i Se 3 KS Ree me Ae a a Oke Seay eaten a as “i Sh ay ee ay thst Tigh detly BRIA Ra, ees VR, ASI ete eR AER: oy ne = Wie? 23D tai - F ‘ . ee ee ee Base 2 KER ‘ 2 ae Ce et ee cs St Shp phe te th EB ance A ge Re -Oy eh Re Oe Eee Ra A ae “ a E r y ee te a Rt AE DE: x cris Pat a8 2 Go te ete Mott ae ob St Seite Bo 6 are EE. od : 3 oa 3 z ‘ : Lor Riera He A : Site : . ; - ) — Si sel aw — WY : ep) ks \ey a “a “yy ” 3 = vase” om wri BN om Noo” 9 m ap) = Ww > = aN > Ss Neon 5’ Pa ” = ~ ee a ALILSNI NVINOSHLINS S3J!1¥VYUYEIT LIBRARIES SMITHSONIAN II ~N NOLLALILSNI- IWS § INSTITUTION William Healey Dall fa} ie Division of Mollusks (a | Sectional Library oe “SMITHSONIAN ep) Lil oa << oO ~m al PLO MVINISMLIAS oa) byug ss | IAN” > = —— — ‘a Si , — = re s ox Ww AWN q — ia : & NO oo \ = VY hy ow SA » - J cm , ak / Y Uy 35 Nw 2 ce 2) 2 15 Gey > ~ \ SS = > r; ‘ Mee > 2 =e ‘ ONG t r (3 9:) < y y/, : f wrs/ Ps) A RS oa NE RE De) = Ss V4 y, te A =m \ MWY Ww) ‘ Ah Ly = o/ = : ae SAS m ~ > Se WAS, mM m x 3 uw? = 7p) 2ARIES SMITHSONIAN INSTITUTION NOILALILSNI_NVINOSHLIWS | s ~ OUINIAT tp. fj Li UY SH LIV SONIAN Qe ee WS Na : XN WON Ss N - ri fax ry ERO Rd SM Cc E em) yz) PRN \* era ’ < MCh SS a NLIZSNI_NVINOSHLINS S saravugiq LIBRARIES SMITHSONIAN 1 mit SMITHSON IAN _ NVINOSHLIWS ! TO NGS -— = — DAW oe=h»ys:C is VARs -—sC=“*X ee ty ae ” is WAST” =m SY ” 5 wasn m Rahs nm” z w ie = an “2 ]_LIBRARIES SMITHSONIAN INSTITUTION NOILMLILSNI NVINO LIBRARIES SMITH \ Ns \ x N NOILALILSNI_ NVINOSHLIWS 4 ’ SMITHSONIAN NVINOSHLIWS SMITHSONIAN NYINOSHLIWS SMITHSONIAN nw 2 ” > ” uJ w” tu lu Vises sh. o 4 es UY ys. —s Y ps z & iS « 67 fea) = a0) = rea) , =| a 7 LIBRARIES INSTITUTION NOILNLILSNI NWINO! r z z iri ow ae = = : cw 2 EF ¥ i > \ a i 2 or b Zz Zz He N NOILNLILSNI LIBRARIES SMITH: z ” 2 & Lor ae ie z= a a SS = ke O i: ae AS . x O = = WW ie ra E = 2 ie = = > 2 n a ol Sam ee GpMITHSONIAN INSTITUTION NOILALILSNI_ NVINO o z .o Yi a WW es wo. a oc ie WY SW) POH 2 Gu) Quy 2 © — fea) — faa} pre O | a Gs Oo = ro) N NOILNALILSNI NVINOSHLINS S3IYVYUEIT LIBRARIES SMITH : ea : ; 3 a = . - 4G i 7 2s eT = Apes mai = a s Up = = i i - S m 24 ne wn = wn e w = 7 LIBRARIES “ INSTITUTION NOILNLILSNI NVINO a2 - we S31NYVYG!IT LIBRARIES SMITH SMITHSONIAN ate, Lote NVINOSHLINS SMITHSONIAN NVINOSHLIWS SMITHSONIAN SX N i NOILNLILSNI_ NVINOSHLIWS cm _ WILLIAM HL DALE ’ SECTIONAL LIBRARY DIVISION OF MOLLUSKs Unio Margarttifrer. and pe ar. EE — ——— BRITISH CONCHOLOGY. OR AN ACCOUNT OF THE MOLLUSCA WHICH NOW INHABIT THE BRITISH ISLES AND THE SURROUNDING SEAS. Vie Hirsles 4 tara } ry 7 “et VOLUME I. LAND AND FRESHWATER SHELLS. By JOHN GWYN JEFFREYS, F.RS., F.G.S8., &c. “O come hither, and behold the works of the Lord!””—PsaLmM xlvi. 8. LONDON: JOHN VAN VOORST, PATERNOSTER ROW. MDCCCLXII. [The right of Trauslation is reserved. } 7 PY tp at Li = " FOOIONS | ! « ‘ ." —_ ~~ ) a aGvk GHA ‘. r -———- a Pod i | ow —— ee i~ »* — ~~ i en ea ~ ‘ ey I ch - 7 ee be - Si > 4 ' Ff, -2™ 7 hy CPT UT OT FT 7 ie? at 2 O. "Fs VTa VI oy ht e Dry t m a7 ee rah Vie des Viléoyt réh Bay rae & etnds A qa oh, bles oh ten 0 > a eee Oe ee A er, id iia ar ‘ ‘ Pe) : : ‘ — — 4 es ;“oaKnod Po a 4, " * Oo pRINTED BY. TAYLQR AND FRANCIS, |. | BERL yi RED LION COURT, Fl FLEE STREET. P hiv Ae! ‘ m , . “ i ° iv 4 he “s ae ; ae P sal * pee ow . . . , TO THE MEMORY Nit PRIS ae a! OF MANY DISTINGUISHED NATURALISTS AND VALUED FRIENDS, WHO ARE NOW NO MORE, AND IN GRATEFUL ACKNOWLEDGMENT OF THE KIND SYMPATHY OF THOSE WHO STILL HAPPILY SURVIVE, FROM ALL OF WHOM I HAVE RECEIVED MUCH ASSISTANCE IN THESE CONCHOLOGICAL STUDIES, I DEDICATE THE PRESENT WORK. AVivaue ¥ PREFACE, THE question whether another book on the British Mollusca is wanted by the scientific world, when there is at present a complete history of the subject by the late Professor Edward Forbes and Mr. Hanley, is answered by the notoriety of the fact that the price of that admirable work puts it beyond the reach of most naturalists ; and the enterprising publisher of those, as well as the present, volumes was so fully impressed with the necessity of another work at a more moderate price, that he invited me to undertake the task, which I fear I have inefficiently performed. In doing this, however, I have endeavoured to make the present work quite distinct from its predecessor, as may be seen by comparing the two; and those who are not fortunate enough to possess a copy of “A History of British Mollusca and their Shells,’ and who can afford the money for its purchase, will not regret the expenditure. With regard to the animals or soft parts of the Mollusca described in this volume, I have been greatly v1 PREFACE. indebted to the invaluable work of Moquin-Tandon, entitled “ Histoire naturelle des Mollusques terrestres et fluviatiles de France,’ in which the physiology and anatomy of the land and freshwater Mollusca have been treated in a far more able and exhaustive manner than had been previously done by any author. My old and esteemed friend, Mr. Alder, has most kindly promised to assist me with a notice of the Nudi- branchs, so as to make that part of the subject as com- plete as possible ; and the value of such cooperation will be fully appreciated by all naturalists. | A volume of supplementary plates will probably be published, to contain figures of every species and well- marked variety. The figures now given illustrate the genera; but the cost and price of the work would have been greatly increased by the other mode of illustration, except by resorting to the inartistic and unsatisfactory substitute of woodcuts. In the prosecution of this task I have been actuated by what I trust will not be deemed a selfish consideration. The study of our native Mollusca has been to me from childhood such an inexhaustible source of pleasant and innocent occupation, it has given me so many happy hours, and it has taken away or alleviated the sting of so many sorrows, that I am desirous to assist in making it more an object of general cultivation than it has hitherto been. This field of research has by no means been exhausted ; and whether regarded in a zoological - PREFACE, Vil or geological point of view, or as tending to increase our imperfect knowledge of the habits and instincts of these humble works of our Common Creator, very much yet remains to be done. No lover of nature need share in Alexander’s sigh, or regret that he hasno more work to do in any department to which he chooses to devote himself. ‘“ Nulla dies sine linea”? was the favourite maxim of the great Linné; and our days are too few for the accomplishment of all that we propose to do, let our aspirations be ever so modest. A few explanatory remarks as to the scope of this work may be here introduced. It was at first my intention to give, in an Intro- duction,-a general outline of the subject, and to treat at considerable length some of the principal topics which are more especially interesting to naturalists and geolo- gists. But the space which is necessarily occupied by the body of the work (although the synonymy has been compressed within the shortest limits and the descrip- tive characters have been printed in small type) will not admit of justice bemg done to this part of the subject, without making the volume too bulky ; and I must there- fore content myself with offermg in the proper place a few observations, so as to elicit further discussion. In describing the dimensions of shells, 1 have taken the measurements from average and adult specimens, dividing inches into decimal and centesimal parts ac- cording to the size of each species. This mode of vill PREFACE. admeasurement I have considered preferable to stating the largest dimensions to which each species attains, which would not give a fair idea of the usual size, or to adopting the method used by some Continental authors of giving the range or extreme limits of such dimensions. Any extraordinary difference of size presented by speci- mens or varieties will be noticed. In giving the ad- measurement of bivalve shells, I have considered the length to correspond with the line of growth (viz. from the apex or beak to the front margin), and the breadth from one side of each valye to the other. In the case of univalve shells I have adopted the same rule, viz. taking the line of growth for the length (the apex or point of the spire representing each beak of the bivalve), and the widest part of the shell, or its greatest diameter, for the breadth. At the end of the work I propose to give some prac- tical hints to collectors. For the benefit of such of my lady readers as have not added a knowledge of the classics to their other accom- plishments, I have marked the accentuation of all the names of genera and species described in this work. One word of frequent occurrence I have noticed to be too often mispronounced by many who ought to know better, and that is the specific name of our common eatable oyster, mussel, and cockle. This word (edilis) has the middle syllable long, as is evident by remembering one of the various gastronomic maxims of Catius, “Vinea PREFACE. ix submittit capreas non semper edules.” My late friend, the Rev. Dr. Goodall, when he was Provost of Eton, impressed on my memory a rule of pronunciation, which it may be here useful to repeat. It is, that in words which end in inus, and are derived from the names of animals, the last syllable but one is generally long (as im Neritina and anatinus), while in those words which have a similar termination, but are derived from vegetable or mineral names (such as Janthina and crystallinus), the penultimate syllable is generally short. The first are Latin, and the last are Greek forms. I have also endeavoured to render as literally as possible the English meaning of all generic and specific names, although the barbarisms are nearly as frequent in the nomenclature of natural history as they are in the materia medica. The way in which the name of the great Swedish naturalist and founder of scientific classification ought to be spelt has been long the subject of controversy. It was originally Linneus; but on his receiving a patent of nobility, he assumed the name of Linné. The latter name is given in the twelfth (and most perfect) edi- > and in all his subse- tion of the “Systema Naturee ;’ quent works and correspondence he always used this title of distinction. The learned Society which bears his name in this country is Linnean and not Linnean, as appears by their charter and Transactions. Under these circumstances, I have adopted the name which he asd X PREFACE. himself preferred, and which is prefixed to the work by which he is best known as a conchologist. A parting word to the critics! When a mere youth, I was encouraged by my lamented friend, Mr. Dillwyn, to commit to print what little I then knew of the subject comprised in the present volume; and my first essay, entitled “A Synopsis of the Testaceous Pneumono- branchous Mollusca of Great Britain,’ was honoured by the Linnean Society by publication in their Trans- actions. Now, in mature years, I have become still more bold, and venture to appeal to the public. _ But, although I cannot hope to be exempt from the fate of all authors—criticism (and indeed, for the sake of science and the elucidation of truth, I would rather invite it, instead of considering it a calamity), I cannot send forth this little work without a mixture of the same feeling of hope and doubt, which made the ancient poet thus apostrophize his book :— “ Paucis ostendi gemis, et communia laudas, Non ita nutritus. Fuge, quo descendere gestis : Non erit emisso reditus tibi.” 25 Devonshire Place, London, 24 May, 1862. INTRODUCTION. Geran. ) tye CLASSIFICATION. DEFINITION OF THE TERM ‘“‘CONCHOLOGY.” — CONFORMITY OF SHELLS WITH THEIR INHABITANTS.—CEPHALIC MOLLUSKS OR UNIVALVES. —- ACEPHALA OR BIVALVES. — TUNICATA. — SPE- CIES.— VARIETIES. — MONSTROSITIES. —- REVERSED SHELLS. — SYNONYMY. NOMENCLATURE. Definition of the term “ Conchology.”’—Conchology *, as a branch of Natural History, treats of the Mollusca or that great division of invertebrate animals which have soft bodies and an organization superior to that of insects and only inferior to that of fishes. It properly comprises the study, not only of the shell or outer cover- ing of the mollusk, but also of the whole animal,—al- though it has sometimes been used in a more limited sense, in contradistinction to the term “ malacology,” which has exclusive reference to the soft parts of the animal. Linné included the Mollusca in his great class Vermes—some of them as Vermes Mollusca and others as Vermes Testacea; but as the first of these divisions comprised a very heterogeneous assemblage of inver- tebrate animals, and as the testaceous Annelids were united with the latter, the classification proposed by him * Compounded of two Greek words, royxn, a shellfish, and Ndoyos, a treatise. X11 INTRODUCTION. [cH. has not been adopted by modern naturalists. Cuvier was the first to restrict the term “ Mollusca” to its present meaning. Nearly all the Mollusca have a shelly cover- ing, which protects either the whole of their bodies or the more important organs. Even the Nudibranchs or Sea-slugs, in their embryonic state, are provided with a unispiral shell; and the Limacide or Land-slugs possess a shelly plate, which is imbedded in the shield or mantle. The term “ Conchology ” may be therefore considered sufficiently appropriate to express the nature of this science, especially when the origial meaning of the word is taken into account. I do not profess to be conversant with the anatomy and morphology of the Mollusca; and I must refer those who wish to study this part of the subject to the admirable treatises of Cuvier, Milne-Edwards, Quatrefages, Troschel, Von Sie- bold, Vrolik, and other Continental writers, as well as to those of our own equally eminent countrymen, Owen, Gray, Huxley, and Hancock. A complete knowledge of the Mollusca is of course unattainable without such study; but I must content myself with having made such progress as time and opportunities have permitted. ‘‘ Est quadam prodire tenus, si non datur ultra.” Conformity of shells with their inhabitants.—The im- portance of studying all the parts of the Mollusca is undeniable, and especially for the purpose of arranging - them in generic and higher groups ; but the distinctive characters afforded by the soft parts alone, which have been erroneously termed by some writers the “ animal,” cannot be much relied on in making out species. Phi- lippi has completely demonstrated the insufficiency of such characters im the case of the genus Rissoa; and a careful comparison of the descriptions given in the fol- lowing pages of our Land and Freshwater Mollusca Ty) INTRODUCTION. xii ought to satisfy any naturalist, who is inclined to con- sider the question in an unprejudiced spirit, that the body or soft parts of the mollusk, taken without re- ference to the shell, offers an extremely slight and variable criterion of specific difference. The shell of itself generally enables the conchologist to distinguish one species from another, without regard to the soft parts; and as the latter are seldom observable, the con- venience of such a mode of distinction is obvious. It would be rather difficult for a malacologist to describe any particular kind of testaceous mollusk without no- ticing the shell; and for the same reason a crab or sea- egg would not be easily recognized by the description, if all mention of the carapace or test were omitted. The shell of the mollusk may be in some respects considered as a pseudo-skeleton, serving not only to protect the soft and tender body, but also to keep the whole frame together, like the true skeleton of any vertebrate animal. There is, besides, an intimate connexion between the shell and the tissues of the body, which is only dissolved by death or violence. The shell is (to use the words of Mr. Searles Wood) “part and parcel of the animal itself.” I am aware that this opinion has been controverted by high authority, and especially by Dr. Gray, whose valu- able contributions to the science of zoology, in many of its branches, are familiar to all. He, at one time, dis- turbed the minds of geologists as well as students not a little, by a statement that some shells which were per- fectly alike were inhabited by animals so extremely dissimilar as to be referable to very different orders of Mollusca*, This statement, however, he afterwards quali- fied to a considerable extent by admitting that, “in the distinction of the larger and smaller groups of Mollusca, * Phil, Trans. 