lamarck, but of which there are several species. It retains suf- ficient of the characters of CancellaricB to show its true affinity to them, for the exterior surface is longitudinally ribbed, and rough with little points, and there are two distinct folds, or rather one deep groove, at the base of the pillar : but in all essential respects the true cha- racters of Rhinedomus are remarkably different : the basal canal is fully developed, being deeply notched ; and, what is very unusual, there is a distinct, though not a very deep, sinus close to the base of the outer lip. The animal, made known to us by the valuable researches of MM. Quoy and Gaimard, is most remark- able ; but, until we are acquainted with that of Cancel- laria, it furnishes no comparison with them. The other species of Rhinedomus have the spire less elongated, and thus open a passage to our new genus Polytropa, examples of which will be found in two well-known British shells, the Purpura lapillus and imbricatus of Lamarck : this genus agrees, indeed, with Purpura, in common with many other of its prototypes, in having the inner lip flattened ; but the base of the shell, in- stead of being truncate, forms a short straight channel; the spire is always as long (generally much longer) as
* Ency. Mt'thod. pi. 431. bis, fig. 1.
CHAP, 111. THE EBURNIX^. 81
the aperture ; there is also no internal canal : the inner lip sometimes has a row of tubercles. The most typical species^ however, is the Polytropa crispata.* As we re- cede from this genus, and approach to Plicatella, we find the spire increasing in length ; the numerous crisp undulations give place to small nodules and Uttle tubercles at the base of the inner lip, so that the two genera became united : the circle of the ScolymincB is closed ; and this, without the deficiency of a single link in the chain of connection which binds all the five genera together,
(71.) The next sub-family, EburnirKP, is one of very great interest, since it brings together certain genera whose station has hitherto perplexed us all. For- tunately, how^ever, Mr. Gray has characterized the re- markable little genus Cyllene ; and the possession of other species, joined with those of Rhinedomus, before alluded to, have prevented us falhng into some errors : the discovery of the basal sinus, also, on the outer lip of Rhinedomus, at once opens a passage to Cyllene, which still retains a costated and somewhat cancellated exterior, with the basal sinus of the last genus. It deserves es- pecial notice, that the species described by Mr, Gray has a distinct channel round the suture, but the other we possess has not. Now, this variation is precisely what is met with in the genus Ebiirna, the types of which are channeled, the others not. The slight striae at the base of the pillar in Cyllene, are explained by its analogy to Oliva, just as its obsolete notch typifies its reference to Stromhus. Other species will no doubt soon come to light ,• so that, with these facts before us, we have no hesitation in placing Ehurna as the next type. Between this last, and Striithiolano. there exists the most intimate relationship in regard to their animals ; both have a comparatively small foot, but a probosci- diform mouth of excessive length, particularly that of Struthiolaria, which, when fully protruded t, is more
* Chemnetz, 187. fig. 1802, 1805. Ency. Meth. pi. 419. fig. 2.
f See the animal of Strutk. crenata. Voy. d'Astrolobe, pi. 31. figs. 8, 9.
6
82
SHELLS AND SHELL-FISH.
PART I.
than equal to the entire length of the shell, while the operculum is only rudimentary. A singular unde- scribed shelly, just communicated to us by Mr. Stuch- bury, is evidently intermediate between the shape of the shells of Ehiirna and Struthiolaria ; so that this part of our series is definite. We must now return to Cyllene, for the purpose of showing its close approxi- mation to the fourth genus^ Pseudoliva, the type of which is the Buccinum plumheum of Linnsean authors. The very aspect of this {^fig. 3. a) is quite sufficient to show its proximity to Cyllene, and its abso- lute connection with the VolutidfB by means of Olivillahiplicata (&). Last of all, as forming a passage to the Py- rulcBy we have Lati- axis MawcB* (Sw.), where thechannelround the whorls is so broad that they become almost discon- nected. At first sight, this shell would appear a mon- strosity, did w^e not remember its prototype, Scalaria pretiosa, not to mention the tribe of Tuhulihranchia. We consider it therefore as perfect in its kind, related to aU the types we have noticed by its channeled suture, to Ehurna by its large umbilicus, and to Rapella (the first genus of the PyrulhKv) by something, very difficult to de- scribe, in its general shape. The whole sub-family may therefore be defined as shells whose base is truncate, having a channel more or less developed round the whorls, an aperture contracted at its base, and generally either emarginate as in Ehurna, or very slightly notched as in Struthiolaria and Latiaxis : the inner lip is much developed and spreading, without having a defined margin. The following table will also exhibit some of its analogies ; the group, as a whole, being evidently a representation of the NassincB in the neighbouring family of the Muricidce.
