si i / m , j 8 THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA PRESENTED BY PROF. CHARLES A. KOFOID AND MRS. PRUDENCE W. KOFOID ^;v-;.^ m . m :V-:;- ,:-.._.; A HISTORY OF THE BRITISH MARINE TESTACEOUS MOLLUSCA, DISTRIBUTED IN THEIR NATURAL ORDER. MOLLUSCA TESTACEA MARIUM BRITANNICORUM. A HISTORY OF THE BRITISH MARINE TESTACEOUS MOLLUSCA, DISTRIBUTED IN THEIR NATURAL ORDER, ON THE BASIS OF THE ORGANIZATION OF THE ANIMALS ; WITH REFERENCES AND NOTES ON EVERY BRITISH SPECIES. BY WILLIAM CLARK. LONDON: JOHN VAN VOORST, PATERNOSTER ROW. M.DCCC.LV. PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. ALF.BK fV KLAMMAM. TO THE % INHABITANTS OF EXMOUTH, IN TESTIMONY OF HIS SINCERE WISHES FOR THEIR WELFARE, AXD FOR THE PROSPERITY OF THEIR TOWN ; AND ALSO IN ACKNOWLEDGMENT OF THE UNVARIED KINDNESS WHICH THEY HAVE EXHIBITED TOWARDS THE AUTHOR AND HIS FAMILY IN THEIR VISITS TO THAT LOVELY LOCALITY DURING THE LONG PERIOD OF FORTY-FIVE YEARS, THIS VOLUME IS RESPECTFULLY DEDICATED. 47639 PREFACE. IT has long been the fashion to present the reader with a prologue ; which, however, I have observed, of late years, has become shorter and shorter. The utility of this practice is questionable, as the body of the work includes all that caa be said in a preface, and by it we forestall the pleasures of expectation ; besides, be it good or bad and the author is frequently not the writer it often unjustly decides the fate of a book, causing a bad one to be read, or a good one to be thrown aside; nevertheless I have in some measure complied with an old custom, by giving a few prelimi- nary remarks in the introduction to the classification. It will be observed that some of the families and genera of the Cephalopoda and Pulmonifera have been admitted into the sketch of the classification to com- plete the chain of the Molluscan series; to enter on their consideration forms no part of the plan of this work, which relates exclusively to the British Marine Testaceous Mollusca. In some instances " nobis " is attached to the name of well-known species ; this has been done, not from any desire to assume credit for the labours and disco- viii PEEFACE. veries of others, but simply to markeither that we have made some alteration in the nomenclature of the species, or that we have included under the name forms hitherto regarded as distinct. Many of the memoirs have been admitted into the 'Annals of Natural History/ but as it would occupy "about four years to have the remainder of them inserted in that excellent work, I have determined to print the whole at once in a collective form, and the Editors of the ' Annals ' have liberally accorded me permission to reprint those which have appeared in the pages of their journal. My reason for making this arrangement is, that, at my age, it would be almost presumptuous in me to calculate upon being able to watch the publi- cation of my observations during such a long period as four years. I can entertain no doubt that my work is very de- fective, and, on such a subject, it would still be so, if I were to bestow the labour of another half century upon it. Were it at all probable that I might re- examine the whole matter, with the advantage of having first impressions defined and corrected by intermediate study, I should probably not have chosen this desultory form of publication ; but if any justification of such a course be required, I have at least the opinion of Pro- fessor James Forbes to support me. That eminent philosopher, in his excellent ' History of Norway and its Glaciers/ well observes, "But a pretty long experience in such matters has convinced me that they act wisely and well, who, having used their opportunities to the best of their power, PREFACE. ix communicate the results of their observations to the world without waiting for a period (never perhaps to arrive) when they may themselves have the credit of completing and perfecting them. It is better, whilst the freshness of recollection is undimmed, and the mind is in a position to draw a correct parallel between older and quite recent observations, and thus to give our descriptions the necessary development, to throw into them whatever there may be of value in our peculiar experience or habits of investigation, and frankly to invite our fellow-labourers to do in our stead what we would gladly have done but for some inevitable want of health, leisure, or opportunity. Were this course more generally followed in the sciences, both of obser- vation and experiment, I am persuaded that by grasping at less we should attain more even in personal repu- tation and should unquestionably advance the interests of knowledge." Norfolk Crescent, Bath, November, 1854. TABLE OE CONTENTS. PAGE SYNOPSIS OF THE CLASSIFICATION 4 ACEPHALA 20 SPECIFIC DESCRIPTIONS OF THE ACEPHALA 35 GASTEROPODA 225 SPECIFIC DESCRIPTIONS OF THE GASTEROPODA 226 LlST OF THE EXOTIC SPECIES THAT HAVE BEEN IMPROPERLY ADMITTED INTO THE BRITISH LIST 509 APPENDIX 511 INDEX . 529 ERRATA, CORRIGENDA ET ADDENDA. Page 16, line 5, for and term read and term one of. 36, 19, read^to^. 42, 19,20, for the A.striata, which is the A. patelliformis, read the A. striata, which is a mere form of the A. patelliformis. 54, ,, 35, for Lima subauriculatus read Lima subauriculata. ,,123, ,, 11, ,, rectum read intestine. ,, 128, ,, 30, 31, for BRTMACULATA read BIMACULATA. ,,131, 1, for the branchial artery read the branchial artery or vein. ,, 135, ,, 28, as it has many features of the Myadce and Anatinidce, read as some authors say it has many features of the Myadce. 168, 10, Having written to Professor Ed. Forbes in Feb. 1849, on what I conceived to be the improper association of Lutraria with the Mactridae instead of being placed with the Myadce, he replied thus :- ^^ ^^ ^ g Ig49 " My dear Sir, I quite agree in all you say about Lutraria, and shall keep your letter for the Appendix. So entirely did I agree in the view you take, that I sent the MS. to be printed with the Myadce. The printers, however, mis- laid it, and I was forced to put it in the old place. " Believe me, dear Sir, with many thanks, " Most sincerely yours, " W m Clark, Esq." " EDWARD FORBES." ,, 246, 31, for in the Articulata read in the annelidan Articulata. ,, 247, ,, 17, van read rear. 296, 31, Chemnitzidce read Chemnitzice. 310, ., 20, branded read brindled. ,, 331, ,, 16, ,, tenebra read terebra. 444, ,, 22, 23, Dele the words " the cause has perhaps been its anomalous aspect." BRITISH MARINE TESTACEOUS MOLLUSCA. CLASSIFICATION. IT will be convenient, with reference to this work on the British Marine Testaceous Mollusca*, that a synopsis of the classification of the whole tribe should be submitted, accom- panied by a short analysis, that the incidents and position of any particular family may at once be examined. Most naturalists have their own plan of distribution with respect to natural order ; perhaps, then, I shall not incur the imputation of an unmeasured presumption, if I venture to offer a sketch of mine, founded on forty years' sedulous investigation of our indigena. I have not the vanity to suppose that my scheme is superior to the methods of my brethren ; but it is novel, and exhibits, as I think, a progressive advancement of animal organization and harmony of arrangement from the beginning of the class to its termination, by which groups of similar affinities are insensibly united as far as is possible, and suc- ceed each other, on the basis of external and internal anato- mical considerations. These memoirs are the result of numerous visits to the * The main object of this work is the description of the animals of the British marine testaceous Mollusca, and though a few of the freshwater and land families and genera are mentioned, it is only incidentally, and to fill up the outline of the British classification, but no account of their species will be given. 2 BEITISH MAKINE TESTACEOUS MOLLUSCA: South Devon coast at Exmouth, where I have passed my leisure in the dissection and examination of the Marine Tes- taceous Mollusca. Nearly every animal has undergone, in a living state, my personal examination, and in many species often repeated. I have had my own dredger, and I may say with some confidence, that there are few individuals who have had better opportunities of observing the organs, their functions, and the habitudes of these varied and interesting animals, than myself. I trust that my dissections and in- vestigations will give such a general, and in some measure particular account of their external configuration and internal anatomy as will suffice to furnish the younger students of this branch of zoology with some knowledge of their organization, and afford them sufficient aid to discriminate the organs of the animals, so as to let none pass without careful observation ; for how many curious creatures, which perhaps only occur once in a lifetime, have been overlooked for want of such assistance, and are for an indefinite time lost to science ! I speak with deep regret on this point ; as in my earlier career I have neglected opportunities that have never occurred since, and which I have felt the loss of. The anatomies of Pholas dactylus, Teredo megotara, Denta- lium tarentinum, Bulla hydatis, and other desultory anatomical observations by myself, with references to M. Cuvier, the " principium et fons" of faithful comparative anatomy, will sufficiently explain the structure of tlie Acephala and Gastero- poda that have been treated of in these memoirs ; which are by no means to be considered as strictly local ones. Though the species have been obtained from one vicinity, they will be found to give, I hope, a faithful portraiture of most of the animals of the entire class of the British marine testaceous Mollusca. There are, however, gaps which it has never been in the power of malacologists to fill up ; but the hope of acquiring the rare desiderata ought not to be considered as forlorn. I have lately fallen in with very unexpected acquisitions which afford a practical illustration of the quotation " Turne, quod optanti Divum promittere nemo Auderet, volvenda dies, en ! attulit ultro." CLASSIFICATION. 3 I may mention that these remarks were scarcely dry, when I received from Exmouth a pine log fall of magnificent Teredo megotara alive, which species I had not seen for thirty years, and enabled me to supply the anatomy of the Teredines. And in 1852 I reaped a splendid crop of rare desiderata, which I had almost despaired of. The gleanings of the harvest still remain, and will amply repay the labours of the energetic naturalist. We have given no figures of the animals or shells, and only occasionally in the text, short notices of the hard parts ; but we have supplied this want, by referring to the excellent and recently published ' British Mollusca/ by Professor Forbes and Mr. Hanley, of which we will observe, that no mala- cologist can dispense with this vade mecum, wherein will be found delineations, and copious descriptions of the shells of every animal mentioned in our work, with figures of many typical animals, and we have added references to those British species that have escaped our researches. Sir Walter Scott tells us, that nature having denied Mr. Croftangry a pencil, he endeavoured to make words answer the purpose of delinea- tion ; I almost think, though fancy may be equally expansive in both cases, that if one has any general knowledge of the subject, a particular description of any of the variously formed objects of nature would ensure as good a distinctive resem- blance as if drawn pictorially from life ; the only exception is the human race, in which nature having arrived at the ex- treme limits of animal composition, illustrated by there being absolutely the same number and quality of the external organs in every tribe, the chef-d'oeuvre of her works may, perhaps, be better expressed by portrait than by description ; but all the other objects of animated nature, even in the same divi- sion, differ so exceedingly from each other, for example, in the present case, the Mollusca, that descriptive notes may possibly be preferable to artistical representation. BRITISH MARINE TESTACEOUS MOLLUSCA : SYNOPSIS OF THE FAMILIES AND GENERA OF THE BRITISH TES- TACEOUS ACEPHALA, GASTEROPODA, AND CEPHALOPODA, DISTRIBUTED IN SIX DIVISIONS, ON THE BASES OF SEXUAL ORGANIZATION. Eirst Division. ACEPHALA PALLIOBRANCHIATA. Hermaphrodita, sine concubitu. TEREBRATULID.E Hypothyris. Terebratula. Argiope. CRANIAD.E Crania. Second Division. ACEPHALA LAMELLIBRANCHIATA. Hermaphrodita, sine concubitu. * Mantle open, no tubes. ANOMIAD.E Anomia. PECTINID^E Pecten. OSTREAD.E Ostrea. ** Mantle open, no siphonal tubes or sessile. MYTILIDJE Mytilus. Dreissena. Modiola. Crenella. Pinna. Avicula. UNIONID^E Unio. Anodon. *** Mantle open, tubes sessile or short. ARCADE Area. Pectunculus. Nucula. Leda. Galeomma. Lepton. CLASSIFICATION. LUCINIDJE Lucina. KELLIAD^E Kellia. MONTACUTID^; Montacuta. TURTONIAD^E Turtonia. CYCLADID^ Cyclas. Pisidium. **** Mantle open, tubes short. CARDIAD^ Cardium. MACTRID^ Mactra. CYPRINID^E Cyprina. Circe. Astarte. Isocardia. VENERID^ Venus. Pullastra. DONACIDJE Donax. Ervilia. ***** Mantle open, tubes long. TELLINID^ Tellina. Syndosmya. Scrobicularia. Lucinopsis. ****** Mantle closed, tubes short. ANATINIDJS Anatina. CORBULID^E Corbula. Sphsenia. Pandora. SOLENID.E. . , Solen. ******* Mantle closed, tubes long. SOLENID^: Solenicurtus. GASTROCHJENIDTE Gastrochaena. Saxicava. Venerirupis. MYAD^: Mya. Panopaea. PHOLADID^ Pholas. Teredo. Xylophaga. BRITISH MARINE TESTACEOUS MOLLUSCA: Third Division. fLATERIBRANCHIATA. GASTEROPODA^ CYCLOBRANCHIATA. LCERVICOBRANCHIATA. Hermaphrodita, sine congressu. * Lateribranchiata. DENTALIAD^E .................... Dentalium. ** Cyclobranchiata. CHITONID.E ...................... Chiton. *** Cervicobranchiata. PATELLID.E ...................... Patella. Acmaea. Pileopsis. Calyptrsea. Emarginula. Fissurella. Puncturella. Haliotis. Eourth Division. rPLEUROBRANCHIATA. CRYPTIBRANCHIATA. GASTEROPODA^ I PULMONIFERA. LPARS-PECTINIBRANCHIATA. Hermaphrodita, congressu . * Pleurobranchiata. PLEUROBRANCHID^: ................ Pleurobranchus. ** Cryptibranchiata. APLYSIAD^: ...................... Aplysia. Bulla. Bullsea. Otina? CLASSIFICATION. *** Pulmonifera. LIMNEAD^E Limnea, &c. LIMACID.E Limax, &c. HELICID^: Helix, &c. CONOVULIDJB Conovulus. Pedipes. Carychium. **** Pars-pectinibranchiata. Holostomata. PTEROPODIDJE Spirialis. TROCHID^E Trochus. Phasianella. Scissurella. Valvata. VERMETJDJE Caecum. Turritella. Fifth Division. GASTEROPODA PECTINIBRANCHIATA. * Holostomata. . Bisexual. CYCLOSTOMATID^E Cyclostoma branchi- ferum terrestre. Acme branch, terrest. PALUDINID^E Paludina. NERITIDJE Neritina. LITTORINID^; Littorina. Assimima. Rissoa. Truncatella. TORN ATE LLID^E Tomatella. HETEROPHROSYNID^: Jeffreysia. Barleeia. PYRAMIDELLID^: Chemnitzia. Eulima. Aclis. Stylifer. BRITISH MARINE TESTACEOUS MOLLUSCA : ** Subcanalifera, vel ecanaliferu, et subproboscidifera. PELORID^ Scalaria. lanthina. Natica. Lamellaria. Velutina. *** Canalifera, convolutifera, et proboscidifera. ALATID^E Rostellaria. MURICID.E Murex. CYPRJEAD^E Cyprsea. Ovula. Marginella. Sixth Division. CEPHALOPODA DIBRANCHIATA. Bisexual. OCTOPODID^: Octopus. Eledona. DECAPODID.E Loligo. Sepia. Sepiola. Spirula. CLASSIFICATION. SYNOPSIS OF THE GENERA IN NATURAL POSITION. Hypothyris. Cyprina. Patella. Littorina. Terebratula. Circe. Acmaea. Assiminia. Argiope. Astarte. Pileopsis. Rissoa. Crania. Isocardia. Calyptraea. Truncatella. Anomia. Venus. Fissurella. Acme. Pecten. Pullastra. Emarginula. Tornatella. Ostrea. Donax. Puncturella. Jefireysia. Mytilus. Ervilia. Haliotis. Barleeia. Dreissena. Tellina. Pleurobranchus. Chemnitzia. Modiola. Syndosmya. Aplysia. Eulima. Crenella. Scrobicularia. BuUa. Aclis. Pinna. Lucinopsis. Bullsea. Stylifer. Avicula. Anatina. Otina ? Scalaria. Unio. Corbula. Limnea, &c. lanthina. Anodon. Sphaenia. Limax, &c. Natica. Area. Pandora. Helix, &c. Lamellaria. Pectunculus. Solen. Conovulus. Velutina. Nucula. Solenicurtus. Pedipes. Rostellaria. Leda. Gastrochaena. Carychium. Murex. Galeomma. Saxicava. Spirialis. Cypraea. Lepton. Venerirupis. Trochus. Ovula. Lucina. Panopaea. Phasianella. Marginella. Kellia. Mya. Scissurella. Octopus. Montacuta. Pholas. Valvata. Eledona. Turtonia. Teredo. Caecum. Loligo. Cyclas. Xylophaga. Turritella. Sepia. Pisidium. Cyclostoma. Sepiola. Cardium. Dentalium. Paludina. Spirula. Mactra. Chiton. Neritina. If these positions are correct and we have endeavoured to test them by the examination of near three hundred animals, all of which are confirmatory we shall have placed the whole division of the Testaceous Mollusca on the sound basis of natural position. It is scarcely necessary to remark, that the subarrangement of the families, genera, and species, in their respective divisions, is of minor moment, and may almost be committed to the ad libitum of the naturalist ; all that is necessary is, to collect similar objects, and deposit them, with- 10 BEITISH MARINE TESTACEOUS MOLLUSCA : out the hopeless attempt of a rigid, natural, precessional and sequential progression. We almost think these facts and views go far to determine that the true progressive course of the essential order of nature of the class Mollusca, indeed of every other distinct class of animated nature, is within our reach, and that what we look for, depends on the more or less perfection of the reproductive system in each well-characterized group of the four grand types of the animal kingdom, in all which, if closely examined, we think the progressive advance of gene- rative organization is sufficiently apparent. ANALYSIS OF THE SYNOPSIS. First Division. ACEPHALA PALLIOBRANCHIATA. I have removed this section of the Acephala from its posi- tion at the head of the bivalves, to which I think it has no pretensions. I consider it a distinct inferior group forming the passage from the Ascidise and Cirripoda to the Acephala lamellibranchiata ; by its pallial branchiae it has relations with the Ascidise, and with the Cirripoda through the long convo- luted cilial buccal appendages, which, though not articulated, in consequence of advanced animality, still prove its connec- tion with that tribe. If the Palliobranchiata have the sexes distinct, as some authors have stated, the position I now place them in, with the strict hermaphrodite Acephala, would not be correct, and in harmony with my sexual distribution ; but I believe that these views of bisexuality in the bivalves are erroneous, and the causes that have led to them are those mentioned in the anatomy of Pholas dactylus under the head of the "reproductive organs." The Brachiopoda are very rare British productions : I have only met on the southern coasts with the minute Argiope cistellula but the Terebratula caput serpentis and the Crania anomala have been taken in North Britain sufficiently plen- tiful to determine their anatomical structure. I refer for an CLASSIFICATION. 1 1 account of the animal of the T. caput serpentis to the f British Mollusca/ and for other general observations to Professor Owen's paper on this family in the first volume of the ' Zoo- logical Transactions/ Second Division. ACEPHALA LAMELLIBRANCHIATA. The animals of this group are strict hermaphrodites, though it is said that in some of them the sexes are distinct. We dissent from this view, and have assigned in another place our reasons for not concurring in this opinion. The anatomy of the internal organs of the entire tribe as to generalities is so similar, that it scarcely affords sufficiently decided generic distributive points ; my anatomies of Pholas dactylus and Teredo megotara confirm this position ; I have therefore had recourse to an arrangement which combines both internal and external organs, to assist the distribution of this numerous class into convenient groups. A divisional order has been attempted on ligamental bases of internal or external position ; but it has been found so unstable and arbi- trary, that if strictly followed, the most incongruous species would be associated : for instance, Mactra solida would march with Anatina praetenuis, and the Cardia with the Saxicava. The disposition of the adductor muscles has been tried, and appears to be delusive and unsatisfactory, as most, if not all, Lamarck's Monomya have two adductor muscles, though the volume of one is much greater than the other. We think the only true Monomya are the Pholadida, as we have shown in the memoir on the anatomy, and these are Dimya with that eminent zoologist. The teeth and foot as general guides are so variable as not to be available ; the best of these aids is perhaps the greater or less closure of the mantle; this last we have adopted. It appears then that the animals cannot be allocated in a continuous natural order with perfect satisfaction by any of these modes : all that can be done by those who make use of such assistance, is to throw the tribes, genera, and species 12 BEITISH MARINE TESTACEOUS MOLLUSCA: together by the best mode that agrees with their compo- sition. It has long been the fashion, without any particular good reason, to commence the Acephala with Pholas, Teredo ,&c., and to terminate them with the Pectines, Ostrete, and Anomia, &c. I admit, as regards the essential points of natural order, that it is not very material whether Pholas and Teredo stand first or last in the scale. But in the classification I have adopted, which is founded on the progressive advancement of the repro- ductive organs, and having removed the Brachiopoda, which custom has placed at the head of the bivalves, to a position of less pretension, it has become necessary to invert nearly the usual order of arrangement, that animals of similar relations may be associated. This change entirely hinges on, and is the result of, the transference of the Brachiopoda from the position they have so long occupied; otherwise the ancient distribution would have been nearly as satisfactory. But the false position of the Brachiopoda, according to our views, has admitted of no alternative. In conformity with these observations, the Anomia, Ostrece, and Pectines naturally follow the Brachiopoda with which they have relations, and are succeeded by the Mytilida, &c., and brought, according to the intervening genera of the synopsis, to the Gastroch&nidce ; the remaining families of the Myadae, Solenida, and Pholadidce, are thus placed at the head of the list, and form a very natural group ; and I think that their decidedly higher organization I particularly allude to the Pholades and superior fuiictions, as those of excavation, together with the compound structure of their shells, as is evidenced by the complication of the accessorial appendages as well as the consideration of the increased importance of the siphonal tubes and the enveloping mantle, bring them by these advances in composition into closer connection with the Gasteropoda than with the Ascidise, in the vicinity of which they have been placed from their muscular siphonal sheaths and closed mantle, which have been considered to bear a resemblance to the coriaceous envelopes of those animals. We have no difficulty in admitting Venerirupis into the family of CLASSIFICATION. 13 the Gastrochanidce, though, by the teeth, it is allied to the VenereSj but we consider the character of the teeth of very inferior value to the closed mantle, which points out its natural position. Teredo terminates the Acephala and passes them to the Dentaliadae, our primary family of the Gasteropoda, agree- ably to the indices that are pointed out in the last page of the anatomy of Teredo. Third Division. TLATERIBRANCHIATA. GASTEROPODA < CYCLOBRANCHIATA. LCERVICOBRANCHIATA. The animals of this division are strict hermaphrodites with- out congression. The Dentaliada are the Lateribranchiata of the synopsis, of which family I have already given in the ' Annals of Natural History ' a detailed anatomy ; they have claims which appear not to be ill-founded, to stand as the first family of the Gasteropoda, from the connection between them, by the position of the branchiae, with Teredo, the last family of the Acephala. The Chitons are the Cyclobranchiata. The Patella, Acmaea, Pileopsis, and Calyptraea are the Cervico- branchiate patelloid forms with a single non-symmetrical branchial plume; and Fissurella, Emarginula, Puncturella, and Haliotis are in the same Cervicobranchiate category, but differ from the first patelloid group in having two symmetrical branchial leaves. Fourth Division. {CRYPTIBRANCHIATA. PLEUROBRANCHIATA. PULMONIFERA. PARS-PECTINIBRANCHIATA. In this division there is an important advance in sexual arrangement ; pure hermaphroditism is abandoned, and that of mutual congression has succeeded. The families are the Pleu- robranchida, Aplysiada, Bullidte, Pulmonifera, Pteropodida, 14 BEITISH MARINE TESTACEOUS MOLLUSCA: and Pars-pectinibranchiata. The first four carry branchiae, or respiratory network in particular cavities of the back and neck ; they all swim or float, except the Limacidas and Heli- tida. It is necessary now to state why the Pteropoda do not constitute with us a separate class ; their anatomy is so nearly identical with the hermaphrodite Pectinibranchiata of this division, that I have preferred placing them in conjunction, as they have the same sexual characters, rather than letting them remain in a false position, between groups of the Acephala and Gasteropoda, both of which are strict hermaphrodites, or intercalating them between the bisexual Gasteropoda and Ce- phalopoda, an equally inconsistent situation. The term Ptero- poda, inferring that the foot, or locomotive, is formed like wings, and fixed more or less around the neck, does not, we think, militate against these animals being considered modi- fied Gasteropoda ; in like manner as the Trachelipoda of La- marck, that have them under the neck, which is only a modi- fication of the foot, that in many tribes occupies the entire length of the body. The wings of the Pteropoda are little more than broad membranous extensions of the anterior lateral portions of the foot to assist natatory locomotion on its natural element. The Pleurobranchida are fully noticed hereafter, and the Aplysiada are too well known to require any remark. The Bullida are a difficult family, many of the animals being very minute, and some have never occurred to any naturalist. We have preferred depositing the Velutina otis of authors, Mr. Gray's Otina, ad interim in this family, rather than amongst the Conovuli ; at the same time, it is as probable it may belong to them, especially if it has not a gizzard. The distinguishing character of most, if not all, the Bullidae, is the testaceous hard gizzard, in respect of which our opinions are not changed, of its being in some shape or other the invariable concomitant of this group ; but we admit that in the minuter species it is so exceedingly small as easily to escape attention; we have found it so in Bullaea punctata, and only succeeded in finding it after several examples had been examined. It is possible that some of the species may have strong coriaceous gizzards, but in every Bulla and Bullcea that we have observed CLASSIFICATION. 15 it has always been found of a testaceous substance ; for these reasons, though we have doubted, we now think that the Bulla hyalina, the Amphisphyra of Loven, may be a true Bulla. Bullaea, an undoubted branch of this family, is copiously illustrated in our account of B. aperta, and by recent full de- scriptions of B. pruinosa, B. catena, and B. punctata, origin- ally published by us more than twenty years ago, in vol. iii. p. 339 of the Zoological Magazine. With respect to the Conovuli it has been said, that except Carychium, they are bisexual. We do not think so, as, be- sides their close connection with the Helices by the respiratory structure, we observed in more than twenty examples of the Pedipes bidentatus that all had well-filled ovaria. We believe they are congressional hermaphrodites ; at least for the present we consign them as members of that reproductive character. In consequence of the curious discovery, if it be substan- tiated, which is related in the chapter on the Trochidts, that all the Pectinibranchiata, with circular multispiral opercula, hitherto considered bisexuals, are like the Helices hermaphro- dites with mutual congression, the Trochidce, including the genus Valvata, and the new family of the Vermetida, con- taining the genera Ctecum and Turritella, are admitted into this division. It seems, however, inexplicable why the strictly circularly operculated Pectinibranchiata should have the ge- nerative system of the Helices, and that all the others, of whatever shape the opercula may be, otherwise than circular, should be bisexuals. Though the other hermaphrodites, with mutual congression, as the Limneada, Limacida, and Helicida, are admitted into our main line, it is impossible to place them therein satis- factorily ; they are an aberrant group ; nevertheless they form amongst themselves a closely connective line. The remaining hermaphrodites are the marine Pleurobranchus, Aplysia, Bulla , Bullaa, and Otina ? These are another aberrant tribe ad- mitted into line, but equally intractable as the last, yet they are pretty closely allied to each other. It appears then, that the general bond of consentaneity between all the families of 16 BRITISH MAKINE TESTACEOUS MOLLUSCA: this division, and which plants them in it for ever, after our method, is their mutual hermaphroditism. Some malacologists isolate these discordant groups from the systemic line, and term them Opisthobranchiata, from the heart being anterior to the branchiae, in opposition to the Proso- branchiata, which have the heart, in the greater part of the Gasteropoda, posterior to the respiratory organs ; this arrange- ment causes Pleurobranchus, Aplysia, and Bulla to enter into line after the Cypr&ada, a more unnatural position, we think, at least it is an isolated one, than that we have adopted ; and as there are other inconveniences in this plan, we have preferred, however incongruous and aberrant they may be with what follows, or precedes, or with themselves, to deposit them in the general line after the Patellida; and we are further induced to adopt this arrangement, as they are thereby at once brought within the limits of an important sexual scheme, which we think more conducive to a sound natural position than the posterior or anterior relation of the heart to the branchiae. Nature herself is here discordant, and will not allow us to symmetrize her works as the squares of a chess- board. This is a vain idea, and however often repeated, will as signally fail as the hopeless tasks of the Belides. The Nudibranchiata, which have neither external nor in- ternal testaceous appendages, do not come within the scope of our work, they are only mentioned as a numerous molluscan tribe ; their position as hermaphrodites is in the Third and Fourth Divisions. The Tunicata, comprising the Ascidiada, although they have some points of alliance with the Mollusca, we do not consider entitled to range with that class. Fifth Division. GASTEROPODA PECTINIBRANCHIATA. Bisexual. The genera Cyclostoma, Acme, Paludina, Neritina, the Littorinidce, Tornatellida, Heterophrosynida, Pyramidellida, Pelorida, Alatidce, Muricida, and Cypneada are probably all CLASSIFICATION. 17 bisexual, and so largely mentioned hereafter, that extended analytic remarks are not required. We will only point out the curious fact that all the Pyramidellida have the eyes immersed at the internal bases of the tentacula, and the apex of the shell is, I believe, always more or less reflexed on the succeeding volution : these two points will invariably detect the Chemnitzian animal ; the tooth also is of excellent value when present, but as the shell is as often without as with it, it is not always available. Chemnitzia, though a proboscidal animal, seems to have some alliance with the amphibious pulmoniferous Conovuli and the land Carychium. Though the family of the Cerithiadae, with its genera Cerithium and Aporrkais, in which some British species are deposited by authors, has no place in our method, it is proper to make a few remarks on it. We propose hereafter to show that the Cerithium reticulatum of authors is an elongated Rissoa, and that the C. adversum, from its spiral operculum, is also a probable Rissoa : we think C. metula, a Cerithiopsis with some, is an elongated Murex, ranging with our Murex tuber cularis. It has been stated that the muzzle of C. reticulatum differs from that organ in the LUtorina and Rissoa ; I am unable to discover a tangible difference, and think that the animals are in every respect the prototype of each other. As for the Aporrhais pes pelecani, which has sometimes found its way into the Cerithiada, it will be seen that it has little alliance with it, for we shall prove, in our family of the Alatidce, one of Lamarck's groups, to which it is transferred as Rostellaria pes pelecani, that it is a nearly strict muricidal animal. We think the family of the Cerithiadae, even as regards exotics, is altogether conchological and artificial; it is pro- bable many of its animals will turn out simple Rissoideans, and many, elongated Murices. 18 BRITISH MARINE TESTACEOUS MOLLUSCA: Sixth Division. CEPHALOPODA DIBRANCHIATA. Bisexual. These singular and highly organized animals are distributed in two families : the Octopodidce include the genera Eledona and Octopus; the Decapodidte, Loligo, Sepia, Sepiola and Spirula : they all creep and swim. They are elaborately and anatomically described and illustrated by M. Cuvier in his memoirs, and by Professor Owen in the second part of the second volume of the ' Zoological Transactions/ We have merely mentioned these animals to preserve intact the chain of the synopsis. To attempt to add novelty to this almost exhausted subject would be a vain and fruitless labour. This is a most aberrant group, and cannot be placed in line ; they are the most advanced in composition of the yet discovered undoubted Mollusca; but there appears so large an hiatus between them and the class they terminate, that they can only be considered an anomalous lateral branch. I have now finished a limited analysis of my method of the distribution of the British marine testaceous Mollusca. I am led to think the sexual arrangement natural and well-founded, as it cannot fail to have been observed that as the generative influences are more or less perfect, there is a corresponding energy and activity. If we cast a glance at the strict herm- aphrodites, as the Acephala and Patella tribes, we find them either fixed or of the most limited locomotion ; but as soon as the generative structure is improved, the animals become more lively and locomotive. This view is exemplified in the hermaphrodites with congression, for instance, in the natatory Gasteropoda and Pulmonifera ; but when bisexuality is esta- blished, there is an evident increase of motion, functions, and, I may say, even of intelligence and structural composition. And lastly, on arriving at the most highly developed genera- tive influences that can attach to the Invertebrata, we see an energy and activity that even exceed those qualities in some CLASSIFICATION. 19 of the vertebrate animals, I instance the powers and loco- motion of the Cephalopoda. In conclusion we observe, that Nature has put a veto on any arrangement that shall be exempt from anomalies and incongruities ; we must look at her largely as a class, with a few well-marked divisions, and not be too sensitive about Utopian details of strict natural order. We are prepared to expect that the present scheme will follow the fate of every other system of classification that has preceded it, however great may be the authorities from which they have sprung. It is universally admitted that the most accredited plans are unsatisfactory, and I venture to predict, that to the end of time our successors will make the same remarks. Mathema- tical nature is not an attribute of this sphere ; the votaries of that condition must seek for it " extra flamraantia mcenia mundi." The synopsis of the genera, we again impress it, shows the impossibility of such an arrangement. We have here perhaps as much connective harmony as the Mollusca can receive. We do not say that there may not be transpositions and cer- tain modifications of the genera to meet the particular views of malacologists, but the general outline may perhaps be as near the truth as the subject will admit of. If zoologists demand a natural line, they cannot have it without excluding from the grand main various families. In consequence, our classification, at certain points, presents incongruities that no art can arrange satisfactorily, but they are brought as near to each other as Nature will allow of. We must submit, as we cannot alter her laws and dispositions. The fact of our line not according a direct totality of strict affinities, proves that Nature cannot be thus arranged, because the Supreme Creator, whose handmaiden she is, has not invested her with the power of effecting a symmetry beyond what she has accomplished. c 2 20 BRITISH MAEINE TESTACEOUS MOLLUSCA : ACEPHALA PALLIOBKANCHIATA. A few general remarks on the Palliobranchiate Mollusca, in addition to those in the synopsis of my classification, will be a useful reference in respect of this class of acephalous animals. I include in the general matter on the Pallio- branchiate Mollusca, the meagre notices and references to the very few recent species of this tribe that now exist ; these, however, contain all that is known of the organization of this numerous group of one of the epochs which preceded that in which our orb has been described as "rudis indigestaque moles." For the reasons stated in the analysis of the Mol- lusca, I have reversed the position of this section of the bivalves, and made it the alpha instead of the omega of the Acephala. These animals derive their appellation from the respiratory apparatus forming a vascular network on the substance of the mantle, instead of being provided with the distinct sym- metrical, usually double laminse, on each side of the body of the Lamellibranchiata ; they are the Brachiopoda of Lamarck, and form two families in respect to the British iiidigena, the Terebratulidte, containing three genera and four species, and the Craniada, with only one genus and one species. This class of Acephala formed the great mass of the Mol- lusca in the palaeozoic ages, as is proved by the almost infinite variety of their fossils, which are more numerous than all the other groups of Mollusca united. But in these latter days it would appear, from the excessive rarity of living species, that the race has nearly become extinct, or live in unapproachable depths ; I believe that not half a dozen species have ever been examined, and we can scarcely hope that several anomalies in the structure of these animals and their shells will ever be explained; no comparison can be made the same animal must be observed. The British collector cannot hope to pos- sess more than five recent species, two of which, the Hypothyris psittacea and Terebratula cranium, may be considered almost ACEPHALA PALLIOBKANCHIATA. 