1834, p. 302. X1V INTRODUCTION. [ CH. the characters derived from the animal, the shell, and the operculum, which all have a mutual relation to each other, are of equal value and constancy ;” and he ob- served “how thoroughly they depend on each other, and what excellent and permanent characters they afford, both separately and in combination with each other*.” Dr. Gray seems now to be quite sensible of the value of conchological characters, as nearly the whole of his numerous genera of Mollusca have no other foundation than the shell. I believe that the form and structure of the shell will be invariably found to correspond with the habits and wants of the animal which produces it. The mechanical principles involved in the construction of shells, and the adaptability of these habitations to the uses of their builders, have been admirably explained by the Rev. Canon Moseley, in an essay “On the Geometri- cal Form of Turbinated and Discoid Shells,” which was published in the ‘ Philosophical Transactions’ for 1888, and to which I would invite the attention of my readers. The uniformity of the laws which are here so ably ex- pounded, and the correlation which exists between the mollusk and its shell, exhibit in no small degree the in- finite wisdom of the Creator of all things, thus oe “dimly seen In these thy lowest works ; yet these declare Thy goodness beyond thought, and power divine ! ” Cephalic Mollusks or Univalves.—The Mollusca may be considered in a general point of view as divided into Cephalic and Acephalous, and their shells into Univalves and Bivalves. The former arrangement was proposed by Lamarck, and the latter by his predecessor, Linné, who also added a third division—viz. that of Multivalves, which would almost be warranted by the anomalous * Ann. & Mag. Nat. Hist. Sept. 1855, p. 425. .] INTRODUCTION. Xv organization of Teredo and Chiton. All these divisions, however, are clearly artificial. The Cephalic or Cephalo- phorous Mollusks have a distinct head, and usually ten- tacles or horns, with eyes at their tips or base, and a foot or muscular disk for crawling or floating. A few of them have arms for swimming. Some inhabit the land, and others the water. The Snail, Whelk, and Cuttle- fish are instances of this kind of Mollusca. Acephala or Bivalves.— Although the bivalve Mollusca have no heads as a distinct part of their bodies, they are not deficient in those organs of outward sense which cha- racterize other Mollusca, and their brain is as largely developed. Many of them have numerous eyes for seeing, otolites or ear-stones for hearing, filaments for touching, lips for tasting, a mouth for taking in their food, and (according to some physiologists) also an organ of smell. The fry of the Oyster, Terebratula, and other bivalves, which, in their adult state, are permanently attached to other substances, swim about freely, and are provided with distinct eyes, which afterwards disappear. All the Acephala are aquatic, and respire by means of gills, like fishes. The Oyster, Mussel, and Cockle are familiar examples of this kind of Mollusca. Tunicata.—The Tunicata or Ascidians can scarcely be said to belong to the Mollusca, from which they differ, according to Milne-Edwards, in many essential par- ticulars, especially as regards their circulation and re- production. They appear to have a considerable affinity to the Polyzoa (or what are generally called “‘ Polypes”’), and may with them constitute the great and separate class of Molluscoidea. Each division of the animal kingdom has so many points of resemblance to others, and the network of organization is so closely inter- woven, that it would be very difficult to define any one Xvi INTRODUCTION. [cH. class by characters which others do not share in common with it. Mr, Alder is at present occupied with the sub- ject of the British Tunicata; and it will doubtless re- ceive from that talented and experienced naturalist the same elucidation as was bestowed on his celebrated Monograph of our native Nudibranchs, Species.—I now venture to offer a few remarks on a very difficult and perhaps insoluble problem, viz, the nature of species. The difficulty of this investigation is greater in the study of the Mollusca and other Inver- tebrata than in that of more highly organized animals, because one characteristic element, from the nature of their reproductive system, is here wanting or beyond the reach of observation, Nearly all the land Mollusca, the habits of which it is comparatively easy to study, have both sexes united in the same individual; and not even the aquarium will enable us to make those experi- ments as to the fertility or sterility of hybrids to which such importance is attached in the discussion of this question in the case of vertebrate animals, The forms of some shells appear to be more perma- nent or capable of being reproduced without any modi- fication than others, The Silurian Lingula, which claims the precedence of all Mollusca in point of antiquity, is said to be undistinguishable from an existing species ; and its mould must therefore have been continued from the womb of time to the present day without the slight- est change. The secondary strata contain many well- known instances of a similar persistence of form, espe- cially those of Terebratula caput-serpentis and some Foraminifera, which are considered by competent autho- rities not to differ from species which now live in the adjacent seas. A large proportion of the fossil shells found in the lowermost of the Pliocene strata (or 1.] INTRODUCTION. xvi “ Coralline Crag ”’) are precisely similar in every respect to the recent shells of species which bear the same names and still survive; and it is impossible for the most critical species-maker to distinguish one from the other. Even their varieties and monstrosities or abnormal forms are still repeated. The opinion of the late Professor D’Or- bigny, which has been adopted by Agassiz, that all tertiary species became extinct, and that they are only repre- sented at present by analogous forms, evidently resulted from a preconceived theory, against which a concordance of fossil with recent species would have militated. Without, however, entering into an abstruse (and perhaps useless) inquiry into the origin of species, or how far they have been modified during any period of time, however vast, by external circumstances or condi- tions, it is undeniable that certain definite forms, called “species,” exist, and that they constitute more or less extensive groups of individuals, which resemble each other as well as their parents and offspring, to the same extent that we observe in the case of our own kind. These groups, to deserve the name of species, must be distinct from others; because if any of them are so intimately blended together by intermediate links as to make the lne of separation too critical, the test fails, and a subordinate group, or what is called a “variety,” is the result. For this reason it is indispensably necessary to compare as great a number of individuals as possible, and especially a series of different ages and sizes com- mencing ab ovo, as well as specimens collected from various localities. The study of abnormal or monstrous forms is also important in order to ascertain the range of variation in growth. By such investigations a crying abuse of the present school of natural history (an ex- cessive multiplication of species) would be avoided, Xvill INTRODUCTION. [CH. juster views would prevail as to the distmction of spe- cies, and the well-deserved reproach of those philo- sophers who are confirmed in their denial that species have any real existence in nature by the notorious dis- agreement of naturalists as to their limits would thus cease. There is no judge or “ arbiter specierum ;” and every naturalist is at perfect liberty to follow the bent of his own discretion or inclination in the extension or reduction of species, subject only to the opmion of his scientific compeers. He is amenable to no other autho- rity. Hence arises that great and continual diversity of opinion as to the determination of certain species among naturalists, whose opportunities or experience are more or less great, or whose minds are differently constituted— the nature of some being rather analytical and of others syuthetical. The same remark of course applies to the distribution of species to genera, and of these, again, mto families and higher groups or sections. To a cer- tain extent all classification is artificial and arbitrary ; but the necessity for some arrangement of the kind is | obvious, considering the immense number and variety of objects to which some name or symbol of distinction must be given for the sake of those who pursue or study any branch of natural history. Systems of classification are as indispensable to a naturalist as tools to a work- man. ‘This necessity of science equally applies to the discussion of the imteresting question as to the origin and mutability of species, which in the absence of such data could not be satisfactorily conducted. Varieties.—Besides species, and holding a subordinate rank to them in the great host of Nature’s works, are certain forms called “varieties,” which are not less defi- nite, but more difficult to separate from the typical or specific forms. They are offshoots of species, and origi- 1. | INTRODUCTION. XIX nate in some peculiarity of climate, situation, composition of the soil or water which they inhabit, the nature or supply of food, and various other conditions. The cha- racters by which they usually differ from species consist of size, comparative proportions of different parts, colour, and degree of sculpture ; and the investigation of forms thus changed or modified is often extremely perplexing. Some species are more liable than others to variation ; and, as might be expected,:the tendency to variation is greater in those species which most abound in individuals, by reason of their offering a wider scope of observation to the naturalist. Varieties are of two kinds, perma- nent and local. The former are called “races,” and have many of the characters of true or typical species, with which they associate. Great experience and good faith are essential to the vestigation of this eaxperi- mentum crucis; and the only reliable test of distinction between species and races appears to be the discovery of intermediate forms. In the absence of such diseovery ‘we may proceed to classify,—although after all we must not lose sight of the great probability that all species, and even higher groups, may have originally descended from races or permanent varieties, and these again from local varieties. The latter are more readily distinguished from species and are never found associated with them. I believe it may be now considered a well-established rule, that all distinct groups of individuals living toge- ther and having a common feeding-ground, and which are not connected or blended with each other by insen- sible gradations, are primd facie entitled to the rank of species. A coutrary opinion used formerly to be enter- tained by some naturalists; and it was not unusual to found a claim to specific distinction on the fact that the specimens thus distinguished did not oceur with the XX INTRODUCTION. [CH. species from which it was proposed to separate them, They apparently forgot that the very difference of locality or habitat, with its accompanying conditions, caused the variation in question. Monstrosities—These abnormal forms of shells are frequently repeated, and even appear to be hereditary ; and it is not easy at first to distinguish them from varie- ties. Both are probably owing to an irregularity, or an excessive or defective power, of secretion in the mantle of the animal. The monstrosity seldom, if ever, occurs in the first stage of growth; and the examination of the top whorls or apex of a univalve, or of one of the beaks of a bivalve (being in each case the nucleus of the shell), offers a good criterion to distinguish monstrosities from species. The normal or regular form becomes distorted at a subsequent stage of growth, instead of pursuing the usual course of formation. Reversed shells —Among the numerous cases of mon- strosity to which the Mollusca are liable, by reason of their comparatively simple organization, none is more remarkable than the reversed turn and position which the spire of univalve shells and the valves of some Acephala not unfrequently assume. The twist of the spire in univalves is, with a few exceptions, dextral or from left to right, the shell being placed with its spire towards the observer and its mouth downwards. If the shell is held in this position before a mirror, the spire will of course appear to be sinistral or turning from right to left, which is termed “reversed”? This phenomenon occurs in most species of Mollusca which have spiral shells; but it is more rare in some than in others. In certain genera the shell is naturally reversed; and a dextral spire becomes the exception or monstrosity. In a few species the spire is as frequently sinistral as dex- 1.] INTRODUCTION. XXl1 tral. The direction of the spire is attended by a corre- sponding change in the position of those organs of the animal which are usually placed on one particular side ; and it may be compared to the case of a man having his heart on the right and his lungs on the left side of his body. ‘The structure of a mollusk is, however, not so complicated; and the consequence of such a reversal in the position of its organs is probably not very import- ant to its economy. One curious case of this kind of malformation is worth noticing. During the deposit of that part of our upper tertiary strata which is called the “Red Crag,” nearly all the specimens of the almond whelk (Fusus antiquus) appear to have been sinistral or reversed, dextral specimens being comparatively very scarce in this formation. The same species still exists and is common in our seas; but the proportion of dex- tral to sinistral specimens is at present exactly the con- trary to what it was in the Crag epoch—the former being now the rule and the latter the exception. A reversed spe- cimen in a recent or fresh state is worth half a sovereign ; while dextral specimens may be had at any street stall (with the fish) at the rate of four fora penny. A few bivalve species, which have one valve larger than the other and are therefore called inequivalve, have also their sheils occasionally reversed,—their right or left valve being the largest, contrary to the usual rule in these species. In the prosecution of any inquiry into the nature of species or varieties, or as to whether there have been any special or successive creations since this world was called into existence by the fiat of its Great Creator, I do not believe that it can have any irreligious or sceptical tendency. Holy Scripture is not a work of natural his- tory, and it is silent on the subject of this investigation. XXH INTRODUCTION. [CH, As Dr..Carpenter has well observed, in his Researches on the Foraminifera*, “The creation of any organism seems to me just as much to require the exertion’ of Divine Power when it takes:place in the ordinary course of generation, as it would do if that organism were to be called into existence de novo; the question, being in reality whether such exertion takes place in the way of continuous exercise according to a settled and compre- hensive plan, or by a series of disconnected efforts.”” . _ Synonymy.—Although the prevalent habit of multi- plying species is much to be deprecated, an equal amount of injury has been done to the cause of science by the unnecessary addition, from time to time, of fresh names for species which had been previously described ;- the consequence of which is that an overgrown mass of nomenclature encumbers most works on natural history. For our common Cockle and its varieties no less than sixteen, and for the Oyster fourteen different names have been given by British and Continental writers; a genus of minute shells (Odostomia) has received from various conchologists twenty different names ; and in an essay of M. Bourguignat on the species of Pisidiwm (a small freshwater bivalve) the synonymy of P. amnicum comprises eighty specific names and extends over more than. five octavo pages. The student may well stand aghast at this fearful array of names, which bewilder him and obstruct his entrance into the portals of the edifice of natural. history! This’ redundancy of names for the same object has partly arisen from the want of inter- course which naturalists of this and other countries experienced formerly, and especially during that chronic state of international warfare which so long debarred us from any communication with foreigners. Such an * Phil. Trans. vol. cl. p. 570. ta}, INTRODUCTION. XXli unfortunate state of things certainly retarded scientific progress in Great Britam to a very great extent; and the friendly sympathy which now exists between the naturalists of all countries cannot be sufficiently ap- preciated. In one sense the multiplication of species and addition of synonyms are convertible terms; and that is, where local varieties have been described and raised to the rank of species. This evil it is impossible to prevent. but as science does not march “ pede claudo,”’ but regularly and steadily, it is to be hoped that each succeeding year will bring with further discoveries the occasional publication of monographs by experienced na- turalists, so as gradually to rectify this cryig evil. The introduction to the ‘ Flora Indica,’ by Drs. Hooker and Thomson, contains a valuable remark which deserves the attention of zoologists as well as botanists, viz., “The discovery of a form uniting two others, previously thought distinct, is much more important than that of a totally new species, inasmuch as the correction of an error is a greater boon to science than a step in advance.” ~ Nomenclature.