* Griff. Cuv. pi. 25. figs. 3, 4.
CHAP. III. THE PYRULIN^. 83
Analogies of the Eburnix^.
Genera of the 4..„;^„;„„7 r'A„..„^/^v„ Families of the
Eburmnj^.. Analogical Characters. Zoopkaga.
Struthiolaria. Shell nodulous or muricated. MuRiciDiE.
Eburm. I ^'deUbped.' ' '^^ "'"'' ^'^ """'^ ] Turbixellid^.
Cyllene. P Uncfsinus.''"*" ''^ '''^^ ^ ^''' ] StROmbid^.
Pseudoliva. Oval, smooth. Cypr^id^,
r^/,-^.-» f Spire excessively short and irre-^-tr^, r,^,
Lahazis. I 'g^i^^. jhg ^^^J^^ sub-coronated, j Volutid^.
This comparison explains the relation which Sti'uthio- laria has been thought to have, by some writers, to the murexes : the smoothness of all the Ehm'nirKx is remarkable, and is no doubt an indication of their re- lation to the typical TurhineUidcE. The lobe of Cyllene, again, is borrowed, as it were, from the Stromhidte, in order to show the analogy of both. The excessive short spire of the two next is explained on the same ground ; while the irregular spire of Latiaxis is to be found in no other shells of the zoophagous tribe, than those of the typical volutes or melons.
(72.) In the Fyridince, or the fourth division of the family, we place the greatest part of those exceedingly diversified shells forming the genus Pyrula of modern writers. They are so designated from their generally being pear-shaped ; the basal portion representing the stalk end of that fruit, and the spire and w^horls the other. This comparison, indeed, is so far apt, that it gives a very good idea of the shape most prevalent among them, notwithstanding the great differences they present, in other respects, among themselves. This is one of the few natural groups in malacology, of which we shall endeavour to give as complete an analysis as a long and protracted investigation of their relations will permit. We have invariably found, that where natural assemblages such as this, in any division of the animal kingdom, contain a great number of subor-
G 2
84 SHELLS AND SHELL-FISH. PART I.
dinate variations, such groups are the best calculated for discovering the true principles of variation. The interchange of characters between one division and another is better marked — the gradations more gentle — the links more perfect ; and hence, by carefully tracing the transitions from one form to another, we have a better chance of correcting our previous errors, and of discovering the fallacy of any preconceived theory, than if the hnks were so wide apart as to leave the imagination to till them up, by supposing that they have existed, or that they are not yet discovered. The complete analysis of any one group, where these defi- ciencies do not occur, is far more worthy the attention of the scientific, and even the general, reader, than numberless others whose links are incomplete.