21 beyond acquisition ; the only chance is, that a fortunate hit may be made, and these rare productions brought to light from the deep sea beds. That the animals of this tribe are of inferior organization to the lamellibranchiate bivalves, is, I think, shown by their invariable fixity of habitat. By-the-by, it is said that in this family, and also in the Ostreadce, the sexes are distinct : if this be so, how can the genial influences pass ? for we must pre- sume some sort of congression. Is it contended that the germs of vitality are committed, at hap-hazard, to the waves ? I cannot concur in this doctrine. I believe all the bivalves are strict hermaphrodites, that is, without congression, and contain within themselves the elements of bisexuality. I return from this digression to make a few more observa- tions on the value of the palliobranchiate organization. In addition to the fixed state, it may be added, that in it the circulation is more simple, the motive power consisting only of an auricle on each side, without a ventricle. The spiral ciliated arms, though not articulated, in consequence of their hollow structure producing an equivalent flexibility, are to me sufficient evidence of an alliance with the Cirripoda ; and I think the structure of the respiratory apparatus equally con- clusive that these animals are closely related to the Ascidia. Let us examine the upper valve of Crania, fixed as it is to the animal only by muscles. I can consider it in no other light than as the analogue of the operculum of the Balani, for the protection of the animal, and support and regulation of the issue of the long, spirally-coiled, ciliated, tentacular buccal appendages ; and I think that the longer or shorter internal opercula of the Balani, which are imbedded, with a limited movement, in a cartilaginous mass, are only tantamount to the internal apophysary processes of such of the Pallio- branchiata as have them ; and for those which are destitute of these peculiar supports, the issue of the long spiral arms is regulated, as in the pedunculated Cirripoda, which have not the moveable opercula of the Balani. The spiral arms in both species of Balani, as well as in the Brachiopoda, besides tenta- cular and buccal functions, may also serve as the muscular 22 BEITISH MARINE TESTACEOUS MOLLUSCA : agents for the opening and closure of the valves, in aid of other special muscles. It may be said that these views are far-fetched, or imagi- nary; but if naturalists would seriously consider that the oper- culum of the Balani is of the nature of an apophysis for a particular purpose, they can only come to the conclusion that such an appendage can have no other use but for the support, issue, and regulation of the buccal tentacular arms. If it is asked, what is the use of the apophyses of the Palliobranchiata? the same answer only can be given. These subumbonal blades appear in the Pholades and Teredines ; their use is the same as the processes in the Palliobranchiata, and the opercula of the Cirripoda, for the support and regulation of certain organs of the animal. With the exception of the genus Hypothyris, the shells of these animals are invariably covered with punctures or fora- mina, which would appear to give them a slight cross with still inferior classes. There is nothing peculiar in the repro- ductive organs ; a similar disposition of them is seen on the mantle of Anomia and in some of the Pectines. In this group the animal is deposited in its shell differently from the Lamel- libranchiata ; the larger or convex valve, though uppermost, is really, with respect to the animal, the dorsal one, and the under valve the ventral one ; an approach to a similar position of the animal may be observed in Anomia, Pecten and Ostrea. In the Palliobranchiata the nervous system is more sparingly developed; they have lost the knotted spinal cord of their remoter relatives, the Cirripoda, which in them is disposed in detached ganglions, the result of the change they have under- gone in the plan of their organization;* and for the same reason, the articulation of the spiral arms has disappeared, and is replaced by their tubular flexibility, the use and form of the organs still remaining the same in them as in the Cirripoda. I think enough has been said to show that the pallio- branchiate bivalves are of inferior organic structure to that of the lamellibranchiate Acephala. We refer those who are desirous to be informed of what is known of the organization ACEPHALA LAMELLIBEANCHIATA. 23 of this interesting and almost undeveloped class, to Professor Owen's Memoir, vol. i. of the ' Zoological Transactions/ and to M. Deshayes and Milne-Edwards' s comment and observa- tions, vol. vii. p. 305-329 of their second edition of Lamarck's ' Animaux sans Vertebres/ We conclude by repeating our opinion that the Pallio- branchiata are not of co-ordinate organization with the Lamel- libranchiata, but an inferior group, having many connective links with the Cirripoda. Our notes are unavoidably scanty, from the dearth of materials and difficulty of the subject. We have done : as facts cannot be stated, hypothesis ought not to supply their place. ACEPHALA LAMELLIBRANCHIATA. I shall now give an outline of the anatomy of the lamelli- branchiate bivalves, to serve as a standard of comparison. The internal structure of the animals of this division is less complicated than in the Gasteropoda, and presents such a similarity throughout the whole class, as to render it unne- cessary to give more than a detailed account of the organs and functions of the animals, without reference to a particular species. This generalization will include all the genera of the subsequent groups of the Acephala that may be noticed, except that especial care will be had to note any essential departure from the general organization in any particular genus or species. The circulation, including the respiration, is complete; it usually consists of a pair, of infinite variety of outline, of suboval vascular plates, fixed under the mantle on each side the body ; these are composed of a network of branchial tubes, and are each furnished with an arterial and branchial vein, the one to receive the blood from the venae cavse for aeration, and the other to convey it through the auricles to the heart, to be again transmitted into the system ; the artery of each lamina is situate at the upper margins of the branchiae, at 24 BRITISH MARINE TESTACEOUS MOLLUSCA : their junction with the body, under the mantle, at the dorsal range, and is of concurrent length with them ; each branchial vein coasts the margins of its respective lamina. The motive power of the circulation is a heart, which is a simple ventricle, and two symmetrical, oblong auricles, one on each side of it; it is placed subcentrally on the dorsal range, rather nearer to the posterior half, and with the auricles embraces the rectum or intestine, which thus apparently passes through it. But this is not the case with every bivalve, though the major part of them are thus constituted; the Ostrea, Area, and some few others are exceptions. The heart and auricles are nearly pellucid, of the thinnest texture, and apparently of feeble power; the auricles have valves to prevent a reflux of the blood; they are usually situate at their junction with the heart, sometimes at the point where the branchial veins unite with them, and they sometimes are found at both contacts. The inspirations and expirations are each about seven or eight in a minute. The heart gives forth at least two aortic branches, which ramifying furnish arteries to the system, and at their invisible termini the venous reflux has its origin, and by continual anastomoses and inosculations, in their progress to the arterial centre, terminate in one or more trunk veins or vense cavse, which effect a coalition with the branchial artery. Though the circulation is what is called complete, it may be liable to interruptions, divergences and retardations ; that is, if the opinion of some zoologists, Mr. Garner amongst them, is well founded, that the whole of the blood is not returned to the body in each circulation, and a part of it, from various organs, passes to a set of veins which are concentrated ante- riorly, on each side the dorsal range, in an elongated sinus, extending to and under the pericardium ; and that these veins, by small lateral internal sacs, ducts or orifices, pass the secre- tions, or fluids they have distilled, to the mantle, in aid of structure and coloration, for the use of the ova and other organs ; and that branches from this fasciculus of veins, after the depuration of their contents, transmit the blood into the branchial artery; it is also said that other portions of the ACEPHALA LAMELLIBRANCHIATA. 25 venous blood enter by branches into the principal branchial vein and auricles, and is sent into the circulation without being transmitted to the branchiae for aeration. Part of these views I can confirm, as far as relates to the spongy excretory glands at the anterior end of the sinus above alluded to ; they are visible in Pholas dactylus, and conspicuously in P. parva ; their uses are fully described under the title of excretory organs of P. dactylus. As to a portion of the blood being returned to the heart without receiving the dose of oxygen, I have not had it in my power to verify that fact. From this statement it would appear, that in some of the bivalves, if not in all, the circulation is not without interrup- tion, and that there is a particular one for the special purpose of providing the necessary secretions. With regard to these points I am inclined to think, that the veins of each organ form and supply the secreting glands for itself, in its own immediate vicinity; for instance, the liver, the bile for the stomach; the ovarium, the mucus for the ova; the byssal gland, the filamentous fluid; the mantle its own pigments; also that thin membrane which is the external duplicature on the shell, springing from its margins, and spreading more or less on all shells, as well as on some of the exposed soft parts of the animal, producing what is termed the pilose skin, epi- dermis, and exterior ligamental covering. There is a difficulty in supposing that all the secretions are elaborated and distilled from a mass of veins collected in a particular cavity, and pro- duce the peculiar secretion for each organ, conveying it thereto by a separate sac or distinct duct. I can scarcely believe that such a concentrated olla podrida can act harmoniously, and produce simultaneously, from a fasciculus of veins deposited in the same reservoir, mucus, pigments, carbonate of lime, &c. With respect to the digestive organs, the mouth there being no head, eyes, nor tentacula is a large, plain, trans- versely oval aperture, covered by the mantle, and is placed towards the upper part of the anterior range, having on each side of it a pair of palpi, which appear to be both of a tenta- cular and respiratory nature, and perhaps assist the cilia that clothe the branchial laminae to beat and divide the water in 26 BRITISH MARINE TESTACEOUS MOLLUSCA : aid of the extraction of the vital principle. The mouth leads by a short oesophagus into the stomach, concerning which, the elastic stylet, and the tricuspid membrane or stomachal attritor, we refer to the account of the digestive organs of the Pholas dactylus. The food of the bivalves appears to be animalculse and soft Crustacea. From the stomach, which is of suboval or pear- shape form, the intestine plunges obliquely into the lower part of the body, amidst the ovarium, and forms 2-5 or 6 convo- lutions, and at the last turn it ascends to the dorsal range, and, as rectum, discharges at the posterior extremity, either into an anal tube, as in the Pholades, Mya, &c., or without one, fixed externally or floating free, as in the Pectines and Anomice. -The liver is usually a large, green, granular viscus, on the dorsal region, almost enveloping the stomach, into which it pours the bile by several ducts or orifices. The reproductive organs scarcely require mention, as they are largely noticed in the anatomy of the Pholas dactylus, above alluded to. We may, however, say, that all the bivalves are strict hermaphrodites without congression. The ovarium varies greatly in form and consistence at different seasons ; in winter it has generally the aspect of homogeneity, but when under the stimulus of the genial months it becomes tumid, flaky or granular, and as fecundation advances the congeries of ova appear in progressive development until the term of gestation is complete, when they are ejected and deposited on A^arious marine receptacles. These animals, though termed self-sufficient, have doubtless mixed up with their ovaria the male influences, which are apparently minute pear-shape bodies, only discoverable in the genial season, containing a glairy fluid, which may be to communicate the vital spark. In some genera, as Anodon, Mytilus, and a few others, the ova are deposited for a time amongst the network or interspaces of the branchial laminae, in which they are farther developed, and become testaceous, when they are finally ejected. In reference to the secretions already spoken of elsewhere, we will only observe that the mantle envelopes the entire animal; its edges are often ciliated, and the posterior end ACEPHALA LAMELLIBKANCHIATA. 27 extended into siphonal tubes; the external surface lines the shell, and is the constructor thereof, by the exudations of calcareous matter from its vessels ; the inner surface embraces the body, and is hung and this observation introduces those on the muscular system by some inconsiderable muscles ; but the grand supports of its position, in all bivalves, are the ad- ductor muscles which pass through and suspend the body by being fixed to each valve, and when detached leave cicatrices, termed muscular impressions, which have been applied to assist generic and specific determinations. It is said that in the Anomice, Ostrea, and Pectines, there is only one subcentral muscle : this is a mistake ; as in those genera, as well as in the Mytili and some others, I have found a second muscle, though often of very inconsiderable volume, under the beaks ; we may therefore consider the monomyal and dimyal charac- ters as untenable. The mantle in the Anomia, Ostrea, and Pectines is entirely open from the beaks, and destitute of siphonal tubes ; in others, as in Lucina, Mytilus, &c., it is more closed, and shows only two sessile orifices ; in the fami- lies of the Veneridce and Mactridte a still further closure is apparent in that membrane, which in them is produced into two short tubes ; in the Tellinidce it forms rather long slender siphons ; and finally, in the Pholades, Lutraria, My&, Gas- trochcence, and the Saxicavce, it is entirely closed, except a pedal orifice, and is often produced into two long tubes, either soldered on each other or inclosed in a retractile sheath ; the lower siphon is called the branchial, the upper the anal one ; the former conveys water to the branchial cavity and expels it. We do not believe the doctrine that the water enters by one tube and is discharged from another; we think it is admitted both from the branchial siphon and pedal orifice, and expelled indiscriminately from those apertures. In many genera both, and in others only one of the siphons are pro- vided with valves at their orifices, to regulate the entry and expulsion of the water, and, with one or more circles of ten- tacular filaments, to capture and transfer the animalculse into the branchial cavity : on this point see our observations on the Pholades. 28 BEITISH MARINE TESTACEOUS MOLLUSCA: The foot is a very variable organ, implanted usually in the subcentral lower portion of the body ; when at rest, in many families it represents a pedicle, with, an elbow doubled up at its side, but in action it becomes instantly straight, pointed, flexible, and extensible more or less in all directions, full of energy and activity. Many of these animals have at the bend at the pedicle a byssal groove, from which tenacious filaments are spun, that enable the animal to fix itself in situations where such action is required, and detach again, which is always effected by the extraction of the byssus from its origin, leaving it fixed at the last locality, and when necessary, spin- ning another with great celerity ; not as a matter of course, but in case circumstances, as currents and rapid tides, require such aid. As to the nervous masses, they are few and scanty, a single ganglion being placed above the mouth, the other posteriorly ; but they are connected with each other by filaments, from which threads ramify to all the muscular supports of the body, particularly those important ones the adductors, the foot, siphonal retractors and minor muscles : the muscular compo- sition of these organs appears in their textures under every imaginable superficial, horizontal, and perpendicular angle. As the shell or hard parts of the bivalves are essential ele- ments of their composition, I am bound to give them some consideration ; I shall however only make a few remarks on the ligament and cartilage, as well as the teeth ; the former is chiefly intended, aided by the teeth, to maintain the valves in a symmetrical position, when the cartilage is unbent, by the relaxation of the adductor muscles. The cartilage is the great source of elasticity, arising from the impacted mass of fibres of which it is composed, that give its substance almost the appearance of homogeneity. When the animal closes the shell by the retractive action of the adductors, its spring is then bent, and on relaxation the valves are opened to the extent the adductors are relaxed ; but if they are divided by the knife, the elastic power of the cartilage opens them to the fullest extent, at least until they are stopped by the beaks and umbones. Whether the cartilage is termed external or in- ACEPHALA LAMELLIBRANCHIATA. 29 ternal, or half within and half without, its modus operandi in either case is as I have described; and the ligament, as far as its power extends, acts precisely the same. The ligament is always exterior in reference to the cartilage, often covers it, and is fixed to the external margins of the shell, whilst the cartilage rests on the internal marginal surfaces and callosi- ties that act as a fulcrum, which in many species is aided by an apophysis, pit, or excavated internal process. The teeth, with which a large portion of the bivalves are furnished, are strictly of a calcareous nature ; and I am not aware that they have other uses than literally to act as a hinge, and to assist the ligament and cartilage in strengthening the closure of the valves and maintaining their proper position. In some genera where there are no teeth, an accessorial ossicle clasps the two valves as an equivalent; and in those that are entirely mute, the power of the adductor muscles is invariably increased. I have stated, in the preceding paper, that the teeth, ligaments, cartilages, and cicatrices of the muscles, afford, from their variableness and instability, no efficient assistance in forming a continuous natural order; therefore these appendages of the shell will receive no further consideration in any remarks I may make on the natural arrangement of the families of the Acephala ; they may, how- ever, assist in specific distinction, and as accessories and make- weights in balanced investigations. I will now make a few observations on the lacunose doc- trines that have lately been promulgated by the French and Belgian naturalists, which we believe have their origin in M. Cuvier's celebrated Aplysia case, in which it is stated that the vena cava or great branchial vein is perforated so as to permit its contents to mingle with the fluids of the abdominal cavity. M. Cuvier considered this structure so unusual, though he communicated it to his friends, that he hesitated to make it public for many years, until he had by every possible test satisfied himself of this almost unnatural phenomenon, which he declared to be the most extraordinary he had ever met with. I think, if that illustrious naturalist had lived in our days, he would have seen cause to change his opinion, and that 30 BRITISH MARINE TESTACEOUS MOLLUSCA: the strange appearances he observed were the result of the contraction of the muscular fillets of the vena cava rupturing the extremely thin and almost invisible films of the interspaces of the vein, in consequence of the shock the animal received from sudden death, by spirit, boiling- water, or any other mode of asphyxia. I have already stated, in the observations on the Lamelli- branchiata, that some malacologists are of opinion, that in the Conchifera all the blood conveyed by arteries to the system is not carried back to the branchiae for aeration by a direct vascular apparatus, and that a portion of it is again passed into the system either through the auricle and heart or other- wise, without having undergone the respiratory process of purification. But the moderns have gone far beyond these venous irregularities, and assert that in every molluscum, from the Tunicata to the Cephalopoda, though the blood enters the system by arteries, a part of it reverts to the respiratory centre, by lacunae, cavities, canals, hollows, and fissures, not by veins and walled tubes, which exist in the tissues of the flesh of the animal ; and that the blood, by meanderings, exu- dations, and filterings through these labyrinthine sinuosities in its passage for respiratory aeration, is mixed with the abdo- minal and alimentary cavities and their fluids, from whence they are collected by what are called branchio- cardiac vessels, and transmitted to the heart. With respect to this process I doubt it altogether, and make the same observation on it as on the Aplysia case above, that the excessively fine vascular membranes are at their larger terminations attenuated and often destroyed by contraction and lost by collapse, and become in the animal killed by violence so amalgamated with the tissues as to be invisible, and thus their sites have the appearance of lacunae, &c. I believe this to be the true solution of the apparent absence of venous ducts, and that, though of extreme tenuity, they exist in the live animal. Nature always acts with order and consistency, and it is difficult to suppose she would so far depart from these attri- butes, after having constituted a particular set of vessels to ACEPHALA LAMELLIBRANCHIATA. 31 convey the blood throughout the system, and another visible elaborate apparatus to eliminate the vital element, that she would stop in the midst of her career, and, instead of a set of vessels to convey it back to the branchiae for oxygenation, substitute and allow the stream of vitality to find its way through a mixture of cavernous sinuosities, and percolate amidst the ordures of the visceral contents to the mouths of the branchio- cardiac vessels, to pass it to the respiratory me- chanism to repair the usual exhaustions and adscititious impu- rities of its passage. Neither of these opposite views can be verified in the living animal, and the examination of the dead one is equally unsa- tisfactory, because uncovered sinuous canals may appear to exist in the tissues ; but who can say that the excessively thin walls may not have vanished by contraction attendant on the peculiar mode of death, leaving only the sinuosities of their sites ? The above remarks are confined to the circulation of the blood. I fully admit that in many of the Mollusca, aquiferous canals and pores exist in the tissues of the foot and its pedicle, and other organs for the admission of water to assist in pro- moting the tension of those organs in aid of locomotion ; but I do not believe that the water enters the visceral regions except by the mouth, unless in consequence of a rupture of the parti- tion-membrane between the cavities of the foot and the abdo- men ; it has been stated that the Lucirue are instances of the water passing through the foot into that cavity. For these reasons we repudiate, as contrary to nature and all analogy, the doctrine of even a qualified lacunose system for the blood circulation; that is, of its being sent by arteries to all parts of the organism, and returned partly by walled vessels, and partly by sinuous canals worked out of the paren- chyme. And in the tribes of inferior organization to the Mollusca, we consider, however imperfect the mechanism of the susten- tation and circulation may be, that both these functions are distinct, and in no case confounded; we believe that nine- tenths of the matter that has been advanced by authors on 32 BEITISH MARINE TESTACEOUS MOLLUSCA: these points are little better than hypotheses, and rest on unsound demonstrations. It is well known that the mind, deeply intent on the examination of the very minute objects of natural history, when jaded and exhausted by the pressure of high microscopical powers, often deceives itself, and from preconceived impressions, idealizes and fancies it sees objects that have only an imaginative existence, and strongly distorts real ones through optical illusion. We admit that in the lower Invertebrata there is no mecha- nism for sustentation, circulation, and respiration, of the com- plex and advanced character of the Mollusca, as heart, auricles, arteries, and veins; but though these inferior grades do not present the strict homologues of these organs, we think that there are in them analogical substitutes, which rescue the simplest of these beings from the confusion and unnatural admixture of organs and functions that have not the commu- nity which authors have ascribed to them. Though a heart and circulatory vascular structure cannot be demonstrated in the minuter, and even in some of the largest of the Radiata, we nevertheless believe that they exist, as well as a distinct visceral cavity and canaliferous walled recipient for the aliments, and that the two mechanisms are not otherwise connected, except by the former receiving from the laboratories of the latter the influences and elements to invest the blood with the power of sustaining life, after it has received the impress and interchange of the gases with those of the exterior or interior fluid aerating elements by endos- mose or exosmose, and thus establish the vital principle. And further, we are of opinion that muscles and nerves are present in the lowest of these organisms to excite motion and sensation to an extent commensurate with their wants. On this head we cannot help quoting a passage of ours in the 'Annals of Natural History/ vol. v. p. 161, N.S., in a paper on the Foraminifera : ' ' On the question of the nervous and muscular influences, which Lamarck only admits, as independent of sensation and interior sentiment, in his apathetic animals, amongst which are the Polypi, I must be allowed to make a few observations, ACEPHALA LAMELLIBRANCHIATA. 33 to explain my reasons for not concurring in the views of that great naturalist. Lamarck contends that sensation, or interior sentiment, does not exist in the lower animals, and that in them all movements arise from irritabilities excited by exter- nal impressions : I demur to this doctrine, and firmly believe that no created being can exist and exhibit evidences of vitality, by motion, without having implanted in it a certain degree of sensation or interior sentiment, by the influence of which the nervous and muscular powers are put in action. I grant that external causes may produce motions and contrac- tions, not I think by exciting an irritability independent of sensation, as Lamarck terms it, but by the agents and after the manner I have just stated. " It will be admitted that the sensations in the lower animals, which are the origin of the nervous and muscular influences, are of the most subdued qualities ; and though the points of departure of the nerves, and the muscular supports dependent on them, may not be discernible by the most powerful instru- ments, still I believe that they exist, and produce those move- ments which are observed in the monad as well as in man. In the superior and larger animals, we can perceive the causes of these influences and admit their existence, because they are apparent ; and why not in the smallest, though they escape our vision ? In the nearest fixed stars we can observe their proper motions, but in those which are plunged in the deeper regions of the sphere, these motions, though we may presume that they undoubtedly exist, are inappreciable. Why may we not apply a similar reasoning to the doctrine of the sensations or interior sentiment, and the resulting nervous and muscular influences, being implanted in the lowest as well as the highly organized animals, according to their several structures, and not consign vast classes to exist without sensation ? It ap- pears to me that the lines of separation between apathy, sensa- tion, interior sentiment, and intelligence, as laid down by Lamarck, are erroneous and arbitrary. I believe that apathy in its strict sense, as applied to animals, does not exist ; and I repeat, that the most inferior created animal being is not without that portion of sensation or interior sentiment, and 34 BRITISH MAEINE TESTACEOUS MOLLUSCA: its concomitant nervous and muscular influence, that produces the motions which are the tests of vitality. I may state that Lamarck does not admit the distinction of intelligence and instinct ; he very justly considers the different degrees of what is called instinct, in animals, as only subdued intelligences consequent on their imperfect organs, when compared with the highest standard man." The contents of the visceral cavities or walled ducts, whether they consist of solid food or chyliferous fluid, have precisely the same function as in the higher animals, that of susten- tation ; and whatever may be the nature of the blood fluids which fill the vascular apparatus of every living being, and all have one, we think they ought to be termed the true blood, as it always flows in parietal contractile tubes, arteries, or veins, and never in excavations called lacuna, burrowed in the parenchyme of the animal. These lacuna do not apply to visceral matters ; they are simply aquiferous canals to give tone to the various muscular organs of the Invertebrata, and not for the circulation of blood. When we say that a vascular circulating and respiratory system exists in the monad as well as in man, we admit that these organs are often simplified to the extent of the requirements of the various tribes. We do not contend that the elaborate structure of the higher inverte- brates obtains in the radiate organisms; but we think that if there be not a heart receiving blood by auricles, and con- veying it by arteries and veins through a general circulatory and respiratory apparatus, there are in the simplest beings equivalent conditions, and that the typical heart of systole and diastole agency is often represented in the vascular me- chanism by receiving from muscular contractibility and relaxa- tion a power which gives a sufficient impulse to the blood to secure its enrichment and aeration. And further, with respect to the circulatory apparatus of these inferior organisms, though its tubes and cavities may not have the gradual decrease and increase of the arteries and veins as in the higher animals, nor consist of an afferent and efferent set of vessels, we consider that the substitutes of these organs are sufficiently supported by analogy, if the blood is TEREBKATULA. 35 transmitted for the nourishment of the body through tubes and variously-shaped walled canals or cavities, though they be neither typical arteries or veins ; we go further, and believe that in many of these beings a blood circulation may be as effective through a single walled canal as by a more complex arrangement, and thus receive the necessary aeration, which in most of the lower Invertebrata is probably cutaneous and effected by endosmose, and that in those animals in which the ambient element can only be admitted into visceral cavities, it is oxygenated by exosmose. ACEPHALA PALLIOBRANCHIATA. TEUEBEATULID^l. Having already mentioned most of the incidents of this family, I have only to add, that it consists of three genera, Hypothyris, Terebratula, and Argiope. None of the animals or the shells have occurred on the Devon coasts, except the Argiope cistellula, and that only in a dried state. HYPOTHYRIS, Phillips. H. PSITTACEA, Chemnitz. H. psittacea, Brit. Moll. ii. p. 346, pi. 57. f. 1, 2, 3. We can only refer to the first vol. p. 150, of the ' Zoological Transactions/ for Professor Owen's account of this animal. The shells of this genus are never punctated. A very doubt- ful British species. TEREBRATULA, Bruguiere. T. CAPUT SERPENTIS, Linnaeus. T. caput serpentis, Brit. Moll. ii. p. 353, pi. 56. f. 1, 2, 3, 4. The valves of this genus are always punctated, and particu- larly so in this species ; it is taken plentifully on the Scotch D2 36 TEREBKATULID7E. coasts. We refer to the second vol. p. 355, of the ' British Mollusca ' for a description of this animal. T. CRANIUM, Miiller. T. cranium, Brit. Moll. ii. p. 357, pi. 57. f. 11 ; and iv. p. 257- This species is said to have occurred in Zetland. The animal has not heen observed. ARGIOPE, Deslongchamps. A. CISTELLULA, Searles Wood. A. cistellula, Brit. Moll. ii. p. 361, pi. 57. f. 9, and iv. p. 257- We have taken this species in the coralline zone, at Ex- mouth, with the animal in the shell, but perfectly dry ; and all that is known of it is, that it has spiral arms supported by an apophysary process. The present shell is quite fresh ; it is of subquadrate form, pale brown colour, much more compressed than the Shetland specimens, and has the mesial groove more distinctly deve- loped; still it is only a variety of the Megathyris cistellula, which M. Philippi states to be subject to much variation of out- line. Axis et diameter y 1 uncise. I have again recently taken from the coral zone of the South Devon coast, at Exmouth, in thirteen fathoms water, the M. cistellula, now Argiope cistel- lula of the ' British Mollusca/ the Terebratula seminulum ? Philippi, which I believe has not been found so far south in the United Kingdom, except fide Turtoni, in Torbay ; I am sure that Professor Forbes and Mr. Hanley will feel pleasure in the corroboration of the correctness, in this instance, of Dr. Turton' s habitat : see the note in the ' British Mollusca/ vol. ii. p. 362. I have had on several occasions personal inter- course with Dr. Turton, and became the original purchaser of his collection of British shells, which, during my temporary secession from malacological pursuits, passed out of my pos- session ; Dr. Turton also did me the honour of the dedication of his Manual of the Land and Freshwater Mollusca. Under CKASIA. 37 these circumstances, I consider it to be my duty, to say, in respect to the note referred to, that I am confident my old friend never intentionally led us into error ; nor do Professor Forbes and Mr. Hanley state otherwise. The fact is, that Dr. Turton was a man of great simplicity, and so far from age giving an increase of caution, it appears, with him, to have had a contrary effect ; if it were necessary, I could relate several curious and laughable stories of his being duped by the frauds of crafty shell-dealers. Whilst I admit that Dr. Turton lent too credulous an ear to the impositions of unscrupulous com- municators, which has impaired our dependence on the habi- tats of various doubtful testacea recorded in his ' Conchologi- cal Dictionary/ I trust I have cleared the memory of my friend, to whom British conchology is much indebted for his care and nurture, from every suspicion of gross and indesinent error : we must not forget that Dr. Turton and the excellent Montagu fanned the flame of this branch of natural history when almost extinct, and its supporters were few and far between. CRANIAD.E. This family has one genus and one recent species. CRANIA, Retz. C. ANOMALA, Miiller. C. anomala, Brit. Moll. ii. p. 366, pi. 56. f. 7, 8, and pi. U. f.2 (as Norvegica). Animal with pale pink, fringed, spiral arms. The ovarium is red-brown, and deposited partially on one of the lobes of the mantle. It is taken plentifully in Scotland. It is to be hoped that some qualified northern or wayfaring naturalist will fur- nish science with a more extended account of it, and of the Hypothyris caput serpentis, as I apprehend it will be long before an additional recent species will occur. 38 ANOMIADJE. ACEPHALA LAMELLIBRANCHIATA. ANOMIADJB. The only genus of this family, Anomia, is one of the Ostra- ce& of Lamarck's monomyal order, which cannot be main- tained in its integrity; zoologists have long removed the Mytilidas from it to the Dimyte. It will be as well at once to state, that all the monomyal animals of that eminent naturalist are really Dimyae. It will probably create some surprise when we say, that the only true Monomyce are the Pholades and Teredines, as, we think, we have satisfactorily demonstrated in their respective anatomies. All other bivalve genera have two adductors; the anterior one in Anomia, Pecten, and Ostrea is of so small a volume, as almost to have escaped notice; and the great subcentral muscle in those genera appears of a size as if the two ordinary dimyal ones were amalgamated ; still the anterior adductor exists, and if carefully searched for will be found under the beaks, pointed out either by a single minute cicatrix, or by a little group of five or six closely united, very small, muscular scars*; this dis- position of the cicatrices varies in all the genera, so does the main subcentral mass, as to shape and size. Careful dissec- tions of the animals will show the muscular filaments adhering to the circumscribed area under the beaks; but in oyster- shells that have been exposed to the action of the sun and air, and vicissitudes of weather, the minute anterior adductor is perfectly visible. In the three genera we have mentioned, these muscles are of small size ; they, however, in the next family, the Mytilidte, though still small, have become more developed, and in the following one of the Arcada they have completely acquired the typical size and position, which is maintained in all the remaining families, until they reach the Pholadidte, when they merge into a single medial adductor, both in the Pholades and Teredines. Lamarck has made Pecten and Lima the types of the Pecti- nidae, and Ostrea that of the Ostreada ; so far we concur ; but we must remove Anomia from the Ostreada, with which, though it has the relations of the great subeentral muscle, and absence of tubes, still there are closer ones, of a different character, with the Palliobranchiata and the Pectinidce. Though the characters of the great subeentral or posterior adductor muscle, the rudimentary, or no foot, and absence of siphons, are very decided ones, and common to this particular order or race, still it is not necessary that Anomia, Pecten, and Ostrea should on those accounts form a single family, any more than the Veneridae, Mactrida, and Cardiadcs, because they have distinct tubes, foot, and are strict Dimyae therefore these reasons, and those under each particular head, have determined us to constitute Anomia, Pecten, and Ostrea as distinct families. Anomia then, with its single species, constitutes the family of theAnomiada, which we fix, according to our method, the first of the Lamcllibranchiata, as it forms the decided point of passage from the Palliobranchiata, by its constant state of fixture, by a prolongation of the adductor muscle, through a perforation of the valve, to marine substances, either by a ligamentous or testaceous point of adherence; it also shows a similarity in the disposition of the ovarium on the mantle, and posi- tion of the animal in the shell. It will be observed that in this statement there is not a single point of community between Anomia and the Ostreada. Though Anomia, by the small byssiferous foot, and the very singular doubled-up struc- ture of the branchial laminse, shows a very intimate connection with the Pectinidae ; nevertheless, from its constant fixity, the perforated valve, ligamentous attachment, the texture of the shell, its proteiform shape, and the hinge, it cannot, without violence to established distinctions, be allocated with that group. I think I have adduced sufficient reasons to support the severance of Anomia from the Pectinidas and Ostreada and I consider that there are equally good reasons for the separation of Pecten and Ostrea. 40 ANOMIADJS. ANOMIA, Linnaeus. A. EPHIPPIUM, Linnaeus. A. ephippium, Brit. Moll. ii. p. 325, pi. 55. f. 2, 3, 5, 7 ; and animal, pi. T. f. 2. Anomia ephippium, A. electrica, A. cepa, A. squamula, A. aculeata, A. striolata, A. punctata, A. cylindrica, A. tubularis, A.striata, A.fornicata, A. coronata, A. patelliformis, A. undulata, Aucto- rum. A. aculeata, Brit. Moll. ii. p. 332, pi. 55. f. 4. A. patelliformis, Brit. Moll. ii. p. 334, pi. 56. f. 5, 6. A. striata, Brit. Moll. ii. p. 336, pi. 55. f. 1, 6, and pi. 53. f. 6. Animal subdepressed, with its periphery suborbicular ; mantle circular, the upper portion, or the one forming the convex valve, of very thin and pellucid texture, except at the anterior margin, which is thick ; and the under part, or that lying on the flat valve, is also thin, but has the appearance of being fleshy from having the ovarium soldered to it ; both are clothed with a double fringe, which diminishes in breadth as it approaches the beaks, and passes round the aperture of the operculum, there throwing out cilia, and then is fixed under them. The outer circle of fringe consists of long, yellowish white, sharp-pointed tentacular filaments, which are, when undisturbed, continually protruded beyond the shell, and on the inner circle there are long and short cilia of the same colour distributed irregularly ; but the colours of the fringes and their marginal areas vary from a mixed blotchy red to yellow or purplish brown. No ocelli can be detected. There are a pair of circular branchiae varying from pale red to dark brown on each side of the body, with fine longitudinal and transverse vessels, presenting the appearance of a delicate net- work ; the plates of each pair have a part of their outer sur- faces double, and form circular open pouches, the upper part of which is well defined by the branchial vein : thus each single plate presents the aspect of two, and the two pair of branchiae appear composed of eight plates; but the doable parts can easily be placed in length, by the insertion of a camers-hair brush in the hollows, and again be returned to the double ANOMIA. 