—Very often the longest and most un- pronounceable names have been bestowed on minute and almost microscopic species. When the student meets with such names as Cerithiopsis tubercularis and Omalo- gyra nitidissima, he is scarcely prepared to find that one of the objects designated by these more than sesqui- pedalian words is scarcely more than a quarter of an inch in length, and that the other is only about one- fifteenth of an inch m diameter !. There is, however, no way of preventing this abuse of language for scientific purposes, except by making a new coinage; and this would be attended with more inconvenience to naturalists in the substitution of new for old and familar names, than in the retention of a few long words. XXIV INTRODUCTION. [cH. The general rule is not to alter the name which has been first given to any species, in order to establish a con- ventional right of priority and to prevent confusion, But this rule is not without an exception—especially where the original name has been accidentally misspelt, either by the author or prmter. Thus “ Suediense”’ has been properly changed to Swecicum ; and “ Syndosmya” ought to be replaced by Syndesmia. Such trivial corrections are necessary in the works of our best authors; and in those which have largely benefited the cause of science, non ego paucis Offendar re quas aut incuria fudit Aut humana parum cavit natura.” CHAPTER tt. ORGANIZATION AND HABITS. REPRODUCTIVE SYSTEM.—-FECUNDITY.—HYBRIDISM.—PROGRESSIVE DEVELOPMENT, —ORGANS OF SIGHT——-HEARI MOTION.—FOOD.—SIZE.—HABITAT.—CARE OF YOUNG.—SOCIA- BILITY.—— ZSTIVATION AND HIBERNATION.—NESTS.—MODES OF ATTACK AND DEFENCE.—RENEWAL OF PARTS.——PHOSPHORES- CENCE.—-PERFORATING POWERS,—OCCASIONAL APPEARANCE AND DISAPPEARANCE.—TENACITY OF LIFE,—AGE,—RESUME. Reproductive system.—The modes of propagation among the Mollusca are varicus. In the case of uni- valves, many of them (e. g. the Whelk tribe) have distinct sexes, and are what botanists term “ dicecious ;” while most of the land-snails are nearly “‘ monecious,” each individual being at the same time male and female, but incapable of fertilizing itself. Some of these even change their sex at different periods,—the Valvatide being at 11. | INTRODUCTION. XXV first male and afterwards becoming female. In the case of the Conchifera or bivalves, they are probably all strictly “ moncecious ” and fertilize themselves. It was at one time supposed that the Oyster and freshwater Mussel were exceptions to this rule, and that some in- dividuals were male and others female; but the re- searches of Davaine, Moquin-Tandon, and other able physiologists have disproved this idea*. The external organization of the Conchifera, as well as the complete isolation of the Teredines and many other kinds from all intercourse with each other during the whole of their lives, would make it very unlikely that they are of dif- ferent sexes. Some of the Mollusca are ovoviviparous, the eggs being hatched within the body and the fry ex- cluded in a perfect form. This is the case not only with “moneecious ” kinds (such as Anodonta and Kellia), but also with some snails (Helix rupestris and Pupa umbili- cata) and even with “ dicecious”’ kinds, such as Paludina and certain species of Littorina. Some particulars will be found in the following pages with regard to the amours of the land and freshwater snails ; and much more might be said on this curious subject. The tender passion seems to take up much of their time and attention. M. Turpin has observed a pair of the common garden-snail (Helix aspersa) engaged in love-making for the space of more than ten hours ! Fecundity.—The extreme fertility of some mollusks is not exceeded by that of fish. It has been estimated that the oyster spawns annually at least three millions. Ac- cording to C. Pfeiffer the gills of a freshwater mussel of moderate size contain at least 400,000 eggs ; and Jacob- son has given a much higher figure (two millions) for the. * See also Hancock “ On the Organization of the Brachiopoda,”’ Phil. Trans. vol. exlviii. p. 816. b XXV1 INTRODUCTION. [CH. product of a large individual of this kind. If this rate of increase were unchecked, our seas and rivers would in a comparatively short time (reckoning geologically) be filled up with the remains of shell-fish. Hybridism.—Although many surmises have from time to time been hazarded as to the production of abnormal forms of Mollusca by means of an unnatural union be- tween individuals of different species, the only direct experiments or observations that appear to have been published on the subject have been made by French naturalists. M.Gassies, in his descriptive Catalogue of the Land and Freshwater Mollusca found near Agen, mentioned several cases of what he called ‘ accouple- ments adultérins,” which he had observed between in- dividuals of Hehe virgata and H. Pisana, as well as between those species and Bulimus decollatus. M.Gassies enclosed the snails during a thunderstorm im a vessel covered with metallic gauze; and he beheved that the electricity with which the air was then charged induced the unnatural union. Great care appears to have been taken to prevent any error in the result, by selecting individuals which had not been previously fertilized and keeping them after fecundation separate from any others. The product of these unions was as follows. The young of H. Pisana had perfectly white shells,—their mother having the usual coloured bands; and the young of H. virgata had shells of a darker colour than that of their mother. In the other case, the product of the Helices which had been coupled with the Bulimus was various. Many had shells which were almost scalariform ; the shells of others were pyramidal; but the greater part of them had shells exactly like that of their mother. The product of the Bulimus did not differ from their maternal form. M. Gassies had also observed the product of .a 1. | INTRODUCTION. XXV1l union between Helix nemoralis and H. hortensis, in which the colour of the lips of their shells in each case varied indifferently from brown or rose-colour to milk-white. Professor Lecogq and M. Miergue have celebrated the voluntary nuptials between individuals of Helix nemo- ralis and H. aspersa, as well as between Pupa cinerea and Clausiha papillaris ; but these unions do not seem to have been blessed with any offspring. The fact, however, of such unions having taken place in a state of nature, and not under forced or accidental conditions, is remarkable, and the more so because the individuals belonged to what are considered different genera. ' Progressive development.—The researches of geolo- gists have established by positive evidence, that the organization of many animal and vegetable types has not become more specialized or rendered more perfect since _ the period to which we ascribe their creation, and that, notwithstanding the enormous lapse of time which is indicated by the accumulation of fossiliferous strata, the modification or change which these types have under- gone has been remarkably slight. There is abundant evidence of variation, but none of what is usually under- stood as progression*. The theory of “ progressive de- velopment” appears to have been very hastily advanced, and is by no means borne out by geological facts. It is a curious circumstance in the history of the growth of certain land and freshwater Mollusca, that the young of some species of Pupa resemble those of Helix, the young of the latter those of Zonites, and the young of the last those of Vitrina. These genera are enumerated in the order of their organization, Pupa being the most, and Vitrina the least perfect of them. * See Professor Huxley’s Address delivered at the Anniversary Meeting of the Geological Society, 21st February, 1862. b2 XXVIL INTRODUCTION. [cH, Organs of sight.—The eyes of a Cuttle are more perfect than those of many kinds of fish ; but the so-called eyes of land-snails are supposed to be only organs of touch and not of vision, although endued with a greater sensi- bility than the tentacles which support them. The coloured bulbs which frmge the mantle of a Scallop are also called eyes; but their structure is very simple. According to Mr. Lea, several kinds of Unio are sensi- tive to light. These organs are entirely wanting in many of the Mollusca, and even in some species of genera which usually have eyes. Hearing.—In the Pectinibranch Mollusca the contents of the auditory capsules consist of spherical ear-stones, which in every respect but that of form are similar to the otolites of fishes. In the Pulmonobranch Mollusca they are called octoconia and consist of a chalky pulp, which is separable into minute elliptical granules. Frey has observed organs of hearing in many of the land and freshwater Mollusca, both univalve and bivalve. He counted as many as 200 otolites of different sizes in one of the auditory vessels (of which there were two) in an adult snail. In Spherium (or Cyclas) each individual appears to have never more than a single otolite. He believes that these bodies are formed by a subcrystallization of the liquid contained in the auditory vessels. Smell.In the Helicide, or land-snails, this sense is supposed to lie in the bulbs which surmount their ten- tacles. It is probable that the carnivorous or zoophagous Mollusks have the power of scenting out their prey or food. Quantities of the common “almond-whelk” of dealers in shell-fish (Fusus antiquus) are procured on the Cheshire coast by the fishermen placing a dead dog on the sands at low-water mark during spring tides. The bait is then completely covered with stones, which II. | INTRODUCTION. XX1X are piled up like a cairn, partly to prevent the carcase heing carried away by the tide, and also because the fishermen have a scruple about eating shell-fish which have been fed on such carrion. On the next turn of the tide the heap of stones is visited and the whelks are found on the surface in great numbers, having been apparently attracted by the smell of the bait, but unable to get at it. Locomotion.—The methods by which Mollusca move from place to place are exceedingly varied. Most uni- valves crawl on the lower part or disk of a large fleshy organ, which is the homologue of a foot and supports the body. The Melampus uses this organ in an unusual way, by first planting the front half, like a caterpillar, and then drawing up to it the other half, and repeating this alternate movement in a fashion called “ looping.” _ The celebrated French naturalist, Adanson, gave that genus the name of Pedipes on account of this peculiarity. Many of the aquatic univalves can swim, or rather creep underneath the surface of the water, the position of their bodies being reversed, with the poit of the shell down- wards. A few of the bivalves (e. g. species of Lepton and Galeomma) sometimes walk about with their valves spread out like the cover of a book when left on the table by an untidy person. The Cuttles and Pteropods swim as rapidly as fishes, but in a different manner— viz. by taking in and expelling by means of their mantle successive volumes of water, so as continually to propel them onwards. One kind of Cuttle is said even to pos- sess the faculty of flying, and to dart for a considerable distance out of the water through the air like a flying- fish. Most of the Acephala or bivalves have a tongue- shaped organ of progression, which is muscular and extremely flexible. By means of this kind of foot the 4.4 « INTRODUCTION. [cH. Cockle, Razor-fish (Solen), and other kinds burrow in sand and mud. The Scallop and Lima fill their bodies with water, and then, suddenly collapsing and closing their valves, execute a series of leaps or jerks, by which they can traverse a considerable distance, although in an irregular course. Certain small bivalves (Spherium and Kellia), while floating on the surface of the water, spin filaments which serve to moor them and prevent their being drifted about. Several kinds of slug secrete glutinous threads by which they suspend themselves from trees and either remove from one branch to another or drop safely to the ground. ‘Thus it will be seen that the Mollusca partake of all the modes of locomotion pos- sessed by other animals—that they can walk like quadru- peds, fly like birds, crawl like serpents, swim like fishes, and even spin threads like spiders. The action of creeping in a snail is performed by the close appression of its foot to the substance over which it moves, as well as by muscular force. Any unevenness in the surface to be traversed is filled up by folds of the foot, which is extremely flexible. This action may be compared to the application of one piece of flat glass to another. Musical sounds, resembling those which are given out by the Eolian harp, may be observed on a dry summer evening by putting a garden-snail to crawl out- side a window; and this phenomenon has frightened many a timid or superstitious person, who could not imagine whence these mysterious sounds proceeded. A curious calculation was made by Mr. Thomas, an Ameri- can conchologist, as to the rate of a snail’s pace. He found that it takes 16 days and 14 hours for a moderately fast snail to do a mile. Food.—By far the greater part of the Mollusca are zoophagous or animal-eaters. The food of the Acephala 11. | INTRODUCTION. $9.0 al consists of Infusoria and other animalcules, which are conveyed to their mouths, by an action analogous to that of suction, through the inhalant tube or the outer folds of their mantle. The Buccinum or whelk tribe prey upon other mollusks (especially bivalves) by drilling holes in their shells with their proboscis, which is armed with a formidable apparatus of teeth. The whelks are also very troublesome to fishermen, being often found sucking and sticking to the bait when the lines are taken up. Numbers of them may be caught in lobster-pots baited with fish or meat, if laid down on a sandy instead of a rocky ground. Most of the littoral univalves feed on sea-weed. ‘The common Limpet forms by means of its foot a shallow excavation in the rock. When the tide returns it goes out to its pasture, browsing like an herbivorous quadruped ; and it returns to its hole when the tide retires. The track left by its grazing on the submarine vegetation which clothes the adjoming rock is very perceptible and is sometimes tortuous or maze- hike. Land and freshwater snails, as well as slugs, are for the most part herbivorous, as gardeners know to their cost in the former case; but some of them also devour animal matter, and a few are cannibals. The food of the Testacella consists almost exclusively of living earthworms; and a full account of its carnivorous and voracious propensities will be found in this volume. Snails have been taken with insects in their mouths, which they were swallowing by degrees; and, accord- ing to M. Bonnafoux, the Heliz aspersa has been known to perforate birds’ eggs in deserted nests, in order to feed on their contents. The number of curved si- liceous teeth which arm the tongues or lingual plates of snails is prodigious (amounting in some species to many thousands), being arranged in several rows. Some XXX INTRODUCTION. _ (cH. of the marine Mollusca are parasitic, or live upon the secretions of other animals. Among the bivalves Mon- tacuta substriata, and among the univalves Stylifer Tur- toni, are instances of these parasitic habits. Size.—This appears to depend on the supply of food ; and it is probable that, owing to the vast shoals of mol- lusk-eating fish which abound im the northern seas, the shell-fish there are thinned to such an extent that the fortunate survivors have a proportionally larger share of food than those which inhabit southern seas, where both species and individuals are more numerous. Northern Mollusca are generally larger than those of the same species from the South*. The same law is observable with regard to cultivated fruits,—thinning being resorted to for the purpose of reducing the number and in- creasing the size of those which are allowed to remain. Habitat.—There is probably not a square foot of land, either im a cultivated or uncultivated state, or co- vered with fresh, brackish, or salt water, that is not inhabited by Mollusca of various kinds. Trees, herbage, and sea-weeds are the chosen stations of many sorts, for the sake of the shelter or food which they afford ; and even our cellars and kitchens are not free from them. Some live only in the ocean, and never approach land unless when driven on shore by the winds and waves. These are called “ pelagic.” Among them are the Lanthina, or “ blue-snail,”’ and a few small Ptero- pods, which are occasionally found in our seas. The former is provided with a cellular apparatus, by which * See also Draparnaud (Tabl. Moll. p. 35) as to the comparative size of land shells inhabiting the North and South of France. ‘“ Le climat influe beaucoup sur la grandeur des individus. Chez les Mollusques, comme chez les Mousses et un grand nombre d’autres plantes, la méme espéce acquiert un volume d’autant moindre, qu’elle habite dans un pays plus chaud.” 