(73.) The most striking characteristic of the shells composing this sub-family, next to their pear-shaped form, is that belonging to the inner lip and the colu- mella, or pillar. It will be remembered, that in the Pu7'- puriiKT, the inner lip, properly speaking, is merely a thin glazing spread over that part of the pillar which forms the left-hand side of the aperture : in this respect they differ not from the shells now before us ; but the pillar, instead of being broad, flat, and even concave, as in all the Purpurce, is invariably rounded, and conse- quently very convex : the shape of the Pyrulce, also, necessarily renders the base of the shell much narrower, and the canal much longer, than in their prototypes ; although the degree of length of this channel, as well as that of the spire, cannot enter into the general defini- tion, since it will be seen that these are subordinate cha- racters. The five principal modifications of form under which we arrange all the species, are these: — 1. Pi/rula, where the shells are strong and solid ; the whorls ge- nerally muricated ; the spire short, yet elevated, well defined, and often slightly papillary ; the inner lip en- tirely wanting; and the canal considerably lengthened. The Pyrula perversa may be taken as the type of this genus, all of which are strong, solid, and muricated spe-
CHAP. III. THE PYRULIN^. 85
cies. 2, Ficula, where the great elongation of the canal is still preserved^ but the shell is differently formed, and its substance very thin. The body-whorl is nnore or less ventricose, and without any spines or protube- rances; the spire also is so small and depressed, that the shell has very much the appearance of a Bulla, length- ened out at the base; and there is little or no indica- tion of even the thin glazing which forms the inner lip: such, at least, are the characters of the typical species *, which are few and easily recognised. In P. caudataj, a new modification of form begins to be developed, — slightly, indeed, but quite sufficient to leave us in no doubt as to the characters of the next genus : this species has the general form of Ficula, but the spire is somewhat more elevated, and the inner lip is so much developed that it begins to have a defined margin at its lower part ; the body-whorl loses nothing of its ventri- cose or inflated aspect ; and the shell is remarkably thin and brittle. It is a fact highly interesting to our present purpose, that there is a shell in almost all re- spects similar to the Ficula caudata (of which it has been described as a variety), but which has a decidedly short canal. Here, then, is the point of junction so desirable to be established between Ficula and our new genus Rapella, typically represented by the Ficus rapa of authors.;]; The spire, although pointed, is still re- markably short, and almost turbinated ; the body-whorl equally ventricose with the last, but the lower portion is no longer lengthened — it becomes very short, and, by the more sudden contraction of the aperture at the basal point, the canal becomes so very small as almost to be obsolete. From the absence of the inner lip in the last two genera, the shells have no umbilicus, but in Rapella both these characters are apparent ; the umbi- licus is usually very large, while the base of the inner lip is partially or entirely reflected over it. The sub- stance of these shells varies according to the species, and
* Pyrulaficus Lam. Ency. Meth. pi. 431. fig. 1.; fig. 2. is another species, t Ency. Meth. pi. 436. fig 1. c. X Ibid. pi. 434. fig. 1.
G 3
86
SHELLS AND SHELL-FISH. PART I.
each presents a graduated link between the thin and brittle Ficula papyracea and the strength and solidity of the other types. The whole of the Ficula are smooth, except one species *, which has some very slight tubercles ; but in Rapella, these tubercles, where they exist, begin to put on that foliated structure so prevalent in the next genus ; and in others there are indications of longitu- dinal plaits upon the body whorl : the outer lip, how- ever, is still very thin, and the whole may be described as a group of generally smooth shells : in one or two species, the inner lip is so much developed at its base, as actually to fill up and cover the umbilicus. Yet, in all the variations we have enumerated, the chief generic characters are constant, and the basal canal is always small.
(74.) We now come to the fourth type, or the genus Myristica, — a name we exalt from a specific to a generic signification for the shell now known as the Pyrula my- ristica, and which we shall here call Myristica coronata. These are the most dissimilar from the typical groups we have yet noticed : the form indeed, somewhat pear- shaped, — inasmuch as the spire is not longer than the contracted part of the aperture, from which the canal may be said to commence ; but they have nothing of the lightness or the basal elongation of Pyrula and Ficula, or of the effuse aperture and contracted chan- nel of Rapella. They may thus be described as very short, strong, fusiform shells _; the umbilicus either entirely or partially concealed ; the outer surface armed with muricated and semi-foliaceous spines, and marked with transverse striae ; the inner lip vitreous, but thin ; the outer lip with an ascending channel above, and a wide and distinct one at the base. Now, between this and the last group there is a series of connecting links which unite them in the most perfect manner to each other ; few of them, however, are figured in the more general conchological works. We may here remark, that the P. hippocastanum and lineatai of Lamarck are
* See Sowerby's Genera. f Ency. Meth. pi. 432. fig. 4, 5. .