41 position. This curious configuration of the branchiae is that of the Pectines, but not of the Ostrea. At the anterior side, which is easily known by being oppo- site the conspicuous anal tube or if the shell is placed on its front edge, with the perforated valve to the right hand of the observer, it will be farthest from him is situate the oval margined mouth with its large aperture, which is very high towards the dorsal range, and has around it two plain linear membranes that are continuations of the branchiae, which at this point have become slender. These laminae expand at each side the mouth into two pair of long delicate labia, fixed by the entire length of the longest sides, folding on each other ; they are finely striated on both surfaces ; the colour is light to dark brown. The foot is almost reduced to nothing ; it is fixed to the body under the mouth, and is a small, yellow, obtuse, subcylindrical, pendulous, deeply-grooved organ, capable of spinning a byssus, which we have seen, and may serve to fix the animal in conjunction with the operculum. It is strange that nature should have furnished this animal with a foot and byssal groove of so small a size as apparently to be of little use, unless we suppose it to have the power of freeing itself from the bodies to which it is attached; and this idea is by no means without the verge of possibility. It is known that the Area, Pectunculi, and other byssal bivalves, can detach themselves from their fixed position by abandon- ing the byssus. May not the Anomus dissever the end of the adductor muscle from the calcareous operculum? This in- ference arises from the presence of a byssal foot, which would then have &pro tempore use, whilst the animal in a change of locality is again fixing itself. These ideas are fortified by the statement of our dredger, who affirms that he is constantly hauling up pieces of rock studded only with opercula : this fact is certainly no proof that the animals detached them- selves, but it is a link in a chain which has a certain value. Nevertheless we are inclined to think the genus a fixed one for life. The ovarium is an extensive, inflated, sinuated lobe, origi- nating on each side the liver, coasting the body, and glued to 42 the lower half of the mantle ; this organ has been mistaken for a large foot, but its soft, pulpy, granular composition shows that it is the organ of reproduction, and the milky humours arising from various pyriform membranes, in the genial season, which are only then discoverable, are probably the male organs of fecundation. The colour of the ovarium, as well as of the body in general, is very various ; sometimes they are of a pure vermilion, and from that, passing into every hue of that colour, as well as into all the shades of yellow and pale red-brown. I have seen all these colours in groups of the Anomia ephippium, on the same Pecten -, whilst in others all the objects on the same shell have maintained a uniformity of colour. The same discrepancies prevail in A. aculeata, A. striolata, A. cylindrica, and A. squamula. These differ- ences, combined with the various markings, shapes, spines, ribs, and striae, generally resulting from similar markings on the substances on which the shells are fixed, have doubtless been the cause of the multiplication of the species, as in all the varieties enumerated, not excepting the A. striata, which is the A. patelliformis of the ( British Mollusca/ the organs, as far as they have been examined, have not presented marked differences, except in colour. The liver is always of the va- rious shades of green, placed under the beaks, at the centre of the dorsal range ; the passage from the mouth to the stomach is a short gullet, and these organs are situate under, and partly surrounded by the liver ; from it the intestine descends to the centre of the body, where it makes some turns, then ascends through it and the ovarium to the dorsal range, and issuing therefrom, passes behind the body and the posterior sinuation of the ovary, slightly attached to their membranes, and debouches at some distance from the base of the posterior ventral range, as an uncovered rectum. In most bivalves the muscular impressions are supposed to assist specific distinction, but this idea is fallacious with re- spect to the Anomia. In this genus the circumscribed line in the convex valve contains the impressions of the muscular mass, which divides itself into three cicatrices, one by itself and the others on the right and left of it ; these impressions AXOMIA. 43 are never exactly of the same size, nor do they preserve their relative positions in any of the varieties, in consequence of the animal dividing the muscular mass into three fasciculi of fibres, varying in quantity, thus altering the shape and relative distance of one portion from the other ; therefore these impressions are of little distinctive value. Finally, as regards the animal, it may be observed, that in this singular unsymmetrical genus, even its organs display, like the shell, varieties of form ; this arises from the entire animal being deposited in the convex valve ; it only rests on the flat one, and the organs, in consequence, vary with the ever-varying figure of the upper valve. I will now make some remarks on the various markings and aspects of the shells of the so-called British species, of which I have examined above a thousand. And as regards their general shape, they vary from all grades of subcircularity to every subtriangular form. I have seen on the same Pecten, on the shells of which genus the Anomia are oftener fixed than on any other, two individuals of the typical dirty- white A. ephippium, the one displaying its strictly squamous cha- racter, and marked not only with ribs, but the vaulted and arched spines of the Pecten ; the other, in contact, without a rib or spine, and only showing the regular squamae of increase. I have also seen the A. ephippium with half the transverse portion of the shell of a perfectly squamous character, and the basal half ribbed and spiny, and vice versa. The same inci- dents are seen in the rosy purplish A. cepa and bright yellow A. electrica of British authors, which are mere deviations of colour from the type. As for A. striata, otherwise the A. undulata of some authors, which is certainly the most aberrant form of the A. ephippium, the distinctness of which has been insisted on from the iri- descent green colour of the inside of its valves, the radiating muscular impressions and the intense vermilion of the ani- mal, I have to observe that in young specimens, of one and a half inch diameter, having the anastomosing radiating striae found on the smooth insides of the Pecten max'mius, I have noticed these characters to be by no means constant, having 44 ANOMIAD^E. frequently taken delicate, pale, dirty white-brown shells with similar markings, without an appearance of the green insides, and instead of the vermilion animal, they presented a pale yellow aspect ; in addition, I have taken from rocks hauled up from the coralline zone, A. ephippium of 3 inches dia- meter, with and without anastomosing striae, and the insides varying from green to light brown and white; and I have little doubt that all the variations I have mentioned are those of the type, A. ephippium, which under no circumstances loses its characteristic squamous character. With regard to the young or dwarf A. ephippium, A. squa- mula, A. aculeata, and A. striolata, grouped and crowded on the Pectines, I believe they are mere dwarf varieties of the type; these often adopt the markings of the substances on which they are fixed, and as often show a complete disregard thereto. I have seen shells combining all the supposed di- stinctive marks in one individual, in which the decided, smooth, glossy A. squamula has commenced the umbonal part of the structure, gradually in respect of the middle portion, gliding into the squamous A. ephippium, and dividing the basal part right and left, the one into the asperities of the A. aculeata, the other into the delicate smooth striulae of the variety^. striolata. Nothing is more common than to see shells half A. squamula and half A. ephippium, and other admixtures of the characters of two or three supposed species. The last- named four varieties are also found at the roots of Algae, but both in colour and the union on the same shell of each other's distinctive marks, they present the same incongruities and discrepancies as their brethren on the Pectines. The A. cylindrica or A. cymbiformis, a variety of the A. ephippium, takes its hollowed appearance from embracing the roots of the Fuci; the A. tubularis, another variety of the type, has the margin of the aperture elongated, to suit its condition to some irregularity of the substance on which it is placed. The A. punctata is also a young A. ephippium with papillae-like eminences on the convex valve, and corresponding depressions on the flat one, arising from similar markings on the substances on which they are fixed. I do not know the 45 A. fornicata and A^ coronal a recorded by Mr. Bean, but I learn from the ' British Mollusca' that they fall into the same category with those I have named. I have now noticed all the varieties of A. ephippium termed by authors species, and there is certainly no sculpture on them of such a decided character as to denote specific distinc- tion; therefore all the markings^ shapes and colours of this Protean genus being inadequate for the foundation of species, we must have recourse to our sheet-anchor the malacology of the animal to assist our determinations; and after the examination of a great number of individuals, of nearly all the recorded species, we have come to the conclusion that they are varieties of the only British one of this genus, the A. ephippium, which, by the identity of its organs with the pseudo-species, puts a veto on a longer continuance of the dismemberment of its unity, by allowing forms based on mere varietal distinction to march pari passu with it, and which have no solid grounds for aspiring to higher honours. PECTINHLE. The British Pectinida comprise only the genus Pecten, which is a part of Lamarck's monomyal order. The genus Lima, usually associated with Pecten, is merged in it as a section. Our reasons for distributing the Anomia, Pectines, and Ostrece in three families, are given in our remarks on the Anomiadce, wherein the essential points of the differences of the organs and habitudes of their animals are shown ; we may add, that the texture of the shells of this group has lost the leafy imbricated character and become firmer, solid, and of a more porcellanous nature ; their form is infinitely more symmetrical than in either Anomia or Ostrea. A careful examination of the descriptive notes of the animals of the Pectinidte will show that they are not of the same family as either of the other groups. 46 PECTINID.E. PECTEN, Bruguiere. * Shell firm, solid, of a porcellanous texture. P. OPERCULARIS, Linnaeus. P. opercularis, Brit. Moll. ii. p. 299, pi. 50. f. 3, pi. 51. f. 5, 6, and pi. 53. f. 7- Animal suborbicular, thick, lentiform; this shape results from the support given to the organs by the powerful central circular adductor muscles ; the colours are very variable, white, pink, fawn, orange and brown; the body, with the amalga- mated ovarium, is a compound of flake-white meandering lines, spots and blotches, and its conical termination is of the palest vermilion to the intenser hues of that colour ; it de- scends from the dorsal to the ventral range, on the anterior side of the great subcentral muscle. The mantle is thin, except at the fleshy margins, and open throughout, with the exception of a short dorsal area; there is not a trace of siphons; it would be too large for the shell if it were not doubled on itself and fixed a little within the duplicature to the shell by very slender muscular pallial threads. At the folding a cord-like margin springs, but the true mantellar margin floats loose, and is considerably within this line ; both are furnished with 2-3 rows of irregularly deposited, conical, white, pointed cirrhi of three different lengths ; those of the inner circle are tinged with brown ; the outer or fixed range has the longest filaments, and in addition 35-10 subglobose ocelli that have pearl-coloured pupils within black circles; these vary in size, and extend at equidistances throughout the peripherial range to the auricles. The foot springs from the body just below the palpi ; it is yellowish white, subcylindrical, of small volume, deeply cloven or furrowed, and scoop-shape at the termination; it appears to have no locomotive use, and only to be the vehicle for pro- ducing a byssus for occasional fixation, especially of the young animal. I have seen most of the species thus fixed. There are a pair of subcircular branchiae on each side, vary- ing in different individuals to all shades of the colours above PECTEN. 47 named, deep, and of similar depth, very thin and delicately reticulated ; the outer surfaces of each pair, as in Anomia, with which Pecten has alliances, are doubled on each other, and form circular pouches when in natural position ; but these duplicatures can be put straight and again returned. In connection with them, on each side, are a pair of broad short palpi, rounded at their extremities, fixed laterally to the body and to each other, so that they fold as the leaves of a book ; they are smooth without and well pectinated within, of a yellow-brown or pale orange colour ; each pair is united with the other around the mouth by two cordons of 5-6 short, dull orange, fimbriated cirrhi; the mouth is between them, and passes by a short oesophagus into the stomach, which is im- mersed in the extremely dark granular liver, and contains the usual stylet and attritor or tricuspid membrane ; the intestine plunges to the bottom of the body, and again ascends to the dorsal line passing around, embraced by the heart and becoming fixed to the posterior side of the great muscle, debouching at nearly the ventral level. The ovarium is mixed up with the body ; its surface is studded with ova, and the vermilion termination contains a milky fluid which may be the fecun- dating influence; it is only in the genial season that this appearance is seen. We have no faith in the doctrine of the bisexuality of the Acephala ; in many it is impossible for a contact to ensue. The locomotion is effected by the animal with the posterior end in front suddenly opening and closing the valves, which action, as we have repeatedly witnessed, produces a motion as rapid as that of a Lobster or a Sepia. This species being more universally distributed than any other, may be considered as the type of the British Pectines, in which the organs present almost an identity of form. The specific differences consist chiefly in the colours, and in the arrangement and size of the cirrhi of the margins of the mantle, together with a general but unmistakeable aspect in each species, which affords the practised eye sufficient di- stinctive characters ; but if the younger student is at a loss to appreciate the animal specialties, he will obtain much aid from 48 PECTINID.E. the conchological indices, which afford valuable corroborative assistance. At Exmouth this species is taken in the coralline zone in great abundance j so much so, that they might be, perhaps, preserved in jars, if their delicacy did not prevent sufficient firmness, and would prove a more delicious morsel than the pickled oysters of the Italian warehouse. P. VARIUS, Linnseus. P. varius, Brit. Moll. ii. p. 273, pi. 50. f. 1. The general structure and composition of this animal is so similar to that of the type, P. opercularis, that it will only be necessary to note the specialty variations. In this species, the reflected or inner free margin is, as to colour, marked with pale red or brown irregular blotches, with the edge fringed with a single row of thin, white, blunt filaments, which, though short, vary in length ; the outer or fixed margin has at the innermost part, at equal distances, a row of long, conical, light yellow cirrhi ; to these succeed 30-35 ocelli, which have more black and a less pearly appearance in them than in the type ; and the outermost paraphernalia of this margin consists of two irregular rows of extremely fine, snow-white filaments of three lengths. The branchiae are in all respects similar to the type, except in being of the palest drab ; the body and ovarium, which is amalgamated with it, is of a pale yellow cream-colour, mottled with thick-set flakes, which have the aspect of ova ; we are not sure if the vermilion colour ever appears in this species ; all its organs are of a much more deli- cate, elegant and refined aspect than in any of its congeners of similar bulk. The intestine terminates by a short, white, slightly grooved rectum, spatulate at the end. The labia are pale fawn, and the two connecting foliated rows of fringe of light drab. The ovarium, or that part of the body consti- tuting this organ, is at this season, August, full of ova, and an opake red milky fluid, as in the type. We here repeat, that we do not believe in the bisexuality of the Acephala, by which term is meant that each individual is either male or female. PECTEN. 49 The foot emits a powerful coarse byssus, which cannot be detached without laceration of the body, but the strands are easily separated from the substances on which they are fixed ; this is contrary to the usual plan of the Bivalves, which, when a change of locality takes place, is effected by drawing the byssus from that part of the foot-groove close to the body, and leaving it moored to the substance on which it was fixed : this operation we have witnessed even in confinement. This species is given as an example of the variation of specialties ; all the others afford nearly as decided ones. I trust that some northern observers will compare the P. tigrinus, P. striatus and P. furtivus, all of which we believe are identical, and communicate the result: if they are distinct, malacologists will have no difficulty in seizing the distinctive characters. Speaking conchologically, we should say that the three so-called species are only variations of the old P. obso- letus of authors, now styled P. tigrinus. This species is either free, or adheres by the byssus to marine substances, but is not imbedded in them by the under valve, as in the P. pusio. P. PUSIO, Pennant. P. pusio, Brit. Moll. ii. p. 278, pi. 50. f. 4, 5, and pi. 51. f. 7- P. distortus, Montagu. P. sinuosus, Turton et Auct. The body and ovaiy throughout are either intense vermi- lion, or of a uniform pale yellow-white, and not half white and half vermilion, as in P. opercularis ; at least in P. pusio we have never observed this to be the case. The branchiae are dull red-brown, and the palpi pale brown ; there are two connecting rows of pale red cirrhous fringe around the mouth. The back or free margin of the reflected mantle has two to three rows of irregular, short, yellow- white, blunt filaments. The ocelli are larger, fewer, and more distant than in the type. The fixed or anterior marginal circle has a row of large, long, conical, pointed, yellow filaments, and in front of it two to three irregular rows of shorter cirrhi of different E 50 PECTINID^E. lengths ; the mantellar marginal areas are a blotchy mixture of fawn, yellow, pale red-brown, and lead colours. This species comes much closer to the type than P. varius. From the great variableness of the colours in the same species, and the general similitude in the structure of the organs, it is sometimes difficult to seize the specific distinctions of closely allied animals ; in such case we must call in aid the figure and markings of the shell, which being dependent on the dispo- sition of the secreting glands of the mantle, cannot well be malacologically appreciated. This case strongly supports the views laid down in the paper on the Littorina, in the May ' Annals of Natural History/ 1850, wherein we strenuously contend for the examination of both the animal and the shell to ensure a true distinction of species, as when the soft parts do not aiford sufficient characters, the shell may assist in re- solving the difficulty. This species is usually imbedded in masses of Flustra and old bivalves by the under valve. P. SIMIUS, Laskey. P. similis, Brit. Moll. ii. p. 293, pi. 52. f. 6, and (animal) pi. S. f. 1. Shell suborbicular, depressed, but equally convex on both surfaces ; the auricles are not greatly dissimilar, the posterior, however, is the smallest, their terminations are sometimes rounded and sometimes obliquely truncate. There is very little sculpture on either valve beyond the fine subcircular striae of increase, and rarely there are faint traces of ribs, but the markings on both surfaces are very variable in figure and colour ; they exhibit every combination of blotches of all hues, and sometimes a series of markings simulating radiating ribs so closely as to be difficult of detection ; but these appearances, under proper optical powers and light, will be found to be in the test, with the surface quite smooth. We have taken such specimens alive in the coral zone at Exmouth, from one of which are derived the notes on the animal. Diameter less than a quarter of an inch. Animal of the same form as the shell, and as variable in its PECTEN. 51 colours. The mantle is pale yellow, furnished, as is usual in the Pectens, with a fixed and free margin ; the latter is clothed with about twenty long, white, triangular, frosted cirrhi with shorter intermediates ; from the minuteness and delicacy of the animal the filaments of the fixed margin were not detected ; the free margin between the cirrhi is marked with blotches of all sizes, of the colours yellow, bistre, rufous, and black ; the ocelli are 16-20 ashy circles, having in their centre a minute ring or pupil of a smoke colour. The branchiae vary from light yellow to dark lead colour, but the very fine darker lines are generally relieved by intermediate lighter ones ; they, like their congeners, have the lower part of the area of each gill- plate reflexed on the upper, forming subcircular pouches. The small foot, producing a byssus, is situate very high, almost immediately under the anterior dorsal margin, and varies from white to vermilion. These variations in colour of the shell and organs of the same species are one of the characteristics of the tribe. The foot appears to have little power of loco- motion, but by spinning a byssus it produces a mooring appa- ratus. The animal, by flapping the valves, effects a rapid progression. This very distinct species has been considered by some as the young of Pecten maximus, but the convexity of both valves negatives this idea. At all ages the P. maximum has the upper valve flat, with a concave area at the beak. P. MAXIMUS, Linnaeus. P. maximus, Brit. Moll. ii. p. 296, pi. 49. In this beautiful and well-marked species, both by the shell and the animal, the inner margin of the mantle has only a simple row of very short, white cirrhi; the fixed anterior margin has three ranks of filaments of different lengths not deposited in perfect serial order, the largest and longest are pointed, and on retraction become curled in a spiral form; all the cirrhi on the upper or flat valve are marked in the centre, from base to point, with a pale red-brown line, the under surfaces being white; the cirrhi of the convex valve E2 52 PECTINIM;. are pure white on both surfaces. The membranous marginal areas of the mantle are elegantly arranged in meandering lines of pale red, brown and yellow, forming various-shaped lozenges. When the valves are opened, and the mottled surfaces of the double margins of each valve are in conjunc- tion, and the various circles of filaments and cirrhi fully ex- serted in a shallow basin of sea- water, it is scarcely possible to conceive a more beautiful and interesting appearance. There are two rows of sea-green ocelli relieved at one part of the circle by a black point, with the pearly pupils deeply sunk in their hollows; there is usually a large eye under each rib of the shell ; the others are much smaller, deposited in a row under them; they all amount to about thirty to thirty-five. The branchiae are small for so large a species; there are a pair of palpi on each side, pale drab or brown, laterally attached, folding on each other, subquadrangular, composed of twelve to fifteen strands pectinated on both sur- faces, but more intensely on the inner ; the buccal fringes are two rows of very bright red, well-foliated and branched fillets, which connect the palpi ; the mouth is in the centre of them. The body, and the ovariurn amalgamated with it, are of very small volume and usually white. The foot is snow-white, short, grooved, with a spatulate extremity. The liver is quite dorsal, black-brown, or an intense dark green. The brown suboval secreting glands on each side are as conspicuous in Pecten as in Ostrea. We may observe, that in all the Pectines the mass of the organs is small, and appears scarcely commensurate with the area of the shell ; perhaps the deficiency is made up by the mantellar extensible margins and cirrhi, which coast the pe- riphery, being only interrupted by the very short ligamental area, from which point, on each side, they gradually increase in width and size to the centre of the aperture. The animal can effect a rapid progression by flapping together the valves, with the ventral margins in front and the flat valve upper- most. This elegant and edible species, the Prince of the British Pectines, is frequently taken in the coralline zone at Exmouth. PECTEN. 53 Some malacologists think that the P. niveus of the Caledonian shores is a variety of P. varitts ; we believe from the shell it is distinct, but the animal must determine ; it has not occurred on our southern coasts. The P. tigrinus, the P. obsoletus of authors, is frequently taken alive in Exmouth Bay ; but it is a variety, though ribbed at the margin, of a smoother mould than the Scotch specimens, which from their variableness have been manufactured into three or four species, as before observed. The P. danicus is Scotch, and the P. islandicus probably spurious. ** Shell thin and of vitreous texture, varying from a perfectly symmetrical to an oblique outline. P. FRAGILIS, Montagu et nobis. Lima Loscombii, Sowerby. , Brit. Moll. ii. p. 265, pi. 53. f. 1, 2, 3. We have yet to learn why this animal has received the spe- cific title of " Loscombii :" surely the far prior and more ap- propriate appellation of the excellent Montagu and other authors ought to be adopted. We do not understand the changing old accredited names for complimentary ones. This animal presents no essential difference from that of Pecten ; it is even difficult to appreciate the specialties, which only consist in the greater length of the three rows of the tentacular filaments of the mantle, which are long, close-set and numerous, of the various hues of pink and white. We have seen twenty of these animals alive; they exhibit the same character of the liver, branchiae, palpi, minute foot, pink ovaria, of most of the Pectines ; the ocelli in the minuter spe- cies are obsolete, but the rudiments of them are perceptible ; the same kind of locomotion in the so-called Lima, as in Pecten, I have frequently observed when placed in sea- water, in a shallow dish, and is effected by opening and suddenly closing the valves, with the posterior end in front, and thus rapid progress is made. When the adductors are unbent, the animal protrudes the mantle and mass of filaments, which then appear too large for the shell ; this is not so, as on the slightest disturbance all vanishes instantly within the valves. 54 PECTINIDJE. The shell also only shows specialty- variations, the principal one being sometimes, not always, a more oblique outline ; in it we observe the same character of the ligamental and carti- laginous areas, a similar disposition of the longitudinal ribs, and the greater or less emargination of the valve under the posterior auricle, for the byssus, by which they are all fixed at some part of their existence, usually when young, and becoming often free when adult. With these views, I am compelled to consider Lima as a superfluous genus, and merge it in Pecten ; I cannot call the same animal both Lima and Pecten. The conchologists, perhaps some malacologists, will condemn these innovations ; but the knowledge of the animal configuration gives me the moral courage to perform the necessary amputations, for the benefit and safety of the system. This animal is rare at Exmouth at present, but was more plentiful some years ago ; it is, with its only two congeners, the P. Mans and P. subauriculatus, taken occasionally alive in the coralline districts. We have often seen it spin a byssus and fix itself. The animals of this section often collect and agglutinate in a mass minute nullipores, thus forming a nidus and harbour of refuge. The following Pectens have not been observed : P. NIVEUS, Macgillivray. P. niveus, Brit. Moll. ii. p. 276, pi. 50. f. 2 ; (animal) pi. S. f. 3. P. DANICUS, Chemnitz. P. danicus, Brit. Moll. ii. p. 288, pi. 52. f. 1, 2, 7, 8, 9, 10. P. ISLANDICUS, Miiller. Vide Brit. Moll. ii. p. 303. P. TIGRINUS, Miiller. P. tigrinus, Brit. Moll. ii. p. 285, pi. 51. f. 8-11. P. striatus, Brit. Moll. ii. p. 281, pi. 51. f. 1-4 ; (animal) pi. S. f. 2. P. obsoletus, Mont, et Turt. P.furtivus, nonnull. P. SUBAURICULATUS, Mont, et nobis. Lima subauriculatus, Brit. Moll. ii. p. 263, pi. 53. f. 4, 5. P. HIANS, Gmelin et nobis. Lima hians, Brit. Moll. ii. p. 268, pi. 52. f. 3, 4, 5; and (animal) pi. R. under the name of L. tenera, L. tenera, Turton. OSTKEA. 55 OSTKEAD.E. One genus, with a single proteiform species, constitutes this peculiarly British family. Ostrea is the Lamarckian monomyal type. What has been said on the Anomiadce and Pectinida renders further detailed remarks unnecessary. We will only observe, though the general form of the branchial laminae is similar to those of the Pectines, that they are in their composition very distinct ; the complete absence of the byssal foot is another important deviation, and in other re- spects it is eminently distinguished from Pecten; Ostrea is generally fixed by the under or convex valve, and has, if any, a very limited locomotion, whilst Pecten is almost always free, and can perform the most rapid leaps and movements. OSTREA, Linnaeus. O. EDULIS, Ibid. O. edulis, Brit. Moll. ii. p. 307, pi. 54, (animal) pi. T. f. 1. O. parasitica, Auct. Animal orbicular, subcompressed, of a pale drab colour throughout ; mantle thin at the beaks, gradually thickening to the ventral range, entirely open, except a short dorsal area, and has no trace of siphons or sessile apertures; the margin is not reflected on itself as in Pecten ; there are two rows of tentacular filaments springing from cord-like offsets of the margin; the front one is furnished with very thick, short, white, blunt cirrhi, disposed in a disorderly double line ; the other is more within the shell, and has a simple series of short, pale brown filaments of different lengths ; these are rarely seen exserted, from the habitude of the animal to keep the valves closed. The body, including the dark green liver with the incorporated cream-coloured ovarium, proceeds from the centre of the dorsal area on the anterior and posterior sides of the great subcentral muscle, at which point it termi- 56 OSTREADJE. nates. There are on each side a pair of simple branchiae that are without the reflected pouches of Pecten, nearly of equal depth, closely and conspicuously striated on both surfaces; they extend anteriorly to the palpi, but posteriorly only reach a little above the ventral range; with them are connected around the mouth, by plain labial cords, two pair of subtri- angular, moderately long and large palpi, each plate being hung separately to the body, as in the ordinary Bivalves ; they are smooth on the outer surfaces, and well pectinated within ; the plates of each pair lie one on the other, but not being attached laterally, they do not double as a book shuts, or like those organs in Pecten. The body has not the rudiment of a foot ; the animal is, I believe, deprived of all locomotion ; when the shell is not free, it is fixed by the under, which is the convex, valve. This species, when it inhabits the crevices of rocks, is sub- ject to great distortion; but the animal, though the shell forms a cylinder, or a right angle, or a disk, flatter than that of a Placuna, adapts itself to these irregularities. There is but one British species, exhibiting infinite varieties, the effect of habitat and cultivation. The stomach contains the attritor or tricuspid appendage, that is worked by a short, grooved, elastic stylet, which, as there is no foot, has a resting-place in the upper part of the body. The intestine pierces the body to its fundus, then ascends, passing the heart without contact, which is one of the exceptions to the almost universal position of that organ in the Acephala; it then issues at the upper part of the dorsal slope, from which point it coasts in view, and is glued to the great adductor, terminating in a short, floating rectum nearly at the ventral level. The ovary appears to be amal- gamated with the body, and from April to July is continually discharging the ova into the branchiae, where they remain until they are ready to be replaced by another batch, and so on, until all are committed to their natural habitat ; then the animal recovers its exhaustion, and is edible about the middle of August, but is not considered fat and in full flavour until September. MYTILIDJE. 57 MYTILID^S. We comprise in this family the genera Mytilus, Modiola, Crenella, Pinna, and Avicula. In coming to this arrangement we have had difficulties to contend with. At one time we were inclined, in consequence of M. Deshayes' remarks, to include Modiola and Crenella in Mytilus-, but having very lately examined species of the three genera, we are by no means satisfied of the propriety of such a procedure. We think, from the configuration of the branchial laminae and the partly closed mantle in Crenella, it must stand as a genus. With respect to Modiola, our accounts of two of its species show that there are in them considerable variations : this cir- cumstance, with the pinnated character of the mantle in My- tilus and the differences of the branchial and anal mantellar terminations of the two genera, have made us hesitate to merge Modiola in Mytilus. The variations in the two do not perhaps amount to generic ones, and a coalition may even- tually take place. We have no difficulty in placing Pinna with the My tili ; its animal in almost all points, particularly in the shape and position of the adductor muscles and internal nacreous aspect of the shells of the two genera, appears to support this determination. With Avicula we have greater hesitation ; but the recorded accounts by Poli, of the animals of that genus and Pinna, show such a similitude as to consti- tute a primd facie case for depositing them with the Mytilida. With these views, the family of the Aviculada may be dis- pensed with. This location of Avicula must not be con- sidered as settled, even with reference to our method, for it is not improbable that it may have considerable alliance with the Ostreadte ; but it is really immaterial as regards natural order whether it ranges with the Mytili or Ostrece, or constitutes an independent family, for in that case it must be fixed between the Mytilida and Ostreadce. We would recommend to naturalists a strict re-examination 58 MYTILHXE. of this family. We may have opportunities of again observing Mytilus, Modiola, and Crenella, but the animals of Pinna and Avicula are not met with on the South Devon coasts in my district of Exmouth; I should therefore be extremely obliged to malacologists who have opportunities of seeing these animals to communicate their remarks. I shall at pre- sent give a short account of them from Poli, which I trans- late from M. Deshayes* extracts from that eminent zoologist, in the last edition of Lamarck's ' Animaux sans Vertebres/ to enable naturalists to compare and weigh well their rela- tions with each other, and with the families of the Mytilidce and Ostreada. MYTILUS, Linnaeus. M. EDULIS, Linnaeus. M. edulis, Brit. Moll. ii. p. 170, pi. 48. f. 1-4, and (animal) pi. Q. f. 5. M. incurvatus, M. pellucidus, M. subsaxatilis, Auct. Animal elongated, thick, subconical; at this season, 5th August, the general colour varies from white to all the hues of orange-yellow, except the foot, and the dorsal and ventral, posterior and anterior extremities of the mantle, which perma- nently exhibit the various shades of a deep reddish brown. The mantle is open from the very large, short, oblong oval, white, simple membranous tube, situated on the upper poste- rior slope, which serves for anal purposes, and a separate branchial communication by a transverse fissure in the in- ternal septum into the ventral cavity, which, though it com- municates with the same common tubular process as the rectum, has no further connexion with the anal conduit. The mantle has a double margin, a plain outer and an inner one, which, from the point of the siphonal tube to the centre of the ventral range, is furnished with tentacular dendroid cirrhi, 15-25, of a pale brown on the main stems, with the ramose subfoliated fimbrire shadowing to pale yellowish white ; the remainder of the ventral range, in which the byssus and foot act, is only broken into long white dentations ; the two MYTILUS. 50 margins are connected by short close-set perpendicular mus- cular threads, which act not only by the lines of junction, but also by a general subcircular contraction and dilatation of the fibres of connexion into a still closer or more lax union ; the effect of this combined action is to throw out and withdraw the tentacular fringes of the posterior lateral and ventral portions of the mantle; these vertical muscular lines also supply the adherence of the mantle to the margins of the shell, as in this species there are no longitudinal muscular bands emanating from the adductor muscles to support it. The foot is thick, fleshy, narrow, moderately long, proceed- ing straight from the heel, of an almost black-brown, marked with occasional lateral white lines; it produces coarse light brown byssal filaments from a groove at the posterior under part which is continued to the point ; the upper surface is plain, not grooved. The animal can detach itself from the byssus, by extracting and leaving it fixed to the substance on which it is moored, and in a very short time it is replaced by another; this is the operation with the free My till. It is almost needless to remark that the great mass of these ani- mals are closely impacted in the sublittoral and laminarian districts. There are a pair of light brown branchiae, of similar form, depth, and position, which run the length of the dorsal range, passing their diminished and well-fixed posterior ends into the branchial aperture; they are scarcely visibly pectinated on either side ; they also anteally diminish in depth, curving to the pair of palpi on each side the mouth ; they are connected by narrow labia, and at the basis with the palpi, which are long, very thick, triangular, pointed, of the same colour as the branchiae, each having in the centre a raised line, probably an artery or branchial vein, from which they bevel on each side to a sharp edge, each pair folded together, being well striated within, not " partially," as is stated in the ' British Mollusca' on my authority, and plain on the outer surface. The liver is pale yellowish green, and granular. The crystalline stylet and stomachal attritor are present. The lateral dorsal secreting glands, which I believe produce the cartilage and a portion 60 MYTILID^E. of the ligament, are well developed and of very dark colour. The body is the least I ever saw in so large a shell ; this is occasioned by the ovarium not being mixed up with it, but that organ is spread in great thickness over the major part of the inside of the mantle on both sides, and at the date above noted contains many hundred thousand ova, which at the latter part of the autumn are discharged into the sea, leaving the mantle a white thin membrane, after which the body of the animal increases in bulk and grows fat, becomes edible and in season, which is two months later than the oysters, as they are not considered good until the end of October. They are much eaten at Exmouth by the working people, but in some constitutions they have either a deleterious or the opposite quality, a pruriginous effect. It is a mistake that the ova are received in any part of the branchiae for protection and maturation for some time pre- vious to ejection, as not one-tenth of the immense masses of the ovarian membranes could be located there; the branchiae, from their smoothness, are very ill adapted for such an asylum, and if they are ever seen there, it is from the unavoidable contact of the ova when in progress of exclusion : the pulli are never seen in the animal in a testaceous state, as in the fresh- water Unionida, but are at once cast to the waves, where they become the prey of various animals ; still, enough escape de- struction to maintain their enormous numbers. The sea in autumn is filled with the ova : at ten miles from land in 14 fathoms water, if the fishermen's lobster-pots are left for two or three days, they will be covered with very young testaceous muscles, and in a week or two more than half an inch long ; but the parents never inhabit more than half a mile from the shore; of course the ova are floated out to sea, and sink as soon as they become testaceous. That the animal never carries testaceous pulli is manifest from its being more or less at all seasons edible. Though this is one of the commonest of the bivalves, it is an object of great interest to the mala- cologist from its elaborate organization. I may state that this is amongst the very few marine Acephala which have the ovaria attached more or less to both sides of the mantle ; bv MODIOLA. 