11. | INTRODUCTION. XXX1 it is enabled to keep always in a floating position on the surface of the water, with the poimt or spire of its shell downwards, and which apparatus also serves as a nidus for its spawn. A description of this curious appendage or “ float,” as well as of the equally remarkable habits of the Lanthina; will be found in its proper place. The Pteropods have feet like wings, and flutter through the water hke butterflies. They have conical, and some- times spiral, shells as fragile and transparent as the finest blown glass. Care of young.—Many of the bivalve Mollusca, inha- biting the sea as well as fresh water (e.g. Teredo and Anodonta), retain for some time their fry, after being excluded from the egg, in the folds of their mantle, this beimg in some degree an analogous provision to that which is possessed by the marsupial quadrupeds. The common Limpet and some kinds of Pupa (small land- snails) have also been observed to carry about. their young, the former within the folds of its foot, and the latter attached to the shells of their mother. These eases of Molluscan oropy?) are nearly as wonderful as any which have been adduced in accounts of much more highly organized animals. Sociability.— Although many of the Mollusca are gre- garious and assemble together on the same feeding- grounds, it does not appear that they ever associate for a common object, like bees or ants. Each Pholas and Teredo makes a hole for itself; and although the com- mon garden-snail often fastens itself to the shell of its companion, when they hibernate and form clusters, a smooth stone or any other object is used for the same purpose. Aistivation and Hibernation.—Many animals in a state of nature have their periodical seasons of repose, espe- b5 XXXIV INTRODUCTION. [CH. cially in the winter when there is a deficiency of food. For this reason it may be supposed that all the Mol- lusca hibernate; and we know that the land-snails in this country have such a habit. Most of them bury themselves in the ground, or nestle in the crevices of rocks, under the bark of trees, or even in the hollow stems of the larger umbelliferous plants. They also cover the mouths of their shells with a calcareous plate of various degrees of thickness, which they secrete, in the same way as the shells, by means of their mantle. This plate is called an “epiphragm,” and in the apple-snail (Helix pomatia) is of considerable thickness. But in dry weather and during the heat of summer they form another and slighter kind of epiphragm, im order to keep their bodies always moist and lubricated, as without such protection the tissues would soon dry up and the snails perish. The Rev. H. B. Tristram, in his account of the Great Sahara, says that the snail-shells which he found there were much thicker than those of the same species from more temperate parts of Europe, apparently as an additional means of preventing evaporation in so dry a climate. The simile in the 58th Psalm (verse 8) which is rendered in our translation for the ‘ Common Prayer,’ “consume away like a snail,’ may have had reference to the inability of these Mollusca to endure exposure to the great heat of the sun in an Eastern climate. None of the naked Slugs occur in the lists of land Mollusca collected by Professor Roth in Palestine, and by Dr. Schlafli and M. Mousson in the East. The circulation of land-snails is affected to a great extent by the temperature. In some kinds the rate of pulsation varies from 30 to 110 per minute during summer ; and it ceases altogether in winter. Although the temperature of the sea is nearly the same in summer II. | INTRODUCTION. XXXV and winter, except at its surface, the circumstance that most sea-weeds are annual would lead us to conclude that the marine phytophagous Mollusca also retire into winter quarters, and that, as these are preyed upon by the zoophagous kinds, the habit of hibernating is common to all shell-fish. In shallow seas near the land, the number of marine animals is perceptibly diminished during cold and inclement seasons; and this was noticed by several naturalists to have been the case in the wet year of 1860. The period of hibernation differs among the Mollusca. Some retire earlier or emerge later than others. Ac- cording to M. Drouet the Anodonte or freshwater mus- sels hibernate before the close of autumn, and bury themselves deep in the mud until the middle of spring, when the water begins to get warmer. Nests——A few marine bivalves, which do not spin a byssus or bundle of threads with which they can moor - themselves to rocks, or which have not the power of exca- vating for themselves a place of residence in stone, wood, the tunic of Ascidians, or other substances, form a kind of rude nest out of broken shells and zoophytes, which they cement and line internally with a slimy exudation from their bodies; and thus they remain snugly ensconced and protected from their natural enemies. Among these nest-builders are the Modiola radiata, Lima Loscomdii, and the northern form of LZ. hians. So little is known of the habits of the marine Mollusca, that Iam not pre- pared to say whether these are proper nests and used for the protection of the young, as in the case of stickle- backs and other small fishes, or are constructed solely for the use of the adult shell-fish. Modes of attack and defence.—Some aquatic mollusks have the faculty of emitting from their bodies a purple or dark fluid, apparently for the purpose of securmg XXXVI INTRODUCTION. (CH. their prey or concealing themselves from fishes or other predaceous animals. The inky cloud which the Cuttle ejects is of a glutinous or viscous nature, and does not readily mix with the water. It seems to be better adapted for entangling small fishes than to cover the retreat of the Cuttle, which is extremely rapid in its movements. The Aplysia, or sea-hare, gives out a purple dye which is also glutinous and has an offensive smell, As this mollusk crawls but slowly, it may use the dye to obfuscate some more active animal which it may have taken a fancy to make a meal of, all the Nudi- branchs being said to be carnivorous. Several kinds of Planorbis (freshwater snails) yield, on bemg irritated, a quantity of their own purple blood. These are vege- table-eaters; and we can therefore conceive no other object in this voluntary blood-letting than to elude ob- servation. A few land-snails (e. g. Bulimus obscurus and Pupa secale) in their young state, as well as some small freshwater bivalves belonging to the genus Pisidiwm, have their shells covered with mud and other extraneous matter ; but it is difficult to say whether this is the re- sult of design or accident. One might suppose that the sharp eyes of a bird or a frog would easily detect their prey through this feeble disguise. Some marine bivalves (as Lyonsia Norvegica and species of Neera) are covered with a coat of sand, which may to some extent answer the purpose of concealment. If the safety of these animals is ensured by such means, how great must be our admiration of that wonderful yet varied plan of con- trivance which makes the humble Mollusk, as well as Man, the object of Divine care ! Renewal of parts.—Some Mollusca, which had been accidentally deprived of their feet, tentacles, eyes, and even of their entire heads, have been known to repro- 11. | INTRODUCTION. XXXVl1 duce them. Nearly a century ago, the experiment of decapitating unfortunate slugs and snails was con- ducted on a wholesale scale on the Continent, and every philosopher was anxious to cut off a head. Even the great Voltaire followed the universal fashion ; and his experiences were published in the ‘ Questions sur l’ En- cyclopédie.” In these he mentions having operated on twenty brown slugs and a dozen snails; and he after- wards records with great pride and satisfaction “ mes Limaces” and “ mes Escargots ” showing their budding heads and horns, and doing as well as might be expected under the circumstances. Phosphorescence.—Although a great many animals, from the highest order of fishes to the imperfectly orga- nized Noctiluca miliaris, as well as several of the Tuni- cata, emit or exhibit a phosphorescent light, I am not aware that any of the Mollusca possess the same property, except some kinds of Pholas ; and it is possible that the phenomenon in their case may be owing to animalcula which infest them or are found in their holes. The eggs of a common slug (Arion hortensis) are said to be luminous for the first fifteen days after they have been laid. But both the nature and object of this common phenomenon requires further investigation. Perforating powers.—Many shell-fish, and especially bivalves, burrow in sand or mud for protection against their natural enemies ; but some of them excavate wood, peat, or stone of various degrees of hardness, for the same purpose. The process of burrowing is undoubtedly performed by the foot of the Mollusk. It is exemplified by the case of the common Cockle, which uses its tongue- shaped and flexible foot m the same way as a gardener uses his dibble, and, having thrust it into the sand and expanded it, thus makes a hole large enough to contain XXXV1ll INTRODUCTION. [cH. the shell. The limpet (Patella vulgata) slightly perforates calcareous rocks by the muscular action of its sucker- like foot or disk, which occupies all the lower part of the body. The shell exactly fits the space thus excavated, so as to prevent the limpet being easily dislodged by a bird or a crab. The common garden-snail excavates hard limestone rocks for the purpose of hibernation ; and as its shell is covered with a delicate epidermis, which remains on specimens having just emerged from their winter quarters, it may be safely inferred that the shell is not the instrument of perforation in this case. But with respect to the Teredo or ship-worm (which tunnels through wood), the Pholas (which pierces wood, peat, clay, and chalk), the Gastrochena (which penetrates hard sandstone, chalk, and limestone, as well as old oyster-shells), and the Saaicava (which perforates the hardest calcareous rocks), it is not so easy to form a definite conclusion. This volume would scarcely con- tain all that might be said on the subject. Forbes and Hanley have given an excellent account of the discussion which had taken place up to the time of publishing their work ; and I will content myself with stating briefly the result of their investigation and adding a few remarks suggested by my own inquiries. The opinions which had been expressed on this subject when the ‘ History of the British Mollusca’ was pub- lished, were classed by its authors, when treating of the Pholas, under five conclusions, which are as follows :— “], That the boring Mollusca perforate by means of the rotation of the valves of their shells, which serve as augers. 2. That the holes are made by rasping, effected by siliceous particles studding the substance of certain parts of the animals. 8. That currents of water, set in action by the motion of vibratile cilia, are the agents. II. | INTRODUCTION. XXX1X 4. That the animal secretes a chemical solvent—an acid which dissolves the substance into which it bores. 5. That the combined action of a secreted solvent and rasping by the valves effects the perforations*.” The first of these views is advocated by Forbes and Hanley; and the other naturalists to whom they have referred as having expressed an opinion on the subject are as follows, taking the several views in their order of succession :—1l. Dr. Gray, Dr. Fleming, Mr. Osler. 2. Mr. Hancock. 38. Mr. Garner. 4. Dr. Gray, Dr. Drummond, M. Deshayes, M. Cailhand. 5. Mr. Thomp- son, M. Necker. As I believe that all these different views, except the first, have been successfully refuted by the arguments of Forbes and Hanley, it only remains for me to adopt their view, or to substitute another for it. If we only consider the shell of Pholas, with respect to its efficiency as an instrument of mechanical perfora- tion, there might be sufficient reason for supposing that it can by this mode drill a hole im peat, submerged wood, clay, or even in chalk.when softened by the continual contact of water. The shell is certainly harder than any of these substances ; and the animal is provided with muscles of unusual strength for effecting the rotatory motion which would be necessary for such an operation. But we must also consider the cases of other perforating mollusks whose shells are not so hard. ‘The shell of Gastrochena is more fragile than that of the oyster into which it bores, and very much more so than the lime- stone in which it not unfrequently lodges itself. The helmet-shaped valves of Teredo could only be used to rasp the sides of the tube which this mollusk forms in wood; and they are not adapted for excavating the cons * « British Mollusca,’ vol. i. p. 104. xl INTRODUCTION. [CH. cave end of the tube. The shell of Sazicava is coated with a delicate epidermis, which would unquestionably be scraped away in perforating the solid limestone rock, if the theory advocated by Forbes and Hanley is appli- cable to this case. And, to take the case of other marine animals which excavate rocks and shells for the same purpose as the Mollusca, we know that the boring Annelids or sea-worms have no hard substance in their composition. For these reasons, I do not think that the mechanical theory (viz. that the shell is the sole instrument of perforation) has been established. Since the publication of Forbes and Hanley’s work, the controversy has been continued with unabated ardour ; and to the list of naturalists who have taken a part in it, other names may be added as supporters of the under- mentioned theories. Mechamcal. Mr. Robertson and M. Fischer. Chemical. Dr. Mantell, M. Thorent, and Mr. Reeve. M. Cailliaud now contends that both methods of per- foration are adopted by the same kind of mollusk ac- cording to the material acted upon ; and M. Bouchard- Chantereaux, who was at first in favour of the mechani- cal theory, is now strongly of opinion that a corrosive secretion of the animal is the agent of perforation. But there is another point of view in which the ques- tion may be considered, and which does not appear to have received any attention, although in my humble judgment fully deserving it. Nearly 130 years ago, a very learned but eccentric Dutch philosopher, named Sellius, wrote and published, for the benefit of his country, an elaborate monograph on the Teredo. In this remarkable production he discussed at great length, and im the most exhaustive style, all the various theories which had been propounded up to 1. ] INTRODUCTION. xhi that time as to the means by which the ship-worm bores into wood. He showed conclusively that their shells could not be the instruments of perforation; and he asked how it was possible that the extremely tender shell of the young Teredo (in fact a mere film) could make a hole in solid oak, a material ten times harder than itself. Besides, as he justly remarked, the form of the tube is evidently not the result of an auger-hke in- strument, because it is broader at the bottom than at the top and sides. The conclusion he formed, after a most laborious and impartial investigation, was that the Teredo perforates by suction, aided by continual mace- ration and softening of the wood. One of his numerous quotations from the ancient poets, in support of his argument, may be here appropriately repeated. It is from his favourite, Ovid :— “Quid magis est durum saxo? quid mollius unda? Dura tamen molli saxa cavantur aqua.” I profess myself to be a follower of Sellius; and | am convinced that the sole instrument of perforation by the Mollusca of stone, wood, and other substances, is in every case their foot or muscular disk, which is closely applied to the concave end of the hole and is constantly supplied with moisture through the glandular tissues of the body. The strength of this organ may be easily tested by any one who tries to remove a limpet from its native rock, after having touched it and thus given it due notice of his intention. By this simple, yet gradual, process the fibres of wood or grains of sandstone may easily be detached or disintegrated, time and patience bemg allowed for the operation. When it is considered that the hole made by an adult Pholas or Savicava_is only a few inches deep, and that an aged Patella scarcely penetrates a quarter of an inch into a limestone rock, xlii INTRODUCTION. [ cH. there can scarcely be a question that these mollusks have abundance of time to effect their purpose. It is said that even the hardest marble is not proof against the softest impressions, and that the big toe of St. Peter’s statue in the Vatican has been nearly worn away: by the lips of fair devotees. The osculatory process is not un- like that of suction. Occasional appearance and disappearance.