CHAP. Ill, THE PYRULIX^. 8/
typical examples of Myristicn; while the well-known Pij^ Tula melongina, from having a much wider aperture^ puts on something of the characters of Rapella. There are, in fact, many other species ; but of our last genus Cuma
there is only one that we are yet acquainted with, which can be termed truly typical : this we have named C. sulcata {Jig. 4.). Its characters may be simply de- scribed as shorter, but more gra- dually fusiform, than the last, — the middle of the pillar being crossed by a single transverse and very prominent fold : this cha- racter is altogether without pa- rallel in this sub-family ; and dis- tinguishes this type, at the first glance, from all the others : the form of the shell is much more slender at its two extremities than any of the Myristicce, and, although much shorter, its aspect at once reminds us both of Fusus and of Plicatella. Nevertheless, although this shell, from having a distinct plait upon the pillar, seems to us the true type of the connecting genus be- tween Pyrida and Fusus; it is quite evident that the common Pyrula carnaria *, and the more rare P. canaliculata Sw. t, so closely agree wdth the foregoing definition, that but for their smooth pillar, and the greater elongation of their base, they would both enter into the same genus. In one point of view, it may be said that these very characters, which preclude their ad- mission into Cuma, may yet bring them wathin the con- fines oi Pyrula; so that, being followed by such shells as P. carica ^, Sec, we come again to the typical genus with which we began the series ; and yet, on the other hand, we may suppose these dubious species, to form the first genus of the FusincB, connecting that sub-family with the PyrulcB by means of Cuma. In either way, however,
* Ency. Meth. pi. 424. fig. 3. t Ibid. pi. 424. fig. 2.
X Ibid. pi. 433. fig. 3.
G 4
88 SHELLS AND SHELL-FISH. PART I.
there is abundant evidence, even if these species are omitted, that the PyruUnce form a circular group, in which scarcely a link is wanting. This will be more evident upon arranging the whole of the genera in a tabular form, and placing the few species we have already named in the natural series of their succes- sion.
Genera of the Pyrulinje.
List of the Species, sJiowing the progressive Change of one Genus to the
other.
"tuba. Ency. Meth. pi. 426. fig. 2, perversa. lb. fig. 4.
candelabrum. lb. pi. 437. fig. 3. ; pi. 438, fig. 3. Pyrula <| carina. lb. pi. 433. fig. 3.
canaliculata. lb. pi. 436. fig. 3. spirata. lb. pi. 433. fig. 2. _Burdigalensis. Sowerby's Genera, fig. 2.
rtricarinata. lb. fig. 3. T?,r„T A 3 fi«^"s- Ency. Meth. pi. 432. fig. 1.
ricuLA ■) reticulata ia?«. lb. pi. 432. fig. 2.
tcaudata lb. pi. 436.
Rapella
Tpapyracea. lb. pi. 436. fig. 1.
3 abbreviata. lb. pi. 426. fig. 2.
ieffusa Sw. lb. pi. 434. fig. 1. {Pyrula Rapa.)
C nerito'ides. lb. pi. 435. fig. 2.
Smelongina. lb. pi. 435. fig. 3. a. — d. lineata. lb. pi. 432. fig. 5. coronata Siv. lb. pi. 432. fig. 3. a, b. hippocastanum. lb. pi. 432. fig. 4.
CuMA sulcata Siv. — followed by Pyrula tuba. Sec.
(75.) The strong resemblance of the Pyrulince to the PurpurincB is a constant subject of remark among conchological writers, and is so strong as to be often exceedingly perplexing. We now allude only to the latter group, as left by Lamarck ; but many of these are so like our genus Myristica, that it is only upon close inspection their distinguishing characters are detected. Now, this strong resemblance can be accounted for in two ways : first, by supposing that the two groups re- present each other generally in their own respective circles ; and secondly, that this strong analogy actually extends to the particular genera of each sub-family.