61 which it establishes a connection with the Anomiada, and perhaps in part with the Terebratulidce. I am not sure that any other except Anomia is in the same category, and in that genus the ovary is only glued to the area of the mantle, which rests on the lower valve. MODIOLA, Lamarck. M. BARBATA, Linnaeus et Auct. M. barbata, Brit. Moll. ii. p. 190, pi. 44. f. 4. M. Gibbsii, Auct. Animal elongated, thick ; mantle open, double-edged, with red-brown simple margins. The body is large, subrotund, brown ; from it springs a byssal foot, having a large fissure at its hinder part, from whence a fine bushy dark byssus issues ; the anterior part is finger-shaped, white, not long or pointed, with a longitudinal central depression. On each side the body are a pair of narrow branchial laminae, the upper not half the depth of the lower ; they are coarsely pectinated, and entirely coast the body, being brought close to the posterior extremity to receive the water. This structure of the branchiae is the substitute for the absence of tubes or any sort of siphonal fold of the mantle. The palpi are red-brown, long, flat, strongly striated transversely within, smooth on the outer surface. The shell of the present animal was 2J inches transverse measure ; it was taken in the dredge in 15 fathoms water in a six-mile offing at Exmouth ; they are rare in that locality. M. TULIPA, Lamarck. M. tulipa, Brit. Moll. ii. p. 187, pi. 45. f. 7, and pi. 48. f. 6; and (ani- mal) pi. Q. f. 6. Animal elongated, body thick, pale red; mantle open, margin simple, plain, forming two very short, of the same length, scarcely separated pale yellow siphons, each fringed with about 20 close-set short cirrhi. Foot long, flattish, slender, with an intensely flake- white longitudinal line in the centre, having a byssal groove, increasing in depth from point to heel, from which, on its posterior side, a fasciculus of strong 62 filaments issues, by which the animal, wherever it may be placed, immediately attaches itself, and however frequently removed, refixes itself in a few minutes. On each side there are a pair of pale brown branchiae, narrow, linear, coarsely pectinated, but less on the inner than on the outer surface ; the palpi are short, pointed, triangular, and usually lie rolled together laterally ; they are of the same colour as the branchiae, smooth within and strongly striated externally. This very elegant species is frequently taken alive in the coralline zone at Exmouth. It differs very materially in the organs from its congener M. bar bat a. M. MODIOLUS, Linnaeus. M. modiolus, Brit. Moll. ii. p. 182, pi. 44. f. 1, 2. M. phaseolina, Brit. Moll. ii. p. 186, pi. 44. f. 3, juv. M . Eallii, Brown. , Brit. Moll. ii. p. 192. The M. modiolus and its young shell, styled by some M. phaseolina, are seldom met with on the South Devon coasts. The M. Eallii is of very doubtful British parentage; we can refer to no figure; and the animals of the first two have escaped our researches. CRENELLA, Brown. C. MARMORATA, Forbes. C. marmorata, Brit. Moll. ii. p. 198, pi. 45. f. 4. Animal suboval, thick, pale yellow ; mantle closed on the anterior ventral half, at which point is a large aperture for the foot ; the margin of the opening is plain, it is then closed, and forms a mixed purplish-red and flake-white membrane, which is produced into a small cylindrical anal tube, grooved at the base, with four or five minute dark cirrhi at the termination; and on its sides the mantle forms two pendulous puckered flaps of the same colour as the tube, with which the animal by bring- ing their margins into contact produces a canal, in conjunction with the groove, to convey the water to the branchiae. The foot is white, with a deep byssal groove, from which a strong CKENELLA. 63 filamentary mass issues, and fixes the animal to Ascidue and marine substances. The anterior part of the foot is white, narrow, finger-shaped, and moderately pointed ; when in full extension it takes the form of a narrow, flat tape, marked with a slight brown line running from base to point; it is pro- truded close to the anterior side of the byssus, but as an organ of locomotion it only comes into action when the animal is detached from its mooring, which it has the power of effecting by withdrawing the end of the byssal lamina from the groove in the heel, and it can refix itself by spinning a new byssus ; this operation we have frequently seen; when fixed, the foot appears to be an organ of tact, as it is often exserted, and the point kept in movement as if searching or feeling. There are a pair of branchial laminae on each side of the same size, and smooth on all surfaces ; the palpi are long, subtriangular, pale brown, and pectinated. The animal differs from Mytilus and Modiola in the perfect symmetry of the four branchial plates. This species is often attached to old bivalves and masses of Serpuke, but is more usually imbedded in the coriaceous mantle of the Ascidia mentula, from which twenty of all sizes have been extracted. It inhabits plentifully the coralline districts at Exmouth. We have not seen alive the following species : C. NIGRA, Gray. C. nigra, Brit. Moll. ii. p. 202, pi. 44. f. 5, and (animal) pi. Q. f. 7. C. DECUSSATA, Montagu. C. decussata, Brit. Moll. ii. p. 210, pi. 45. f. 2. C. RHOMBEA, Berkeley. C. rhombea, Brit. Moll. ii. p. 208, pi. 45. f. 3. C. DISCORS, Linnaeus. C. discors, Brit. Moll. ii. p. 195, pi. 45. f. 5, 6, pi. 48. f. 5. C. COSTULATA, RisSO. C. costulata, Brit. Moll. ii. p. 205, pi. 45. f. 1. C. FABA, Muller. C. faba, Brit. Moll. iv. Appendix, p. 256. Of the above, C. costulata is a variety of C. discors, though admitted by authors as a species. The C. faba, taken from a 04 MYTILIM3. duck's stomach, shot in Northumberland, sub fide Kingii, is considered by him of doubtful British origin. We have the specimen. PINNA, Linnaeus. P. PECTINATA, Ibid. P. pectinata, Brit. Moll. ii. p. 255, pi. 43. f. 1, 2, and pi. 53. f. 8. P. ingens and P. papyracea, Auct. Animal elongated, body large ; mantle open, of delicate tex- ture except at the margin, which is furnished at the posterior end with two rows of tentacular cirrhi, but only one at its anterior portion. There are on each side a pair of large branchiae of nearly equal size and crescent-shaped, united by two wide labia, foliaceous on the internal surface, which fall on each side the body, connected with the buccal orifice and a pair of short, narrow, lanceolate palpi, which appear dispro- portionate for so large an animal. The mantle forms neither siphons nor even sessile orifices. The foot is conically sub- cylindrical, not long, with a byssal groove at the posterior bend, from which a large fine silky byssus of attachment issues ; this the animal has the power to discard when it wishes to change place, and can refix itself by spinning in a very short time a new one. Having only seen very young examples alive, we have for descriptive assistance had recourse to M. Poli, ' Test. Sicil.' AVICULA, Lamarck. A. TARENTINA, Ibid. A. tarentina, Brit. Moll. ii. p. 251, pi. 42. f. 1, 2, 3, and (animal) pi. S. f. 4. Animal suboval compressed; mantle entirely open, having the margin fringed, as in Pinna, with tentacular filaments ; there are no siphons nor orifices. The dorsal range of the shell usually forms a slender linear posterior elongation, which is lined by a fold of the mantle. On each side of the body there are a pair of nearly similar-formed branchiae of crescent shape, AECAD^E. 63 which around the mouth are united by two foliaceous labia, accompanied on each side by a pair of short palpi that on their free margins are obliquely truncate. The body is dimi- nutive in proportion to the size of the shell. The foot is small, subcylindrically conical, grooved at the posterior part, and emits a coarse byssus, which has all the active incidents of that of P. pectinata. We have been assisted in this account by extracts from Poli's ' Test. Sicil.' It appears then that Avicula scarcely differs from Pinna. We think that on comparison of the two genera, malacologists will be inclined to consider that their natural position is with the Mytilida. It may be in my power to supply a fresh description of Pinna, but extraneous aid will be required for Avicula, which has not occurred to us at Exmouth, though it has been fre- quently captured by the trawlers on the Plymouth ground. ARCADE. The Arcadts form a family of five genera, four of which, Area, Pectunculus, Nucula, and Leda, are so well characterized by animal distinctions, as not to require further remark ; we add a fifth, Galeomma, which, though an aberrant genus, we think we shall satisfactorily show has close relations with this family, wherein it is placed until the animal receives additional elucidation ; but this, from its rarity, may be far distant. It is to be regretted that near twenty years ago, when we had it alive for some days, we did not make better use of our oppor- tunities. Several observers have seen it, but, it appears, not with perfectly satisfactory results. Naturalists are earnestly invited to look after this elegant animal, and not fail to note at least its external organs and habitudes. Notwithstanding the uncertainty attached to this genus, we think its provi- sional residence in this family will become a permanent one ; at all events, almost any position will be more satisfactory than its present association with the Kelliada. F 06 ARCADE. The family of the Arcades is the first, according to our method, in which the adductor muscles are established in their pyriform shape, similar size, and lateral position : the departure from the muscular disposition of the Qstreada, to the lateral one of the great mass of the bivalves, commenced in Mytilus, and has become complete in this family. Since the above was written we have added to this family a sixth genus, Lepton, under which head our reasons for this procedure will be found. ABCA, Linnaeus. A. TETRAGONA, Poli et Auct. A. tetragona, Brit. Moll. ii. p. 234, pi. 45. f. 9, 10; (animal) pi. P. f. 1. Animal elongated, thick, white; mantle open throughout the ventral range ; its edge is plain, but the upper part of the posterior margin is marked, as in the Pectunculi and Pectines, with about 40 close-set, equidistant dark dots or ocelli, which become obsolete and vanish anteriorly ; the margin, or area within the ocelli, is mottled with pale yellow flake markings, which are also seen, though more faintly, on the under sur- face. The foot is white, and when at rest is bent, but, ex- serted, tapers subconically. There is a deep byssal groove at the posterior geniculated portion, for the green filamentous mass, which at the point of insertion into the cavity is split into two laminae ; a neighbouring gland appears to supply a green glutinous fluid, from which the filaments are formed ; we conclude so, as whenever the byssus was extracted, the animal immediately produced from the fissure a flow of matter which almost instantly resolved itself into byssal threads ; and it is quite certain it can free itself from a state of fixity, which is effected by drawing the byssus from the groove, and entirely deserting it. This manoeuvre we have also seen performed by the animals of Area lactea and Galeomma Turtoni. There is little doubt that all byssus-bearing mollusca, when not con- fined in stony cavities, have the power of a limited locomotion by abandoning their moorings. The foot, independent of the deep fissure at the base for the ABCA. 67 insertion of the byssal lamina, has a shallower continuation of it to the point. We have only seen the foot when protruded in a linguiform or subcylindrical shape, but it is probable that the longitudinal groove can expand and assume a spatulate character like that of Nucula and Pectunculus ; but the animal is very sensitive, and during a long examination never showed any kind of locomotion. There are on each side a pair of brown branchial laminae of nearly similar size, of small depth, which run quite horizontally; they are slightly crenated at the edges, and the outer surfaces are less striated than the inner. There are no pendulous palpi, but the linear branchiae are continued in a narrowed form on the buccal area, and meeting with their fellows, constitute expanded labia instead of strict palpi. Without entering into much anatomical detail, we may observe that the organs which supply the motive power to the circulation have a different arrangement in those Area which have the beaks widely separate; in them, there are on the medial line of the dorsal range two ventricles, each accompa- nied by an auricle, instead of, as in the ordinary arrangement, a single ventricle with an auricle, on each side : but this de- viation does not extend to all the genera of the Arcada ; it appears to be the result of the distance of the branchial vein, on each side, from the motive power. In Pectunculus, in which the beaks are close together, and the points where the branchial veins pour the blood into the auricles are little sepa- rated, the ordinary structure of the single ventricle prevails. This species is very rare, but it has been taken by us more than once alive, in the coralline zone at Exmouth, in the sinuosities of masses of Serpulae that are deposited in old bivalves. A. LACTEA, Linnaeus. A. lactea, Brit. Moll. ii. p. 238, pi. 46. f. 1, 2,3. Animal oblong, thick, body white ; mantle pale red towards the middle of the dorsal range, entirely open, having the under surface of the ventral line marked with irregular flake-brown blotches on a pale yellow ground, and the upper, for some F2 68 ARCADE. little depth, with a sand-like rusty-brown belt, and a darker interrupted line nearer the margin, which is finely dentated ; but there are no equidistant points or ocelli, as in the last species. The mantle is without siphonal folds. The foot is white with a deep fissure at the bend, and is provided with a green filamentous membrane for attachment, which has all the same incidents as in Area tetragona. The foot is pure white, and can be exserted to a considerable length; it is fleshy, tapers cylindrically, and is very like that of Galeomma. There are on each side a pair of similar-sized, very thin, pale yellow symmetrical branchiae, which gradually taper and unite around the mouth, forming a double lamina, of the same character as in Area tetragona and Pectunculus glycimeris. This species is frequently taken free in the dredge, in the coralline zone at Exmouth, and also fixed by the byssus amongst the masses of Serpula in old bivalves. We had in our possession the identical Area barbata first introduced as British by Dr. Turton in his ' Conchylia Di- thyra/ and, on showing it to Dr. Goodall, he expressed an opinion that it was an exotic specimen. We have not seen alive the A. RARIDENTATA, Searles Wood. A. raridentata, Brit. Moll. ii. p. 241, pi. 45. f. 8. PECTUNCULUS, Lamarck. P. GLYCIMERIS, Linnaeus et Auct. P. glycimeris, Brit. Moll. ii. p. 245, pi. 46. f. 4, 5, 6, 7 ; and (animal) pi. P. f. 6. Animal suborbicular, lentiform, bluish white ; mantle open throughout the periphery of the shell, except the dorsal line ; the margin is plain, having its upper surface for the depth of an eighth of an inch powdered with minute sand-like, pale red, brown or black points. There are at the posterior side, for half its length, at the verge of the mantle, about twenty- five minute equidistant black dots or ocelli, besides short, brown, transverse bars; the under surface is marked with short flake-white cross-lines. The mantle has neither tubes nor PECTUNCULUS. NUCULA. 69 orifices, but under the posterior termination of the branchiae there is a very short anal duct issuing from the body, with a small round reflexed margin. The foot in the live animal is snow-white, without a byssal gland and groove, but deeply cloven in the longitudinal line of its base to effect a subdiscoidal extension ; it springs from the centre of the basal portion of the body; when in full action it ranges anteally and posteally, forming an elongated suboval disk at the central portion, and tapers at each end to a moderately pointed termination ; when the foot is not fully protruded, it forms three or four folds at the margins; the animal does not execute a direct progressive locomotion, but only turns the shell round on its disk, or from side to side. There are on each side a pair of symmetrical branchiae of the same size, which, instead of having the transverse striae or circulatory vessels linear, present the appearance of white wavy ringlets, and are crossed by other sinuous lines ; both surfaces have much the same depth of markings. The branchial laminae hang very obliquely, and from the smaller or anterior extre- mity a pair of very narrow, light brown, linear labia or palpi, smooth on both sides, originate, and pursue their course around the mouth, and meet with the fellow pair. In their linear form and drooping position, these appendages much resemble the labia or palpi of Nucula. This species is frequently taken alive in the dredge in the coralline zone at Exmouth. We observe a close alliance be- tween Pectunculus and Nucula ; both have the same sort of suboval foot disk, and a similar quality of progression ; and the linear connecting branchial palpi greatly resemble each other. NUCULA, Lamarck. N. NUCLEUS, Linnaeus. 2V. nucleus, Brit. Moll. ii. p. 215, pi. 47. f. 7, 8 ; (animal) pi. P. f. 4. IV. decussata, Brit. Moll. ii. p. 221, pi. 47. f. 1, 2, 3. N. radiata, Brit. Moll. ii. p. 220, pi. 47. f. 4, 5, and pi. 48. f. 7. Animal suboval, thick, having the ventral portion of the body mottled flake- white ; the liver is dark green, with the 70 AKCADJS. snow-white ovarium attached to it, full of ova in July. The mantle is open from the anus to the buccal aperture, its margins plain; there are no tubes, not even an orifice, but the rectum terminates within it by a simple perforation in the body. There are two branchial laminae on each side, brown, of an elongated triangular form, and fixed horizontally; the broader part of them is at the short truncate or anterior end of the shell, from whence they gradually taper to the posterior termination, close to the debouchure of the rectum ; the upper lamina, which is contrary to the usual plan of those organs in most of the Acephala, is by far the largest, and entirely envelopes the under one of similar shape ; they are finely striated on the outer surface, but more visibly on the inner. There are two labia or pendulous appendages on each side ; the one nearest to the anterior end of the branchiae hangs vertically, the upper part of it being of a white, elastic, coriaceous substance as far as the middle, when it changes into a transversely striated brown narrow leaf-like lamina, the half of which is longitudinally doubled on the other portion ; the second labium, or that nearest to the buccal orifice, coalesces with its counterpart on the other side, encircling the mouth, and then accompanies the other, on the same side, in a pen- dulous direction to the ventral region; it is long, linear, coarsely transversely striated as its fellow, and has also the one half folded on the other. This is a very singular struc- ture of these organs, but the foot exhibits a still greater de- parture from the ordinary forms of that organ; it is pale yellow, of a regular oval form, deeply serrated at the margin into about fifty denticular points; one-half the disk when within the shell lies folded on the other, but when in action it becomes a flat subcircular disk ; the motion of the animal, though progressive, is not direct ; it turns round as on a pivot, and its path describes an irregular ellipse. The animal is shy, and requires continual attention to observe these manoeuvres. This species is extremely common alive in the Exmouth coralline region. Conchologists have exercised their ingenuity in convert- ing some very trifling varieties into distinct species. The NUCITLA. LED A. 71 N. radiata of authors is beyond doubt the " nucleus" and so is the N. decussata. We have examined the animals of the three, and they are absolutely identical. The Exmouth variety of the " nucleus" termed " decussata" does not attain so large a size as the Irish examples, but I challenge the most acute observer to point out an essential conchological variation ex- cept the one stated. N. NITIDA, Sowerby et Auct. N. nitida, Brit. Moll. ii. p. 218, pi. 47- f. 9. The organs of this species are similar in essentials to those of the N. nucleus. We may state, the specific distinctions are, that the foot is of much paler colour, and the disk less deeply dentated ; the branchiae are paler and smoother on the outer surface, but more striated on the inner, than in the N. nucleus. It inhabits in company with its congener, but is twenty times more rare. N. TENUIS, Montagu. N. tennis, Brit. Moll. ii. p. 223, pi. 47. f. 6; (animal) pi. P. f. 5. We have not seen it alive ; it is a Scotch production. LED A, Schumacher. L. CAUDATA, Donovan et Auct. L. caudata, Brit. Moll. ii. p. 226, pi. 47. f. 11, 12, 13; (animal) pi. P. f. 2. Area minuta, Auctorum. We can say little of this genus except that it appears to differ from Nucula in having the mantle produced into two siphons of moderate length, partly united, but bifurcating at their terminations. We have only rarely taken the dead shells of this species at Exmouth. It is an abundant Scotch pro- duction, and differs much in the outline and markings. L. PYGM.EA, Minister. L.pygmcua, Brit. Moll. ii. p. 230, pi. 47. f. 10; (animal) pi. P. f. 3. This species, if distinct from the L. caudata, is unknown to 72 ARCADE. us; we believe it has only occurred in. the Hebrides. We doubt the distinction. GALEOMMA AND LEPTON, Turton. The genera Galeomma and Lepton have received from the hands of Dr. Turton a conchological constitution, but as respects natural position, they have been buffeted from place to place, in accordance with the various views of naturalists. In some systems they are associated with the Kelliada, though doubtfully, on account of the want of knowledge of the animal. These disturbing causes are happily in a great measure removed, and we have it in our power to fix permanently these wanderers in the only British family that has with them a sufficiently corresponding community of attributes. Though they are aberrant genera of the Arcadan type, when strictly consi- dered they undoubtedly belong to that family, and it will be shown that they have the strongest claims to this their natural lineage. To establish a new family for these beautiful genera would indeed be a superfluous labour, and repugnant to our well- known feelings to add unnecessarily to a host of worthless positions, when there is already an unmistakeable resting-point. But our descriptive notes will further explain these matters. GALEOMMA, Turton. G. TURTONI, Sowerby. G. Turtoni, Brit. Moll. ii. p. 105, pi. 36. f . 1 1 ; (animal) pi. O. f. 5. Animal oval, fleshy, pure white; mantle of thin texture, except at the edge, which is muscular, and forms a tumid cord that extends beyond the shell, from which are thrown off undulated double margins, one of which lines the shell, and is marked with equidistant frosted-white eminences or ocelli, eight or nine on each side, with fine white filaments between them. The mantle is partly closed in front, but there is an anterior pedal aperture. The foot is long, cylindrically taper- ing to its termination ; at the heel, close to the body, is the GALEOMMA. 73 byssal fissure, from which a fasciculus of fine filaments issues, which fix the animal so firmly to whatever it is placed on, as to require some force to detach it ; in fact, the hyssus is discarded by being altogether withdrawn from the slit in the foot whenever an attempt is made to remove the animal by force; but though we repeated this operation several times, the little creature did not appear to be injured or less lively, but as soon as it had crawled to some distance, we had the good fortune to witness the formation of a new byssus, which was effected by the discharge of a light green glutinous opake matter from the fissure at the heel of the foot, which by its ponderosity resolved itself into delicate fibrous filaments that instantly adhered to the saucer : we detached the animal several times, the byssus was always left, and a new one formed. On leaving it for the night, in a marked position, we found in the morning that it had detached itself by aban- doning the byssus, and formed another at a considerable distance. The animal marches with great vivacity, by flattening the valves into the form of a circular disk ; it then, by the foot, aided by the muscular margins of the mantle, makes rapid progression. We are unable to speak of the branchiae j or the particular character of the palpi or labia, and whether they are distinct free pendulous palpi, or the drooping folded labia of the Nucula-, nor is it clear, from M. Mittre's or Dr. Philippics account, which of the two forms is the true one. I blame myself greatly for my inattention to these points when I had it in my power to verify them ; they have now become important, either to support or impugn my reasons for placing Galeomma in the family of the Arcada. But if even the palpi or labia should show a difference from the usual structure of those organs in the Arcada, it must be considered as an aberration of an aberrant genus ; however this may be, abundance of facts will be adduced to justify the removal of Galeomma to the Arcada. My memory will not allow me to say anything of the siphonal apertures, or of the long anterior stylet. We have twice taken this beautiful creature alive in the coralline zone off Budleigh Salterton, Devon. 74 AECADJE. It will be observed in the account of this animal, taken from notes made twenty years since, that the mantle is partially closed in front ; this is the only point against the Arcadan position, as in the typical species that organ is open through- out the ventral range. We certainly did not then observe so critically as now ; there may be an error ; the animal requires further investigation, which we confidently believe will confirm our present views. Galeomma, by the contiguity of the beaks and very limited ligamental central facet or area, together with the minute glossy circular porcellanous nuclei of the umbones, is closely allied to Pectunculus, also, perhaps, more so to Area y particularly^, tetragona, by the linear character of the hinge and ligament, which has the central portion semi- internal, and is carried on each side to the termination of the dorsal line, being throughout as straight as in Area ; the impressions of the adductor muscles scarcely differ in the two, and there is in both the same dull scabrous irregularly nodose aspect of the inside of the valves. The ventral gape in the regular specimens of A. tetragona is similar in Galeomma. The character of the striae or minute ribs is the same as in Area lactea, except that in it the bifurcations are seen inter- nally, whilst in Galeomma they are external. With high powers, the oblique, though nearly obsolete teeth may be observed on the ligamental line, and the internal linear areas are similar to those in A. tetragona and P. glycimeris. Many other minute similitudes may be mentioned, but enough has been advanced to show that the conchological indices decidedly fix Galeomma with the Arcadae. Let us speak of the internal organs. The foot in Galeomma is byssal, and precisely of the same form and character as that of A. tetragona. As a last, but, as we think, very convincing proof of the relation of this genus to the Arcada, are the regular equidistant frosted-white eminences or ocelli, which, except in colour, entirely resemble those in the typical Area ; and as there are no other genera but the Area and Pecten in which the mantle of the animal is furnished with ocelli, it follows, from the entire difference of the position of the ad- ductor muscles in Pecten and Galeomma, that this species, on LEPTON. 75 malacological considerations, can belong to no other family than the Arcadae. LEPTON, Turton. L. SQUAMOSUM, Montagu. L. squamosum, Brit. Moll. ii. p. 98, pi. 36. f. 8, 9 ; and (animal) pi. O. f. 6. Solen squamosus, Auct. Animal inhabiting a very flat, subrhomboidal, white, porcel- lanous, punctured shell ; its ground colour is a clear white. The mantle is very large, having the margins sinuated, often puckered into two or three folds at the will of the animal ; they extend beyond the shell more than one-third of the ver- tical measure at its centre, from which springs a row, on each side the middle of the ventral range, of twenty-five rather long, slender, milk-white tentacular pointed filaments; but the mantle thus clothed is only protruded largely beyond the shell, from the middle of the anterior side, throughout the ventral range, to the same level as the posterior end ; from these points to the umbones it is never seen, being either closed or not protruded, but its suture or edges are furnished with about forty long, strong, blunt, frosted-white, rather close-set cirrhi varying in length ; a part of these range at the posterior side of the beaks, above the sessile anal orifice, which occupies a small space without cirrhi, between the termination of the protrusion of the margin and the commencement of the larger filaments on the broader, larger, and posterior side ; of that part of the filaments at the anterior side of the beaks, one is thicker, broader at the base, and double the length of the others ; this is the last of the larger ones, which at one time I thought was tubular and might be an oviduct, but further examination seemed to disprove this idea. None of the fila- ments show much motion ; the long one only, when the animal advanced a step, made an arcuated contraction, similar to that of the fore-finger in extenso when quickly brought down to the palm of the hand; it then resumed the straight position to await another step : all the other cirrhi are either retractile or contractile, separately or en masse. 76 ARCADE. The foot is hyaline azure, with a broad longitudinal medial line of intense snow-white, and a still intenser flake at the anterior end ; it is fixed to the centre of the body by a mode- rately long pedicle; on first protrusion it takes a vertical position, and has a linguiform tapering aspect, but this part almost immediately, after feeling about, ranges itself anteriorly and horizontally ; and at the same time, on the other side of the pedicle, a bevelled, attenuated, pointed portion issues, somewhat shorter than the first ; this is longitudinally cloven as far as the pedicle, and can form a sort of oval disk, but on the march it is rarely expanded : at the base of the cleft is the byssal gland, which occasionally pours out a glutinous red filamentous matter, that in confinement is copious, and discharged anteriorly, which at first I thought was faecal matters, and was puzzled to account for such an issue anteally, but the subsequent view of the single sessile posteal anal conduit and the ejection of pellets cleared up the difficulty. This foot is in every respect similar in miniature to that of the Pectunculus pilosus and of the Arcada, and in no other bivalve family does the foot exhibit a similar structure : this singular pedal characteristic of itself would sufficiently confirm the natural position of Lepton and Galeomma. The animal is vivacious, and allowed itself to be examined many times daily ; it marched with quickness, but I only once saw it progressing in a vertical position ; the usual posture of the shell is to rest on one of the disks, which is frequently changed for the other ; the adductors did not appear to allow of a greater opening of the valves than the ordinary extent. The animal, when placed at the bottom of a glass, always crawled up and moored itself by a filament at the side ; some- times, however, it slipped its moorings and floated free on the surface of the water with the umbones downwards, and after an interval refixed itself by spinning a byssal thread. I cannot speak at present of the branchiae and palpi, as the animal and shell are in my collection, and are thus preserved to show that the shell, though usually described by concho- logists as gaping, can, in consequence of the flexibility of the thin laminar valves, be completely closed. There is no LEPTOX. 77 branchial siphon ; but there are mantellar folds, which, with the great ventral opening, amply provide for the admission of the water. The animals of this interesting group exhibit, in the tenta- cular filaments and curious foot, as well as in the sculpture of their shells, very considerable variation from Kellia rubra and Kellia suborbicularis, the types of one of the genera of the family in which they have been located by authors, doubtless from the want of knowledge of the animal. Taking into consideration that the Leptons have many of the attributes of the Arcade, and especially giving due weight to the re- markable similarity between the foot of Lepton squamosum and the Pectunculus pilosus, I am almost induced to believe that it is in a false position, in connexion with the Kelliada, and that it ought to follow or precede Galeomma, which, with me, is an undoubted genus of the Arcada. The punctures of this species and of L. convexum are in the test; with respect to its congener, the L. nitidum, it has been stated that it is smooth and without punctures : this is a mistake, as I can show fifty specimens not only well- marked on the greenish epidermis, but in the substance of the shell. I have the satisfaction to state, that I have observed another live L. squamosum, and also obtained fall notes of the animal of one of our great desiderata, the L. nitidum, from a most lively animal, which for several days gave me every facility for examination. The L. squamosum, just alluded to, was kept thirty-four days in a glass of sea- water, changed daily, and was apparently as vigorous as when first placed in captivity; it thus appears that the Conchifera can exist for a long time in pure sea-water, on the animalculse it contains, though that aliment may not be their sole resource in freedom. I may observe, that the habitude of crawling and swimming with the foot uppermost in Lepton, and in several other minute bivalves, perhaps in all, shows the close alliance of the Acephala with the Gasteropoda, all of which, in their minute condition, have precisely the same peculiar system of dorsal natation. I ought to have mentioned that the liver is light green and 78 AECADJE. mixed up with a flake-white ovary; but from the extreme tenderness of the branchiae, I cannot speak of them and the palpi with certainty as to form and number. July, 1852. As I had just finished the above, a lively specimen of this species was met with, which, on being placed in water, at once unfurled its long and beautiful fringes, and exserted the ample niveous mantle and foot. This is certainly the Prince of British bivalves ; the snow-white colour of both animal and shell sheds over this interesting creature the in- expressible charms of purity and elegance. It now lives in the same vase with its pigmy congener, the L. convexum. L. CLARKI^E (nova species), Clark. L. Clarkia, Brit. Moll. iv. p. 255, pi. 132. f. 7- L. testa fragili, obliquo-subovali, compressa, postice et antice ro tun data, albida, mediocriter nitida, striis concentricis, confertis, tenuibus notata; apices minutos, prominulos, subtilissime punctatos gerente. Latus rostris anterius, quoad longitudinem transversam, duplo posterius superat. In valva dextra, utroque, dentes laterales, duplices, distantes apparent ; in sinistra, simplices ; inter quos, utra- que valva, dens unicus, primarius, erectus, acutus, oritur. Mensura obliqua y 1 ^-, trans versa -j^, altitude aut crassitude ^ uncise. Zonam corallinam Devonise meridionalis, prope ostium Iscse, rarius habitat. Animal ignotum. Of this minute and elegant species, a series of eighteen perfect specimens have occurred, and having compared the hinge and dentition with forty examples of the L. convexum and L. nitidum, I can state that there is not the slightest variation in this respect in the three species. Its distinguish- ing characters are the almost perfect obliquely oval shape, being without a trace of the subangularity which is invariably seen at both extremities of the congeneric Leptons ; and, as to the punctures, it is more devoid of them than the glabrous varieties of the L. nitidum, which, however, in the forty spe- cimens I possess, all show more or less the punctured aspect on the umbonal area ; but in the L. Clarkia only the apical circumscribed space is in some, but not in all examples, almost LEPTON. 79 invisibly punctured, which condition is rather more pronounced within than on the outside of the apices. At one time I almost thought that the L. nitidum and L. convexum might march together as a single species, subject to many varieties ; but an increase of my series of both has, at least for the present, made me doubt the propriety of considering the two as identical. The animal of the L. con- vexum is still unknown, and until it occurs, a safe determina- tion on these points cannot be made. The animal of the L. nitidum I know well, having in the last summer observed two examples for four days; it only differs in some minor peculiarities from the L. squamosum, one of which I kept in sea-water thirty-four days, when it was killed whilst still vigorous, in consequence of my departure from the sea-side. I may state, that in L. Clarkite the concentric striae of increment are close-set and sharp, and sometimes broken into very short waved streaks ; these in some of the specimens are crossed by gently raised lines of an intenser snowy-white than the general colour, which radiate sparingly from the beaks to the basal margin. This delicate species cannot be confounded with any of the minuter bivalves : by its hinge it is essentially a Lepton : the nearest approach to any other species is to the Montacuta bidentata, which differs in form, colour, and fragility, and in having the lateral dentitions almost close together, without the primary teeth between them ; instead of which, there is a minute moveable ossicle, convex on one side and concave on the other, as in the Anatirue or Thracia ; this locks into a sloping pit that has sometimes the appearance of being ridged, which is only due to portions of the ruptured ossicle adhering to it ; but in Lepton the primary teeth are persistent or integral parts of each valve. Fresh examples, new facts, and further investigation have all but convinced me that L. convexum and Li. nitidum are distinct. Our Leptons, which I name according to rarity, will stand thus : 1st, L. convexum ; 2nd, L. Clarkite-, 3rd, L. nitidum ; 4th, L. squamosum. One of the distinguishing marks of the new species has been already alluded to, the oblique rounded outline ; but another 80 AKCAD^E. equally important is, that the side anterior to the beaks is double the transverse length of the posterior one ; whereas in all the other Leptons, of which I have more than a hundred examples, the beaks are nearly central, and they have more or less subangularity at the sides ; therefore the oblique outline, rounded sides, and position of the beaks, are unerring guides to distinguish the L. Clarkice from its congeners. The animal has not been observed. L. CONVEXUM, Alder. L. convexum, Brit. Moll. ii. p. 102, and iv. p. 255, pi. 36. f. 10, mag- nified. L. nitidum, Turton et Auct. Kellia nitida, Brit. Moll. ii. p. 92, pi. 36. f. 3, 4. The animal inhabits a light greenish-yellow or pure white, subrhomboidal, moderately convex, more or less punctured shell. The mantle is frosted- white with the margins plain, but as much proportionately protruded beyond the edge of the shell as in L. squamosum ; it is in like manner clothed with cirrhal filaments of about the same length, and of pruinose white, but unlike that species, they are rather less developed dorsally than ventrally ; each filament at its terminal edge is studded with four or five white points or cilia, so sharp and minute as to require a powerful lens to see them. There is no conspicuous leading process, as in the preceding species, but the mantle, at the same anterior point, forms a visible pro- jection or fold. In this species, and contrary to L. squamosum, the longer and broader end is anterior, but the beaks are so central, that there is little difference in the sides ; the single sessile anal tube is exactly as in the last species ; there is no branchial siphon, the water enters at the extensive ventral aperture. The foot is almost in every respect similar to that of its congener ; it is perhaps larger in proportion, of pale azure hue, marked with intense but irregular flake-white minute blotches; the posterior extremity is as long as the portion anterior to the pedicle; its termination is perfectly aciculate, and like its congener deeply grooved as far as the junction with the body, at which point is the byssal gland, LEFTON. 