—Both sea and land furnish instances (some of which are difficult to explain) of the periodical appearance and disappear- ance of certain species of Mollusca in particular places. Their arrival and departure are often sudden and seem- ingly capricious. In the case of marine species, this phenomenon is probably the result of changes in the eourse of tidal and other currents, as well as of the migratory habits of fish. These currents, by accumu- lating or removing deposits of mud, sand, and gravel, which afford shelter and food to Mollusca, conduce greatly to their congregation or dispersal. When such deposits are rapidly formed, the shell-bed becomes co- vered up or silted; and the Mollusca are entombed alive for the benefit of future geologists. When their chief enemies, the fish, desert their former quarters and migrate to another feeding-ground, the Mollusca then increase and multiply, bemg unthimned except by the tigers of their own kind, or occasionally by the curious conchologist, or by all-devouring death. The destruc- tion of shell-beds by marme currents may account for the prevalent notion that some parts of our sea-coast (as for example South Devon), which used to yield such regular and plentiful harvests of shells to collectors, are now scarcely worth searching,—it being said that the shells have “ deserted” the coast. The unexpected occurrence of some kinds of land and freshwater Mol- U1. | INTRODUCTION. xl lusca in places where they had not been previously noticed is not unfrequent. Many a wonderful tale of a “ shower of snails”’ has helped to fill the pages of country newspapers, arising out of the sudden appearance in a limited area of Helix virgata and Bulimus acutus, which are abundant on most of our sandy downs and plains. This has been sometimes caused by a mere change of wind to the south-west, in consequence of which the air has become charged with moisture, and tempted all the snails to leave their retreat at the roots of grass during the night, and to present themselves in the morning to the eyes of astonished rustics. It is not, however, so easy to account for some kinds of freshwater snails (e. g. Limnea glutinosa) bemg found in the same spots so abundantly some years, and scarcely at all in others, as has been noticed by Mr. Bridgman of Norwich. This is one of the minor, but numerous, problems in the pre- sent branch of Natural History which still remains to be worked out, and the solution of which will reward the diligent and observant conchologist. Tenacity of life-——Many of the Mollusca, as before remarked, pass the winter in a state of torpidity, their vital functions being apparently suspended during hiber- nation. But some of the land-snails have been known to live many years shut up m boxes and drawers, or affixed to tablets as specimens. This capability of sub- sisting for a long period without food is probably owing to the snail being able to close its shell by an epiphragm, which not only prevents the evaporation of its natural moisture, but also produces a kind of protracted hiber- nation. Miller relates that some snails, from which he had cut off their heads, lived more than a year in this state without food, crawling about, and at the usual time forming their winter epiphragms. Some marine xliv INTRODUCTION. (CH. Mollusca, both univalve and bivalve, possess also a cer- tain power of endurance under altered conditions. Thus Trochus lineatus, which inhabits rocks only uncovered at low water, can live in a warm room for a fortnight ; and specimens of Mya arenaria, which burrows into muddy gravel in the sublittoral zone, have been noticed by Mr. Rich (an intelligent collector and dealer) to sur- vive their captivity for three weeks, being all that time in apparently a healthy state (evidenced by the with- drawal of their tubes when touched), at the end of which period they were killed for commercial purposes. No sea-water was supplied in any of the above cases. The gills must have been kept moist by the fluid contained within the mantle—a provision nearly similar to that by which the camel is able to endure the heat and fatigue of a journey across the desert after having filled its paunch with a stock of water. M. Joly observed with respect to some freshwater mollusca (Anodonta cygnea and Paludina vivipara), that they may be frozen up, and kept for some time enclosed in ice, without being killed. Some of the Paludine even produced young after being thawed *. Age.—Little or nothing is known with respect to the duration of life in the Mollusca. According to Sir Emerson Tennent, the pearl oysters of Ceylon only live seven or eight years; and it is said that snails do not attain a greater age. This is not improbable as regards the latter, because most of them become adult at the end of their first year. Whether the numerous lamin of old oyster-shells afford the same indication of an- nual growth as the rings of a forest tree is another question. Résumé.—In concluding this chapter, I cannot do better than quote the résumé given by M. Moquin-Tandon * Comptes Rendus, 1843, xvi. p. 460. 111. | INTRODUCTION. xlv of his admirable observations on the land and freshwater Mollusca of France :— “ Les Mollusques ont des ruses et des industries, des sympathies et des imimitiés, des guerres acharnées et des amours bizarres. Beaucoup sont a la fois male et femelle, et par suite pere et mére .... Malgré leur apathie apparente, les Mollusques sont des étres qui ne ~ manquent pas d’intelligence. Leur vie privée et leur vie commune nous montrent des détails extrémement curieux.” Oi 5 RS ld gd 0 a SHELLS. FORMATION.— COMPOSITION. —- SHAPE. —- NUCLEUS.— GROWTH. — COLOUR.—DECOLLATION.—EROSION.—OPERCULUM.——EPIDERMIS. Formation.—The shells of Mollusca are formed by a secretion from glands of the mantle or cloak. In uni- valves this part of the body only covers the front, and in most cases surrounds the head like a loose collar; but it is very flexible, and it can be withdrawn or folded back nearly to the top of the spire to repair a fracture of the shell in that part. In bivalves it is double, like - the cover of a book. Composition.—Carbonate of lime is the main ingre- dient ; and the shells of Mollusca differ from the bones of vertebrate animals, as well as from the shells of crabs, sea-eggs, and birds’ eggs, im the absence of phosphate of lime. In all these cases, however, the mineral ingre- dients are cemented together by an animal gluten. According to M. Delacroix, the shell of a Helix pomatia xlvi INTRODUCTION. [cH. is composed of the following materials, in every 100 parts :— Oreanicmaatier: 03.. 29215. 8909. SE AIDS 18:64 Corbanatoro€ limes. .we. fys- tei epee cites 64:96 \ 81-36 Other mineral substances, undetermined...16°40 100-00 The structure of some shells is fibrous, and of others crystalline; and they differ considerably in the degree of compactness. Nearly all the secrets of this wonderful laboratory have been made known through the researches of Mr. Hatchett, Dr. Carpenter, and others; but no philosopher has been able to explain why this process of formation has continued from generation to generation in the same uniform mould, according to the nature of each species, or how the newly-born Mollusk works out, with unerring and undeviating imstinct, the pattern which was originally designed by its Creator. Humboldt justly observed that there are mysteries beyond our com- prehension ; and it might be good for us that some check should be put on the overweening pride of intelligence in the “ audax Japeti genus.” Shape.—All shells assume the form of a cone. Uni- valves are generally spiral, so as to accommodate the folds of the body. Even the common limpet (Patella vulgata) has a distinct spire in its embryonic state, resembling ‘that of Fissurella or Emarginula. The Chitons are in some respects abnormal, having several testaceous joints, which overlap each other, like the plates of ancient ar- mour or the scales of a fish; but all these joints taken together may be considered as forming a depressed cone of greater length than that of a Patella, the lines of growth on each side of the apex (which is compound in Chiton) being equally symmetrical in both cases. Bi- valves offer no exception to this conical law of growth, 111. | INTRODUCTION. xlvii the apex or nucleus of each valve being analogous to the same part in a spiral shell; but in bivalves the deposit of shelly layers is formed on both sides, in consequence of the mantle or organ of secretion being double. Every part of the shell, whether univalve or bivalve, enlarges by growth in the same relative proportion. Nucleus.—This part of the shell furnishes the concho- logist with an important character of distinction. Odo- stomia, Nassa, Cerithiopsis, Ianthina, and many other genera of univalve shells have the apex of their spire differently formed. In the adult Cyprea (or Cowry), the whole of the spire, including the apex or nucleus, is covered and concealed by an extraneous deposit of shelly matter; and the same process, although to a partial extent only, takes place with regard to the genus Margimelia. Yn many spiral shells the upper whorls (which origmally formed the nucleus) are deserted by the animal, in consequence of the volume of its body having increased so rapidly that these whorls were too small to receive any part of it, and they therefore became unnecessary. Growth.—Owing to the difficulty which exists in keep- ing and observing Mollusks in a state of confmement for any length of time, and especially those which live in the open sea, very little is known as to the mode and rate of their mcrease. Some interesting experiments on the growth of land-shells were, however, made by Mr. E. J. Lowe and communicated to the Royal Society in 1854 *. The result of his observations is as follows :—Ist, The shells of Helicide increase but little for a considerable period, never arriving at maturity before the animal has once become dormant (or hibernated). 2nd, Shells do not grow whilst the animal remaims dormant. 3rd, The * Proceedings, vol. vil. p. 8. xlvili INTRODUCTION. [CH. growth of shells is very rapid when it does take place. 4th, Most species bury themselves in the ground to increase the dimensions of their shells. Helx pomatia and many other shells retreat for that purpose in summer, having their heads and the mouths of their shells down- wards (this position being reversed during hibernation) ; H. rotundata burrows into decayed wood for the same purpose ; while Pupa umbilicata, Clausilia nigricans (C. rugosa) ,and Bulimus obscurus bury their heads only while the increase takes place. With regard to marine shells’ it may be observed that sea-water does not everywhere contain the same relative proportion of mineral and chemical ingredients, and that the admixture of fresh water has a material effect on the substance, texture, and composition of sea-shells. In estuaries, where the water is brackish, oyster-shells are smaller and thinner than usual, owing to the deficiency of calcareous salts ; while the shells of oysters procured from considerable depths in the open sea and at some distance from the land are remarkably large, thick, and heavy. Colour.—The dye by which the outer layer of shells is stained, and which often forms bands, streaks, spots, and other markings of the most beautiful and varied hues, is secreted by special glands of the mantle. Owing, however, to some defect in this organ of secretion, the colouring-matter is occasionally wanting; and nearly every kind of shell, which is usually tinted, has what is termed an “ albino” or white variety. This is the case with regard both to land and marine Testacea. The late Professor Forbes, in a paper which was published in the ‘ Proceedings’ of the Royal Society *, entitled “‘ Note on an indication of depth of Primzeval Seas, afforded by the remains of colour in fossil Tes- * Vol. vii. p. 21. nt. | INTRODUCTION. xlix tacea,’”’ observed that, “‘in our own seas, Testacea, taken from below 100 fathoms, even when they were indivi- duals of species vividly striped or banded in shallower zones, were quite white or colourless; that between 60 and 80 fathoms stripmg and banding were rarely pre- sented by our own shells, especially in the northern provinces ; but from 50 fathoms shallow-wards, colours and patterns were well marked.” I cannot help thinking that there must have been some mistake as to the first and second of these obser- vations. At least, my own experience induces me to form a different conclusion. Instances of depths exceeding 100 fathoms in our seas are very rare. I only know of two. One of them is a submarine trough off the Mull of Galloway, called “ Beaufort’s Dyke,” where the depth is 145 fathoms ; and the other is a pit in the Sound or Sleat of Skye. The results of dredging in Beaufort’s Dyke are recorded in the ‘Annals of Natural History*.” Although shells usually inhabiting comparatively shallow water, and distinctly striped or banded (Tapes virginea and Venus ovata), were obtained alive from this remarkable depth, no deficiency of colour or markings is noticed in the account of these results. In the other case, I can state from my own knowledge that the shells were as highly coloured and the markings quite as vivid as in specimens found at a depth of 30 fathoms in another part of the Sleat of Skye. Soundings were taken with Massey’s patent log, and living Testacea were brought up in the dredge from 118 fathoms. On this occasion Captain Otter was with me, and I had the benefit of his great ex- perience in such matters. Last year I dredged for some weeks off the Shetland Isles at depths between 60 and — * Vol. x., Sept. 1842, p. 21. INTRODUCTION. [cH. 80 fathoms ; and not only were live shells which I pro- cured from those depths as brightly coloured and marked with as distinct patterns as shells of the same species (e.g. of Trochus ziziphinus), taken at low-water mark, but colourless or white varieties of such species were found in the same spots. The Star-fishes lately got by Dr. Wallich in the Arctic Sea from a depth of 1260 fathoms still retain their former colours; and, during the recent expedition of Torell and other Swedish naturalists to Spitzbergen, a portion of the sea-bottom was brought up from a depth of 1400 fathoms, when, among other ani- mals of different types, a Crustacean of bright colours is said to have made its appearance. The extent to which light penetrates into the abysses of the ocean, as well as the mode of its transmission, does not seem to be known. DecollationSome univalve Mollusca, both terrestrial] and aquatic, the shells of which have a long and slowly enlarging spire, desert the first or top whorls, and get rid of them by a process called decollation or truncature. The suture, or point of junction between this part of the spire and the rest of the shell, is usually very shght ; and the animal effects the process of decollation by burying itself in the earth if a land-snail, or rubbing its shell against a stone or other hard substance if a freshwater or marine species, in order to disengage itself from the empty and useless whorls. Before doing this, however, it reconstructs the top of its spire by forming a hemispherical plate of shelly matter between that part of the shell which is to be retained and the empty top. Among land-snails Bulimus decollatus is a well-known instance of this peculiarity, among freshwater snails Limnea glabra, and among the marine univalves Trun- catella truncatula. Erosion.