CHAP. III.
THE FUSINiE.
89
The best way, therefore, of testing this theory, is to place these groups in separate columns^ and to examine the result.
Analogies of the Turbinellid^ and the C^ssid^e.
Sub-families of Turbine llidcE.
TURBINELLIN^.
SCOLYMIN^.
FUSININ^.
Py RULING.
Eburnin^.
Analogical Characters.
f Shell large, ponderous, heavy, and \ I mostly smooth. j
f Shelis rough, muricated, and ge- 1 t nerally spined. J
("Body of the animal, and spire of? i the shell, excessively long. J
Spire always shorter than the aperture; the pillar straight and smooth.
Base and canal very short ; inner "^ lip generally formed by a thick ^ enamel. 3
1
I
Sub-families of MuricidcB,
CASSINJi. MURICIN^.
buccinin*. purpurin^.
Nassin^.
(76.) Without enlarging upon the evident traces of a systematic series of analogies, running through the dif- ferent groups here brought into juxtaposition, it is at once seen that the PyrulincB and the PiwpurincE actually come opposite each other : and having already shown (73.) how intimately their genera correspond, we may pass into the next division.
(77.) The Fusing are our last sub-family, and are composed of those numerous shells arranged in the genus Fusus of Lamarck, and are the most elegant and delicate we have yet noticed. Their general form is that of a spindle, tapering very much at both extremi- ties : hence the spire is very long ; and as this contains the body of the animal, the circumstance forms a ge- neric character, both for the moUusk and its shell. The canal is almost invariably long, and generally equals the spire, while the basal volution is typically small : the pillar is constantly destitute of any appearance either of plaits or teeth, and the tip of the spire is acute : this latter character, more especially, separates them from the Turhinellince, where there are, in the aberrant
90 SHELLS AND SHELL-FISH. PART I.
genus Clavalithes Sw .* , several shells of an equally fusi- form shape^ but having the tip of the spire papillary. The shape of the FusincF, and the elongation of the body^ render them very distinct from the PyruUncB, excepting at that point of junction where the two groups are united. Nothing satisfactory is known^ so far as we can discover, of the general nature of the animals.
(78.) The Fusinm being thus defined as a whole, we may now proceed to the series of the genera, and their peculiarities. — 1. In the first or typical genus Fusus, the spire and channel are both very much lengthened_, and remarkably slender ; the outer lip generally cre- nated, — the indentations corresponding with the internal striae, — 2. Chrysodomus, distinguished from the last by the comparative shortness of the basal channel_, and the ventricose or enlarged shape of the body-whorl. The beautiful orange mouthed wilk of England is a typical example ; and the few others^ now known^ are all of a large size, and chiefly found in northern seas_, where they represent the more elegant Fusci of tropical latitudes : the outer lip is always thin and smooth. — 3. Leiostonms, where the body -whorl is still larger than the last, while the spire, although remarkably short, is acutely pointed ; the inner lip is highly polished, and the contracted base of the shell is equal, or rather longer than the aperture ; the outer lip, like that of Chrysodomus, is thin and sharp, but thickened within. All the species of this form we have yet seen are fossil, of which the Fusus bulbiformisf is one of the best and most common types: the outside and the mouth of these shells are always smooth ; hence their generic name. — 4. The next genus we have named Strepsidura, from the twisted shape of its tail or channel : the form of these shells is very much like the last, but the base or channel is equal with the spire, and is turned in an oblique direction; the outside
* We had originally called this genus ClnveUa ; but as this name may be thought too closely resenihling, in sound, those of ClavagcUa and Clavalula (Lamarck), we now substitute another, — more appropriate, indeed, as all the species we have yet seen are fossil.
t Ency. Mcth. pi. 428. fig. 3.