81 and the superabundant filamentous matter is similarly dis- charged. The L. squamosum is a lively creature, but this, not one- third of the size, is far more active, creeping up a glass as easily as a Gasteropod ; but the posterior portion of the foot is not expanded; perhaps in freedom it is deployed on the march ; in confinement both shell and foot are carried laterally. The liver is light green, united to a flake-white ovarium, now, in June, full of ova. Transverse length J, vertical y 1 ^, dia- meter -Jj of an inch. It would appear that this species in every essential is identical with the L. squamosum, and it settles the position of the yet undiscovered L. convexum. This is the first record of this rare animal that has appeared. Exmouth, June 20, 1852. I have this day the pleasure to state, that the problem is solved as to the identity or distinctness of the Lepton nitidum and L. conveocum by the capture of a live specimen of the latter, having the shell sculptured with the rough and intensely marked characteristic punctures of that species. On putting the animal into water it instantly deployed its organs ; and for their description I have only to refer to the preceding account of the L. nitidum, which in future will take the appellation of a variety of its old associate. The two are so identical, that after ten days' examination I can make no alteration in the minutes, except the having seen the animal march on the disk of the foot, more than once, with the shell in a vertical posi- tion ; it has all the same habitudes as the L. squamosum, and of course differs in no respect from its smoother variety, the late L. nitidum. It is now alive, and probably by changing the water daily it will live as long or longer than the L. squa- mosum mentioned above. It is therefore evident that the punctures of this species are very variable, ranging from the most minute granules that scarcely interrupt its smoothness to the coarsest sculpture. As the specific appellation of nitidum is obviously improper, the more significant one of convexum ought now to be adopted. Since the above was written I have taken two examples, one this morning (July 18), of the smoothest variety of the ' con- G 82 LUCINIDjE. vexum' late the 'ititidum'', both are in the vase with the highly- punctured one captured 20th June last, now quite vigorous, in company with the L. squamosum alluded to as taken 2nd July ; this capture has given me the advantage of a live examination of the two completely opposite conditions of the ' convexum' whereas the one above was only referable in comparison with an account of a live ( nitidum ' taken last year. And I can again state that the two varieties are identical. I give another proof of identity. I have just (1852) taken alive a curious example, that shows one half of each valve finely punctured and the other grossly granular. LUCINID^l. This family has only one genus, Lucina, which includes about eight species. Live specimens of the typical L. borealis are of rare occurrence ; we have met with none for forty years on the Devon coast, and of the L. rotundata only a small example has been examined. Nor have the animals of the L. flexuosa and L. ferruginosa been seen by us, but we receive them sub fide Forbesii et Hanleyi. Since this was written, it will be seen below, that fortune has been favourable, and enabled us to fill up some of the gaps in the species of this family, but the curious incidents attending it are so largely noticed in the descriptive history as to dispense with further remarks. LUCINA, Bruguiere. L. ROTUNDATA, Montagu et nobis. Diplodonta rotundata, Brit. Moll. ii. p. 66, pi. 35. f. 6 ; (animal) pi. M. f. 7. The present account of the species was written at Exmouth, in the summer of 1849, and the reason of noting the date will shortly appear. Animal lentiform, moderately thick; mantle plain, some- LUCINA. 83 what closed anteriorly and posteriorly, leaving a large pedal opening in the centre of the ventral range ; no siphonal pro- cess appears, not even an orifice ; the branchiae must be sup- plied through the pedal aperture. The body is very small, pale brown, with the intestine passing through the liver. There are two subquadrangular branchiae, and two palpi, on each side ; the former are finely pectinated above, and smooth on the under surface ; the palpi are moderately long and pointed, as well as striated on one side ; both are of a good brown colour. The foot is clear white, moderately long, flattish, and lanceolate-shaped laterally and at the point. The L. rotundata has been consigned to a new genus, termed Diplodonta, by the learned authors of the ' British Mollusca/ on our authority as to the animal structure. I feel pleasure that they state this allocation is provisional, as the animal presents anomalies of so peculiar a nature, that malacologists are earnestly called on for a minute examination of this curious creature. I accept the invitation, and hope either to confirm my observations, or offer rectifications. This species has many of the characters of the type, L. borealis, and I think, whether my notes are confirmed or not, it must be considered an out- lying branch of this family. The hinge and other distinctions will not, in any case, allow of the suggestion of handing over this species to the Kelliada. Fresh, though dead shells are commonly taken in the coral- line zone at Exmouth, but I never met with more than two specimens alive ; the one examined was less than half an inch diameter. The following addenda were made at Exmouth on the 22nd July, 1850, a year after the preceding notes. The account in the ' British Mollusca/ vol. ii. p. 65, of the Diplodonta rotun- data, our Lucina rotundata, was made from the sketch above. The possession of a live specimen of f of an inch diameter, enables me to say that my account, as far as it goes, is nearly correct ; but I can offer some amplifications, particularly on that important organ the foot. Beyond all doubt, I state, that there are, on each side, a pair of branchiae and palpi; the branchiae are transverse, though somewhat elongated, G2 84 LUCINIDyE. subangular laminae, sinuated at the margins, pectinated, and fixed, as is usual, to the dorsal range, the upper plate being little more than half the depth of the lower one. The palpi are short, pointed, pectinated, and subtriangular ; they lie on each other, and I may say, that neither of these organs present any remarkable variation from the usual run of the Acephala. The liver on the dorsal range is of an intense black-brown granular substance, with the ovary mixed up with it, more anteriorly. There are no siphons, but only a short pendulous rectum, which is a very minute cylinder, discharging by what I considered to be a crenulated slit in the mantle high up in the posterior dorsal range. If I am mistaken as to the slit, which possibly may have been an accidental lesion, in that case it would discharge within the walls of the mantle, and finally eject from the central pedal aperture, which is a large opening commencing from the posterior closure of the mantle to the anterior adductor muscle, situated very low, near the anterior ventral range, from whence the mantle becomes closed to the anterior dorsal range ; therefore there are only two apertures in the mantle, the small posterior slit, for the ejection of the excessively minute faecal pellets, and the very large ventral opening for the foot. The possession, as yet, of only one good-sized specimen has not enabled me to speak positively as to the existence of the anal fissure, but beyond doubt there is neither anal nor branchial siphon. The foot is a most curious organ; it is characteristic of the typical Lucinae. It proceeds from the centre of the body, and represents a long, lax, flat, rugose, annulated, retractile hose, with a wrinkled, elastic, clavate continuation or off- spring, with slight shoulders to the terminus, which appears to be perforated ; this latter, somewhat club-shaped portion, when in quietude, folds on the penultimate part, and the whole lies within the mantle. It is difficult to conceive how a flat, lax, strap-shaped, tubular pedal appendage should in action suddenly assume the appearance of an elongated, arcu- ated, pointed conical foot, as is represented in the figure of the ' British Mollusca/ which, however, cannot be improved as to actual appearance when the foot is exserted, except LUCINA. 85 to show a minute terminal perforation. This metamorphosis is probably effected through its elasticity, and being distended with water. In the large specimen, of which this is the de- scription, the animal was more apathetic than the small one of the first part of these notes ; the foot was never protruded, and of course no siphons, as none exist ; the only movement for forty-eight hours was a central opening to admit the branchial water, and the exsertion of the margins of the mantle, which are quite plain. We have here the decided foot of the typical LMCITMK, agreeably to the descriptions of M. Poli and M. Valenciennes ; but if the latter is right as to there being but one branchial lamina on each side, in all the true Lucina, our present spe- cies, which beyond doubt has two on each side, would be an aberration from the typical Lucina, though so closely allied to it by the foot, which is of so singular configuration, that we think it a generic characteristic of far greater value than the single branchial plate on each side, which form prevails in all the Anatinas, and in some of the Tellina. We therefore would prefer to place this animal as a Lucina, even if it should turn out that all the Lucince have but one branchial lamina, which fact at present is by no means to be depended on; we consider the character of the tubular foot to be more worthy and important, in this case, than that of a singularity in the structure, or rather in the disposition, of the respiratory organ; and as to the branchial plate being a single one, it is more so in appearance than in reality, which is fully explained in the notes on Anatina phaseolira. In this very delicate animal we could not trace the connection of the foot with the viscera of the body, if it exists. M. Valenciennes says, that the water from the foot must enter and mix with the splanchnic con- tents ; we greatly doubt this fact, and refer for our reasons to the preliminary observations on the Lamellibranchiata. L. BOREALIS, Linnaeus. L. borealis, Brit. Moll. ii. p. 46, pi. 35. f. 5, and (animal) pi. M. f. 6. Exmouth, 2nd June, 1852. This day a live specimen, about fths of an inch diameter, 86 LUCINID^E. was met with, close in shore, at Littleham Cove. Though im- mediately put into water no organ was exserted, except at the centre of the ventral range a small portion of a pointed foot. As the animal continued apathetic it was opened, when a large corrugated subcylindrical foot became visible, which on being divided proved to be tubular, but near the body it appeared slightly geniculated. On each side there was one rather elongated branchial plate, apparently divided by the branchial artery in two portions ; these were connected and doubled on each other, forming one thick plate, of a darkish brown colour, shot with a hue of pink, very closely and strongly decussated by the branchial vessels. No palpi were seen. The liver is brownish-green. The margins of the shell are plain, and the edges of the mantle loosely sinuated. The posterior adductor scar is pyriform, the anterior one narrow and strap-shaped. Of the two primary teeth in each valve, one of each is cloven ; there is also an anterior lateral one in both valves. Another specimen has this year (1853) occurred, of the same size, and at the same habitat. It proved lively, and has enabled me to offer some additions and explanation. The foot is very narrow but lancet-pointed, and when fully ex- tended is nearly as long as the vertical measure of the shell ; it is always in the first instance exserted from the ventral central point, and from thence can move itself anteally to a right angle. It is transversely and longitudinally wrinkled, and when alive has the aspect of being roughly shagreened ; when dead it appears intensely corrugated across and length- ways ; it has a decided heel near the junction with the body, and is beyond doubt tubular to within a short distance of the termination, and possibly may be entirely perforated. I made with the scissors two sections before the tubular structure was visible, but in so delicate an organ the pressure of the knife might close a real perforation, which I believe exists ; not to admit water either to the branchiae or viscera, as some natu- ralists think, but to render the foot a potent locomotive organ by inflation, and having the power of opening and constricting the perforation for the issue and admission of the water. The LTJCINA. 87 mantle is slightly dentated, and open from the anterior ad- ductor throughout the ventral range to near the posterior muscle ; it is then closed by a knotty stop, and a linear fissure is visible, I presume, for the dejections, and then the mantle is finally closed. Nothing is ever protruded beyond the shell except the foot. The water must reach the branchiae from the ventral range. There is certainly on each side the mouth, a short, coarse, thick, subcylindrical, striated' palpum, and I am not sure that there are not a pair on each side. The only action of the animal was the exsertion and retrac- tion of the foot, which is well represented in the 'British Mollusca/ pi. M. f. 6. This species is the type of the genus. L. FLEXUOSA, Montagu. L.flexuosa, Brit. Moll. ii. p. 54, pi. 35. f. 4. Exmouth, 2nd June, 1852. Animal inhabiting a white, irregularly globular shell, with a longitudinal posterior furrow. It was apathetic, and pro- truded no organs. On being opened, the plain-edged mantle showed only one anal fissure. In the middle of the ventral range lay a long corrugated cylindrical tubular foot, which appeared capable of great extension ; it made its way through the body to the branchiae, and there threw off vessels, right and left, which appeared to communicate with those organs, so that it would seem that the foot performs both the functions of a locomotive, and is a vehicle to convey water to the branchiae, in lieu of the usual posterior siphon ; and it is pro- bable that throughout the genus Lucina the foot performs this double duty. There is only one thick branchial plate, as in L. bo^ealis, doubled on itself, of a red-brown colour. No palpi were detected. The liver, formed of two minute leaf- shaped light green granular masses, curiously lines the body and part of the foot on each side. This animal was taken in company with the L. borealis above described, close to the shore, at Straight Point, Little- ham Cove, near Exmouth. 88 KELLIAD^E. The undermentioned references have not occurred on the South Devon coasts. L. SPINIFERA, Montagu. L. spinifera, Brit. Moll. ii. p. 49, pi. 35. f. 1. L. LEUCOMA, Turton. L. leucoma, Brit. Moll. ii. p. 57, pi. 35. f. 2, as L. lactea. L. FERRUGINOSA, Forbes. L.ferruginosa, Brit. Moll. ii. p. 60, pi. 34. f. 1, magnified. L. DIVARICATA, Linnaeus. L. divaricata, Brit. Moll. ii. p. 52, pi. 35. f. 3. KELLIAD^E. This group of minute bivalves has lately been distributed in five genera, Kellia, Montacuta, Galeomma, Lepton, and Turtonia, but the four latter are so generically discordant with Kellia (proper), the type, that we may say they have no connection with it. We have therefore, without hesitation, removed Galeomma and Lepton to the Arcada ; Montacuta, for one of its species, to the new family of the Montacutidce -, and Turtonia, for its only species, to another new family, the Turtoniadce -, under which heads our reasons for these changes will be found. The lately acquired knowledge derived from an examination of all the Leptons except L. Clarkia, impera- tively requires a family rectification ; they have not the vivi- parous and tubular specialties of Kellia, and exhibit such other different characters and structure as fully to sanction the junction of Lepton with Galeomma, and the removal of both to the Arcadce. Again, with respect to Montacuta, we have relieved it of one of its late members, by consigning the M. bidentata to the Anatinidae, as by the testaceous moveable ossicle it certainly belongs to that family, which we confidently think will obtain another recruit in M . ferruginosa ; that is, if it should be found to have the characteristic ossicle of the tribe. The Kelliadce, therefore, in our method, consists of only one genus, Kellia (proper), with two species. KELLIA. 89 We digress, and for the second time earnestly recommend naturalists to observe, in sea-water at least, the external organs and habitudes of the minute animals of all genera, bivalve and gasteropodan, for little more can be done from their minuteness, and publish notices of them in our natural- history records; not mere names and habitats, as is too often the case, but their peculiarities. Opportunities of meeting with rare live animals do not often occur; we spe'ak from forty years' experience ; none ought to be passed hy, and all should be examined without delay; the interval of even an hour often paralyses the animal functionV: let our motto be " carpe diem " many rare creatures, from its neglect, have been lost to science. The almost total dismemberment of the Kelliadce is the moral of the above ; we wish to impress the necessity of a more careful examination of the minuter Mollusca. We ought to state that the true Kelliada have the hinge furnished with variable minute irregular primary teeth under the beaks, with flattish triangular laterals on each side in each valve, those of the right one being obscurely double, and a long, strong, very oblique, white internal cartilage, which is often ruptured into two parts, one of which lies in each cartilage-pit. KELLIA, Turton. K. SUBORBICULARIS, Montagu. K. suborbicularis, Brit. Moll. ii. p. 87, pi. 18. f . 9 and 9 a, 9b; and (animal) pi. O. f. 4 and 4 a. Animal suborbicular, pure white ; the mantle may be termed partially closed, though there are three openings in it ; the ventral one is considerable, and serves for the admission of water to the branchiae, and as an issue for a small hyaline linguiform byssal foot, which usually lies centrally exserted, to be prepared to act anteally and posteally ; it is also at the anterior or shorter end, to which the beaks curve, produced into a conical entire tube, not divided within, almost as long as the shell, plain at the orifice; this anomalous production is, 90 KELLIAD.3L as far as we know, confined to this species and Kellia rubra ; the third orifice in the mantle is a small sessile anal one. We believe the water to aerate the branchiae enters by the pedal fissure, and when used, is expelled therefrom ; it is possible that the curious anterior tube, which is a continuation of the mantle, may, in conjunction with the central opening, also admit some water to the branchiae ; but we will observe on this point by and by. On each side of the body there are a pair of narrow, symme- trical, pale yellow, striated laminae, and correspondent pairs of short, thick, strong, subtriangular, coarsely striated palpi ; the liver is pale green, and in close connection with the ovarium, which is a thin membranous sac full of ova in the genial season. It is now proper to inquire into the probable uses of the anterior anomalous tube. As there is no ostensible reason why nature should have departed from her accustomed plan to place that organ before, which in every other bivalve except K. rubra and this is behind, we cannot rationally conceive that this singular appendage is a special branchial tube, as the pedal orifice is most ample for the entry and expulsion of the aerating fluid; we therefore think the following facts will afford malacologists assistance in determining its functions. Whilst examining some K. suborbicularis, my attention was suddenly attracted by observing several testaceous young ejected from the anomalous tube ; these I collected and have them now by me. Notwithstanding this fact, I have never, until lately, been able to discover, in any of the numerous ovaria I have inspected, anything except ova in different stages of advancement ; but it is exceedingly probable that the shells I saw ejected may have been deposited in this tubular appendage of the mantle, and there received the development in which I found them. Since this was written, I have to state subsequent facts resulting from the examination of a very large Kellia suborbi- cularis. I placed it on the umbones, when it immediately exserted and opened the tube ; by the aid of a powerful lens, I counted at its fundus fifteen largely developed ova, and I KELLIA. 91 have no doubt that this animal and that of K. rubra are furnished with these unusual appendages to minister as organs of reproduction. I have farther to state, that on submitting the animal to my scalpel and one of Mr. Ross's microscopes, I received the fullest confirmation of my conjectures, having found in the ovarium, resting on the fundus of the tube, ova in advanced conditions, together with fully -formed testaceous young. I have carefully preserved the ovarium. 'Therefore this species, like K. rubra, is undoubtedly viviparous : the only difference between the two is, that one of the young phases of K. rubra is greatly matured in the ovary, and only requires the open tubular fold as an oviduct, and to convey the water to the pulli, which, from their position high up on the dorsal range, could not receive the ambient element without such an appendage, whilst the K. suborbicularis has the tube entire, as it is for some time a nidus for the young before exclusion. I have also to add, that on opening a very large K. sub- orbicularis, I found the contents of the ovarium converted from its usual ova-like aspect into many thousands of com- pletely testaceous young, to be further developed before their issue from the anterior tube or oviduct, without which the water could not well be conveyed and retained for the use of the young. The reason why this state of the ova has so long escaped detection is, that the ovarium has not been examined at the proper season. To see it as I have described, we must attend to the injunction of Lucretius "Athens et terrae genitabile quserere tempus." K. suborbicularis , though often taken free in the muddy deposits of old bivalves, is also found in the crevices of the triassic rocks at Exmouth, in company with the Saxicava and Pholades, in which it rubs out a kind of cell, and thus becomes entitled to enter the category of the boring fraternity ; it is attached by a byssus, not merely thread-like filaments, such as the freer ones throw out when placed in a saucer, but a decided membranous white hyaline byssal lamina, which cannot be detached without some force ; it always parts from the animal and is left in the cell ; if it is placed in water 92 KELLIADJj]. in a piece of hollowed-out sandstone rock, it will produce another : of these facts we speak with certainty. This species, when imbedded in the crevices of rocks, is more globular and of firmer texture than those which are found in the muddy deposits of old bivalves, taken in the coralline districts, six miles from the shore ; these are very thin and almost mem- branous at the umbones, of larger size and subtriangular figure, and have the tube marked with flake-white longitudinal lines that are not apparent in the thicker varieties. Having examined many of both these variations, without detecting a difference in the organs, we must consider them as dependent on habitat. K. RUBRA, Montagu. K. rubra, Brit. Moll. ii. p. 94, pi. 36. f. 5,6,7; (animal) pi. O. f. 3. Animal suborbicular, white; mantle partially closed and with only two apertures ; the anterior is the anomalous tubular projection, which is not entire as in K. suborbicularis, but slit open at the base, and serves as a passage for the foot. When the animal marches it is generally pushed therein, displacing the sides of the scission, which on its withdrawal assumes the aspect of an entire tube. This combined pedal aperture and tubular appendage is divided by a septum from another con- siderable fissure in the mantle, from which the points of the branchiae are visible; through it the water to supply the vital principle reaches them, and when effete is expelled by the channel at which it entered ; the anus is a sessile orifice completely within the slit of the mantle, and discharges therein; in fact, the fissure is the entrance of a common cavity that serves to admit the branchial water and receive the rejectamenta before exclusion. The anterior tube being nothing more than an open protrusion or continuation of the mantle, some water may reach the branchiae through it, and be expelled therefrom in combination with the strict pedal aperture ; but its principal use, as we have shown in K. sub- orbicularis, is to act as an organ of reproduction to convey water to the pulli in the matrix, which from their dorsal posi- tion could not well receive it without the aid of such an KELLIA. 93 appendage, which also serves as an oviduct. We have omitted to say, that when the faeces are received within the mantle, they are instantly ejected in light yellow or greyish cylindrical pellets. In this respect there is a difference between K. sub- orbicularis and K. rubra\ in the former the anal orifice is protruded in a trifling degree externally, in the latter it is within the mantle. The foot is broad at the base, long, linguiform, and has the termination rather rounded than pointed; its bluish-white hyaline texture is marked from base to point by a dull intenser flake- white line. When in a basin of sea- water, it at once attaches itself by thread-like filaments that issue from a distinct byssal fissure. The foot when exserted, but not in action, occupies a central position; it usually progresses anteally by being pushed through the anomalous fold of the mantle, and fixing itself by a species of suction, is drawn forward by muscular contraction with much vivacity, and it can also in a more limited manner progress posteriorly. The animal never remains long without forming a byssal attachment, but has no difficulty in slipping its cable when inclined to move, which is always discarded, and when required another is bent. The dark liver and yellow ovarium are situate high in the dorsal region; the latter in the genial season contains from 10-20 or more fully-formed testaceous pulli, and at the full time, the viviparous colony are ejected through the tubular fold of the mantle. In a parcel of animals examined in the winter, the ovarium contained no young ; I therefore presume that " Alma Venus" does not influence the self-sufficing loves of these Mollusca until " species patefacta est verna diei, Et reserata viget genitabilis aura Favoni." A review of these notes, and a comparison of them with those of K. suborbicularis, will, I think, prove that this species and its congener are nearly similar in organs, habitudes, and functions, with slight variations of specialties, and that they form a well-defined small genus which I believe only contains the two species that are described. 94 MONTACUTIDJL The habitat of this singular creature is at a far greater elevation in the littoral zone than any other bivalve, and nearly as far removed from the sea-water as the Littorina petraa, which in many positions is never completely sub- merged. These minute bivalves are plentifully imbedded in the Lichina pygm&a, and in the higher levels exist for weeks, without complete immersion ; they are consequently deprived of regular branchial currents, which in this case can only have a very limited operation, as in even the most favourable levels they must be deprived of sea- water for very many hours out of the twenty-four. We presume, that when these animals are in elevated positions, the tides washing the bases of their rocky habitats, combined with the saline mixture of floating atmospheric particles, supply sufficient humidity for the sus- tentation and well-being of these singular bivalves. MONTACUTIDJE, Clark. Notwithstanding our disinclination to create new families, we have no choice but to constitute the Montacutida, though it be for only a single species, the Montacuta substriata, a late sojourner of the Kelliada. It has little in common with Kellia (proper), except a partial resemblance in the structure of the hinge and presence of a byssus, but it differs essentially in the absence of the singular and anomalous anterior tubular processes, and the probable want of a viviparous reproduction. With Lepton and Galeomma, both former members of the Kelliadae, now of the Arcadae, to which we refer, it has nothing in common but having a byssus. With Turtonia, also removed from the Kelliadce, it cannot be associated, from the hinge-teeth and internal long linear white cartilage, as in that genus the hinge-ligament is strictly external, and the teeth are altogether of a different composition. No existing genus or family can receive M. substriata without violence to natural order. Therefore, as we have undertaken a new arrangement of the Kelliada, we are bound, as far as possible, in the reconstruction, to march with malacological rigour. MONTACUTA. 95 The only set-off to our chagrin in being compelled to form two new families is, that they will acquire a lasting fame by their titles, in conjunction with the present generic ones, by ministering double honours to two of the most eminent British naturalists, Montagu and Turton. We have already, in our preliminary remarks on the Kel- liada, accounted for the disposal of the Montacuta bidentata, formerly of this family, by its transference to the Anatinidte ; and we now state that the third and last member of Monta- cuta, the M. ferruginosa, Brit. Moll. ii. p. 72, pi. 18. fig. 5, 5 a and 5 b } is consigned to the company of its congener, for the reasons stated under Anatina. MONTACUTA, Turton. M. SUBSTRIATA, Montagu. M. substriata, Brit. Moll. ii. p. 77, pi. 18. f. 8 and 8 a; (animal) pl.O.f. 2. Animal suboval, thick for its size. It has an oblique out- line, the longitudinal measure being greater than the trans- verse ; the body and mantle are pale yellow, the liver dark green; the mantle has a simple margin, and is largely open ventrally for the passage of a hyaline foot, that has a byssal groove at the heel, from which strong coarse filaments issue, and attach it to the ordinary habitat, the spines of the Spatangus purpureus : all the observed specimens were thus attached, and could not be removed without injuring the animal or shell. They were cut off by scissors, and on being placed in a watch-glass of sea-water immediately protruded the large foot, far exceeding in length the shell; it is mus- cular, raised in the centre, bevelled on each side to a fine awl- shaped edge, and tapers to a very rounded termination, not showing a trace of the lanceolate point. Locomotion would appear to be incompatible with the apparently fixed habitat, but it, as well as the other byssal bivalves, has the power, which we have seen them exercise, of changing place. When the animal marches the foot is extended, and its rounded ter- mination is instantly fixed to the vase in which it is deposited; 96 TURTONIAD.E. then by the retractor muscle it is drawn forward, making such rapid progression as to cross a watch-glass in a minute, and on the passage turns itself several times by a twist of the foot from side to side. No siphonal processes, nor even a simple orifice, were observed. When opened, the large foot is the most prominent object ; with a good lens the byssal fissure is distinctly visible. Though there are traces of a branchial lamina, we could not detect its configuration, nor the presence of palpi. In the hinge, under the beaks, there is a minute obsolete primary tooth or two, with only a single compressed triangular lateral, in both valves, but on the longer side only, which is the anterior one. This structure differs much from Kellia. Some malacologists call what we term the lateral teeth in Kellia and this genus, the cardinal ones ; but as in them there is no moveable ossicle, we consider the minute denticles at the edge of the cartilage-pit, directly under the beaks, the primary ones. But the case is different in those minute species styled by authors Montacuta bidentata and M. ferruginosa', these have been removed by us to the Anaim, as they have the characteristic ossicle of the family ; in them there are no minute cardinal teeth, and what in Kellia and Montacuta are termed laterals, here become of cardinal value. TURTONIAD.E, Clark. We have been obliged to establish this family for Turtonia, with a single genus of only one species, planted by authors in the Kelliadce, though it has not the slightest community of attributes or structure with any of the genera of that group. Lepton, Galeomma, Kellia and Montacuta are as far asunder from it as the poles. We mention a convincing proof of its heterogeneity : in all the species of those genera, excepting perhaps Kellia suborbicularis, in which the sides are nearly equal, the shortest is the posterior one; but in Turtonia minuta the longest is posterior, and it is the only animal of these tribes that has a considerably produced anal siphon. TURTONIA. 97 TURTONIA, Hanley. T. MINUTA, O. Fabricius. T. minuta, Brit. Moll. ii. p. 81, pi. 18. f. 7 & 7 a ; (animal) pi. O. f. 1. Mya purpurea, Montagu et Auctorum. I have never seen this animal, and can only record the slight notes of authors, that the foot is very large, strong, geniculated, and issues from the shorter end of the shell ; the mantle is largely open anteriorly, and a slender somewhat produced siphonal tube proceeds from the longer side. The shell, except in contour, in many respects agrees with the Lutirue. The ligament is external, and there are in perfect specimens two cardinal teeth ? in each valve, one or both is often bifid ; the teeth vary much from being deeply cloven ; and thus in some examples the appearance of two, three, or four is presented, and in old shells they are otherwise con- fused and indistinct. The pallial impression is entire; the anterior adductor cicatrix, as in many of the L/uciruR, is rather more extended and at a lower level, but not much more, than the posterior one. Under the microscope we discover traces of the vertical lines so conspicuous in the margin of Lucina borealis ; and we may also state, it is thickened, dull, and somewhat chalky in some specimens. The slender tube also allies it with that section of the Lucirue which have a produced anal conduit. The foot, when exserted, has the ordinary tongue-shaped aspect of most of the minuter bivalves, but that is no proof that it has not the singular tubular structure characteristic of the Luciruse, as even in the type L. borealis and in L. rotun- data, both of which beyond doubt have the true Lucinidan foot, it shows no trace of the singularity when protruded, probably from being inflated with water to produce tension. It is only when the animal is killed and opened that the curious con- figuration of the pedal organ is seen. We do not mean to say that Turtonia is a true Lucina, or even one at all, but merely mention these facts, which may have the value they deserve. But we will endeavour to obtain this animal. All these con- 98 CARDIAD^E. siderations appear to support us in having transferred this species from the Kelliadte to a separate family. It is well to mention that the figure referred to of this animal is incorrect, from the engraver having placed the foot and siphon at the wrong ends ; the position of each should be reversed. A family of only one genus, of nine species. This is a well- marked group by its radiating ribs, which are either nodose, spinous, or vaulted, with interstitial furrows of transverse waved strise. The tubes are short or sessile, but in some species an imperfect pallial siphonal sinus may be seen. The animal is distinguished from every other bivalve tribe by the extraordinary length of the subcylindrical geniculated foot, and by the external surface of the siphons being clothed with long pendulous filaments. CARDIUM, Linnseus. C. ECHINATUM, Linnaeus. C. echinatum, Brit. Moll. ii. p. 7, pi. 33. f. 2. Animal suborbicular, pale yellow; mantle open, with the margin slightly dentated, pale brown, forming a branchial and anal siphon, which are | of an inch long, in a shell of about an inch- and- a-half vertical and transverse measure; they are of a dirty white hue, united or soldered on each other, and have not the aspect of a single sheath ; the anal is rather the shortest and smallest, and protrudes a plain globular valve at its termination; each is fringed with about 15-20 white cirrhi, having at their bases short, dark yellow, and minute close-set brown lines, which give the orifices of the siphons the appearance of being encircled by a fine line, and on the external surface of each there are long, somewhat curved white filaments, which also for a short distance clothe the mantle above and below them. The foot is subcylindrical, CAKDIUM. 99 narrow, geniculated, and of flesh colour, the result of a deli- cate and easily obliterated epidermis, under which it is pure white ; its length is at least twice that of the shell. There are a pair of semi-oval branchiae on each side, the upper one being as long as the lower, but not half the depth of it ; they are pale brown and well-striated on the outer surface, but less so within ; the palpi are of the same colour, very long, slender, pointed, with decided raised vessels on the inside, though less marked externally. We subjoin a separate account of the young shell, which is the C. ciliare of authors, and has been considered as belonging to the C. aculeatum ; but having had opportunities of exami- ning large suites of both species of Jth of an inch to 2^ inches diameter, we can confidently state that it is the young of this species. C. ECHINATUM, JUH. C. ciliare, Auctorum ; Brit. Moll, (animal) pi. N. f. 4, as C. echinatum, jun. Animal suborbicular ; the specimen examined was fths of an inch diameter, pale yellow ; the mantle is muscular, and coarsely dentated at the edge, which character in a great measure disappears in the older shells ; it is open throughout, forming short tubes, the branchial one having about sixteen short cirrhi and minute red points at the base ; the anal siphon has the usual tubular retractile process and twelve cirrhi, which also have red points at the base ; besides the siphonal cirrhi, there are above and below and on the tubes a few coarser white filaments, which are invariable appendages of all the Cardia. There are on each side the body a pair of pale brown roughly striated suboval branchial laminae, the upper being much narrower than the under ones; the striae are apparent on both surfaces; the corresponding pairs of palpi are long, narrow, subtriangular, pointed, and rather more strongly striated on the inner than on the outer sides ; they are pale brown. The foot is very long, at least double the vertical measure of the shell, subcylindrical, narrow, pointed, angulated, and of a pale flesh colour. H2 100 This species is taken abundantly at Exmouth, of all sizes, in the coralline zone. C. EDULE, Linnaeus. C. edule, Brit. Moll. ii. p. 15, pi. 32. f. 1-4; (animal) pi. N. f. 5. Animal suborbicular ; the body is large, subglobose, and of an opake white; mantle pale yellow, edge fringed. The siphonal apparatus forms two short conical tubes, separate from their bases, and divergent; the branchial has ten long white cirrhi, with two or three intermediate shorter ones springing from the orifice, which is encircled by a dark or red-brown line; the anal tube has a similar line, but no cirrhi; it is provided with a retractile tubular valve ; both tubes have on their surfaces the usual characteristic curly white filaments, and they vary from whitish to pale yellow or red- dish-brown. The foot is considerably smaller than in any of the other Cardia, and has very little of the long cylindrical aspect of that organ in its congeners, being rather flat and lanceolate ; its colour varies from opake white to pale brown or yellow. There are a pair of moderate-sized, pale brown, suboval branchiae on each side, finely pectinated, the upper one being much the smallest ; the palpi are red-brown, longish, pointed, flat, and subtriangular, smooth on the outside and pectinated within. There are many varieties of this common species which result from habitat; they are sometimes excessively thin, arising in certain estuaries from a more than usual affusion of fresh with the salt water, and under those conditions have been named by some naturalists C. rusticum. It is proper to observe, that the true Linnsean C. rusticum is a very different species, which has long been known to collectors, though misnamed C. tuberculatum, the strongest and most ponderous of all the Cardia. The young of one of the varieties, from its umbonal transverse bands, has been mistaken for our (7. fas- datum, the C. elongatum of some authors, but the oblique out- line of the latter species will always distinguish it from any of the young fasciated varieties of C. edule. CABDIUM. 