—The outer layers of the shells of aquatic 111. | INTRODUCTION. hi Mollusca, as well bivalve as univalve, are frequently ex- coriated or decorticated, and sometimes to a considerable depth when the shell is thick, as in Unio margaritifer, or the pearl-mussel. Several marine species, especially those of Astarte, Mytilus, and Littorina, are also affected in the same way. Various theories have been put for- ward to account for this erosion. In the case of fresh- water shells, many naturalists have supposed that it is caused by gaseous action, some have attributed it to the attacks of Myriapodous insects, a few to excavation by the eggs of Neritina fluviatilis, MM. de Saulcy and Fis- cher, as well as Mr. Bland, to other Mollusca eating away the calcareous matter for the purpose of constructing and repairing their own shells, and MM. Cuigneau and Lespinasse to parasitic Confervee and other hydrophytes. But as this phenomenon is not confined to freshwater shells, some other explanation must be sought for. It is very probable that the former class of cases may be attributable to chemical action, and especially that of sulphuretted hydrogen ; but in the other, and perhaps all the cases, the effect may be produced by another cause. Mr. Grove suggests that it may be owing to the want of homogeneity in the substance of the shell, and that the slightest and almost imperceptible inequality in the surface would result in an electrolytic action of the water, which would gradually dissolve portions of the shell. Sea-water is more likely to produce this effect than fresh water, by reason of the stronger galvanic pro- perty of the former. Corrosion of metals by water or moisture may be due to the same cause. As the sub- ject does not appear to have received much attention in a chemical point of view, I trust the following remarks, from so great an authority as Mr. Grove, will help to throw some light upon it. The shells which I submitted bie li INTRODUCTION. [CH. to his examination were those of Littorina litorea, or the common periwinkle. “ March 26, 1862. “ Dpar JEFFREYS,—As you wish me to put on paper the suggested explanation of your difficulty, viz. why it is that substances apparently homogeneous are cor- roded in patches or irregular hollows, I endeavour to do so, premising that it is only theoretical and may be found not to accord with all your facts. “Tf a plate of pure zinc be immersed in dilute sul- phuric acid, little or no chemical action takes place ; but keep in contact with the zine another metal, say an iron nail, and the zinc is rapidly oxidated and dissolved, hydrogen being evolved from the surface of the iron. The action is most rapid at the points most proximate to the iron ; so that, ifthe nail be laid upon the zinc, both being immersed in the liquid, the iron would seem to eat its way into the zine. If a few iron filings be placed upon the zine, the action will be similar, but will begin more slowly and increase as the pomts of iron are exposed, these latter being protected to a great extent by their bemg negative and coated with hydrogen. If an in- finitesimal quantity of copper be dissolved im the acid, it will be precipitated in a metallie state on the negative points and make these permanent centres of action. So, if no iron be made to touch the zine, after a time some want of absolute homogeneity is sure to determine a chemical action; and as any trace of metal existing in the solution will by this chemical (or, rather, electrolytic) action be deposited on the negative points, or those least attacked, the action will continually increase, and, instead of being uniform, will be in patches around the negative centres. Thus a piece of common zinc of com- merce which contains small portions of iron and tin will 1. | INTRODUCTION. hi be corroded in pits or holes. With imperfectly con- ducting bodies the action is similar; at very short di- stances they conduct, and the action spreads or extends from a point to the surrounding points. Sometimes, in- stead of forming a patch, the chemical action eats its way in a dendritic form, pursuing the ramifications of either the more oxidable portion of the substances or of the more accessible negative poimts. The slightest superficial change will produce a corresponding corro- sion: thus, if you were to breathe on a polished plate of iron and wipe away the condensed moisture from half the plate, leaving that on the other half to evaporate, the iron would subsequently rust in a different manner on the two parts. If you electrify a plate of glass having letters cut m paper on it, and subsequently expose it without the paper to hydrofluoric acid, the parts pre- _viously uncovered will be attacked ; and so, if you simply allow the paper letters to remain on the glass for some time (say a day or two), and then blow them off by breathing on the glass, or by the vapour of hydrofluoric acid, the letters will be made manifest. You may easily imagine a number of other instances. The effects all pro- ceed from a want of perfect homogeneity, either original or impressed by some very triflmg circumstance, and from the fact that, points of action having once been established, the corrosion is increased by the effects it itself produces and the deposits it forms. ) I”. cristata, Mull. Verm. Hist. pt. ii. p.198; F. & H. iii. p. 21, pl. lxxi. £/11,:12; 43. Bopy dark grey or brown, with a few small black specks on the upper part, slate-colour underneath: snout prominent, rather narrow and curved, faintly wrinkled: tentacles long, slender, close together but recurved at their points: eyes small and round : foot quite separate from the snout, and resembling, in proportion to its size, that of the last species: branchial plume transparent, bearing about 15 offsets on each side of the stalk : branchial appendage rather shorter than the tentacles. Suet forming a flat coil, concave beneath, rather solid, semitransparent, yellowish or greyish-horncolour, closely and regularly striate transversely : epidermis very thin: whorls 5, the last exceeding in breadth all the rest put together: spire flat, or slightly concave owing to the convexity of the whorls: mouth circular : outer lip thin and slightly reflected: inner lip separate from the columella and continuous with the outer lip: umbilicus very large and open, fully exposing the interior of the spire: operculum circular, concave like an inverted pot- lid, forming a concentric spire of about a dozen whorls, the * Crested ; so called from its branchial plume. VALVATA. 75 outer edges of which are membranous and project in front so as to make slight ridges. L. 0°025, 5B. 0:125. Hasrirat: Lakes, canals, ponds and ditches, with the last species. It has an equally extensive range both here and abroad, except that the present species does not appear to have been found south of Corsica. It is also one of our upper tertiary fossils. A monstrosity is in my collection, which has the last whorl detached and coiled upwards, as is not unfrequently the case with several species of Planorbis. The branchial plume is not always protruded, even when the animal is crawling. Although the spire in some specimens is a trifle more depressed or sunk than usual, [ am not aware that the Valvata spirorbis of Draparnaud (which Moquin-Tandon regards as a variety of the present species) has ever been found in this country. The V. minuta of that author is a totally different species, having a globular shell, with a produced spire, and resembling a miniature V. piscinalis. The present species is the V. planorbis of Draparnaud. There is no difficulty in distinguishing V. cristata from the fry of V. piscinalis, much less from the adult, where the great difference of size afiords a sufficient criterion. The shell of the present species in all stages of growth is quite flat, and resembles that of a Planorbis, constituting apparently a passage into that genus; while the other is trochoid or subglobose, and has a prominent spire. Their bodies, or the soft parts of the animal, do not present such a decided difference. The tentacles of V. piscinalis are, however, rather more slender, and the snout is proportionably larger than in this species. 76 PULMONOBRANCHIATA. Order IT. PULMONOBRANCHIATA*. Bony spiral: respiratory apparatus principally consisting of an internal cavity or sac, formed by a fold of the mantle, and lined with a network of vessels, which serves the purpose of lungs. Suet usually external and spiral, but sometimes internal and rudimentary or wanting. In the two latter cases the mantle is external and forms a shield on the back. With respect to the reproductive system of the Mol- lusca comprised in this Order, it may be observed that each individual of those kinds which do not possess an operculum has both sexes united in itself, but requires to be fertilized by another individual, while those which have an operculum are of different sexes. The former are androgynous, answering im some respects to the botanical term “ moneecious ;” and the latter are strictly “« dicecious.”” The Pulmonobranchs, Pulmobranchs, Pulmonifers, Pul- monates, or Pneumonobranchs, by all of which various names these mollusks have been called, on account of the analogy which their organ of breathmg bears to the lungs of vertebrate animals, respire for the most part atmospheric air. The aquatic kinds obtain also some air from the water by means of auxiliary branchial organs. All the land mollusks, or Snails, belong to this Order. The other members of it are aquatic; but none of them inhabit the open sea, although a few, belonging to the genera, Melampus or Conovulus and Otina, are amphi- bious. These last I propose to include in the marine Mollusca, as they live in the sea for many hours out of the twenty-four, and are only met with on dry land * Having a lung-like gill. by LIMNEID&. 77 when the tide has retired. One species of Melampus is found in brackish, but never in fresh, water. In this country, about three-fourths of the Pulmono- branchs are terrestrial; the remaining fourth live in fresh and shallow water, occasionally rising to the sur- face or crawling out of their native element to renew the supply of air. They are nearly all herbivorous; but the Testacella, or Shell-Slug, feeds exclusively on the earthworm, and the Slugs and many kinds of Snail (both terrestrial and aquatic) eat animal as well as vegetable substances, and are occasionally cannibals. It has been proposed to call the tentacles of the aquatic kinds by another name (viz. vibracles), in consequence of their being contractile, mstead of retractile like the tentacles or horns of land-snails, and also because they do not bear the eyes on their tips or extremities, as in the last- mentioned kinds. This distinction seems, however, to be unnecessary ; and much confusion might result from such an innovation, as the word ‘tentacles’ has been so long and universally applied to the feelers of all the Gastero- poda or univalve Mollusca. They may be conveniently divided according to their different habitats; and the freshwater kinds will be de- scribed first, so as to complete this branch of the subject. These are all covered or protected by a shell, and are comprised in the undermentioned family. Family LIMN AID. Bopy generally long and spirally coiled, but in one genus short and hood-shaped: mantle covering the upper part in front: head short: tentacles 2, contractile: eyes placed on the inner base of the tentacles, a little towards the front: foot oval, used for crawling or floating. SHELL spiral, or hood-shaped. 73 LIMN AIDA. Genus I. PLANOR’BIS*, Guettard. PI. IV. f. 1, 2, 3. Bopy long, twisted in a flat coil: tentacles very long and slender: foot short and narrow, attached to the upper part of the body by a stalk, which is shaped like the lower half of an hourglass. Swett quoit-shaped, or flat: whorls cylindrical : spire dex- tral, or turning from left to right, and visible on each side. This genus has some remarkable peculiarities. One of them consists in the habit of the animal emitting its purple-coloured blood, or a fluid like that which is se- creted by the Aplysia, on being irritated, apparently as a means of defence against its enemies. Another is, having several of its vital organs placed ou the left side of its body, instead of on the right (as is the case with nearly all the other Gasteropoda), while the spire of its body and shell is coiled the other way, viz. from left to right. And a third peculiar feature consists in the form of its shell, which is flat or concave on one or both of its sides, re- sembling that of an Ammonite. The body of these mol- lusks is too small for its shell ; and when crawling, the animal leaves part of the shell empty, putting one in mind of loose and ill-fittmg clothes. O. F. Miller, nearly a century ago, seems to have satisfactorily settled the question that was then raised as to whether the shells were right- or left-handed; but the discussion has lately been renewed. ‘The shell being viewed in its natural position, there can be no doubt of its being dextral. Some of the smaller species of Planorbis, inhabiting marshes and very shallow water which are dried up in summer, close the mouth of their shell with an epi- phragm, or filmy covering, like that of some land-snails. The animal then retires into the interior of its coil and * Flat-coil. |e) ih PLANORBIS. 29 awaits the return of moist and more congenial weather. All of them frequent stagnant or slowly-running water, and are herbivorous. Their eggs are enclosed in a globular bag, which is fixed to stones and the stalks or leaves of submerged water-plants. Owing to the sluggish habits of most of the species, as well as to the nature of their habitat, the surface of their shells is apt to become encrusted with a mineral or vegetable deposit. The genus seems to have been originally indicated by Petiver in his ‘ Gazophylacion.’ There being several species, it may be more con- venient to divide them, as before, into sections. A. Suett glossy ; last whorl very large in proportion to the rest, and partly covering the preceding one. 1. PLanorsBis LINEA TUSs*, Walker. Helix lineata, Walker, Test. Min. Rar. p.8, pl. 1.f. 28. P. lacustris, F. & H. iv. p. 162, pl. exxviii. f. 1-3. Bopy reddish-brown, tinged with violet, dark purple in front with a few black specks: head strongly bilobed: ten- tacles filiform, diverging at their base: eyes small, but distinct, scarcely prominent: foot broad and rounded in front, gradu- ally narrowing and pointed behind. SHELL quoit-shaped, the upper being rather more convex than the lower side, both sides depressed or almost concave in the middle, rather thin, very glossy, semitransparent, reddish or yellowish-horncolour, or grey, closely striate in a trans- verse direction, the striz becoming curved towards the mouth : epidermis very slight: periphery (or circumference of the outer whorl) bluntly keeled: whorls 4, compressed on all sides; the last exceeding in size the rest of the shell, and con- cealing nearly two-thirds of the preceding whorl in its clasp : suture distinct, but not deep: mouth obliquely heart-shaped : outer lip thin and flexuous, obtusely angulated above: wum- bilicus small and rather deep: inside the last whorl are from * Streaked. 80 LIMN EID. 2 to 5 rows of curved plates, which are arranged on each side across the spire, opposite to each other and at nearly equi- distant intervals. L. 0:065. B. 0-2. Hasirat: Slow streams and ditches in the home and eastern counties, as well as in Guernsey (Lukis), Notts (Lowe), and Co. Tipperary (Humphreys); but it is a local species. It is found in our upper tertiary strata. According to Malm it occurs in Sweden; and it appears to have a wide range over the more temperate parts of Europe, as far south as Toulouse. This pretty and curious little mollusk is rather active, and is usually found on duck-weed and other aquatic plants. It lays only from 3 to 8 eggs, which come to maturity in ten or twelve days. The internal plates, which are observable outside the last whorl of the shell, form half-closed chambers; and the animal retreats into the front one for safety. These plates appear to answer the same purpose as the teeth or folds which barricade the apertures of many of the small land-snails. They are also only formed in adult individuals. The peculiarity of this structure induced one of its earliest discoverers, Lightfoot, to call the present shell a Nautilus; and the late Professor Fleming proposed for it on the same grounds a new genus (Segmentina), which has been adopted by Capt. Brown and Dr. Gray ; but, even as a test of concho- logical distinction, this character does not seem to be of any value. Miller noticed, in his description of the next species, that a few of the specimens which he had exa- mined had two streaks, like ligaments, in the upper part of the last whorl, apparently indicating the marks of fracture and mending of the shell, by which he may possibly have meant this species ; but he only described one species of this form, which still bears the name he gave it, Planorbis nitidus. The present species was first PLANORBIS. roll made known by Mr. Walker, an intelligent bookseller at Faversham in Kent, the description of it having been supplied to him by Mr. Jacob. The only share which Mr. Boys appears to have had in the discovery is his having sent parcels of shell-sand to Walker; but the credit of the publication entirely belongs to the latter. Two years afterwards Lightfoot described and published this species in the ‘ Philosophical Transactions,’ under the name of Nautilus lacustris. 2. P. nr tT1pus*, Miiller. P. nitidus, Mull. Verm. Hist. pt.u. p. 163; F. & H. iv. p.161, pl. exxvii. IB BIDS Bopy reddish-grey, with sometimes a yellowish tinge, and marked with extremely fine dark-grey specks: tentacles very long and slender: eyes rather large: foot short, very broad in front, and slightly narrowing behind to an abrupt but not a fine point. Suet shaped like the last, but flatter and with much more of the spire visible above, in consequence of the last whorl not clasping such a large part of the preceding one, very thin, glossy and prismatic, light-yellowish-horncolour or grey, with sometimes a reddish tinge, faintly striate by the lines of growth, with occasionally a few spiral microscopical lines, which are more distinct on the under side, giving an appearance of the sculpture peculiar to the shells of Limnea: epidermis ex- tremely delicate : periphery rather sharply keeled: whorls 4-5, the last covering about one-half of the preceding whorl: sw- ture rather deep: mouth and outer lip formed as in P. lineatus, but larger: umbilicus small, not deep. L. 0:06. B. 0°225. Hasirat: Ponds, marshes, and stagnant water through- out Great Britain, from the Moray Firth district south- wards. It is also one of our upper tertiary fossils. Middendorff has included it in his list of Siberian shells ; and it is extensively distributed over the European con- tinent, having apparently its most southern limit in * Shining. EO 82 LIMNEID. Corsica. Although it is much less local than the last spe- cies, [am not aware of their having been found together. Its habits are slower and more timid than those of P. lineatus ; and it is not so fertile, never laying more than 6 eggs. The shell is often infested by the minute egg-cases of a water-insect, or coated with the spores of Conferve. The shell differs chiefly from that of the last species in being of a lighter colour, flatter, and thinner, m the whorls being more visible above, the keel bemg much sharper, and especially in the absence of the internal septa or partitions. B. Whorls few. 3. P. Nauti’Levus*, Linné. Turbo Nautileus, Linn. Syst. Nat. ed. xii. p.1241. P. Nautileds, F.