CHAP. III. THE FUSING. Q\
also is marked by distinct longitudinal ribs^ and has a coronated row of little mucronate spines^ much like those of the harps : the type is the Fusus ficulneus, a fossil of Grignon.* — 5. and lastly^ we come to those large species represented by Fusus colossus, coronatus, 3forio, Szc, which we have arranged in the genvis Hemif us us j they are^ indeed^ only half fusiform_, as the spire is shorter than the aperture : they are also distinguished by an internal canal^ and the whorls are coronated with compressed spines : it is easy to perceive, by the very aspect of these shells, that they form the passage to the Purpurce ; and their relation is so close, that, until we know something of these animals, we feel somewhat uncertain as to the station of such species as carnaria and Cochlidium. Hemifusus, thus standing betAveen Strepsidura and Chrysostomus, completes the circle of the FusincB.
(79-) Upon taking a general view of these shells, w^e cannot but observe, notwithstanding all their modi- fications, that the predominant characters of the group, more or less, are preserved. In all of them we find shells more or less — equally or unequally — fusiform ; that is, their thickest part is in the middle, and their two extremities attenuated to a point. No teeth, either marginal or internal, are ever seen on the outer lip, while the inner is invariably smooth : the spire, except in one type, is always longer than the basal canal; whereas, in the PyrulmcB, the very reverse of this takes place. It has often been remarked by our leading zoologists, — and we have repeatedly illustrated the truth of the position, — that no groups, whether generic or otherwise, are so natural and so demonstrable as those which are linked to others by mtervening gradations of form. This is, indeed, completely opposed to the old opinion formerly entertained, that no such divisions should be tolerated in systems, but such as were distinctly separated from each other; or, in other words, that, so soon as the
* The Fusus heptagonus (Ency. Mdth. pi. 428. fig. 7.) probably belongs also to this genus, — although as an aberrant species.
92
SHELLS AND SHELL-FISH.
PART I.
links which connected two genera were discovered, the two should be thrown into one. Experience, however, setting aside all other considerations, has long ago con- signed this dogma to oblivion, and has even obliged its warmest advocates to renounce it. Ever^ day, almost, is bringing before us, — particularly in the invertebrate animals, — not only forms altogether new, but such modi- fications of those we already have in our collections, that in a few years we may fairly anticipate not one in ten of the testaceous genera, now apparently isolated, will remain so ; the links which unite them to others will be discovered ; and thus, had we continued to unite one geims to another in the fashion above adverted to, we should be now fast approaching that simplicity of nomenclature which would class all shells under one genus, — the genus Testacea. It is only by following out a theory of this sort, and seeing to what it would lead in a general and extended application, that we can judge of its philosophic soundness or of its practical utility.
(80.) All the types of the FusirKP, as will now be shown, have their representatives in the PyruUiKE.
Analogies of the Fusing and the Pyrulin^e.
Genera of the
Fusing.
Hemifusus.
Fusus.
Chrt/folomus.
Leiostomjis.
Strepsidura.
Analogies.
C Trapeziform, or sub-fusiform;? t channel short. j
C Channel remarkably long; the 7 \ whorls generally angulated. j
Channel moderate.
f Spire very short ; the basal whorl") I large and ventncose. 3
The base of the pillar slightly'^ turned outward, the exterior > rougli and mucronate. j
I
Genera of the Pyrulin^.
Cu7na.
Pyrula.
Ficula.
Rapella.
Myristica.
The first of these resemblances, or that between Hemifusus and Cuma, is obviously an affinity, since the most inexperienced student can perceive that these two groups pass into each other. The greatest elongation
CHAP. III. ANALOGIES OF THE FUSING. QS
of the basal channel takes place among the Fusince in Fusus, and the like character among the Pyrida in the opposite column ; while in Chrysodomus and Ficula this part is but of moderate length. Strepsidura is the only genus in the first column^ which, by its lon- gitudinal plaits and prickly tubercles, corresponds to Myristica ; while the inflated shape of Leiostomus im- mediately reminds us of Rapella — its prototype among the PyruUnce.