101 C. FASCIATUM, Montagu. C.fasciatum, Brit. Moll. ii. p. 25, pi. 32. f. 5 ; (animal) pi. N. f. 3. C. elongatum, Auctorum. Animal suborbicular, body flake-white ; mantle plain. Si- phonal tubes not exserted usually above Jth of an inch, of the same length, united, each with ten simple white cirrhi, and on them are the invariable filamentous appendages. The foot is long, narrow and subcylindrical, or finger-shaped, and, contrary to the Cardia in general, hyaline. The branchiae are subsemicircular, pale brown, the upper one not half the size of the lower, strongly striated on the outside and smoother within; the palpi are very short, triangular but pointed, striated on the outer, and much less on the inner surface. The liver is green and very anterior ; the ovarium white, and full of ova on 4th of August. It inhabits the coralline zone, and is rare at Exmouth. C. NODOSUM, Turton. C. nodosum, Brit. Moll. ii. p. 22, pi. 32. f. 7. C. muricatulum, juv., Auctorum. Animal subglobose ; mantle open, edged with white pointed filaments issuing from the points of the mantle corresponding to the ribs. The siphons are pale yellow and very short, each with ten or twelve flake-white cirrhi at the orifices and red points at the bases, with the addition of the curved white filaments above, below, and on the tubes; the anal one pro< trudes the usual retractile valve. The foot is white, mode- rately long, subcylindrical, and slightly geniculated. There are a pair of semi- oval branchiae on each side, the upper is not half the length and breadth of the under one ; they are strongly pectinated on the upper, and less on the lower surface; there are two very small triangular palpi on each side, pectinated in a similar manner with the branchiae. This species, at Exmouth, is only met with in the coralline zone, but it is not uncommon. We have ascertained by a comparison of the C. muricatulum of authors, of sizes of less than y^th-^ths of an inch dia- 102 CAKDIADJE. meter, with the animals of the C. nodosum, that they are identical. If it had been our practice to generalize, the singular same- ness of the organs of this genus would have authorized a departure from the plan of detailing the specialties of every case : the present work is not intended to be subjected to the dull and heavy labour of being doggedly read through con- secutively; we consider it one of particular reference, and think that we have done good service to the reader in stating the specialties at length in nearly every case. C. NORVEGICUM, Spengler. C. norvegicum, Brit. Moll. ii. p. 35, pi. 31. f. 1, 2; (animal) pi. N. f. 1. C. Icevigatum, Auctorum. Animal thick, suboval, elongated, the vertical measure exceeding the transverse; the mantle is closed throughout the posterior range, and at its lower part forms two short siphons united at their bases and divergent at the extremities, of a pale yellow, marked with flake-white spots and lines ; the branchial tube is rather the shorter, but of greater diameter, and is rarely extended more than half an inch ; its orifice is circled with twenty long yellowish- white cirrhi, having dull red-brown markings around their bases; the anal siphon is simple, and has the usual retractile valve, which is marked on the lower and upper surface with a faint red-brown line, and points of the same colour at the termination. The siphons and the posterior range are clothed with thick-set pale reddish- brown and pale yellow curved filaments. The mantle, from the point where the filaments terminate, is simple and open, with its outer and inner margin of a flesh colour, and affords a passage to a long, powerful, geniculated, cylindrical foot, that has a pointed termination; its substance is rigid, and, except the white point, of a red flesh colour, which the slightest touch removes and shows the white ground ; it is longer than the greatest measure of the shell, and its epidermis appears shagreened and marked with anastomosing fine lines. There are on each side a pair of pale brown suboval branchiae, with the margins of a deeper brown ; the upper one is considerably CAKDIUM. 103 smaller and of less depth than the under one ; they hang more vertically than those of its congeners, and the transverse pectinations are more conspicuous without than within ; the palpi are very long, triangular, united by a labium around the mouth, and with the branchial laminae by a membranous filament ; they are more strongly striated on the inner than on the outer areas. This elegant species is frequently obtained by the dredge in the coralline district at Exmouth. The following species have not occurred to us alive : C. RUSTICUM, Linnaeus. C. rusticum, Brit. Moll. ii. p. 11, pi. 31. f. 3, 4. C. ACULEATUM, Linnaeus. C. aculeatum, Brit. Moll. ii. p. 4, pi. 33. f. 1. C. PYGM.EUM, Donovan. C. pygmteum, Brit. Moll. ii. p. 29, pi. 32. f. 8 ; (animal) pi. N. f. 2. C. SUECICUM, Reeve. C. suecicum, Brit. Moll. ii. p. 33, pi. 32. f. 6. The last may be a young delicate var. of C. edule. MACTRID.E. This is one of the old Linnaean families, with only a single genus, so distinctly characterized as to require few remarks ; it contains four British species. By its open mantle and short tubes it is allied to the Veneres, but we cannot concur in the opinion of some authors, that it presents many features of the Myadas. We take the liberty of saying, that it will be very difficult to find a single accordant point between the two families, except the generalities of every bivalve. Mactra and My a are far asunder : the former has the mantle open, short tubes, and very circumscribed in length, suboval, broad branchiae ; in the latter, the branchiae are narrow, elongated, with a part of them lying in the branchial tube ; the mantle is quite closed, and the siphonal apparatus particularly long. The dentition of the two families is entirely different, with the 104 MACTRID^E. exception of the V-shaped tooth in Lutraria, which genus in our method belongs to the Myadae. MACTRA, Linnaeus. M. STULTORUM, Linnaeus et Auct. M. stultorum, Brit. Moll. i. p. 362, pi. 22. f. 4, 6; and pi. 26. f. 2. Animal suboval, of the palest bluish- white ; mantle open throughout the ventral range, its edge is clothed with a de- licate intensely white fringe of short filaments ; both siphons are short, of the same length, united, covered by a fine brown deposit, which appears to be independent of the epidermis 011 the shell ; the united tubes are never exserted more than half an inch, their orifices are fringed with simple dirty pale red cirrhi; the branchial, which is the longest, with 12-16, the anal has 14-20. The lower part of the body is white, and the dorsal range, containing the brownish-green liver and ovarium, of a dull opake white. The foot is thick, long, bevelled to a sharp margin, and extensible from all the phases of obtuseness to the pointed lanceolate extremity. There are on each side the body two suboval, brown or drab-coloured branchiae, the upper the smallest, and obliquely very finely striated by the vessels of the circulation. The palpi are long, triangular and pointed, of an opake brown, more distinctly pectinated than the branchiae, particularly on the inner sur- face. It has been omitted to be stated that the anal tube is provided with an exsertile hyaline valve, and our experience positively entitles us to say, that the anal tube of almost every bivalve is usually furnished with that appendage, the use of which is doubtless to regulate the entry and issue of the water, which has probably a communication with the ovarium, as well as for other functional purposes, which are alluded to in our remarks on the Pholadida, in the section on the branchial currents. This tubular retractile valve is never attached to the branchial siphon; at least we can bring no instance of its presence to our recollection. This is a littoral animal, and often, after a gale, is abun- MACTKA. 105 dantly cast on the Warren Sands, at Exmouth, from whence we obtained our finest specimens. M. SUBTRUNCATA, Da Costa. M. subtruncata, Brit. Moll. i. p. 358, pi. 21. f. 8; and pi. 22. f. 2; (siphons) pi. L. f. 3. As the external organs of the Madras are very similar, it will only be necessaiy to mention the variations of some of the succeeding species from the M. stultorum, which may be considered the type of the genus. The present animal differs in having no fringe to the margin of the mantle, at least none could be detected ; the siphons are united as in M. . stultorum, and clothed with an evanescent epidermis ; the orifices have simple pale red, white or yellow cirrhi ; and we may conclude our account by observing, that the branchiae and palpi are of a pale brown, and that the foot is of a paler yellow, narrower than in its congener the M. stultorum. We have in this instance, and one or two others, departed from the usual plan of a detailed description ; it is an example of the inconvenience attendant on the omission, as we are here obliged to have recourse to our notes of another species to complete the present one. We think, if possible, such references should be avoided. M. SOLIDA, Linnaeus. M. solida, Brit. Moll. i. p. 351, pi. 22. f. 1, 5; (siphons) pi. L. f. 2. M. truncata, Brit. Moll. i. p. 354, pi. 23. f. 1 ; and iv. p. 253. The animal, like the M. stultorum , has the margin of the mantle fringed; the siphonal canals, as to structure and arrangement, are the same as in the two former species, and of a pale brown colour; the branchial one, which is the largest, has about sixteen, and the anal twenty, shorter pale yellow, or brown, or reddish cirrhi at their orifices, which vary greatly in different localities. The branchiae and palpi differ from the preceding animals in being of a deeper brown, with a decided reddish hue ; otherwise they are of the same shape, and nearly with similar pectinations. The M. solida varies in shape in every locality ; in some it is flat-sided, tumid, and 106 MACTEID^E. triangular; in others, compressed, sharp at the sides, and transversely produced, which variations have caused even the excellent Montagu to err in the creation of his M. truncata from one or other of the varieties of the M. solida or of the M. subtruncata. Without being positively certain, we think the M. truncata of authors must be expunged as a species ; and whether it be a synonym, of the M. solida or M. sub- truncata is doubtful; at any rate, all the shells that have been as yet shown us are referable to one or other of these species. The contour of the M. solida, which is taken abundantly at Exmouth at low water, in the sandy ranges adjoining the Mare rocks, is of the tumid and subtriangular variety : it is from this locality that Dr. Turton obtained the types of his M. crass a. M. ELLIPTICA, Brown. M. elliptica, Brit. Moll. i. p. 356, pi. 22. f. 3 ; (animal) pi. L. f. 1. Animal suboval, compressed ; body flake-white ; liver green, scarcely visible, being covered by the opake white tough dorsal skin ; mantle open, very slightly fringed anteally, plain pos- teally ; siphonal tubes in a specimen f of an inch transverse by \ an inch vertical measure, are not exserted more than fths of an inch, and appear as if enveloped in a sheath; each orifice has about twelve cirrhi at their bases, below which a bright orange line encircles the sheath, which is of pale yellow. The branchiae are light orange, subsemicircular, the upper being much smaller than the lower, and very finely pectinated. The palpi are long, narrow, pointed, pale brown, and more conspicuously striated than the laminae. Foot white, rather large, muscular and lanceolate, by the aid of which the animal turns its shell, with great ease, from side to side. This species appears distinct, and though it is difficult to define distinctions by the organs, which in all the Mactrte are so similar, still there is a delicacy and elegance in the appear- ance of this creature which almost assures us that it is not a dwarfish variety of the M. solida } which at Exmouth is strictly a MACTKA. 107 littoral species, while the M . elliptica is never taken, except by the dredge in the coralline zone, six miles from the shore. M. HELVACEA, Chemnitz. M, helvacea, Brit. Moll. i. p. 366, pi. 23. f. 2. M. glauca, Anglorum. This splendid shell is not British. We have the authority of the French oystermen who bring cargoes of oysters into the port of Exmouth, to plant in the parks, on the Exe, at Lympstone, that it does not even inhabit the Guernsey or Jersey grounds, and that it is a French littoral or laminarian species, and only taken on the in-shore oyster-beds. We have often procured it, the Pileopsis hungaricus, Calyptr. - aurea, Brit. Moll. i. p. 392, pi. 25. f. 5. Venus Sarniensis, anea, nitens, Turt. et Auctorum. Animal inhabiting a suboval shell, furnished with close-set, blunt, rounded, stout, subconcentric striae ; the ground colour is pale yellowish- white ; the mantle is open throughout the ventral range, with its margins anteally dentated, medially sinuatcd, and posteally crenulated, with a few short yellow filaments at each extremity ; the animal emits anteriorly the PULL ASTRA. 121 usual thick fleshy linguiform foot, very moderately geniculated, and capable of all the phases from obtuse to pointed; it is pure white, and has not the byssal groove of the tribe, which is a considerable variation of structure, and the teeth are not so slender, long, or parallel, more resembling those of Venus, from which this animal scarcely defers. The mantle pos- teriorly forms the siphons, which are soldered together three parts of their length, becoming separated for the remaining portion ; the colour is delicate pale lemon, tinged with red- brown at the bifurcation; they are of the same size, the branchial being truncate at the extremity, and clothed with fourteen pointed cirrhi, whereof seven are rather the largest, marked at their bases on each side with a patch of bistre, the interstitial ones are white ; the anal tube curves upwards as in its congeners, and does not appear truncate, in consequence of its edges being a little inflexed ; it has sixteen short white cirrhi at the orifice, which has also around it a dirty red-brown fine line ; the tubes, when folly extended, are less long than in the two preceding species ; they do not, as in Venus, measure more than half the transverse measure of the shell. The pair of subcircular branchiae on each side are pale drab, hung very obliquely; the under ones are at least double the size of the upper, and strongly marked by the transverse vessels of the circulation; the palpi are subtriangular, short, and well striated. The liver appears scanty and of a pale green. This species inhabits the coralline zone at Exmouth, but is rarely taken alive; dead shells in good condition are frequent. We almost think that this species and its variety the P. Sar- niensis should, from the absence of the byssal groove and the greater divergence of the teeth from the type, be transferred to the Veneres. The P. aurea has not occurred alive; is it distinct from the present species? the teeth of the two are of similar character, and if it is without the byssal groove, it would appear that it ought to accompany the P. virginea to the typical Veneres. 122 DONACIDJE. DONACID^E. If this family had only consisted of the genus Donax, we would have united it to the Tellmidce', but as it is conjoined to Ervilia, a more aberrant genus, we adopt it. The siphons appear to be shorter than in the Tellinidce, and their cilia of a more complicated structure ; the dentition is also less simple. There are only three undoubted British species, two in Donax, D. anatinus and D. politus the D. trunculus is probably exotic and one in Ervilia, the E. castanea. DONAX, Linnjeus. D. ANATINUS, Lamarck. D. anatinus, Brit. Moll. i. p. 332, pi. 21. f. 4,5,6; (animal) pi. K. f. 1. Animal elongated, of a purplish- red or yellow ; mantle open on the ventral range, with double margins, the one short, with sinuated or scalloped edges; the other and outer is clothed with three rows of fringe, the two inner being two sizes of moniliform white beads ; the outermost or third row has short, close-set, fine filaments of similar colour, altogether presenting a very elegant appearance. The siphons are of the same length, and, when fully exserted, are not more than half an inch; they do not put on a cylindrical aspect, but appear laterally compressed; they are separate from the bases, and taper gradually to their terminations, which are bordered with very pale orange colour ; the anal siphon is rather the smallest, and furnished with about six white cirrhi; the branchial has 8-10 longer ones, which are fimbriated at the sides, besides plain ones interspersed; when the cirrhi are withdrawn, the terminations of the tubes have a truncate and naked aspect ; a good lens must be used to see their minute developments. The foot is yellow or orange, especially when the animal has been immersed in hot water, very large, flat, bevelled to a sharp edge and lanceolate point when fully DON AX. ERVILIA. 123 extended, but at rest, or half exserted, it is puckered and transversely ridged. There are a pair of light brown suboval branchiae on each side, the upper ones being less and shorter than the lower, hung more obliquely, and scarcely visibly pectinated on either side ; the palpi are rather long, triangular, pale yellow, smooth exteriorly, and well striated on the inner areas. The liver is a pale brown-green. The stylet and attritor are well developed. The ovarium varies in colour from white or yellow to bright red ; it is anterior and under the liver. The rectum, after a convolution or two, passes through the dorsal region, embraced by the heart and white linear auricles, to the anal tube. These beautiful shells are plentifully found with the live animal at Exmouth, and in the littoral and laminarian zones of the Warren sands, between that place and Dawlish. We have not met with the D. politus alive or dead on the western coasts ; we refer to it D. POLITUS, Poli. D. politus, Brit. Moll. i. p. 336, pi. 21. f. 7. D. complanatus, Auctorum. ERVILIA, Turton. E. CASTANEA, Montagu. E. castanea, Brit. Moll. i. p. 341, pi. 31. f. 5, 6. All that can be said of this animal is, that it has not been observed, though we believe it has been taken alive on the Irish coasts by Mr. Barlee, who favoured us with a small fresh specimen. We trust that indefatigable naturalist will, in an excursion he contemplates again to explore the sea-beds of the Emerald Isle, make us acquainted with the external organs of this interesting species. TELLINIDJE. The British TeUinida are distributed in four genera, Tellina, Scrobicularia, Syndosmya, and Lacinopsis ; their 124 TELLINIDvE. shells are, with few exceptions, thin, delicate, of small size, generally having the transverse measure double that of the vertical ; the siphons of the animal are slender, usually sepa- rated to their bases, nearly as proportionately long as in the Pholades, and sparingly cirrhated at their terminations. We consider the posterior flexure of the shell of little distinctive value : all bivalves have it more or less. The most curious incident attached to some of the Tellinidan genera is, the amalgamation of each pair of branchiae into one large lamina, the upper plate being as it were thrown back and perma- nently fixed to the dorsal range, as in the Anatinte a com- munity of structure showing a close alliance between the two families. The genera and species of this group exhibit a greater departure from what are considered the typical points of configuration, than in most others; for example, the external and internal ligament and cartilage march together, as well as the double and single branchiae ; but, notwith- standing the discrepancies of structure, these aberrant genera and species have so much of the family character that they cannot well be placed elsewhere. It may hereafter be necessary to recast the Tellinidce, and constitute some new families and genera ; for the present, we shall distribute the different groups into sections embracing their aberrations and peculiarities in respect to the typical configuration, but we still hope to supply some useful rectifications. The animals of Tellina and Psammobia are all but identical ; a rigorous examination of both does not allow us to state an essential difference either in the internal or external organs ; their shells also scarcely vary ; the posterior flexure in Psam- mobia is almost as apparent as in Tellina. We think the genus might have been dispensed with ; it is probably retained by authors because it forms a break in a long list, if the exotics are included ; but that is not a sound reason for constituting two genera without a difference. We think that an essential service is done to science in relieving it of an artificial genus ; therefore, in our method, Psammobia is merged in Tellina, which forms the first or typical section. As to the supposed difference in the lateral dentition of Tellina and Psammobia, TELLINA. 125 it is of little value, if it even existed, compared with the over- whelming similitude of the entire soft parts, habitudes and habitats of the animals; and we may observe, that in the so-called Psammobia, distinct lateral teeth are often present as well as absent ; the same may be said of Tellina, but in both there are almost always obsolete traces of such laminae. The next section is a small tribe, which, with the external ligament and ordinary dentition of the Tellina, have only one large amalgamated branchial lamina on each side. Lucinopsis next follows, which- we have shown to be nearly a strict Tellina. And lastly, Syndosmya and Scrobicularia, furnished with a ligament, that is, both external and internal, besides a spoon-shaped cavity for an internal cartilage, complete the Tellinidan category; these may hereafter constitute two distinct families, as the former has double branchiae and the latter only one large lamina, as in the 2nd section, but cannot be placed in it on account of the very different hinge. These are the most aberrant of the Tellinida, and immediately con- nect this group with the Anatinidce. The genus Diodonta of Deshayes has been introduced into the British list to receive the Tellina fragilis of Linnaeus and authors. It seems a very useless and artificial one, based on the teeth, and has no new characteristic that differs from Tellina at least we can discover none. We dispense with the genus in its present form, and deposit its only species in the 2nd section of this family. TELLINA, Linnaeus. Section I. The typical species. T. DONACINA, Linnaeus. T. donacina, Brit. Moll. i. p. 292, pi. 20. f. 3, 4 ; (animal) pi. K. f. 4. T. pygmaa, Brit. Moll. i. p. 295, pi. 19. f. 6, 7. Animal oblong, compressed; mantle largely open, not fringed, but finely dentated. Siphonal tubes long, separate from their bases, plain and simple. Foot pure white, flat, broad, long, and lanceolate. On each side of the body there are a pair of pale brown suboval branchiae, nearly of the same 126 TELLINIDJE. size, smooth on the outer surfaces, and on the inner striated with about thirty of the delicate vessels of the branchial circu- lation ; the corresponding pairs of subtriangular palpi are also pale brown, smooth on the outside, except showing a longi- tudinal furrow, and pectinated within. These beautiful shells are frequently taken alive in the coralline zone at Exmouth. This animal may be placed, par excellence, at the head of the typical species. T. CRASSA, Montagu. T. crassa, Brit. Moll. i. p. 288, pi. 20. f. 1, 2. Animal suborbicular, lentiform ; the general ground colour is pale drab ; mantle quite open, double-edged, finely, closely and conspicuously fringed, produced posteriorly into two long rather slender siphons, separate from their bases, the branchial quite plain at its termination ; the upper or anal one, which is apparently rather the largest in diameter, and capable of great inflation, has six triangular points at the orifice ; their ground colour is marked with two or three intenser whitish longitudinal lines. I am unable to state how far the tubes can be extended, as the animal was sent to Bath in 1851, wrapped in moist sea- weed, accompanied by bottles of sea- water, and had become partially collapsed ; but I should think, judging from other Tellints, that in the specimen exa- mined they would, when fully exserted, be at least 2 inches long. The shell was the largest I had ever seen, measuring transversely 2J, and vertically 2J inches. The foot is the usual large, spatulate, thick, muscular, linguiform appendage of the Tellinte, perfectly simple, without a trace of a groove in the heel. The pair of branchiae on each side are subcircular, of very thin texture, the lower of great extent, the upper not half the depth of its larger fellow ; both coarsely but not distinctly pectinated. The palpi, a pair on each side, are nar- row, slender, pointed, of a very elongated triangular shape, quite smooth externally, but well striated within. The liver is anterior, of a dark brownish-green ; the stomach contained the usual tricuspid membrane, or attritor, and the crystalline stylet of large size. The heart, auricles, nervous ganglia, with TELLINJL 127 the stomach and intestine, exhibited no peculiarity. The large posterior dorsal mucous gland was well developed, the colour being a moderately dark brown : this gland crosses the dorsal line near the posterior adductor, and perhaps is a receptacle for the pigments of the mantle. This species inhabits the coralline zone at Exmouth, but is rarely taken alive of good size. T. FERROENSIS, Chemnitz et nobis. Psammobia ferroensis, Brit. Moll. i. p. 274, pi. 19. f. 3. Animal elongated, compressed, white or of the palest brown ; mantle open, with the margin clothed with a short white fringe, or rather fine dentations. The siphonal apparatus con- sists of the usual slender separated tubes, the branchial being rather the longest and largest, having six plain cirrhi at the orifice ; when not fully extended it appears finely corrugated, and has two longitudinal bars on the surface ; the anal siphon curves upwards, the orifice being destitute of cirrhi. The foot is very large, flat, long, bevelled to a sharp edge, and lanceo- late. There are a pair of branchiae and a pair of palpi on each side ; the under lamina are by far the largest, long, deep, and subquadrangular ; the upper ones are not above half the size, of suboval shape, and have a lanceolate ter- mination, hanging on the posterior portion of the large ones ; they are all visibly striated on both surfaces; the palpi are long, subtriangular, and very well pectinated. The liver is pale green, conjoined with the pale yellow ovarium, which in July is foil of ova in all states of development. This elegant and variously coloured species as to the shell, is frequently taken in the dredge in the coral zone in a living state. T. TELLINELLA, Psammobia tellinella, Brit. Moll. i. p. 2/7, pi. 19. f. 4; and (animal) pi. K. f. 1. P. florida, Turton. Animal elongated, compressed, pure white; mantle open, dentated ventrally, and fringed posteriorly from the beaks to 128 TELLINDLE. the tubes. The siphons are moderately long, disunited, taper- ing and divergent; the anal one is the longest and most slender, curving upwards with exceedingly minute cirrhi at the extremity, of frosted white, and eight intenser longitudinal fine lines running from base to point ; the branchial siphon is also frosted white, having six short cirrhi at the orifice, and intermediate shorter ones. There are a pair of pale brown suboval branchiae, which hang obliquely; the upper very small, lapping on the much larger lower ones almost verti- cally ; they are on both sides coarsely striated, the larger by only eight vessels of the circulation, separated from each other by as many fine lines. The pairs of palpi are rather long, subtriangular, pointed, pale brown, smooth outwardly, and within coarsely pectinated transversely, not having the furrow as in those of T. donacina. Foot flat, sharp-edged, slightly geniculated, linguiform, lanceolate at the point and pure white. These animals are dredged in abundance at Exmouth, in a six-mile offing. The following species have not been met with alive. T. INCARNATA, Linnseus. T. incarnata, Brit. Moll. i. p. 298, pi. 20. f. 5. T. BALAUSTINA, LimttEUS. T. balaustina, Brit. Moll. i. p. 290, pi. 21. f. 2. T. FABULA, Gronovius. T.fabula, Brit. Moll. i. p. 302, pi. 19. f. 9. T. PROXIMA, ? Brown. T.proxima, Brit. Moll. i. p. 307, pi. 21. f. 1. T. BRIMACULATA, Linnseus. T. brimaculata, Brit. Moll. i. p. 309. T. VESPERTINA, Chemnitz. Psammobia vespertina, Brit. Moll. i. p. 271, pi. 19. f. 1, 2. T. COSTULATA, Auctorum et nobis. Psammobia costulata, Brit. Moll. i. p. 279, pi. 19. f. 5. We are not certain, though we believe most of the above belong to this section ; but we have doubts on the T.fabula, as the authors of the 'British Mollusca' observe that its TELLINA. 129 animal is like that of T. tennis, which has only a single amal- gamated branchial lamina on each side, and belongs to our second section ; in that case, the T. fabula must march with it. But this point may easily be set at rest, as the species is common, though not in my district. The T. proximo, is exotic or fossil. The T. bimaculata is exotic. The T. balaustina of British origin has much similarity to specimens of T. crassa of the same size ; the hinge, teeth, cica- trices, and pink radiating pencils are identical ; the chief dif- ference is the greater tumidity and tenuity of the valves, and the absence of the short vertical lines between the striae of increment. Section II. Animal with a single branchia on each side. T. TENUIS, Da Costa. T. tennis, Brit. Moll. i. p. 300, pi. 19, f. 8; and (animal) pi. K. f. 3. Animal very flat ; mantle sufficiently open in the ventral range, finely fringed, produced posteriorly into two white siphons, separated from their bases, of about equal length and diameter ; both of them are often exserted beyond the length of the shell ; the anal is usually the longest, and curves up- wards; but these circumstances depend on the will of the animal. There is only one very large pale brown, excessively membranous, subtriangular branchia, on each side, with the finest pectinations, fixed under the posterior dorsal range, where its point becomes united with that of the one on the other side, exactly as in T 7 . splidula, but its margin is not fixed to the body so decidedly ; it is more lax, and can be elevated by a camePs-hair brush, and is connected at the anterior angle by a branchial vein, with a pair on each side of large triangular palpi, but not so much out of size as in T. solidula and Scrobicularia piperata ; they are pectinated on both sides, but more so on the inner surfaces ; the colour is a darkish cloud hue, mixed with paler lines, giving them a mottled aspect ; they are broad at the bases, not very long or pointed. The foot is large, broad, compressed, tongue-shaped, not very pointed, and geniculated. The liver is dark green ; 130 TELLINIDJE. the ovary anterior, running to the lower part of the body, is at this season (July) full of white ova in various stages of maturation. The stylet and stomachal attritor are present ; indeed we believe that they may be found in every bivalve. These notes, with those on T. solidula, suggest the query, ought not the two, and any other of similar branchial struc- ture, to be removed from the typical Telling, to a distinct Tellinidan genus ? The singular character of the single com- pound branchial plate on each side, their oblique, almost vertical position, together with the form, disposition and enormous size of the two pair of triangular palpi, so entirely different in the Tellina of the first section, would appear to sanction such a procedure. T. SOLIDULA, Pulteney. T. solidula, Brit. Moll. i. p. 304, pi. 20. f. 6. Animal suboval, thick ; mantle of strong and firm texture, tumid at the margins, which have a fine short lead-coloured fringe, closed posteriorly, and forming two very long hyaline siphons ; the anal one turns upward, and is often exserted to almost twice the length of the shell, plain at the orifice ; the branchial is usually less extended, and has 46 very minute dentations at the aperture ; in the protrusion of the tubes the animal is very capricious, often exserting the branchial far beyond the anal one and vice versa, which has led authors into descriptive mistakes. The siphons are disunited from their bases. The foot is white, very large, thick and fleshy, of a lanceolate shape, but not very long and pointed, geniculated, and without byssal groove. The branchial apparatus is cu- rious, and a departure from the Tellina type ; it consists of a single rather elongated branchial plate, on each side, situated towards the posterior half of the animal ; it is fixed to the dorsal range by its base running obliquely, indeed almost vertically from the dorsal to the ventral range, becoming joined to its fellow under the posterior and smaller part of the body, by a permanent membrane. The whole area of the plate is well fixed, the two sides being scarcely free at the TELLINA. 131 edges; the branchial artery divides it nearly in two equal parts ; it may be considered as a pair of laminae, which, instead of being folded or falling on each other, as in the ordinary bivalves, are thrown open and permanently fixed to the poste- rior area of the body. The colour is brownish drab, with a yellow or fawn-coloured patch in two or three places ; anteally there are on each side two enormous triangular, broad at their bases, pointed palpi, smooth without and well striated within ; they are so large as nearly to have the aspect of small pairs of branchiae ; they are in connection by one of their angles with the branchial plate, and with each other by labia around the mouth. The colour is drab, aspersed with very minute sand- like, pale red-brown points. The liver is brownish-green and united anteriorly with the ovarium. The elastic stylet and corneous stomach attritor, called by most authors the tricuspid membrane, is particularly firm and conspicuous in this species. It thus appears that our present animal differs greatly from the typical Tellina, in the branchial plate and character of the palpi, and thick obtuse foot. This species has also a rather close alliance with Scrobicu- laria piper ata, which has like it only one compound branchia on each side. T. FRAGILIS, Linn, et Auctorum. T. fragilis, Philippi, Moll. Siciliae. Diodontafragilis, Brit. Moll. i. p. 284, pi. 21. f. 3 ; (animal) pi. K. f.2. We are not aware that any British author has observed this species. The following is a translation from M. Phi- lippi's very insufficient notice of it, in the 'Enum. Moll. Sicilise/ vol. i. p. 28 : "Animal with two siphons, the lower or branchial being nearly double the length of the shell, the upper scarcely so long as the shell; without cirrhi at the orifices ; the foot is small, oblong, lanceolate, with very large oval palpi." We can say nothing of M. Deshayes 3 description of the animal organs. In the ' British Mollusca ' we have some further particulars : Mantle fimbriated at the edge ; siphons of unequal lengths, separated from the bases, and, contrary to K2 132 TELLINIDvE. Philippi, stated to be cirrhated at their apertures; foot not very large, without byssal groove. Nothing is said in either account of the branchiae, and Philippi only observes that the animal has very "large oval palpi"; from which we hazard an opinion that it may belong to our second section, in which there is only one compound branchial lamina, and excessively large palpi on each side of the body. In these extracts we have a strict description of a true Tellinidan, of either the first or second section. The teeth also are those of a Tellina, either without or with obsolete laterals. Diodonta therefore is only synonymous with a Tellina of one or other of the sections. But if, from the very considerable variation of animal structure in the two divisions, it should be thought advisable to con- stitute a distinct genus for the second section, with the single compound branchia on each side, and Diodonta should realize our conjectures as to a similar form of the organs, it would have priority over any other generic term, and in that case would receive as congeners T. tennis, T. solidula, and perhaps T. fabula. These are the reasons that have induced us provisionally to deposit the T. fragilis in the second section, until we have farther information on the required points. And we invite naturalists who are in the vicinity of this interesting species publicly to record their notes. LUCINOPSIS, Forbes and Hanley. The Venus undata of the older conchological authorities, which has been justly separated from Venus by more recent writers under various appellations, and particularly by the learned authors of the ' British Mollusca ' under the title of Lucinopsis undata, has given rise to much difference of opinion amongst malacologists in regard to its natural position. Though the shell of this species, anomalous in several points, has long been known, the aggregation of the curious charac- ters of its animal has never been sufficiently described, from the difficulty of procuring it alive of large size. The quotation from my manuscript in the ' British Mollusca ' is the result of LUCINOPSIS. 133 the examination of very small specimens, not more than of an inch diameter, though it is as correct and full as could well be expected from such materials ; but the receipt from Exmouth of adult lively examples of If inch diameter, has enabled me to review and add to it several unrecorded features, which I think will interest malacologists, and show that this peculiar genus has scarcely yet received its precise natural allocation; and many important circumstances will be de- veloped, which may assist to determine the proper station of some other bivalve molluscan groups, by the concatenation of characters exhibited by this animal, illustrative of its con- nection with them. L. UNDATA, Pennant. L. undata, Brit. Moll. i. p. 435, pi. 28. f. 1, 2 ; (animal) pi. M. f. 2. Venus undata, Auctorum. Animal inhabiting a shell of thin and fragile texture, like many of the Tellina, irregularly subrotund, and not exhibiting the decided lenticular form of its shell ; the general colour is pale pinkish-drab, which, when the animal has been killed by hot water, often changes to +he various hues of orange, red, and brown: this remark is of some importance as regards correct description, for under similar circumstances this con- dition prevails more or less in all the testaceous Mollusca, and particularly in the bivalves. The mantle has its edges sinuated or furbelowed, in some examples irregularly jagged, but not serrated; the ventral aperture is very contracted, only affording space for the issue of a moderately sized foot, in consequence of the basal position and very large size of the posterior adductor; and though the anterior one is nearer the dorsal region, it also, from the length, contributes to the smalmess of the pedal aperture ; the mantle is produced posteriorly into two very long pale orange siphons, divergent and separated to their bases; the branchial one is the smallest and longest, being in adult examples in full extension 1J inch long, and having the extremity margined by a circle of very short, minute dark lines, blotches or dots, with 16-20 white cirrhi of irregular sizes and lengths ; the anal siphon is of rather 134 larger diameter, and when protruded is barely an inch in length; its extremity is furnished with 1215 white, short cirrhi, of more uniform length than in the branchial ; it has not the dark terminal margin of points : the usual hyaline valve was not observed, but it probably exists. This siphonal apparatus has the entire aspect of that of the typical Tellinidee ; but its position when exserted is singular, being very little posterior to the centre of the ventral range, instead of being, as is more usual, protruded from a posterior angle somewhat more basal than a right one to a vertical line drawn from the beaks to the ventral centre; this nearly central basal site is occasioned by the great size and low position of the posterior adductor, which necessarily compels the issue I have described. The foot is white, not large, flat, bevelled, pointed, very little geniculated, without a byssal groove, scarcely differing from the Tellincs and some of the Veneres ; it also, from the causes assigned to the siphons, has a more basal position than usual when protruded, with a very limited anterior action, from which it may be inferred that the motive power is con- fined to the turning from side to side and on its centre. The branchiae are subcircular, the upper plates being much less than the lower, half lapping on them, pale drab, with mode- rately fine but not very distinct pectinations ; the pair of palpi on each side are fleshy, rather long, triangular, pointed, strongly pectinated on the outsides, smooth within, and con- nected with each other around the mouth ; they are also light drab. The body is pale pink, small and subglobular, having the foot fixed to its centre. The liver is grass-green. I have already alluded to the texture of the shell, but it is necessary to add, that in the right valve there are two laminar primary teeth, and in the left two similar ones, with a strong double tooth between them : there are no laterals. It would then appear, that the texture of the shell, the two laminar teeth in the right valve, and the exact similitude to the typical Tellime , of the very long, slender, divergent siphonal apparatus having each tube completely separated to the base, ally this animal by many degrees nearer to the Tellinida than LUCINOPSIS. 