& H. iv. p. 152, pl. exxvi. f. 6, 7. Bopy greyish-brown, with sometimes a faint reddish tinge, minutely speckled with black: head very large and thick: tentacles long and cylindrical, greatly diverging : eyes distinct, scarcely prominent: foot broad, rounded in front, and ending in a blunt point behind. SHELL quoit-shaped, having the upper side flat and the lower side rather convex, thin, not glossy, light-brown or grey, sometimes white, closely striate by the lines of growth, which at distant but regular intervals form strong curved ridges and frequently rise into projections like the rowels of a spur on the outside: epidermis rather thick: periphery bluntly and in- distinctly keeled: whorls 3, depressed above, the last exceed- ing in size the rest of the shell: sutwre rather deep: mouth oblique, and either oval or nearly circular, according to the greater or less depression of the whorls: outer lip thin, form- ing with the inner lip in the adult a complete peristome: wm- bilicus very large and exposing all the spire. L. 0°035. B. 0-1. Var. cristata. Shell having the transverse ridges stronger, and the periphery deeply notched or crested by them. P. eris- tatus, Drap. Hist. Moll. p. 44, pl. i. f. 1-3. * Shaped like a Nautilus. PLANORBIS. 83 Hasitat: On aquatic plants in marshes, lakes, ponds, and ditches, from the northernmost extremity of Zetland to the Channel Isles. It is also one of our upper tertiary fossils. The variety is not uncommon, and merges in- sensibly into the ordinary form. The degree of sculpture appears to depend much on age, as it is usually stronger in half-grown individuals and disappears in the adult. A monstrosity also occurs in which the whorls are more or less twisted and separate from each other, sometimes being raised like a snake lying on its coil. The range of this species abroad extends from Finland to the Pyre- nees and even to Algeria. This pretty little mollusk is slow in its movements, and may be noticed feeding on the decaying leaves of the Tris pseudacorus and water-plants. According to Bou- chard -Chantereaux, it lays only from 3 to 6 eggs, which leave the capsule in ten or twelve days. The sculpture of the shell is extremely elegant; and it is by far the smallest of its kind. The minuteness of its size, dull appearance, and comparatively large umbilicus will at once serve to distinguish it from either of the foregoing species. If the rimgs which encircle each whorl are marks of annual growth, it must attain a very respectable old age for a mollusk, as I have counted as many as 20 Tings in one specimen. In all probability, however, these marks do not indicate the annual, but only the periodical growth, several of them being formed in the first year. 4, P. at’pus*, Miller. P. albus, Mull. Verm. Hist. pt. ii. p. 164; F. & H. iv. p. 149, pl. exxvi. . 9 ° Bopy grey or dirty-brown, sometimes inclined to a reddish hue, with fine but indistinct black specks: head thick, rounded * White. $4 LIMNAEXIDZ. in front: tentacles widely spread at their base, long, slender, and pointed: eyes small and rather of an oval shape: foot narrow, rounded in front and narrowing gradually behind to a blunt point. Suet flat above, with a depression in the centre, slightly concave below, rather thin, not glossy, greyish-white, closely striate in the line of growth, and more strongly striate or ridged spirally: epidermis thick, sometimes hispid or bristly : periphery slightly compressed on each side, but not keeled: whorls 5, the last exceeding the rest in size: sutwre rather deep: mouth obliquely oval: outer lip slightly reflected; the upper part projecting considerably: inner lip spread on the columella, but continuous with the outer hp: wmbilicus very large, but not deep. L. 0:08. B. 0-275. Var. Draparnaldi. Shell more closely and sharply striate in the line of growth: periphery distinctly keeled : wmbilicus deeper. LP. spirorbis, Drap. Hist. Moll. p. 45, pl. un. f. 8-10. Helix Draparnaudi, Sheppard, in Linn. Tr. xiv. p. 158. P. Draparnaldi, Jeffr. in Linn. Tr. xvi. p. 386. Hasrrat: Same as that of the last species, but more generally diffused. The most northern limit in these islands appears to be Aberdeenshire. It is also an upper tertiary fossil. The variety has been found at Holbrook in Suffolk (Sheppard); Cardiff, Bristol, and Church Stretton in Shropshire (J. G. J.). It has been referred by the authors of the ‘ British Mollusca’ to the P. margi- natus of Draparnaud. This common species ranges from Siberia to Portugal and Algeria. The spire is often twisted or distorted in this, as well as in the other species of Planorbis. The spiral striz are always visible, even in dead and water-worn speci- mens which have lost their epidermis. The finest spe- cimens I have seen were kindly sent to me by my friend Mr. Norman, who found them at Kibworth, Co. Durham, their diameter being rather more than a third of an inch. In all probability this was the Helix spirorbis of Linné. ~~ PLANORBIS. 85 The description of its colour (“ alba’’), as well as all the other characters given of this species in the ‘ Fauna Suecica,’ are peculiarly appropriate to P. albus. The present species being common in Sweden, and not likely to be confounded with any other, could scarcely have escaped the keen observation of the great naturalist ; and it was not otherwise noticed by him. However, as the confusion has already been too great in the specific names of this genus, I will not venture to increase it by restoring Linné’s name. 5. P. era’per*, Jeffreys. P. glaber, Setfr. in Linn. Tr. xvi. p. 387 ; F. & H. iv. p. 150, pl. exxvi. £.8,9. Bopy yellowish-grey : tentacles rather short, cylindrical, and ending in a blunt point: foot rather broad, especially in front, with a yellowish edge. SHELL rather convex above and depressed in the centre, concave below, rather thin, glossy and sometimes iridescent, greyish-horncolour and occasionally marked with white curved streaks in the line of growth, finely but irregularly striate transversely, and very faintly and obscurely striate in the op- posite or spiral direction ; the spiral striz are only visible in some lights and by the aid of a strong magnifying power : epidermis thin and smooth ; periphery rounded : whorls 5, con- vex, but somewhat angular, the last scarcely exceeding one- half of the shell: sutwre very deep: mouth rather more circular than oval: outer lip slightly reflected, the upper edge project- ing a little beyond the lower one : inner lip united to the colu- mella, but continuous with the outer lip: umbilicus large and rather deep. L. 0:05. B. 0-15. Hasirar: On aquatic plants in marshes, lakes, and ponds, from Burra fiord in Unst to Penzance ; but it is not generally diffused. It is an upper tertiary fossil. I only know of about twenty localities. The largest speci- mens I have seen were found by Mr. Bridgman near * Polished. 86 LIMN XID. Norwich, and measure nearly a quarter of an inch in diameter. It is distributed throughout the greater part of the Continent, and ranges from Sweden to Corsica and Algeria. According to the Rev. R. T. Lowe, it also inhabits Madeira. This species differs from P. albus in its smaller size and glossy aspect ; in the upper side being rather convex, instead of flat (owing to the rotundity of the whorls) ; in its deeper suture and umbilicus; in the upper part of the outer lip not projecting so much, in consequence of which the mouth appears to be more circular; and, especially, in not having the strong and regular spiral strize which characterize the last species. The mouth is also not nearly so large; and the periphery is never keeled. or compressed. 'The present species is equally abundant where it occurs; but I am not aware that both species have been found living together. It is the P. levis of Alder, and probably also the P. cornu of Ehrenberg from the Nile. The P. Ross- messlert of Auerswald appears to be only a large variety of the same species, having the peristome thickened by an inner rib (as in the next species), judging from Ross- miassler’s description and figure, as well as from an ex- amination of typical specimens in the Museum at the Jardin des Plantes. Von Martens has published, in the ‘Malakozoologische Blatter’ for 1859, some excellent dissertations on the synonymy of a few of the European land and freshwater shells, and is of opinion that this species 1s also the P. gyrorbis of v. Seckendorf and has five other aliases. am. PLANORBIS. $7 C. Whorls many, keeled. 6. P. sptror’pis*, Miller. P. spirorbis, Mull. Verm. Hist. pt.ii. p.161; F.& H. iv. p. 159, pl. exxvii. £79; 10: Bopy purplish-grey or reddish-brown, with minute black specks on the foot: tentacles rather long, slender and pointed : foot short and narrow, obtusely rounded in front and angular behind. — Suett slightly concave above and flat below, or vice versa, slightly wider at the base, rather solid, glossy, brownish horn- colour, closely striate in the line of growth, and marked spirally with very faint and minute strize: epidermis thin: periphery angular, and sometimes bluntly keeled on the lower side: whorls 5-6, gradually increasing in size, the last not exceeding in diameter one-sixth of the whole spire; they are rounded, but angular; suture deep: mouth nearly circular, often thick- ened or strengthened inside by a rib: outer lip very slightly reflected : iner lip continuous with the other lip, but spread over the columella: wmbilicus very large and shallow. L. 0-04. B. 0°25. Var. ecarinata. Shell smaller, ight grey, having one whorl less than usual and no trace of a keel. P. spitrorbis, Moq.- Tand. Hist. Moll. Fr. p. 437, pl. xxxi. f. 1-5. Hasrtrat: On plants and grass in shallow and stag- nant water everywhere from the Moray Firth district to the Channel Isles. It is also a fossil of our upper ter- tiary beds. The variety appears to be very rare in this country. Ihave only found it once; and that was in Oxwich marsh, near Swansea. A monstrosity not un- frequently occurs, in which the whorls are more or less twisted and separated. Some specimens which my late friend Mr. Barlee found at Penzance resemble a minute corkscrew; and in another form of the same kind of distortion which I found in Bishopston Valley, near * Round-spired. 88 LIMN XID. Swansea, the last whorl only is separated from the rest and curled upwards. In the last-mentioned locality there was a great deal of mud which had been brought down by a stream and deposited in the grassy pool where I found the shells. This mud must have inconvenienced the mollusk and prevented its completing the spire of its shell on the usual plane; so that it gave the last whorl an outward twist, apparently in order to get clear of the incumbrance. When the drains and splashy pools in which this kind of Planorbis lives are dried up by the heat of summer, it retires far within its shell and closes the mouth or opening with a yellowish-white and rather solid lid, patiently waiting for the next shower of rain and fasting in the mean time. This species inhabits Siberia, and ranges as far south as Algeria and Sicily. It differs from P. glaber in the whorls being much narrower and consequently more compact, and in usually having a blunt keel on the periphery. The typical or ordinary form is the P. rotundatus of Poiret, P. vortex var. 8. of Draparnaud, and P. leuco- stoma of Michaud, besides having other specific names for several of the varieties. 7. P. von tex*, Linné. Helix vortex, Linn. Syst. Nat. ed. xii. p. 1243. P. vortex, F. & H. iv. p.157, pl. exxvii. f. 6-8. Bopy reddish-brown, with a slight tint of violet, rather distinetly marked with minute black specks: tentacles very long, slender and finely pointed: foot evenly rounded in front and keeled behind. SHELL much compressed, concave above and flat below, thin, glossy, yellowish or greyish-horncolour, finely and closely striate in the line of growth, and occasionally having a few obscure and extremely minute spiral strie: epidermis thin: * Whirlpool. 7 PLANORBIS. 89 periphery slightly keeled towards the lower side, and always angular in consequence of the outward compression of the shell: whorls 6-8, gradually enlarging, the last not exceeding in diameter one-fifth of the whole spire, angular on both sides and sloping gently towards the outer edge: suture well de- fined, but not deep: mouth obliquely oval, ending above in rather an acute angle, and having the inside sometimes thick- ened by a slight rib: outer lip not reflected: inner Lp much spread on the columella, but continuous with the outer lip: umbilicus very large and shallow. L. 0:05. B. 0-3. Var. compressa. Shell thinner and much flatter, with the keel more distinct and sharp and placed nearly in the middle of the periphery. P. compressus, Mich. Compl. p. 81, pl. xvi. f. 6-8. Hasitat: The same as that of P. spirorbis, and having a similar range at home and abroad as far southward as Algeria. It is, however, not so generally diffused as that species. They are sometimes found together. The _ present species is also one of our upper tertiary fossils. The variety is not uncommon. I have a distortion from Clumber lake, Notts, in which the spire is displaced on the lower side, and the first whorls are set at an acute angle to those which succeed. 3 This mollusk is sluggish, but fond of floating. It lays from 10 to 12 eggs. The epiphragm is thin and mem- branous. The shell differs from that of P. spirorbis in being thinner, flatter, and rather longer, and in having a distinct and prominent keel. .This species was first described and figured by Lister. 8. P. carina’ tus *, Miiller. P. carinatus, Mill. Verm. Hist. pt.u. p.175; F. & H. iv. p. 153, pl. exxvii. f. 4, Ds Bopy deep-reddish brown with a yellowish tint, and of a * Keeled. 90 LIMNAID&. lighter colour underneath, finely and rather distinctly marked with black specks: tentacles long, slender, bluntly pointed : foot acutely rounded in front and obtusely so behind. SHELL compressed, concave above and flat or very slightly convex below, rather thin and glossy, yellowish-horncolour, finely and closely striate in the line of growth, with a few slight spiral strive: epidermis thin: periphery strongly keeled towards the middle : whorls 5-6, the diameter of the last being rather less than a third of the whole spire, moderately con- vex above, but much less so beneath, sloping gradually on both sides to the periphery: sutwre deep: mouth obliquely oval, sharply angulated above, the inside sometimes thickened: outer lip slightly reflected: inner lip continuous with it, much spread on the columella: wmbilicus very indistinct, owing to the lower side being nearly flat. L.0-1. B.0°5. Var. disciformis. Shell flatter and thinner, of a yellowish colour, having the last whorl larger in proportion to the others, and the keel more prominent and sharp and placed exactly in the middle. P. lutescens (afterwards altered to disciformis), Jeffr. in Linn. Tr. xvi. pp. 385 & 521. Hasitat: Marshes and stagnant water in our home and eastern counties, as well as in those of Dorset, Somer- set, Northampton, York, Glamorgan, and many parts of Ireland. Dr. Leach says that it also occurs near Edin- burgh. It is, however, local, and never plentiful. It is an upper tertiary fossil. The variety is found in Bucks, Oxford, Cambridge, Glamorgan, Cork, and Tipperary, and is somewhat rare. This variety bears the same relation to the typical form as the P. compressus of Michaud does to P. vortex. The monstrosity, so common in this genus, in which the last whorl is disjomed from the rest, also occurs, but very seldom. It is a Swedish species, and ranges southward to Portugal and Corsica. This mollusk is very slow in its movements, but ap- pears to be fond of floating. It lays from 10 to 20 eggs, which quit the capsule in from ten to fifteen days. It is occasionally met with in company with the next species. PLANORBIS. 91 This is in all probability the Helix planorbis of the ‘Fauna Succica,’ which is described as “plana” and ‘‘margine prominulo ;””. but as the description and figure given by Lister, to which Linné there refers, apply to the Helix complanata of the latter, more confusion will be avoided by the adoption of Miiller’s name. 9. P. compLana tus*, Linné. Helix complanata, Linn. Syst. Nat. ed. x. p. 769. P. marginatus, F. & H. iv. p. 155, pl. exxvii. f. 1-3. Bopy of a deep violet-red, with very fine black specks, espe- cially on the edges of the foot: tentacles very long and slender, bluntly pointed: foot rounded in front, convex behind, and ending in an obtuse tail. SHELL concave above and slightly convex below, rather solid and opaque, not glossy, yellowish-horncolour with some- times a tinge of brown, closely but irregularly striate in the line of growth and more or less distinctly striate in a spiral direction: epidermis rather thick: periphery strongly keeled on the under side: whorls 6, the diameter of the last being about one-fourth of the whole spire, convex above and slightly so beneath, sloping abruptly on the upper, and gradually on the lower side to the periphery: suwtwre moderately deep: mouth roundish-oval, slightly angulated above by the keel, the inside being sometimes strengthened by a rib: outer lip a little reflected: anner lip continuous with it and affixed throughout to the columella: wnbilicus broad and very shallow. L. 0-125. B. 0°6. Var. 1. rhombea. Shell smaller, more solid, rather more convex above and deeply umbilicated below; keel blunt and almost obsolete. Helix rhombea, Turton, Conch. Dict. p. 47. Var. 2. albida. Shell whitish or colourless. Hasitat: Marshes, ponds, canals, ditches and stand- ing water everywhere in England, Wales, and Ireland ; but I am not aware of any Scotch locality. It is one of our upper tertiary fossils. The variety 1. is from Dublin * Flattened. 