(81.) Before taking leave of the Fusince, it will be interesting to ascertain how far the genera put on the aspect of those composing the TurhinellincB, more par- ticularly as, the former being the last, and the latter — TiirhineUincB — the first with w^hich we commenced, it foUows, as a necessary consequence of the circularity of the whole family, that these two divisions join, and blend into each other. This, we think, will be very evident, upon examining the following table : —
Analogies of the Turbinellin^ and the FusiNiE.
i Genera of the . ^^„;„„.„ Genera of the
TuRBiNELLii. Analogies. Fusing.
Turbmella IjaTa. Typical of their respective groups. Fusus.
? Sub-typical. Chrysodomus.
i-^-.^,-,/ „ T ovv, CTrapeziform; the whorls turreted: 7 rr -^
Fasciolaria l.a.m. y canal moderate. j Hetmfusus. .
X,,, ,. fPyriform ; the canal long; the base7 o, j
Pyrella. ^ of the pillar turned inward. j Strepsidura.
r Remarkably smooth ; the spireT Clavalithes. < and aperture of equal length ; >■ Leiostomus.
L the pillar straight. 3
(82.) It would hardly be necessary to repeat, in this place, the fact we have so often adverted to and illustrated in former volumes, regarding the analogies of typical gi'oups, were it not highly probable that they have not met the eye of our conchological readers. It is there- fore, perhaps, necessary to apprise them, that the re- semblances between the typical divisions of two groups, when thus brought into comparison, are almost always
^4* SHELLS AND SHELL-FISH. PART I.
more remote and faint than those which relate to the aberrant divisions^ — and for this simple reason; — the typical groups are furthest apart from each other ; while the aberrant ones, by which they are connected, are consequently nearer. In this branch of science, moreover, the difficulty of discovering the analogies of typical groups is still further increased, when, as in the present instance, we are without that precise in- formation on the animals, which might furnish us with some analogical points of resemblance. Besides, it must always be borne in remembrance, that our ar- rangement is not built upon these analogical compa- risons, but upon absolute or presumed affinities, the result of minute analysis. Whatever coincidences, therefore, arise on comparing the different groups, are more properly the result than the cause of their ar- rangement. Analogy is thought to be of the highest importance for the verification of a natural group, but it must always be subordinate to affinity. Applying these general remarks to the two typical groups which stand first upon our list, it will be remembered that one, intervening between Turbinella and Fasciolaria, has never been made known. Passing these, however, and comparing Fasciolaria and Hemifusus, we find they are almost precisely of the same shape and pro- portions ; and that the shells can only be distinguished by one having the pillar plaited, and the other smooth. The very name of ficulneus, given by authors to the type of Strepsidura, shows its analogy to Pyrella, and consequently to Fyrula ; it is, in fact, completely a pear- shaped shell. The resemblance of Clavalithes and Leiostomvs is equally striking : both are remarkably smooth shells ; with the channel lengthened, and the basal volution more or less enlarged ; both are fossil genera of the same strata; and although Clavalithes in general possess very small plaits on the pillar, and a papillary spire (without which, in fact, the genus could not be clearly defined), yet there are one or two species having the pillar, as in Leiostomus, perfectly smooth.
CHAP. III. MURICID^ AND TURBINELLID^. 9^
If the reader turn to the figures of Clavalithes longcevus, clavellatus, scalaris, Noce^ and rugosus*, and to that of Leiostomiis hulhiformis f, he will at once perceive their mutual affinity much better than from our description. (83.) Having now supplied all the details in our power respecting the two great families of the Zoophaga, or predacious shell-fish, — and which, in fact, stand at the head of the entire class of Test ace a, — we shall lay before our readers the following diagram, which will explain, more distinctly than our usual tables, the circular affinities of each of these families, and the cor- responding analogies of their sub-families.