135 to the Venerida, as none of the genera of the latter family have any resemblance to this siphonal condition; still it cannot be lost sight of, that the three primary teeth in the left valve, which appear in no tribe but in that of the Veneres, give it a decided connecting link with them. As to the alliance of Lucinopsis with Lucina, it is not very near, and principally consists in its lenticular shape, which, however, is that of many of the Veneres, so that a less signi- ficant appellation might have been preferable. I must likewise observe, that there are some differences of shape and position from either the Tellina or Veneres in the adductor cicatrices of Lucinopsis, which have a slight approach to the Lucina ; in other respects there is little in common between the two, there being no siphonal apparatus, and a very peculiar foot in Lucina. These remarks may induce malacologists to take into con- sideration, that, the Tellinidas and Veneridae being so closely allied by the intervention of Lucinopsis, it would be desirable to remove Mactra into the vicinity of Cyprina, to precede it and follow Cardium, in which case the line would march thus : Cardiadas, Mactrida, Cyprinidce, the Venerid and, though much more closely related to the Pyramidellidce, it could not be deposited therein without an inconvenient alteration of some of the characters 2c 2 HETEKOPHEOSYNIDJE. of that family ; no other can receive it, and it is only by this mode we have escaped from our dilemma. JEFFREYSIA. J. DIAPHANA, Alder. J. diaphana, Brit. Moll. iii. p. 152, pi. 76. f. 1. Animal inhabiting a thin, glabrous, snow-white spiral shell of four and a half tumid volutions. Mantle pale yellow, even with the shell. The head is short and flat, and so deeply cloven as to form two distinct flake-white divergent spatulate lobes, with the mouth at the angle of the fissure. These processes have the appearance of a pair of tentacula, but the true ones are external to them, of hyaline flake-white, not very slender nor pointed, and are rather longer than the pseudo-tentacula. The eyes are large, black, placed very far back, on small, very slightly raised eminences, surrounded by a lucid spot or circle issuing from the skin a little within the internal portion of the bases of the tentacula ; they are never exposed, but always carried on the march within the shell, where, from its hyaline nature, they can easily be seen. Foot rather long, but not slender, auricled in front, gradually tapering to a rounded point without any sort of caudal appendage, but with a slight longitudinal medial line on the under surface. The subtestaceous operculum is placed at a little distance from the posterior upper termination of a simple operculigerous lobe ; it is of suboval form, pointed at one end and rounded at the other ; it has marked subannular striae of increment, and is of very pale colour. We have omitted to mention that the operculigerous lobe extends laterally a trifle beyond the pedal disk, forming very narrow arcuated seg- ments. The whole of the foot beneath, as well as at the posterior end above, is pale yellow, but the upper anterior portion with the neck and head, from the mouth posteally, is marked with excessively minute, close-set, red-brown points. The three posterior volutions are occupied by the viscera, comprising an intensely dark red-brown liver, which, with the JEFPEEYSIA. 389 ovarium, when present, between the lobes, are very conspi- cuous through the tenuity of the shell. The animal is not shy; it shows the organs freely and marches with vivacity ; it also swims and floats with perfect ease, as is usually the case with all the smaller and shorter Chemnitzia. It has frequently occurred in the quiet half- tidal pools at Exmouth. ? J. OPALINA, nonnull. ? J. opalina, Brit. Moll. iii. p. 154, pi. 76. f. 3, 4, & iv. p. 267, pi. 133. f. 6 ; (animal) pi. M.M. f. 2. J. globularis, Brit. Moll. iv. p. 268, pi. 133. f. 5. Live specimens of the beautiful so-called Rissoa opalina were received in a bottle of sea-water, from my friend Mr. George Barlee, at Falmouth, whose laborious and painful journeyings " per omnes Terrasque, tractusque maris," of the wilds of the Ultima Thule and Hebridean seas, have enriched science with so many rare and interesting objects ; the present one is invaluable, as it clears up several doubtful questions which might long have remained unexplained, if this curious animal had continued to escape observation. Though somewhat torpid, I have observed the organs, an account of which, I am sure, will gratify many of my readers. There is no recorded description of the animal. Animal inhabiting a spiral, smooth, thin, white, subglobose shell of three volutions. Mantle of the palest azure, slightly canaliculated, otherwise even with the shell. The head is a rounded, short, contractile, proboscidiform muzzle, which is rarely carried beyond the foot and tentacula ; it is vertically cloven at the terminus and under part, and furnished with a pair of subcircular jaws and lingual riband, which in several of the examples I frequently saw protruded after the manner of the Rissoce ; the head and neck are brindled with fine dark lead-coloured lines. There are a pair of tentacula on each side the neck behind the muzzle, springing from a distinct common origin or 390 HETEEOPHEOSYNID^:. pedicle, not formed by the fissure of any part of the head, divergent, very short, thick, very little flattened, of nearly the same size throughout, each pair connate with their re- spective stamens, very moderately setose, quite blunt at their terminations, beneath pale yellow, above delicately aspersed towards the extremities with pale-coloured very minute points. The eyes are large, black, placed very far back on the neck, on very slight eminences, perhaps immersed in them, appa- rently in a line with the centre of each tentacular pedicle. These parts were seen with great difficulty, and only came into view in two examples ; they however may be observed through the paler-coloured shells, but are not exserted on the march beyond the margin of the aperture. The foot is oval in quietude, showing a narrow lead-coloured margin, in action somewhat truncate anteriorly, with very small auricles, poste- riorly forming a gradually attenuated termination, without cirrhi, but slightly emarginate in one or two specimens. The testaceo-corneous operculum is suboval, marked with fine sub- annular striae, with a small central process, rib and groove, sometimes with two minute raised points or nuclei contiguous to each other ; all these characters are occasionally subject to some modification. We have several in our cabinet which differ materially, the annular striae of increment being usually permanent. The operculum is carried rather posteriorly, not on a developed operculigerous lobe. The foot is not labiated so as to produce amentum at least I saw none; it is not so slender proportionately as in the typical Rissoa, nor so long ; beneath it is pale yellow, showing a medial line on the posterior half; above, elegantly mottled or brindled with dark close-set lead-coloured lines, which are sometimes waved ; the colours on all parts vary in intensity in the different indi- viduals. I could detect no head-lappets. These animals float and creep like the Chemnitzia and Rissoce ; they inhabit the littoral and laminarian zones. Axis -gL, diam. -^ uncise. The muzzle of this animal allies it to Rissoa, and the pecu- liar position of the eyes to Chemnitzia ; further investigation is required to determine which is the most essential character. BAKLEELL 391 Notwithstanding the proboscidal muzzle not being a strictly retractile one, I think the balance of characters is in favour of this animal being a transition-form from the Littorinidce, and that it may be considered an aberrant Chemnitzia. I have stated above, that the pair of tentacula on each side are not formed by a scission of any part of the rostrum. I believe that I am in error, in consequence of the minuteness and torpidity of my specimens. I think the J. globularis can scarcely be considered even a variety of the " opalina." It will not surprise me if the three so-called species, J. dia- phana, J. opalina, and J. globularis, turn out to be identical, differing only through climate and habitat, and exhibiting the same phases as the variety of the Littorina rudis termed " tenebrosa" in its minute globular variations, the " neg- lecta" and "fabalis" of authors. A rigorous examination of the peculiar internal aspect of the columella of the three so-called species, and the absolutely identical form of the operculum, even to the minutest portions of the sculpture, which certainly would not be the case if they were distinct, authorize me to express an opinion as decided as can be accorded to a shell inquisition, that the three are identical, and I cannot doubt that the animal of J. globularis will con- firm this view. BARLEEIA, nobis. For many of the reasons stated in the introduction to the Heterophrosynida, and for those in the subjoined account, we have transferred the Rissoa rubra of authors to this family, as a new additional genus. Though Barleeia, like Jeffrey sia, has some Littorinidan attributes, we think that both these genera differ sufficiently from that group to require being arranged in a new family between the Littorinidas and Pyramidellida, with both which the two genera have relations, as well as with each other ; and as some difference of opinion has existed with respect to the position of Jeffrey***, we have adopted for the family the significant title of Heterophrosynida. 392 HETEKOPHKOSYNID^E. Exmouth, June 26, 1853. It is stated in a paper of mine on the Rissoa in tlie 'Annals,' vol. x. p. 262, N.S., "that the R. rubra is very common alive in certain localities/' and that " I have never seen the animal, and can scarcely believe it to be a true Rissoa, as the semi- testaceous operculum and its apophysis are more like those of a Chemnitzia." This view is corroborated by the reception this day, by favour of Mr. Barlee, of many lively specimens, sent from Penzance in a bottle of sea-water by post, which has enabled me to take notes of all the organs. I am not aware that this curious, I may almost say, anomalous species, has ever been mentioned, beyond a very slight notice by one or two authors, which in most respects is so discordant with the animal now presented, that one would almost think some other had been inadvertently observed ; perhaps a young example of the more tumid red-brown variety of the Rissoa ulvae. I judge so, because authors describe their animal with very long and setaceous tentacula, whereas the true Rissoa rubra has those organs particularly short and smooth. M. Philippics account is the best, but sadly deficient in the principal peculiarities of the animal. I think malacologists will be glad of a somewhat enlarged description. B. RUBRA, Adams. Rissoa rubra, Adams. , Brit. Moll. iii. p. 120, pi. 78. f. 4, 5, & pi. 80. f. 3. Shell. The colour is plain red-brown, smooth or slightly wrinkled, of 4J to 5J tumid volutions, which form a rapidly increasing cone. Aperture oval, entire, contracted above, rounded basally ; outer margin sharp, without the callous pad of the Rissoa. Axis Tirth, diameter -^th of an inch. Animal. The mantle is plain, even with the margin of the shell, and without the filament seen at the upper angle of the aperture in many of the Rissoa. Rostrum very short, not corrugated nor capable of much extension, brindled above with dark smoke-coloured, fine, irregular, close-set lines, below pale yellow ; buccal disk of the same colour, of small BABLEEIA. 393 area, crosially and vertically cloven, containing the usual masticatory processes of the Littorinida ; neck dark, but not so much so as the rostrum, quite plain and without appen- dages. Tentacula very short, strong, broad, not in the least setaceous, with perfectly rounded, somewhat spatulate extre- mities ; they are not vibrated on the march j colour very pale yellowish-white, with a line of sulphur-coloured beads or minute flakes running centrally from base to point ; eyes very large, black, fixed on bright sulphur inflations at the ex- ternal bases. Foot an elongated, rather narrow oval, anteally arcuated, labiated, with scarcely perceptible auricular points, posteally rounded, emarginate in the centre of its termination ; colour, in the middle of the upper part, confused flake-white, margined with a belt of pale smoke hue ; sole pale yellow, with a decided depressed longitudinal line on the centre of the posterior half, not constricted under the slight auricles as in Rissoa, and not so slender. The operculigerous lobe is small, very little alated anteriorly, but expands below into a dark, flat, arcuated membrane ; no cirrhus is visible, and I believe none exists; it carries a strong, red-brown, suboval, testaceous operculum, sharp above, rounded below and at the outer edge, and straighter on the columellar side. The struc- ture of the fine striae on the upper surface is of subannular figure, with a longitudinal furrow about the middle, which forms a raised rib on the under part, the whole of that area being thick, coarse and irregular, with, at the nucleus (which is nearer the base than the centre), a testaceous apophysis, more prominent than in Jeffrey sia y and stronger and longer ; indeed, as much so as in some of the Chemnitzia. These animals inhabit the lower littoral levels at Perzance ; their locomotion is deliberate, and they evince considerable shyness. There are many fasciated varieties and a white one. This animal approaches the Littorinidan group, and con- ducts from Rissoa to Jeffrey sia : as the latter and it have analo- gous subtestaceous opercula and apophyses, they naturally lead to the Pyramidellidae. But this species cannot be placed in Rissoa on account of the singular operculum (as the like is not seen in any species of that genus), and many other animal 394 HETEKOPHROSYNID^E. discrepancies. Philippi unaccountably omits all mention of the principal peculiarity, the curious operculum, but he does say that the animal departs somewhat from those Rissoae he has examined, both as regards the organs and the shell ; and I add, that with the exception of the very short muzzle and depressed line in the after-part of the foot, there is not another external organ that has much concordance with the typical Rissoa. Neither can it be associated with Jeffrey sia, which indeed agrees with it, essentially, in respect to the operculum ; but the animals of the two are very different. I have therefore proposed for it a new genus, which ought, I think, with Jef- frey sia, to form a family intermediate to the Littorinida and Pyramidellidae. I have omitted to mention that M. D'Or- bigny's subgenus Rissoina cannot receive it, as with a testa- ceous operculum and apophysis, it is of the spiral or Littorini- dan type, whilst the present object is of subannular elements ; and I consider the operculum, though so much neglected, to afford a most important generic and differential diagnosis; but independent of these points, I could not, agreeably to my views, accord with such an allocation. I repudiate all sub- genera, which I consider as an awkward attempt to define what is undefinable an intermediate condition between a genus and a species. I think, when a species is so discordant with the generic type, that it ought to merge elsewhere, and take on a substantive capacity and become the type of a new genus. There can be no objection to the term sub when used ad- jectively to qualify a word, as subannular, subrotund, and subsymmetrical, &c., but not substantively , as then it be- comes the source of innumerable absurdities : with me a genus has no intermediate state beyond species and their varieties. I would therefore submit to malacologists, as I have shown that no existing genus can with propriety receive this curious creature, that a new one be constituted for it, and en- titled Barleeia, as a just recollection of the exertions of a gen- tleman who loses no opportunity of enriching science with living objects from the Great Book of Nature; and though PYEAMIDELLH)^:. 395 the present animal is locally common, it is malacologically an almost unrecorded rarity. We may all blush for our careless- ness in not noticing this interesting and unique species, which, though within the range of many naturalists, would still, pro- bably, have remained in obscurity, if it had not been deterre and forced into notice by our invaluable friend. PYRAMIDELLID.E. This family forms an important section in the ranks of British malacology, and consists of numerous species, which, though many of them have long been known to our older conchologists, have scarcely, until very lately, attracted the attention of continental naturalists, in consequence of their minuteness and the difficulty of obtaining the animal for examination. The only recent authors who have paid much attention to the malacology of these interesting objects are the Rev. T. Lowe, M. Loven, M. Philippi, and Professor Forbes. The British genera comprise upwards of forty species, more than half of the animals of which I have examined, and think that detailed accounts of them will be acceptable to mala- cologists. These species have run the gauntlet through nearly the entire range of the British Gasteropodous molluscan genera in search of a resting-place. It is needless to allude to these ancient and variable depositaries; I will therefore only mention the recent genera in which they appear to have obtained that sort of improved provisional settlement, which is usually the precursor, from the many malacological facts that have been obtained, of a definitive natural position. The more recent receptacles of these interesting objects are, Mr. Lowe's genus Parthenia, Dr. Fleming's Odostomia, M. Philippics Chemnitzia, and the Truncatella and Eulima of Risso, with M. Loven's Turbinella and Aclis. The admirable manner in which Mr. Lowe has described the animal and illustrated his Parthenia, causes much regret that we must 396 PYBAMIDELLID^E. concur with M. Philippi in not using this appellation, in con- sequence of the pre-occupation of the term. Though we believe Dr. Fleming's genus Odostomia has the priority of time, yet, from the variableness and instability of the prin- cipal conchological character, the fold on the pillar, it cannot be maintained either generically or as a group : for instance, the Odostomia interstincta often has the fold, and often is without it ; the O. indistincta never has a tooth ; the O. exca- vata is sometimes with and sometimes without it. Many of the more elongated and turreted species are without a fold ; nevertheless in some, for instance the O. acicula, the tooth is present, and often wanting, as our cabinet will show ; there- fore the appellation of Odostomia to this tribe is incongruous and a complete misnomer. The term cannot even be admitted as a sectional arrangement, as it would separate individuals of the same species, for example the toothed interstincta and the edenticular one ; on these accounts we are reluctantly obliged to decline the use of the term. Besides, we believe that this fold or tooth has had attributed to it far more generic value than it deserves : it probably gives some support to the body as a point d'appui ; but the malacology of the animal, whether with or without it, affords no corresponding variation. We therefore propose to adopt M. D'Orbigny's genus Chemnitzia for those species with or without a tooth, smooth or plicated, many or few volutions, which have as a component of their specific characters a moderately long, retractile proboscis, and eyes at the internal bases of the tentacula. All these species cannot be mistaken, as whatever may be the specialties of the animals, they have the apical one or two turns reflected on the following descending one. This is a constant character; I have never met with a departure from it. The next genus of this family is Eulima, which, though closely allied to Chemnitzia } is nevertheless distinct in various points to be mentioned. M. Loven's Aclis next succeeds as a Pyramidellidan genus, and only embraces one or two species. Stylifer is admitted provisionally. The natural position of this genus of one species requires further investigation, which, from its rarity, I fear may long be delayed. PYKAMIDELLIim 397 I present an account of many of the animals of Chemnitzia, the most difficult of all the Gasteropodan genera; most of them have been submitted to repeated examinations. The present list is more than fourfold greater than any that has yet been recorded. Before I enter on the descriptive matter, it will be proper to say a word or two in explanation of some of the organs of the very singular genus, which, in my method, includes the Odostomia. and Eulimella, and a few of the species of Aclis. With respect to the organs of the animal, I will first men- tion the peculiar anterior process styled by most authors the mentum, which I think ought to be considered the muzzle or rostrum, as it is a continuation of the neck, over which a bridge is thrown, formed of the eyes and tentacula ; and close under them, but on the upper part of the base, or hinder portion of the rostrum, is the proboscidal orifice, from which, though a circumstance of the rarest occurrence, I have in three species seen the evolution of that organ, in the Chem- nitzia pallida, C. acuta, and C. plicata ; the animals kept it exserted from half a minute to three minutes. Mr. Alder's figure in the ' Annals of Natural History/ N.S. vol. vii. p. 464, from a sketch of M. Loven, gives a very good repre- sentation of it; the remaining or terminal portion of the rostrum appears to be mute, and is for more or less of its length attached to the animaPs foot ; in other words, it is less free than the muzzle of the Rissote, of which I consider it the representative and remnant, and which, it will be seen, has entirely vanished in Eulima. Though authors speak of a mentum in that genus, I can find none ; they have, I think, mistaken for it the upper margin or flap of the foot, which in front is divided by a narrow groove. This separation is more or less apparent in most, if not in all, spiral Gasteropoda ; it has, however, little resemblance to the rostrum of the Chem- nitzia, which is a long, narrow, thick, distinct, and otherwise variable organ, proceeding from the neck as its continuation, and has much the aspect of a mute Rissoidean muzzle ; whilst the margins of the foot of the Eulima and other Gasteropoda, 398 PYBAMIDELLID^E. and they are generally present in the Chemnitzice, are to assist flexibility on the march, in the same manner as the digitations of the feet of all animals assist progression. Loven, who has described the meiitum in his genus Turbo- nilla our Chemnitzia has not, though he has described the animal of Eulima, mentioned the presence of a mentum or rostrum in that genus. The point of issue of the proboscis, from the upper part of the rostrum, is more advanced and visible in Chem. plicata than in any other species I have yet examined ; it was from this animal that it continued evolved more than three minutes, affording me a sight that falls to the lot of few malacologists. I believe I speak within compass, when I state, that I have examined more than a thousand live Chemnitzia of twenty species, yet, except on the three occasions alluded to, I never witnessed its exsertion. All the Chemnitzia have a semitubular fold more or less developed in the mantle, which, though it issues at the upper angle of the aperture, close to the debouchure of the rejecta- mental orifice, appears more like a branchial one than for fsecal functions. In the true C. acuta it is largely exserted and very conspicuous. Can this fold be analogous to the process I have described at the same point in many of the Rissoae ? Can it have the double, though apparently incom- patible, duties of depuration, and to supply the animal, when the operculum on certain exigencies is required to be nearly closed, with the branchial fluid ? The presence of a proboscis brings this genus very near to the Canalifera ; but the Eulima are still nearer, as they have no head or rostrum, and the proboscis issues nearly at the fork between the tentacula, as in the Muricidal families. The rostrum varies greatly in the proportions of its arcua- tions, scissions, and points of attachment to the foot ; in the Chem. unidentata it is plain and truncate, in C. acuta it forms an open subcircular channel with a cochleariform termination, and in Chem. conoidea it is cloven nearly to the base, simu- lating a second pair of tentacula. I have omitted to remark, that the orifice of the rostrum is PYEAMIDELLID^:. 399 not precisely in the position of the proboscidal fissure of the Muricid \Mont., Turt. \ belvacea, J radiata, Mont., Turt. Melania Matoni, Gray. ? Modiola Ballii, Brit. Moll. Murex accinctus, Mont., Turt. carica, Turt. carinatus, Turt., Pennant. despectus, Mont. duplicatus, Donovan. fuscatus, Mont., Turt. gyrinus, Mont. sinuosus, Mont. subulatus, Mont., Turt. Mya decussata, Mont., Turt. 510 EXCLUDED EXOTIC SPECIES. Mya glycimeris, Mont., Turf. nitens, Mont., Turt. Mytilus crenatus, Hanley. fuscus, Turt. plicatus, Mont.) Turt., Las key. striatulus, Turt. ungulatus, Mont., Turt. Nerita canrena, Mont., Turt. intricata, Donovan. sulcata, Turt. tuberosissima, Mont., Turt. Orbicula striata, nonnull. Ostrea crista-galli, Mont., Turt. ? Pandora rostrata, Auct. Patella antiquata, Mont., Turt. intorta, Mont., Turt, militaris, Mont., Turt. nubecula, Turt. ? Pecten islandicus, Turt. Jacobseus, Mont., Turt. Petricola lithophaga, Brit. Moll. Pliolas striata, Mont., Turt. Pinna muricata, Mont., Turt. Psammobia declivis, Turt. Conch. Dithyra. ? Scalaria groenlandica, Auct. ? Skenea rota, Brit. Moll. Solen declivis, Turt. Conch. Di- thyra. fragilis, Mont., Turt. strigillatus, Turt. Strombus costatus, Turt. Tellina bimaculata, Mont., Turt. carnaria, Mont., Turt. fausta, Mont., Turt. fragilis, Fleming. insequistriata, Donovan. Laskeyi, Mont., Turt. lineata, Mont., Turt. pisiformis, Mont., Turt. ? proxima, Brown. - punicea, Brit. Mar. Conch. Tellina reticulata, Turt. similis, Mont., Turt. striata, Mont., Turt. Teredo bipennata, Turt. malleolus, Turt. ? palmulata, Brit. Moll. Triton cutaceus, Turt. elegans, Auct. Trochus cinereus, Mont., Turt. conulus, Turt. Brit. Mar. Conch. Turbo Bryereus, Mont., Turt. calathiscus, Mont., Turt. calcar, Mont., Turt. cinctus, Mont., Donovan, Turt. ' coniferus, Mont., Turt. denticulatus, Mont., Turt. dispar, Mont., Turt. duplicatus, Turt., Donovan. mammillatus, Mont., Turt. marginatus, Mont., Turt. terebra, Donovan. tuberculatus, Pennant. ziczac, Turt. Venus deflorata, Mont., Turt. Dysera, Mont., Turt. granulata, Mont., Turt. guineensis, Mont., Turt. orbicularis, Mont., Turt. pallida, Turt. Papbia, nonnull. subcordata, Mont., Turt. subrhomboidea, Mont., Turt. substriata, Mont., Turt. sulcata, Mont. tigerina, Mont., Turt. Voluta bullaoides, Mont. catenata, Mont., Turt. hyalina, Mont., Turt. pallida, Mont., Turt. triplicata, Mont., Turt. APPENDIX. DURING the progress of this work through the press, we have been enabled to submit many of the animals referred to in its pages to a careful re-examination, which has in some few instances shown that our original impressions were partially incorrect, and in others has caused us to modify our opinions to a greater or less extent. The results of such observations as were made too late to be incorporated in the body of the work, are contained in the following Appendix. SCROBICULARIA PIPERATA. (P. 138.) Exmouth, July 1854. As my original notes upon this animal were but scanty, I have gladly embraced an opportunity of making a fresh ex- amination of its structure, particularly as it presents a very unusual configuration of the branchiae and palpi. I find that these organs are of the palest brown, with a slight red cast. The palpi are regularly triangular, pointed, enormously large as regards length and breadth, compara- tively smooth without, and strongly striated within. There is only a single branchia on each side the body, of a broad triangular shape, very thick, fixed by the longest side to the posterior dorsal range, with the angular point vertical to the ventral line ; it is divided diagonally, by a subcentral narrow groove, into two subtriangular portions, whereof the one nearest the dorsal slope is usually the least. Instead of one part folding on the other, as in the regular two-leaved bran- chiae, it is thrown back and pinned to the posterior dorsal slope, forming one moderate branchial plate, certainly not much 512 APPENDIX. larger than one of the palpi. Each branchia unites with its fellow at the posterior dorsal extremity, and also in the middle of the dorsal line; it effects, on each side, a very slight junction with each pair of palpi. If that part of the branchial plate which is reflected back and fixed, were free, it would range and lap on its fellow portion, and thus constitute the normal pair of branchiae. If this view is correct, we ought to consider the single plate as essentially a double one, though its component parts are abnormally arranged. The mantle is open on the ventral surface, with the margin irre- gularly scolloped. The liver is dark green. The ovarium at this season is studded with young, and occupies the entire surface of the body between the liver and the foot. At one time, from the character of the hinge, we were of opinion that Scrobicularia might have been associated with Syndosmya, but finding the branchiae and palpi of the two so very discordant, we abandoned that idea ; we now think that the genus is superfluous, and that its single species may be transferred with great advantage to the same section of the Tellinae as T. solidula and T. tenuis, with which it agrees as to the soft parts almost precisely ; whilst in the hard parts it only differs in having a semi-internal cartilage, which with us is a point of little or no importance. PANDORA OBTUSA. (P. 150.) Exmouth, July 1854. In our original account of this species, published in Forbes and Hanley's Brit. Moll. vol. i. p. 211, we stated, that there were two palpi, one branchial lamina, and an obsolete one on each side the body; from subsequent observations we were induced to modify our opinion, thinking that there were two perfect branchial plates on each side. A further exami- nation of the animal has proved, however, that our original impression was substantially correct, as the following descrip- tion will show. The animal has two very short, reddish-brown, subtriangular palpi, blunt or rounded at their termination, which often APPENDIX. 513 cover each other so closely as to be mistaken for one; but this is not always the case. It is difficult to separate the two plates, even when floated; we have, nevertheless, often suc- ceeded, and have a preparation which is indisputably decisive of their duplex character. There is one thick, rather narrow, elongated branchia, and a rudimentary one on each side of the body, and not two entire plates, as mentioned in former notes. The green liver is conterminous with the pale red- brown ovarium, which at this period is filled with ova. It appears to be a non sequitur that a single branchia on each side should be accompanied by a corresponding single palpum. We apprehend all bivalves must have two palpi on each side, as purveyors of aliment to the mouth, whether the branchiae be single or double. PHOLAS DACTYLUS. (P. 192.) Since the letter here printed was written, several papers have appeared in the ' Annals/ which largely support, and partly im- pugn, our theory of the action of the branchiae in the Bivalves. Dr. Sharpey's original views on the permeability of the gill-laminae in the Acephala, have, after a lapse of more than twenty years, again been prominently brought forward. It was our lot to become fully cognizant of his discovery in 1834, that is, soon after it was promulgated, as it appeared in vol. vii. p. 108 of ' London's Magazine of Natural History/ to which we subscribed, and it has, as late as 1850, again been mentioned in Dr. George Johnston's excellent volume, entitled ' An Introduction to Conchology'; but considering Dr. Sharpey's views erroneous, and physiologically impossible, we dismissed them from our thoughts. Messrs. Alder and Hancock have also announced an essen- tially similar scheme, as based on original observations ; but this condition has been withdrawn in a paper by Mr. Alder in the 'Annals of Natural History,' vol. xiv. p. 131, N. S. And lastly, Dr. Thomas Williams, in a series of memoirs published in 1854 in the above work, on the aquatic respira- tion of the Invertebrate animals, we particularly allude to those on the Mollusca, has adopted Dr. Sharpey's theory, 2 L 514 APPENDIX. with the addition of a mass of the most minute anatomical and functional details to us so incomprehensible, that we have given up the attempt to unravel them. The key-stone of the theories of these gentlemen is the assumed permeability of the acephalan gill-laminae. I believe that this determination will prove erroneous. I am, of course, open to conviction, but I think my position founded on the rock of " magna est veritas, et prsevalebit." Under these circumstances I cannot, in the present phase of this question, withdraw a single position of the branchial theory I have proposed. Anatomy, even the microscope, chemical tests, and the most ingenious experiments, have hitherto failed demon- stratively to solve this long-vexed question ; all our attempts amount to little more than hypothesis, intrepid assertion and assumption, which often simulate facts, and pass for proofs. DENTALIUM TARENTINUM. (P. 235.) I have stated that "M. Deshayes has omitted to mark the vein which runs at the dichotomous points of his organ, which, when viewed under high powers, is very visible, and which I take to be the branchial vein." I withdraw this observation, whether my conjecture be correct or not, as it would have been inconsistent in that naturalist to figure a branchial vein in an organ considered by him to be the liver. His liver is our branchiae. We have lately re-examined the Dentalium Tarentinum, and we almost think that the artery and vein have a nearly parallel position on the dorsal line, as in the Bivalves. The tumid cord-like appearance of the lower border of this minute organ has perhaps led to an erroneous conclusion. CHITON CANCELLATUS. (P. 251.) CHITON ALBUS. (P. 251.) Though the above are admitted as distinct species, we are now bound to add, that this determination must be considered provisional ; there is reason to believe that both these forms APPENDIX. 515 are nothing more than the young conditions of Chiton asellus, which varies much in the dimensions of its longitudinal and transversal areas, as well as in the density and regularity of the linear punctated sculpture. Or we must conclude that these species are not in our collection, though we have been assured by good conchologists that our shells represent them. Since writing the above we have dissected specimens of both the so-called species, and found all the separate valves finely crenulate, not emarginate ; thus confirming the opinion that our shells are C. asellm. Therefore if Mr. Lowe's C. aselloides the C. albus of authors is bi-emarginate on each side the valves, it cannot belong to the present species. It has however been suggested, that it may be a young, white 3 finely granulated . C. cinereus ; we should have con- curred in this view if it had not been opposed to so accurate an observer as Mr. Lowe. Our so-called C. cancellatus has the same finely crenulated margins as C. asellus, which is, we believe, the only British species thus sculptured. TROCHUS SERPULOIDES, p. 314; TR. CUTLERIANUS, p. 315 ; TR. NITENS, p. 316. Exmouth, 10th July, 1854. I have much satisfaction in stating, that the process under the right tentaculum in these very minute species, which is figured in a woodcut in the ' Annals of Natural History/ vol. viii. p. 45, N.S., and styled "genitals" has not that func- tion. . I am the more pleased with this discovery, as no such organ is to be found in that position in the large Trochi ; and as these minute animals agree with their larger brethren in all other respects, I was puzzled to account for this discre- pancy. The difficulty is removed by finding that the process I have alluded to is part of the right neck-lappet, which is bifid ; both of its strands spring from the same membrane, as I have seen clearly in a brilliantly transparent Trochus nitens under high powers. The right neck-lappet is always longer than the -left, which however is also bifid, but plain, and never ornamented, fringed or serrated, as is sometimes seen 2 L 2 516 APPENDIX. in the right one, for instance in TV. serpuloides. The same inequalities exist in the neck-lappets of the larger Trochi. I have thus removed all aberrations between the organs of the larger and these minute but perfect Trochidans. I believe there are only three vibracula on each side the opercular lobe, instead of four as I have elsewhere stated, but I do not vouch that there may not be four in one of the above species. PHASIANELLA PULLUS. (P. 320.) Exmouth, July 1854. As I have several important additions and corrections to make in my account of this animal, I have thought it best to give a general description of it, as the alterations will thereby be rendered more intelligible. Shell of five obliquely striated, almost smooth, tumid, por- cellanous volutions, separated by a fine sutural line, variously painted with all imaginable hues of colours, forming in many specimens a splendid tout ensemble : the body whorl equals in size all the rest. The aperture is suboval, outer lip sharp, and much advanced beyond the columellar side. Animal. The mantle exactly lines the shell, and is of the palest hyaline sea-green. Muzzle very short, cylindrical, finely wrinkled, mottled with red-brown blotches, sometimes marked with transverse green stripes, and at others with longi- tudinal streaks of the same colour, on a yellow or pale red ground ; its termination or disk is subcircular, finely serrated at the margin, and has a crosial oral fissure ; from this the animal often protrudes the corneous jaws, which with the lingual riband are supported by greenish fleshy plates ; the under surface of the disk is marked with red streaks on a white ground. The tentacula are pale yellowish- white, long, pointed, flattish, crowded with fine setse, and are in constant vibration. The eyes are external, on distinct yellow, white, or green pedicles. The neck-lappets are white, pale, or grass- green subcircular membranes ; the right is the largest, mar- gined with 12-15 distinct white or green cirrhi, of almost equal length, and fimbriated at the sides; the left has only APPENDIX. 