1 M,iricinw/6- =^-^\ -/- <>sTurbinina! \
2 Casshvt^ j\- 'Cj Scolymincs 2
4 Purpurincei
3 Nassin^O^^^ ^^^^hurnirue 3
The analogies of the two typical sub- families (Land 2.) of the circles are very remarkable. We thus find that the MuricincE stand opposite to the TurhinincB, and the Cassince to the ScoIymirKe. These resemblances repose on the relative developement of that portion of the shell which protects the respiratory siphon (which must of course be modified in unison with its covering or sheath) : thus, in the MuricincE and the Turhinince, the basal canal is considerably longer than in the Cassinm and the Scolymince, where, in effect, this part is either short, or absolutely wanting. Thus it is, that we may often overlook, or be ignorant of, some one character, which, when discovered, serves as a common bond of analogy between two groups, in all other respects to- tally different.
* Ency. Meth. pi. 425. f Ibid. pi. 428. fig. 1. a, b.
()6 SHELLS AND SHELL-FISH. PART I.
(84.) The genus Buccinum andthe aberrant genera of Fusus are so much ahke, that they can only be distin- guished by the latter, as Chrysodomus, having the basal canal slightly produced instead of truncated. These two divisions are further remarkable for containing those genera which, by the length of their spire, contain the longest-bodied Testacea in the whole tribe. But for its elongated canal, Fusus colus and its allies would become TerehrcB ; while, but for their truncated base, these latter would be placed among the Fusince. The remarkable analogies between the PurpurincB and the Pyrulincp. (4. 4.), having already been so much enlarged upon, need not be again repeated. The only remaining comparison concerns the EburninfS and the Nassince, — 'two groups so closely related to each other in their typical examples, that even Lamarck, mistaking ana- logy for affinity, actually places them following each other : both, in fact, have the base of the shell obtuse, without any elongation ; the inner lip very thick, and a strong internal groove within the aperture. But it is needless to insist upon an analogy so indisputable : we may, therefore, presume, that in these two comprehensive groups we have made good all our propositions on the laws of the natural system * ; and we shall now endea- vour to do the same in the succeeding families of the Gasteropoda.
* The Geography and Classification of Animals^ Part iii. On the First Principles of natural .Classification, p. ,221. Vol. LXVl. of the Cabinet
CvCLOPJiDlA.
97
CHAP. IV.
THE ZOOPHAGA, OR PREI>ACEOUS SHELL-FISH, CONTIN'UEn. THE
FAMILY OF VOLUTIDiE, OR VOLUTES.
{85.) We now come to one of the most interesting and beautiful families of the spiral Testacea; whether in regard to the elegance of the shells themselves, or as exhibiting a principle of variation in their structure which can hardly be excelled. Our knowledge of the animals themselves has been much increased, of late years, by the French naturalists, and by the exquisite drawings of Guilding. To generalise these discoveries, however, so as to assign some undeviating character to the whole, is almost impossible. The only peculiarity appears to' be the absence of any operculum : in the ma- jority, the eyes are sessile, placed at the base of two short tentaeula, and as much developed, in the typical volutes, as they are in the Stromhidcs : the mouth is probosciform and extensile ; and the foot, in the typical group, of enormous size.
(86.) The shells, however, present us with more tangible characters. The base is never prolonged ; although in some mitres {Tiara) it is contracted: in all others it is truncated, as in the BuccinincB, and deeply notched. The truncated base at once separates this family from the Turhinellince, as there is no in- stance of a volute with an elongated channel. The plaits upon the pillar, again, are always at the base — not in the m.iddle only — of the aperture ; although, in the aberrant groups of Oliva, Ancillaria, and Marginella, they assume peculiar modifications. The proportion of the spire to the aperture varies in almost every genus ;
H
9S
SHELLS AND SHELL-FISH.
PART I.
and is, therefore, but a subordinate character. Nume- rous as is this family, nearly all the species are confined to warm latitudes, particularly those of the tropics. It is hardly necessary to add, that the whole are predaceous, and consequently carnivorous.
(87.) The VoLUTiD*: arrange themselves into five