517 8-10 cirrhi. The colours described are those of the animals examined; they vary greatly, and in individuals exhibit all the shades of red, pink, purple, brown, maroon, bistre-yellow, and all the greens. The foot is long and narrow, with a tumid aspect on the upper surface, rounded in front, without a trace of auricles, obtusely lanceolate at the posteal end, and marked above with red-brown, zebra-like, or narrow, longitudinal, wavy lines; the sole is yellow, having a central depressed line throughout its length, and is sometimes coasted on each side by a narrow, bistre-coloured stripe. The operculigerous lobe is almost co- extensive with the foot, of a dark red-brown colour, and largely alated ; it is furnished with three densely ciliated, flattish, pointed vibracula on each side ; the middle ones are very short and inconspicuous, each bifid, or formed of two strands : with powerful glasses I have never failed to discover them in all the Exmouth examples, and I believe that three on each side is the normal number. The lobe carries a white, highly polished, subcircular, testaceous pauci- spiral operculum, concave within, convex without, and fixed on the posterior extremity about midway. This animal has the peculiar littorean oscillatory quality of progression, which, with the paucispiral operculum, seem to mark it as a trans- ition genus from the Trochi to the LittoriruK-, we, however, must admit, that by the vibracula and neck-lappets it has a close connection with the Trochidce. I am puzzled about the reproduction, on which account I can only at present refer to the original notes. No exserted verge has been detected, and though placed in our first account, provisionally, with the Trochidte, I rather think, by the character of the operculum, it is bisexual, and that in a comparison of the two genera, the balance preponderates on the side of Littorina. It is sometimes infested with a longish, strong, cylindrical, dark brown parasite, with a clavate termination, which hangs to the side of the opercular lobe, and may be mistaken for a vibraculum. CAECUM TRACHEA. (P. 327.) The tentacula are not short, as originally stated, but com- 518 APPENDIX. paratively long, divergent,, thickened, and a little spread at the bases ; the eyes have decidedly an external bias. The operculigerous lobe is certainly without a cirrhal appendage. The general colour is dull white, saturated with a mixture of minute, confused, snowy, closely condensed matter. The convexity of the arcuation denotes the upper parts of the animal, and the concavity the ventral range. TURRITELLA COMMUNIS. (P. 331.) Exmouth, July 1854. The following is the result of another attempt to ascertain the quality of the locomotion of this species. Fifty of these animals, of all ages, were deposited in a large deep dish filled with their native soil, which consisted of a tenacious clayey mud mixed with comminuted shelly matter; in this they buried themselves in every position from the vertical to the horizontal. After three or four hours it appeared, from the evidence of a furrow on the mud, that some of these creatures had certainly moved, but the progression was so slow as not to be perceptible by the eye, and was only seen when a short space had been passed. From this experiment it would seem that this species has the faculty of effecting a very slow march. This inaptitude for motion arises from the shortness of the foot, not from the length of the shell ; as in other animals with elongated shells, such as some Chemnitziae and Eulima, the progression is sufficiently active. RlSSOA FULGIDA. (P. 357.) Exmouth, July 1854. This description is entirely reproduced from lively animals just examined. The species was originally described by us for the ' British Mollusca/ but its almost microscopic size caused some of the organs not to be precisely appreciated. The shell has four rounded, deeply separated, smooth volu- tions, which are spirally encircled by two dullish, red-brown fasciae, varying in breadth on the three basal turns, with a yellow one running between them and filling up the inter- APPEKDBL 519 mediate space. The aperture is suborbicular, not thickened at the outer margin as in the Rissoa, and almost entire. The umbilicus is conspicuous. Axis -^ F> diameter -gV unciae. Animal. Ground colour of the palest muddy yellow. Mantle even with the shell. Muzzle short, smooth, thick, though flat above, cloven at the end, mouth beneath, with a vertical fissure. Tentacula finely setose, divergent, flat, rather slender, gradually tapering from base to point, which is rounded, hyaline- white, suffused with minute snowy points ; eyes large, but rarely exserted, placed on low prominences at the external angles of the tentacula. The foot has three phases ; when at rest it is rounded anteally, and still more so posteally; when the animal swims it becomes narrow and rounded to a similar extent and form at both ends ; on the march it is arched convexly in front, not auricled, and pos- teally has a blunt lancet-shaped termination; the sole is deeply impressed with a longitudinal central line ; the oper- cular lobe is short, but laterally alated, and carries, near the extremity, a grossly spiral, yellow, rissoidean, subcircular, corneous operculum, which has been described as not spiral. This is an error. In clean examples under the microscope, the depressed nucleus and usual spiral turn may be traced ; a dozen examples have been examined, and though obsoletely impressed, they are clearly paucispiral. There is no distinct cirrhus springing from the operculigerous lobe, but in some specimens I have fancied I saw a very short blunt one. Sometimes the point of the main sole is bifid for a very short distance. The animal is most abundant on the littoral levels at Exmouth ; it marches with great rapidity, and is vivacious and free ; on the march the eyes are always under the shell, as are usually the muzzle and foot, the ends of the tentacula only being visible; it carries its shell at an angle of 70. I have elsewhere stated that this species can scarcely remain in the genus Rissoa, but these various rectifications induce me to withdraw that opinion ; it really appears to have as many or more rissoidean attributes than some of the species admitted into that genus. 520 APPENDIX. E/ISSOA STRIATA. (P. 360.) Exmouth, July 1854. In our original notes it is stated that there is no cirrhus on the opercular lobe at its termination. Having reviewed a fine lively specimen, we found, beyond dispute, a short, white, pointed caudal filament. The pendent minute fillet at the upper and external angle of the aperture is present, though, as it is usually withdrawn, it cannot always be detected. The front of the foot forms a deep labium at the upper part by its separation from the sole ; the flap is of the shape of the letter V inverted, the basal points being in front, and the angular one posterior ; it is shadowed out by its flake- white composition, which is visible through the pellucid sole ; but the most singular feature is, that its margins throughout are largely disunited from the upper part of the foot, being only fixed thereon by a central attachment. I have never before observed a similar labial structure, though it may exist in other animals and have escaped notice, for the foot in all the Gasteropoda is more or less labiated. EISSOA COSTATA. (P. 362.) Our notes are exact; in a specimen examined in July 1854, we cannot detect the filament we failed to find in 1852, at the upper angle of the aperture. Can it, instead of pro- ceeding from the mantle, as supposed by us, issue from the neck, and be the genitale of these minute creatures, which are considered bisexual ? It is certainly much lower under the right tentaculum than is usual. If there is any weight in this conjecture, we must conclude that those species and specimens in which the filament is not visible are the females. What militates against these ideas is, that in some of the Rissoae we have found the organ in every example. This process is certainly not an edge of the operculigerous lobe that occasionally comes into view. EJSSOA SOLUTA. (P. 365.) The general colour is hyaline-white, suffused with very APPENDIX. 521 minute points of flaky matter of similar hue. The tentacula are flat and strong, and rather clavate at the tips ; the eyes are always carried considerably within the margin of the shell. The foot is narrow, and when fully extended, as long as the shell, with a rather pointed termination. The caudal cirrhus of the opercular lobe is very long and distinct, flattish at its insertion, and tapering to a fine point. This animal is nearly a true Rissoidean. Axis -^V, diameter -^ uncise, in ordinary specimens. ASSIMINIA. (P. 380.) Assiminia is not placed in the same order as in the Classi- fication, it being removed, provisionally, between Rissoa and Truncatella, as we think, when the animal is better known, it will belong to the latter genus. We have in vain called on naturalists to furnish us with some of these animals ; they abound in the tidal ditches of the Greenwich and other eastern marshes ; if they were sent by post on the day of capture, in an ounce bottle filled with the water or moist mud they inhabit, enclosed in a tin cylinder or small wooden box, they would arrive sufficiently lively for examination. CHEMNITZIA PALLIDA. (P. 415.) The rostrum, or head, is short, broad, rounded or sub- circular at the end, slightly grooved to its base, and speckled with yellow points. The tentacula are not short, -but long, subtriangular, not pointed, and have very distinct, small, flake-white terminal inflations; they are bevelled, rather setose, narrow, not much folded or auriform. The animaL and those of all its numerous varieties, viz. C. dubia, C. alba, C. nitida, C. albella, C. rissoides, C. eulimoides, and C. gla- brata, are more or less variously suffused with very minute yellow points, as well as speckled with irregularly deposited dots or larger points of sulphur-yellow, of various intensity of hue; this characteristic colouring will always detect the C. pallida or any of its varieties, as no other Chemnitzia that can be confounded with it is thus painted. 522 APPENDIX. CHEMNITZIA PLICATA. (P. 418.) Rostrum long, presenting at its termination a flat disk, which exhibits at times the very opposite phases of subcir- cular and subquadrangular form; it issues from raider the coalition of the tentacular membranes, and is attached to the foot by a bridle. The tentacula terminate in rounded sub- lanceolate points which are very slightly marked with the cha- racteristic apical inflations of the tribe. The half of the rostrum nearest the eyes is thick and wrinkled when not much pro- truded, and at its upper basal portion, just below the eyes, the proboscidal fissure is apparent. This is one of the species from which I have seen the issue of the retractile proboscis. The foot has very small auricles; on the march it becomes considerably elongated and reflexed upwards, but still retains an obtuse point. The subcylindrical variety of C. unidentata often passes in collections for this species, which is a decided littoral animal. The slender C. acuta has also been erroneously considered the C. plicata ; but this last, and the C. unidentata, inhabit the coralline zone. CHEMNITZIA ACUTA. (P. 420.) This species shows in a marked manner that the rostrum (the mentum of authors) is really the head of the animal. This organ is channelled from its termination to its base, at which point, between and just under the eyes, the fissure is evident, from which I have more than once seen the evolution of a long proboscis. The anteal portion of the rostrum is without any sort of orifice, but it is probably a tentacular aid, and also one of progression. Every one that examines this organ will unquestionably pronounce it the capitular part of the animal, and will discard the term mentum. In many specimens there is a subrotund congeries of 30-40 flake-white points close behind the eyes. The spire of the operculum is more complete than in any other Chemnitzia I am acquainted with. APPENDIX. 523 CHEMNITZIA CONOIDEA. (P. 422.) The tentacula have moderately large, terminal, flake-white inflations. The continuation of the upper part of the rostrum with the neck is most apparent and cannot be mistaken, the junction being only invaded by the span of the tentacula and insertion of the eyes. The rostrum is slightly grooved from the point of the emargination to the centre of the tentacular veil, under which, just below the eyes, is the proboscidal fissure. CHEMNITZIA RUFA. (P. 423.) The rostrum is spotted with small flake-white points, parti- cularly on and between its grooved central lines. The eyes are on the bases of the short, broad, very little folded, triangular tentacula, the tips of which are not decidedly marked with the characteristic apical inflation. CHEMNITZIA SPIRALIS. (P. 425.) This is a review of the original notes ; there is little to add. The rostrum, in quietude, shows an inflation on which the proboscidal fissure may be detected, with the high power of a Coddington lens, in certain lights; when in motion, it loses the finely corrugated prominence, becomes attenuated in the middle, and has a spatulate rounded termination that rarely, when in action, simulates an emargination or hollo wing-out. CHEMNITZIA INTERSTINCTA. (P. 426.) With regard to the animal inhabiting the shell with flat volutions, we have to add, that when the foot or the rostrum is by excitement produced beyond the usual extent, it becomes greatly hollowed out, and the auricular points increased in length ; but this condition is common to all the Chemnitzia, and when tranquillity is restored, the organs revert to the form we have described. The animal is shy and sluggish, and often marches with the eyes under the margin of the shell. Whether the tumid shell mentioned in our description of 524 APPENDIX. C. interstincta is a variety, or really distinct, may be question- able. This point requires farther investigation. I have stated that the true C. interstincta has usually a fold or tooth on the columella, but that it is not uncommonly found without it. I now amend that opinion, and believe it is never without a tooth : the error has arisen from the casual introduction and mixture in collections of young spe- cimens of the C. indistincta, which are very similar, but invariably without the tooth. I also remark, that the tumid shell, whether it is a variety of C. interstincta, or distinct, is never without the tooth. With these very minute shells, which closely resemble each other, and whose animals do not differ greatly, first im- pressions sometimes prove erroneous, but continual examina- tion of both shell and animal at last elicits the truth. In the reproduction, for "tentacula rather long, slender," read " rather short and broadish." This correction shows the difficulty in these minute creatures, of seizing, in the ever- varying tentacular and other organs, the precise points for description. CHEMNITZIA INDISTINCTA. (P. 428.) We have again examined, in the same vase, the animal of this species, and its variety termed by authors C. clathrata, and still retain our original opinion, that they are identical ; both vary somewhat in colour, the one having a bluish-white cast, the other a pink one, and they also present different degrees of slenderness and tumidity of contour. Neither has a trace of fold or tooth on the columella. The rostrum is moderately grooved on its upper surface as far as the basal tentacular coalition, at which point, somewhat below the eyes, a prominence, caused by a slight degree of contraction, marks well the minute fissure for the issue of the proboscis. CHEMNITZIA DECUSSATA. (P. 432.) In this species the rostrum is attenuated in its course from the tentacula to near the termination, where it assumes a APPENDIX. 525 clavate or hammer-like appearance, becoming thick, angular, bevelled to a sudden edge, straight in front, without auricles or central indentation. The tentacula are very short, and their tips less marked and folded than in many others of this tribe. CHEMNITZIA CLAVULA. (P. 436.) Exmouth, July 1854. After a Japse of two years, a single, beautiful, lively specimen of this rare species has been met with, which enables me to say'that the original notes are correct ; I can only add a few minor particulars, which might have been neglected, had I not wished to give naturalists the means of verifying decisively this elegant and very scarce creature. The tentacula are extraordinarily short and broad, in con- sequence of the auricular portions that spring from their external margins unfolding and forming a large, fine, arcuated membranous leaf, that terminates just under the apical in- flations. The foot on the march, when the animal is agitated, can be pushed into longish auricles, and in consequence shows a con- siderable curved hollow in front ; this fact is common to all the Chemnitzia, but in deliberate progression it becomes trun- cate with subdued angular points ; the posterior extremity in the example observed was slightly emarginate on the right and left sides, giving the central portion the aspect of a rounded or blunt stylet. On each side of the foot, when the animal is in motion, there is a marginal series of about ten very minute glossy points. This beautiful creature was remarkably free, and allowed me to see the fine line of the proboscidal fissure on the ros- trum immediately below the eyes. It was taken in the same habitat as the original examples. I have omitted to state above that the foot is constricted gradually below the auricles ; it is not narrow, and can, on the full march, be extended to the second basal volution : when that happens, its posteal emarginations nearly vanish. The apical reflexion of the shell is less pronounced than 526 APPENDIX. usual, not more so than in C. Gulsona ; in these two species it may be termed sunken or subreflexed. CHEMNITZIA ACICULA. (P. 439.) For the corresponding parts in the original notes, read, " Rostrum considerably emarginate in the centre at its anteal termination, forming the angles of the cleft into two minute subrotund processes. The foot is long, often extending on the march to three volutions, and terminating behind in a narrow, produced, lanceolate point. The front of the foot is square, but expands into rather sharp, auricular points, and is gradually constricted below them to the junction with the body". CHEMNITZIA FENESTRATA. (P. 440.) The neck on each side, as far as the tentacula, is marked with a pale lead-coloured stripe, of unequal breadth in its course, which is composed of a close union of very minute points, giving the narrow fillet a mottled aspect. A tinge of the same colour is also apparent on the basal portion of the tentacula and upper surface of the foot. In this species the rostrum is greatly thickened at its base, and with very high powers the proboscidal fissure may be seen; the terminal portion is much compressed, slightly funnel-shaped, and sometimes simulates a cochleariform depression. The apical flake- white tentacular inflations are very distinct. MUREX GlNANNIANUS. (P. 494.) MUREX BRACHYSTOMA. (P. 496.) The above so-called species have been the source of some controversy amongst naturalists, who have found it difficult to determine their distinctness. With us the " Ginannianus" marches with the ' ' brachystoma -" the authors of the ' British Mollusca' consider it a synonym of M. nebula. We have obtained some specimens of equal size, of our present species, which were deposited in the same glass, and, being lively and free, afforded for some hours an excellent examination, which APPENDIX. 527 demonstrated that the organs of the two objects are absolutely identical in every point as regards anatomical structure. The variations, except in one point, belong to the shells; the M. brachystoma is rather more slender, with stronger strise, more gradually taper, a little natter on the top of the volutions, and the animal has the flake-white markings on the foot much more densely distributed than in its hitherto considered con- gener, the M. Ginannianus. But under the circumstances of the identity of the organs of the two, and the quality of the markings being undistinguishable under the microscope, I shall account for the numerical difference of the spots by the ungallant assertion of the schools, that the masculine is more worthy than the feminine ; and as it is well known that in many animals of the same species the colours and markings of the two sexes vary greatly, they may do so here. I have therefore adopted the opinion, that the more slender shell, termed " brachystoma/ 3 is the male, and the " Ginannianus " the female. M. Philippics appellations for the so-called species are con- temporaneous ; I therefore propose "brachystoma" for this animal, as being the more significant, receiving the " Ginanni- anus" as its synonym. Though the M. nebula has close relations with this animal, I think it distinct. MUREX PURPUREITS, Montagu. (P. 499.) Mangelia purpurea, Brit. Moll. iii. p. 465, pi. 113. f. 3, 4, 5. We beg that the following notes of this species may be substituted for those quoted. Shell. The specimen observed presented eight spiral, moderately taper, dark purplish-brown, closely cancellated volutions, of about half an inch in length in the whole, with a narrow white band in the centre of the body- whorl. Ex- amples of larger growth inhabit the coralline zone ; these are near an inch long, composed of ten turns, which vary in colour from red-brown to pale drab. At the upper angle of the aperture is a distinct sinus or emargination ; the margin 528 APPENDIX. of the outer lip is white, thick, sloped to an edge, marked with strong transverse lines within, and occasionally a few of the cancellations are of a white colour. Animal. Mantle moderately fleshy, quite white, even with the margin of the aperture, except the exsertion of a not very long branchial siphon, which however often floats beyond the limits of the canal; in the example examined, its colour was pale drab with a tinge of yellow. The head, if it may be said to exist, is of the true muricidal type, scarcely interrupting the junction of the tentacula by the intervention of the pro- boscidal fissure. The tentacula are of moderate length, formed of strong pedicles of more than half their extent, on which, at the external angles, the large black eyes are fixed ; the sum- mital portions are attenuated. The foot is slender, very pointed, and, when extended, as long as the shell (this is not often the case), anteally deeply grooved or labiated, with short, but well arcuated, auricles. The ground colour of the foot and tentacula is subhyaline-white, aspersed with very minute, intense flake- white round spots, not larger than sand points; There is no operculum. The animal is an elegant creature, but singularly apathetic, though observed an hour after cap- ture. Habitat, in the offing at Exmouth, six miles from the shore, in 10 fathoms water, in shelly muddy sand. INDEX. The larger groups are indicated by capitals, the families and genera by small capitals ; the names of species are in Roman, and the synonyms in Italic. An ? indicates the doubtful British species. abbreviata, Necera (Anatina), 143. abyssicola, Rissoa, 372. ACEPHALA LAMELLIBRANCHI- ATA, 4, 11,23,38. ACEPHALA PALLIOBRANCHI- ATA, 4, 10,20,35. acicula, Chemuitzia, 439, 526. acicula, Eulima (Chemnitzia), 439. acicula, Eulimella (Chemnitzia), 439. ACLIS, 7, 452. ACM^A, 6, 262. ACME, 7. aculeata, Anomia, 40. aculeatum, Cardium, 103. acuminata, Ovula, 507. acuminatum, Buccinum (Murex), 486. acuta (Odostomia), Chemnitzia, 420, 522. adversa, Rissoa ? ?, 380. adversum, Cerithium (Rissoa), 380. adversus, Murex (Rissoa), 380. anea, Venus (Pullastra), 120. qffinis, Eulimella (Chemnitzia), 439. akera, Bulla, 285. ? alabastrum, Trochus, 309. ALATIDJE, 8, 472. alba, Odostomia (Chemnitzia), 415. alba, Syndosmya, 136. albella, Odostomia (Chemnitzia), 415. albulus, Turbo (Rissoa), 358. albus, Chiton, 251, 514. albus, Conovulus (Pedipes), 299. Alderi, Natica, 466. ANATINA, 5, 140. anatina, Rissoa, 372. ANATINID^E, 5, 139. anatinus, Donax, 122. ancyloide, Propilidium (Acmaea), 263. ancyloides, Acmaea, 263. ANODON, 4. anomala, Crania, 37. ANOMIA, 4, 40. ANOMIAD^E, 4, 38. antiquatus, Solenicurtus, 156. antiquus (Fusus), Murex, 483. aperta (Philine), Bullaea, 286. APLYSIA, 6, 272. APLYSIAD^E, 6, 271. ARCA, 4, 66. ARCADE, 4, 65. ? arctica, Astarte, 111. arctica, Cyprcea, 505. arctica, Saxicava, 161. arenaria, Mya, 166. ARGIOPE, 4, 36. ascaris, Aclis, 453. asellus, Chiton, 250. ASSIMINIA, 7, 380, 521. ASTARTE, 5, 111. athletica, Patella, 261. atomus, Truncatella, 386. attenuata, Mangelia (Murex), 498. attenuatus, Murex, 498. aurea, Tapes (Pullastra), 120. AVICULA, 4, 64. balaustina, Tellina, 128. Ballii, Modiola, 62. Bamffius, Murex, 482. barbata, Modiola, 61. Barleei, Chemnitzia, 446. BARLEEIA, 7, 391. Barvicensis (Trophon), Murex, 482. Beanii, Rissoa, 364. Bernicensis (Fusus), Murex, 483. bidentata (Montacuta), Anatina, 145. 2 M 530 INDEX. bidentata, Auricula (Pedipes), 299. bidentatus (Conovulus), Pedipes, 299. bilineata, Eulima, 452. bimaculata, Tellina, 128. Binghami, Sphaenia, 150. borealis, Lucina, 85. borealis (Trichotropis), Murex, 483. Boysii, Mactra (Syndosmya), 136. brachystoma (Mangelia), Murex, 496, 526. brevirostris, Anatina, 143. Buccinum, 484. BULLA, 6, 274. BULL^A, 6, 286. bullata, Akera (Bulla), 285. BULLID.E, 6, 272. OECUM, 7, 323. Calathus, Rissoa, 372. CALYPTRJEA, 6, 264, 266. cancellatus, Chiton, 251, 514. Candida, Pholas, 177. candidus, Solenicurtus, 157. caput serpentis, Terebratula, 35. CARDIACS, 5, 98. CARDIUM, 5, 98. CARYCHIUM, 7. casina, Venus, 117. castanea, Ervilia, 123. catena (Philine), Bullaea, 290. caudata, Leda, 71. cepa, Anomia, 40. CEPHALOPODA, 8, 18. Cerithiopsis, 490. Cerithium, 490. CERVICOBRANCHIATA, GASTE- ROPODA, 6, 13. CHEMNITZIA, 7, 414. chione (Cytherea), Venus, 117. CHITON, 6, 248. CHTTONID.E, 6, 239. ciliare, Cardium, 99. cinerarius, Trochus, 311. cinereus, Chiton, 250. cinereus, Chiton, 250. cingillus, Rissoa, 372. CIRCE, 5, 111. cistellula, Argiope, 36. Clarkiaj, Lepton, 78. clathrata, Chemnitzia, 428. clathratula, Scalaria, 461. clathratus (Trophon), Murex, 482. clavula (Eulimella), Chemnitzia, 436, 525. coarctatus, Solenicurtus, 156. communis, lanthina, 459. communis, Scalaria, 463. communis, Turritella, 331, 518. complanatus, Donax, 123. compressa (Venus), Astarte, 111. compressa,Mactra(^crobicu\arisi),l3S. conoidea (Odostomio), Chemuitzia, 422, 523. CONOVULID.E, 7, 296. CONOVULUS, 7, 297. conspicua, Odostomia)ChemmtziSi) ,420. conulus, Cylichna (Bulla), 285. ? conulus, Trochus, 309. convexa (Thracia), Anatina, 148. convexum, Lepton, 80. cor, Isocardia, 108. corallinus, Murex, 482. CORBULA, 5, 149. CORBULIDJE, 5, 148. coronata, Anomia, 40. costata, Mangelia (Murex), 498. costata, Rissoa, 362, 520. costatus, Murex, 498. costellata, Necera (Anatina), 143. costulata, Crenella, 63. costulata, Rissoa, 355. costulata, Skenea (Trochus), 315. costulata (Psammobia), Tellina, 128. Cranchii, Bulla, 285. CRANIA, 4, 37. CRANIAD^:, 4, 37. cranium, Terebratula, 36. crassa, Emarginula, 254. crassa, Tellina, 126. crassior (Lacuna), Littorina, 353. crassus, Trochus, 308. ? crebricostata, Astarte, 111. CRENELLA, 4, 62. crenulata, Rissoa, 372. crispata, Pholas, 178. crispata, Scissurella, 322. CRYPTIBRANCHIATA, GASTE- ROPODA, 6, 13. cuspidata, Anatina, 143. cuspidata, Necera (Anatina), 143. cuspidata, Tellina (Anatina), 143. Cutleriana, Skenea (Trochus), 315. Cutlerianus, Trochus, 315, 515. CYCLADID^, 5. CYCLAS, 5. CYCLOBRANCHIATA, GASTERO- PODA, 6, 13. CYCLOSTOMA, 7. CYCLOSTOMATIDJE, 7. cylindracea (Cylichna), Bulla, 281, cylindrica, Anomia, 40. cylindrica, Odostomia (Chemnitzia), 448. CYPR^A, 8, 505. CYPR^AD^E, 8, 504. CYPRINA, 5, 108. CYPRINID^E, 5, 107. dactylus, Pholas, 175, 178, 513. Dalei (Buccinum), Murex, 485. INDEX. 531 Damnonia, Venus (Astarte), 111. danicus, Pecten, 54. DECAPODID.S:, 8. declivis, Anatina, 147. decorata, Chemnitzia, 437. decussata (Odostomia}, Chemnitzia, 432, 524. decussata, Crenella, 63. decussata, Nucula, 69. decussata, Pullastra, 120. decussata, Tapes (Pullastra), 120. decussata, Venus (Pullastra), 120. DENTALIAD.E, 6, 225. DEXTALIUM, 6, 226. denticulatus, Conovulus, 297. depilans, Aplysia, 272. deprexsa, Helix (Rissoa), 373. diaphana, Jeffreysia, 388. DIBRANCHIATA, CEPHALOPO- DA, 8, 18. discors, Crenella, 63. ?discrepans, Chiton, 251. discrepans, Rissoa, 356. distorta (Thracia), Anatina, 148. distorta, Eulima, 450. distorta, Eulima, 451. distortus, Pecten, 49. divaricata, Lucina, 88. divisa, Skenea (Trochus), 314. dolioliformis, Odostomia (Chemnit- zia), 430. DONACHXE, 5, 122. donacina, Tellina, 125. DOXAX, 5, 122. dorsalis, Xylophaga, 224. DREISSEXA, 4. dubia, Odostomia (Chemnitzia), 415. echinatum, Cardium, 98, 99. edule, Cardium, 100. edulis, Mytilus, 58. edulis, Ostrea, 55. electrica, Anomia, 40. ELEDONA, 8. elegantissima, Chemnitzia, 433. elegantissima, Chemnitzia, 435. elliptica, Astarte, 111. elliptica (Lutraria}, Mya, 168. elliptica, Mactra, 106. ' elongatum, Cardium, 101. EMARGINULA, 6, 253. ensis, Solen, 155. entalis, Dentalium, 237. ephippium, Anomia, 40. erinaceus, Murex, 479. erosus, Conovulus (Pedipes), 299. ERVILIA, 5, 123. EULIMA, 7, 449. eulimoides, Odostomia (Chemnitzia), 415. europaea, Cypraea, 505. excavata( Odostomia}, Chemnitzia, 447. exigua, lanthina, 460. exiguus, Trochus, 309. eximia (Rissoa), Chemnitzia, 446. exoleta (Artemis), Venus, 117. faba, Crenella, 63. fabalis, Littorina, 342. fabula, Tellina, 128. fasciata, Tornatella, 386. fasciata, Venus, 115. fasciatum, Cardium, 101. fascicularis, Chiton, 248. fenestrata, Chemnitzia, 440, 526. ferroensis (Psammobia), Tellina, 127. ferruginosa, Anatina, 146. ferruginosa, Lucina, 88. ferruginosa, Montacuta (Anatina), 146. ferruginosa, Mya (Anatina), 146. FISSURELLA, 6, 252. Flemingii, Spirialis, 303. flexilis, Velutina, 471. flexuosa, Lucina, 87. florida* Psammobia (Tellina), 127. formosa, Chemnitzia, 422. fornicata, Anomia, 40. fragilis, Pecten, 53. fragilis (Diodonta), Tellina, 131. fulgida, Rissoa, 357, 518. fulva, Acmaea, 263. fulvocincta, Chemnitzia, 425. fulvum, Pilidium (Acmaea), 263. furtivus, Pecten, 54. fusiforme, Buccinum (Murex), 485. fustformis, Murex, 485. Fusug, 483. GALEOMMA, 4, 72. GASTEROPODA, 6, 7, 13, 16, 225. GASTROCH^NA, 5, 158. GASTROCH^NID^:, 5, 157. Gibbsii, Modiola, 61. Ginannianus, Murex, 494, 526. Ginannianum, Pleurotoma ''Murex), 494. glabrata, Odostomia(ChemmtzieL),4 1 5. glabrum, Caecum, 329. glauca, Mactra, 107. glaucina, Natica, 464. glycimeris, Pectunculus, 68. gracilis (Mangelia'), Murex, 492. graeca, Patella (Fissurella), 252. granulata, Anatina, 1 44. granulata, Corbula (Anatina), 144. granulata, Poromya (Anatina), 144. granulatus, Trochus, 305. Grayana, Assiminia, 380. Grcenlandica, Scalaria, 463. 2M 2 INDEX. HALIOTIS, 6, 255. haliotoidea, Bulla (Lamellaria), 468. Hanleyi, Chiton, 251. HELICID^E, 7. helicinus, Trochus, 317. helicoides, Natica, 467. HELIX, 7. ? helvacea, Mactra, 107. HETEROPHROSYNID^E, 7, 387. Mans, Mactra (Mya), 167. hians (Lima), Pecten, 54. Humphrey sianum, Buccinum (Murex) , 484. Hungaricus, Pileopsis, 264. hyalina (Amphisphyra), Bulla, 285. hydatis, Bulla, 274. HYPOTHYRIS, 4, 35. IANTHINA, 8, 457. incarnata, Tellina, 128. inconspicua, Rissoa, 358. incrassata, Nassa (Murex), 489. incrassatus, Murex, 489. incurvatus, Mytilus, 58. indistincta, Cheranitzia, 428, 524. ingens, Pinna, 64. insculpta (Odostomia), Chemnitzia, 441. intermedia, Anatina, 141, intermedia, Syndosmya, 138. interrupta, Rissoa, 355. interstincta (Odostomia}, Chemnitzia, 426, 523. irus (Donax), Venerirupis, 162. Islandica, Cyprina, 108. Islandicus (Fusus), Murex, 484. Islandicus, Pecten, 54. ISOCARDIA, 5, 108. JEFFREYSIA, 7, 388. Jeffreysii, Spirialis, 303. juffosa, Littorina, 342. KELLIA, 5, 89. KELLIAD^E, 5, 88. ? Kingii, Natica, 467. laMosa, Rissoa, 356. Lachesis, 479. lactea, Area, 67. lactea, Rissoa, 372. Lacuna, 346. laevigata (Helix), Velutina, 470. lavigatum, Cardium, 102. lams, Chiton, 251. laevis, Marginella, 506. ICBVIS, Patella, 257. Icevis, Skenca (Trochus), 314. LAMELLARIA, 8, 467. lamettata, Pholas, 171. LAMELLIBRANCHIATA, ACE- PHALA, 4, 11, 23, 38. lapillus, Buccinum (Murex), 486. lapillus, Murex, 486. lapillus, Purpura (Murex), 486. LATERIBRANCHIATA, GASTE- ROPODA, 6, 13. LED A, 4, 71. legumen (Ceratisolen), Solen, 156. LEPTON, 4, 72, 75. leucoma, Lucina, 88. Leufroyi (Mangelia), Murex, 502. lignaria {Scaphander), Bulla, 285. LIMACID^E, 7. LIMAX, 7. LlMNEA, 7. LlMNEAD^E, 7. lincta (Artemis), Venus, 118. linearis (Mangelia), Murex, 497. lineatus, Trochus, 308. Httoralis, Littorina, 347. littorea, Assiminia (Truncatella), 38,3. littorea, Littorina, 340. littorea, Rissoa (Truncatella), 383. littorea, Truncatella, 383. LITTORINA, 7, 340. littorina, Truncatella, 383. LITTORINID^E, 7, 333. LOLIGO, 8. Loscombii, Lima (Pecten), 53. LUCINA, 5, 82. LUCINIDJE. 5, 82. LUCINOPSIS, 5, 132. Lutraria, 166. lutraria, Mactra (Mya), 168. MacAndrei, Spirialis, 303. MACTRA, 5, 104. MACTRID.E, 5, 103. macula, Buccinum (Murex), 489. magus, Trochus, 310. maminillata (Cylichna), Bulla, 281. Mangelia, 479, 492. marginatus, Chiton, 250. marginatus, Solen, 156. MARGINELLA, 8, 506. marmorata, Crenella, 62. marmoreus, Chiton, 251. maximus, Pecten, 51. megotara, Teredo, 214. , membranacea, Lamellaria (Pleuro- branchus), 267. membranaceus, Pleurobranchus, 267. metula (Cerithium), Murex, 492. millegranus, Trochus, 309. minima, Circe, 111. minimus (Lachesis), Murex, 483. minuta,Arca (Leda), 71. minuta, Turtonia, 97. INDEX. 533 minutissima, Astarte, 111. minutus, Solen (Saxicava), 161. MODIOLA, 4, 61. modiolina, Gastrochaena, 158. raodiolus, Modiola, 62. monilifera, Natica, 464. MONTACUTA, 5, 95. MONTACUTIDJE, 5, 94. Montagui, Natica, 467. Montagui, Trochus, 307. Montagui, Truncatella, 382. MUREX, 8, 479. Murex, 479. rnuricatulum, Cardium, 101. muricatus (Trophon), Murex, 481. MURICID.E, 8, 475. MYA, 5, 165. MYAD.E, 5, 164. my alts, Anatina, 147. MYTILID^E, 4, 57. MYTILUS, 4, 58. nana, Mangelia (Murex), 502. nanus, Murex, 502. Nona, 487. NATICA, 8, 463. navalis, Teredo, 224. nebula (Mangelia), Murex, 494, 495. neglecta, Littorina, 342. NERITID^E, 7. NERITINA, 7. neritoides, Littorina, 345. nigra, Crenella, 63. nitens, Trochus, 316, 515. nit ens, Venus (Pullastra), 120. nitida, Eulima, 450. nitida, Kellia (Lepton), 80. nitida, Natica, 466. nitida, Nucula, 71. nitida, Odostomia (Chemnitzia), 415. nitidissima (Aclis), Chemnitzia, 447. nitidissima, Helix (Truncatella), 386. nitidissima, Skenea (Truncatella), 386. nitidula, Cylichna (Bulla), 285. nitidum, Lepton, 80. niveus, Pecten, 54. nivosa, Chemnitzia, 448. noachina, Puncturella, 255. nodosum, Cardium, 101. norvegica, Anatina, 142. norvegica, Lyonsia (Anatina), 142. norvegica, My a (Anatina), 142. norvegica (My a}, Panopaea, 162. norvegica, Teredo, 224. norvegicum, Cardium, 102. Norvegicus (Fusus], Murex, 483. notata, Odostomia (Chemnitzia), 415. nucleus, Corbula, 149. nucleus, Nucula, 69. NUCULA, 4, 69. obliqua (Odostomia], Chemnitzia, 442. ofolongai.(Lutraria), Mya, 167. obsolete, Pecten, 54. obtusa (Cylichna}, Bulla, 285. obtusa, Pandora, 150, 512. OCTOPODID.E, 8. OCTOPUS, 8. Odostomia, 414. opalina, Jeffreysia, 389. opercularis, Pecten, 46. OSTREA, 4, 55. OSTREADJE, 4, 55. OTINA, 6, 294. otis (Velutina), Otina, 295. ? ovata, Corbula, 149. ovata, Venus, 116. OVULA, 8, 507. palliata, Littorina, 342. pallida (Odostomia}, Chemnitzia, 415, 521. pallida, lanthina, 459. pallidula, Lacuna (Littorina), 349. pallidula, Littorina, 349. pallidula, Nerita (Littorina), 349. PALLIOBRANCHIATA, ACEPHA- LA, 4, 10, 20, 35. PALUDIXA, 7. PALUDINID^E, 7. PANDORA, 5, 150. PANOP^A, 5, 162. papyracea (Pholadidea), Pholas, 170, papyracea, Pinna, 64. parasitica, Ostrea, 55. parva, Pholas, 176. parva, Rissoa, 355. PATELLA, 6, 257. PATELLID.E, 6, 251. patelliformis, Anomia, 40. patula, Littorina, 342. patula, Ovula, 507. PECTEN, 4, 46. pectinata, Pinna, 64. PECTINIBRANCHIATA, GASTE- ROPODA, 6, 7, 13, 16. PECTINID^E, 4, 45. PECTUXCULUS, 4, 68. pediculus, Cyprcea, 505. PEDIPES, 7, 299. pellucida, Patella, 257. pellucidus, Mytilus, 58. pellucidus, Solen, 154. PELORID.E, 8, 455. perforans, Venus (Pullastra), 1 18. perspicua (Coriocella], Lamellaria, 468. perspicuus, Sigaretus (Lamellaria), 468. 534 INDEX. pes-carbonis (Aporrha'is), Rostellaria, 475. pes-pelecani (Aporrhats), Rostellaria, 474. petrous, Turbo (Littorina), 345. phaseolina (Tkracia), Anatina, 140. phaseolina, Modiola, 62. PHASIANELLA, 7, 320. Philine, 286. PHOLADID^E, 5, 169. PHOLAS, 5, 170. PILEOPSIS, 6, 264. PINNA, 4, 64. piperata, Scrobicularia, 138, 511. PISIDIUM, 5. planorbis (S&enea), Rissoa, 373. PLEUROBRANCHIATA, GASTE- ROPODA, 6, 13. PLEUROBRANCHID^E, 6, 266. PLEUROBRANCHUS, 6, 267. Pleurotoma, 479. plicata, Chemnitzia, 418, 522. plicata, Odostomia (Chemnitzia), 418. plicata, Turbo (Chemnitzia), 418. plumula, Pleurobranchus, 270. polita, Eulima, 450. politus, Donax, 123. prcetenue, Cochleodesma (Anatina), 148. prsetenuis, Anatina, 148. prismatica, Syndosmya, 137. propinquus (Fusus), Murex, 484. proxima, Rissoa, 366. proxima, Tellina, 128. pruinosa (Philine), Bullaea, 292. ? psittacea, Hypothyris, 35. PTEROPODID^E, 7, 302. pubescens, Thracia (Anatina), 147. pulcherrima, Rissoa, 358. PULL ASTRA, 5, 118. pullastra, Pullastra, 118. puttastra, Tapes (Pullastra), 118. pullastra, Venus (Pullastra), 118. pullus, Phasianella, 320, 516. PULMONIFERA, GASTEROPODA, 6, 7, 13. punctata, Anomia, 40. punctata (Philine}, Bullaea, 291. punctura, Rissoa, 365. PUNCTURELLA, 6, 255. Purpura, 486. purpurea, Mangelia (Murex), 499. purpurea, My a (Turtonia), 97. purpureus, Murex, 499, 527. pusilla, Chemnitzia, 435. pusilla, Natica, 467. pusillus, Trochus,3l6. pusio, Pecten, 49. puteolus (Lacuna), Littorina, 352. pygmaea, Leda, 71. pygmaa, Nassa (Murex), 490. pygmcea, Tellina, 125. pygmaeum, Cardium, 103. pygmaeus, Murex, 490. PYRAMIDELLID^:, 7, 395. quadrata (Philine), Bullaea, 292. radiata, Nucula, 69. raridentata, Area, 68. reticulata, Emarginula, 253. reticulata, Fissurella, 252. reticulata, Nassa (Murex;, 487. reticulata, Rissoa, 364. reticulatum, Buccinum ^Murex), 487. reticulatum, Cerithium (Rissoa), 375. reticulatus, Murex, 487. reticulatus, Murex (Rissoa), 375. rhombea, Crenella, 63. RISSOA, 7, 353. rissoides, Odostomia (Chemnitzia) ,4 15 rosea, Corbula, 149. rosea, Emarginula, 253. ROSTELLARIA, 8, 474. Prostrata, Pandora, 151. rotundata (Diplodonta), Lucina, 82. ruber, Chiton, 251. rubra, Barleeia, 392. rubra, Kellia, 92. rubra, Rissoa, 392. rudis, Littorina, 342. rudissima, Littorina, 342. rufa, Chemnitzia, 422, 523. rufa, Mangelia (Murex), 502. rufescens, Chemnitzia, 438. rufilabris, Rissoa, 355. rufus, Murex, 502. rugosa, Saxicava, 160. rusticum, Cardium, 103. Sandvicensis, Chemnitzia, 430. Sarniensis, Venus (Pullastra), 120. Sarsii, Rissoa, 356. saxatilis, Littorina, 342. SAXICAVA, 5, 160. scabra (Philine), Bullaea, 292. SCALARIA, 8, 460. scalaris, Chemnitzia, 438. Scillae (Eulimella), Chemnitzia, 447. SCISSURELLA, 7, 322. scapula, Solen (Solenicurtus), 157. scotica, Venus (Astarte), 111. SCROBICULARIA, 5, 138. sculpt a, Rissoa, 364. semistriata, Rissoa, 361. SEPIA, 8. SEPIOLA, 8. septangularis (Mangelia), Murex, 482. serpuloides, Trochus, 314, 515. INDEX. 535 siliqua, Solen, 152. similis, Pecten, 50. sinensis, Calyptraea, 266. sinuosus, Pecten, 49. Smithii, Murex, 500. SOLEN, 5, 152. SOLENICURTUS, 5, 156. SOLENID^:, 5, 152. solida, Mactra, 105. solidula, Tellina, 130. soluta, Rissoa, 365, 520. sordida, Natica, 467. SPH^ENIA, 5, 150. spinifera, Lucina, 88. spiralis, Chemnitzia, 425, 523. spiralis, Odostomia (Chemnitzia), 425. spiralis, Turbo (Chemnitzia), 425. SPIRIALIS, 7, 303. SPIRXJLA, 8. squamosum, Lepton, 75. sguamosus, Solen (Lepton), 75. sguamula, Anomia, 40. striata, Anomia, 40. striata, Rissoa, 360, 520. striatula, Rissoa, 372. striatula, Venus, 115. striatus, Pecten, 54. striatus, Trochus, 309. strigella, Cylichna (Bulla), 285. strigillatus, Solen (Solenicurtus), 157. striolata, Anomia, 40. striolata, Mangelia (Murex), 500. striolata, Odo8tomia(Chemnitzia), 420. stultorum, Mactra, 104. STYLIFER, 7, 454. subauriculata, Lima (Pecten), 54. subauriculatus, Pecten, 54. subcarinatus, Adeorbis (Trochus), 31 7. subcarinatus, Helix (Trochus), 317. subcarinatus, Trochus, 317. suborbicularis, Kellia, 89. subsaxatilis, Mytilus, 58. substriata, Montacuta, 95. subtruncata, Mactra, 105. subulata, Eulima, 452. subumbilicata, Rissoa, 353. suecicum, Cardium, 103. sulcata, Astarte, 111. supranitida, Aclis, 453. SYNDOSMYA, 5, 136, tarentina, Avicula, 64. Tarentinum, Dentalium, 226, 514. TELLTNA, 5, 125. tellinella (Psammobia), Tellina, 127. TELLINIDJE, 5, 123. tenebrosa, Littorina, 342. tenera, Lima (Pecten), 54. tentaculata, Lamellaria, 469. tennis, Nucula, 71. tenuis, Syndosmya, 138. tenuis, Tellina, 129. tere.br -a, Turbo (Turritella), 331. TEREBRATULA, 4, 35. TEREBRATULID^E, 4, 35. TEREDO, 5, 213. teres (Mangelia), Murex, 502. testudinalis, Acmasa, 263. tetragona, Area, 66. Thracia, 140. tigrinus, Pecten, 54, TORNATELLA, 7, 386. TORNATELLID^E, 7, 386. tomatilis, Voluta (Tornatella), 386. trachea, Ca3cum, 327, 517. Trevilliana, Mangelia (Murex), 502. Trevilliana, Scalaria, 463. Trevillianus, Murex, 502. triangularis, Astarte, 111. TROCHID^E, 7, 303. TROCHUS, 7, 305. Trophon, 479. truncata (Cylichna), Bulla, 283. truncata, Mactra, 105. truncata, My a, 165. TRTJNCATELLA, 7, 380. truncatula, Odostomia (Chemnitzia), 448. tubercularis ( Cerithiopsis) ,Murex,490. ? tuberculata, Haliotis, 255. tubularis, Anomia, 40. tulipa, Modiola, 61. tumidus, Trochus, 313. turricula (Mangelia}, Murex, 502. turrita, Odostomia (Chemnitzia), 420. TURRITELLA, 7, 331. Turtoni, Galeomma, 72. Turtoni (Fusus), Murex, 483. Turtoni, Scalaria, 463. Turtoni, Stylifer, 454. TURTONIA, 5, 97. TURTONIAD.E, 5, 96. ulvae, Rissoa, 353. umbilicata (Cylichna), Bulla, 285. umbilicatus, Trochus, 312. undata (Venus), Lucinopsis, 133. undatum, Buccinum (Murex), 484. undatus, Murex, 484. undulata, Anomia, 40. undulatus, Trochus, 317. unica, Aclis (Rissoa), 377. unica, Chemnitzia (Rissoa), 377. unica, Rissoa, 377. unica, Turritella (Rissoa), 377. unicus, Turbo (Rissoa), 377. unidentata (Odostomia), Chemnitzia, 419. UNIO, 4. UNIONID^E, 4. 536 INDEX. VALVATA, 7. varius, Pecten, 48. VELUTINA, 8, 470. VENERIDJE, 5, 1 12. VENERIRUPIS, 5, 162. ventrosa, Rissoa, 372. VENUS, 5, 115. VERMETIDJE, 7, 322. verrucosa, Venus, 117. vesper tina (Psammobia), Tellina, 128. villosiuscula (Thracia), Anatina, 141. vincta, Littorina, 353. virginea (Patella), Acmaea, 262. virginea (Tapes'), Pullastra, 120. vitrea, Rissoa, 369. valuta, Cypra-a (Marginella), 506. vulgata, Patella, 260. vulgatissima, Rissoa, 375. Warrenii (Odostomia), Chemnitzia, 437. XVLOPHAGA, 5, 224. Zetlandica, Rissoa, 372. ziziphinus, Trochus, 306. zonaria, Littorina, 342. THE END. Printed by Taylor and Francis, Red Lion Court. Fleet Street. - m ; - . " . "