92 LIMNAID®. and the South of Ireland; and the other variety has been found by Mr. Choules at Eltham in Surrey. A monstrosity, having the whorls dislocated and more or less separate from each other, sometimes corkscrew- shape, has been found by Mr. Bean near Scarborough, and by myself on Crymlyn Burrows, near Swansea. It is the Helix Cochlea of Brown (Mem. Wern. Soc. pl. xxiv. f.10) and H. terebra of Turton’s ‘ Conchological Dictio- nary.’ This common species is widely distributed in Ku- rope from Finland (according to Nordenskidld and Ny- lander) to Algeria and Sicily. It is a sluggish and slimy as well as a very irritable mollusk, and often indulges itself in floating lazily along the under surface of the water. It lays from 8 to 10 capsules, each of which contains from 6 to 21 eggs; so that it appears to be more prolific than many of its con- geners. Its shell may be distinguished from that of P. cari- natus by its narrower and more rounded whorls, as well as by the keel being placed below, instead of in or to- wards the middle of, the periphery. It is usually larger and thicker than that species and is much more gene- rally diffused and plentiful. | There can be no doubt that this is the Helix compla- nata of Linné, whose epithet “deorsum carinata” is peculiarly appropriate; but both Miller and Drapar- naud have substituted other names (viz. wmbilicatus and marginatus) on what I cannot help considering as very insufficient grounds. If Linné’s name was prior to what is termed “ the binomial epoch,” and therefore inadmis- sible (which is a very questionable objection), still Gme- lin’s adoption of that name, as well as Miiller’s, take precedence of the one proposed by Draparnaud. It must also be borne in mind that this species and P. carinatus PLANORBIS. 93 are connected together through the P. submarginatus of Cristofori and Jan, alias the P. intermedius of Char- pentier. Some of the aberrant forms are as difficult to separate as those of P. spirorbis and P. vortex. The present species was first made known by Lister. The P. turgidus described by me in the ‘ Linnean Transactions’ is not a British species ; and I was mis- informed as to the locality. Its nearest ally is, as I stated, P..corneus ; but it has been erroneously referred by subsequent writers to the present species. D. Whorls rounded and not keeled. 10. P. cor’NEus*, Linné. Helix cornea, Linn. Syst. Nat. ed. xii. p. 1243. —P. corneus, F. & H. iv. p. 147, pl. exxvii. f. 1-3. Bopy dark red or nearly black, of a greyish hue beneath, with black and grey specks on the upper part: tentacles long and curved, with rather blunt tips: eyes of a moderate size and not prominent: foot slightly tubercled, narrow and angu- lated in front, rounded and convex behind. SHELL rather deeply concave above and nearly flat below, somewhat solid and opaque, glossy, whitish-horncolour with a reddish-brown tinge, closely but irregularly striate by the curved lines of growth and marked with fine and close-set spiral strize, which are more perceptible in the first whorls ; the upper surface is also sometimes pitted or impressed in an irregularly quadrangular form like cut-glass: epidermis rather thin: periphery rounded and quite destitute of any keel or angularity : whorls 5-6, more perceptible on the umbilical or lower side, in consequence of that part of the spire being intorted; diameter of the last whorl rather less than a third of the whole shell; they are very convex above and rather compressed beneath: sutwre deep: mouth forming a segment of two-thirds of a circle: outer lip a little reflected, the upper side not projecting much beyond the lower one: cmner lip con- * Horn-coloured. 94. LIMNAID. tinuous, but closely attached to the columella and widely spread on it: umbilicus broad and shallow. L. 0-35. B. 1. Var. albina. Shell perfectly white. Hasrrat: Marshes, ponds, and ditches in many parts of England and Ireland ; but, although gregarious, it is very local. It occurs in a fossil state in the mammalian crag of Suffolk, as well as in the upper tertiary beds of Suffolk, Essex, and Worcestershire. The variety 1s found in Surrey. Itis a Siberian species, and diffused over the Continent as far south as Corsica. M. Terver has found a thin variety of it in Algeria. This far exceeds in size any other European species of Planorbis. Its anatomy, embryology, and habits were accurately described by Lister nearly two centuries ago ; and he seems to have made several experiments, but in vain, with the hope of being able to fix and render useful the purple dye which this mollusk so plentifully yields. It is a sluggish and extremely sensitive animal; and when irritated it emits the fluid or secretion in con- siderable quantity from a gland at the sides of its neck. It may often be seen floating on a warm and still summer day. It lays only two or three capsules, each containing from 20 to 40 eggs, which are excluded at the end of fifteen or sixteen days. The epidermis of the young shell is covered with fine down, its surface resembling velvet pile. In this state it 1s the P. similis of Miller. 11. P. conror’tus *, Linné. Helix contorta, Linn. Syst. Nat. ed. xii. p. 1244. P. contortus, F. & H. iv. p. 160, pl. exxvi. f. 3. Bopy black, with a slight tinge of red; tentacles remarkably slender: eyes very small: foot broad and rounded in front, narrowing behind to a blunt tail. * Twisted. PHYSA. 95 SHEtt flat above, with a deep depression or concavity in the middle, very concave below, rather solid for its size, and opaque, yellowish-brown or horn-colour, closely and deeply striate in the line of growth, but not otherwise sculptured: epidermis rather thick: periphery rounded: whorls 8, extremely compact ‘and much compressed, angular above and slightly so beneath: suture deep: mouth semilunar, occasionally strengthened in- side by a rib: outer lip not reflected, the upper side scarcely projecting beyond the lower one: zmner lip thin, not con- tinuous but attached to the columella: wmbilicus large and deep. L.0:075. B. 0°175. Var. albida. Shell nearly white. Hasitat: On water-plants in lakes, ponds, and ditches throughout the greater part of Britain, and reaching as far north as the Shetland Isles; but it is local. It is also an upper tertiary fossil. The variety was found by me in a lake near Lerwick, with specimens of the ordinary colour. The usual monstrosity occurs in which the spire _ is dislocated. Abroad it ranges from Siberia to Portugal and Corsica. This curious little mollusk is slow, irritable, and fond of floating. It is not very prolific ; for each capsule (of which it lays from 5 to 9 during the breeding-season) contains only from 6 to 8 eggs, giving an annual average of about 50 for an individual. The shell of this, as well as of the last species, is so different from any other which I have described, that it is unnecessary to make any comparison. Their forms are, however, represented by many analogous species in North America. | Genus IT. PHY’SA*, Lamarck. PI. IV. f. 4,5, 6, 7. Bopy rather long, and twisted in a spiral coil: tentacles long and slender: foot rather long, rounded in front and pointed * A bladder. 96 LIMN EID. behind, attached to the upper part of the body by a very short and broad stalk or pedicle. SHELL conic-oval or oblong: spire produced, sinistral or turning from right to left. This peculiar and characteristic genus has intermediate relations with Planorbis and Limnea. It resembles the first in its long tentacles, as well as in some of the organs being placed on the left, instead of on the right side of the body; and it agrees with the latter in the form of its shell: but it differs from both m the spire being sinistral, although that is not a very important cha- racter. The shells of Physa have a remarkably polished appearance, caused in some cases by their bemg more or less enveloped by an expansion or jobe of the mantle, the lubricating friction of which always keeps the surface smooth and bright. These little mollusks frequent shal- low, and generally clear water, and are gregarious. Their eggs are deposited in strips of a gelatinous consistency, which are fixed to submerged stones as well as to the stalks and leaves of aquatic plants. A. Mantle having plain edges and not expanded over the shell, which is covered with an epidermis and has a long spire. 1. Puysa nypno’ruM*, Linné. Bulla hypnorwn, Linn. Syst. Nat. ed. xii. p. 1182. P. hypnorum, F. & H. iv. p. 143, pl. cxxii. f. 6, 7. Bopy lustrous, dark grey, dusky brown, or almost black, with sometimes a faint tint of blue, covered with very minute black or dark-grey specks: tentacles long, slender, and pointed, di- verging considerably at their base: eyes very small and not very distinct : foot lance-shaped, narrow, blunt and truncate in front, compressed and rather pointed behind. SHELL oblong, spindle-shaped, thin, highly polished, semi- * Frequenting the Hypnwm, a kind of moss. PHYSA. 97 transparent, yellowish or reddish-horncolour, faintly striate by the lines of growth, and marked spirally with a few very in- distinct strie, which are only perceptible by means of a high magnifying power: epidermis very thin: whorls 6—7, convex, but slightly compressed at the sides, the last exceeding in size all the rest put together: spire tapering, but blunt at its ex- tremity : suture distinct, though not deep: mouth oval, con- tracted on the inner side by the periphery of the penultimate whorl, acutely angulated above and rounded below: outer lip thin and flexuous: cnner lip spread on the columella, which has a strong and broad fold on its lower side. L. 0°5, B. 0:2. Hasirat: Ponds, ditches, and among grass in pools which are quite dried up in summer, throughout these isles from the Moray Firth district to Guernsey ; but it is rather local. It is also an upper tertiary fossil. A variety occurs in which the shell is smaller and of a dark copper-colour; and I also possess a specimen in which the spire is eroded and truncate, the opening having been filled up bya shelly plate. Muller recorded a specimen which had only the right eye, the other being wanting. It isa native of Siberia, and ranges southward to Nice and the Eastern Pyrenees. According to Gould and Philippi, it is the same species as the P. elongata of Say, which inhabits the northern and western parts of the United States. This mollusk is rather active in its habits, and may be seen in fine weather floating with tolerable rapidity. It is rather prolific ; and the young attain their full size at the end of the second year. The largest specimens I have ever seen of this species were found by me more than a quarter of a century ago, in fish-ponds at Fre- mington, in the north of Devon, some of which are three-quarters of an inch in length. Gmelin supposed that the Bulla hypnorum of Linné might be a variety of the next species ; and Miller, for nearly the same reasons, called the present species Plan- E 98 LIMNZIDZ. orbis turritus. But the Linnean epithets “spira pro- minente” and “ spira obsoleta” appear unmistakeably to distinguish the two species; and, at all events, it would now be very inconvenient to make any change of name by adopting that given by Miller, instead of the one by which this species is so universally known. The late Dr. Fleming proposed to separate it generically from the next under the name of Aplexa; but this separation has only been adopted by a very few conchologists. A well-known European species, P. acuta, seems to con- nect the two British forms, both as regards the soft parts of the animal and the shell. B. Mantle having lobes or digitated processes which expand over the shell; the latter being destitute of an epidermis and having a short spire. 2. P. rontina Lis*, Linné. Bulla fontinalis, Linn. Syst. Nat. ed. xii. p. 1185. P. fontinalis, F. & H. iv. p. 140, pl. exxii. f. 8, 9. Bopy lustrous, dark grey with sometimes a slight tint of yellow or violet: mantle fringed with about a dozen lobes or digitations of unequal size: tentacles rather slender, light grey : eyes conspicuous: foot obtusely rounded in front, and con- tracted behind to a somewhat fine point. SHeELt oval, extremely thin, glossy, semitransparent, greyish- horncolour with a slight tinge of yellow or brown, faintly striate by the lines of growth and microscopically striate in a spiral direction: whorls 4-5, swollen, the last occupying con-~ siderably more than three-fourths of the shell: spzre not much produced, blunt at its point: swtwre moderately deep: mouth nearly of the same form as that of the preceding species, but much larger and wider in proportion: outer hp very thin and flexuous : ¢nner lip much spread on the columella, which has a slight and narrow fold on its lower side. L. 0°35. B. 0-25. Var. 1. inflata. Shelli half as large again as the usual size: * Frequenting fountains. PHYSA. 99 whorls angular towards the suture, the middle one rather more prominent than the penultimate whorl, causing the summit of the spire to appear abruptly terminated. Var. 2. curta. Spire extremely short. Bulla fluviatilis, Turt. Conch. Dict. p. 27. Var. 3. oblonga. Spire considerably produced. Var. 4. albina. Shell of a milk-white colour. Hasitar: On water-cresses and other aquatic plants in running brooks, as well as in slow rivers, canals, and ditches everywhere in Great Britain, as far north as Aberdeenshire. Var. 1. Dublin (Humphreys and War- ren). Var. 2. Clonoony Barracks, Ireland (Brown) ; Bramerton, Norfolk (J. G.J.). Var. 3. Anglesea, on Chara aspera (J. de C. Sowerby) ; Naas, Ireland (Hum- phreys). Var. 4. Birkenhead (Webster). This species is widely diffused on the Continent, and ranges from Finland to Sicily. This common and pretty little mollusk is rather lively, creeping and floating by jerks. € | as the world. | ze ie ae ss —— SS | 3. ooo =| Aguitic (continued). | UNIVALVES. | | Neritina fluviatilis .......,. 1 | | Paludina contecta ......... cel teal | MINIDARE, “ec.casacensnns =H ae | Bythinia tentaculata ...... — | — 4+-— -Siberis. | | Leachii ......... A. sie fr fo iS | Hydrobia similis ............ — |-— UETIEROSE fo cone sciences <4e ar he ea fa Ve aa Valvata piscinalis .........| — | — |— | Siberia. Var. depressa, Rene | eristata .....sROeseithh.. -— | — | — | Siberia and Kamtschatka. Planorbis lineatus ......... Se ee PUMA TIS - Poe —|—|— preeras 51555415 0 — | — | — | Siberia. | radiatulus............... oa Sanaall (heat WANTING 5 5 urd abled dde's —|—!— | excavatris 1.2... 248 —|— crystallinus ............ —|—|— | Talvaee Od, TA. WIR — | — |} — | Siberia; N. America. | Helix lamellata ............ — — aculeata.s. . 2.6. 52.0 RN —}—|— pomatia vi at ASPCPSA .....-.eeeeceerees is | nemoralis ............... — | — | — | N. America. arbustorum ............ — i — b— MAGIA: 4..hieev sess — {| — Cartusiana ............ — | — Siberia. rufescens ..........0.00. —|—|;— | concinnA ........./82% —}—|— hiopida 5.226510. Alin — | — | — | Siberia. | Berices ' 16025, LIAS — | — | — | Irkoutsk; Caucasus. revelate:(0(.25/3..4 800 — | TUBCH .2....... 05.0 —|— REIT fd.» 5 cu oda --- WEIN, vein oss nentansene = | CAPOTAIA, « .......0ss0yeee — ericetorum ............ — | — TOLUNOABUD «055.05... .000% —|—}— FHPOSREIN TA gcc pede... —|— PY SURE Cocasedncaee>.- —|— Siberia. | pulchella ©..:..ssccateres — | — | — | Siberia. | lapiotdat.s:. ..cssmeiete>- —\|—-)|}— obwolatia: sc... eamptee. | - | Bulimus acutus ............ —i|—|? mOnbanis set. Ly. cess —|—|— | OWMGTIEIIAD.;,526>..00venes — | — | — | Siberia. Pape secale us icnvsssHek. 95% — | -- | { ee ee ee TABLE OF DISTRIBUTION: 319 B : Pe Distribution in other parts of aS the world. Pe Species. Northern. Southern. —— — a ee ee Terrestrial (continued). UNIVALVES. Pups FINgens ©... icscacss <0: —|— umbilicata ............ — | — | — ¥ MALLING... oder -ssns — | —.| — | Siberia. Vertigo antivertigo ......... — |} — | — Moulinsiana............ — | — PYZMLA.........sesseeeee —}|—|— HOPOSEPES, ic ghiveble i's. —|—]|? substriata ............06. aa oo PMT Pb cettin dah ae —|—|— BIGUGMOR® 229 ie. sscd- —|—-|— edentula ..........0.56. —|—|— Siberia. N. America ? Siberia. Balia perversa ..........+.+ —|—|]— Clausilia rugosa ..........+. —|—}]— OLDIE . sin. theese a —}|—|— BIpeat ae. sig oiacnds ses —}|—|— Lam AbAG vies icsn0's S50 —}|— | — B 2 = iS) | | | Smyrna. TEUIPTOS Sei acen ie camnc coins — | — | — | Asia, Africa, and America. Carychium minimum ...... —|—|— Cyclostoma elegans......... —|—]|? GIA: TINGED GAs a26 ois Yok Kies =e | at Siberig. Number of terrestrial | BTISCIOR Foie bed. fie: Total number of Spewiedess car... <4 121 |113)115| 80 N.B. Doubtful cases are not reckoned. Siberia. Besides the species enumerated in the above list, four more occur in our upper tertiary strata, but are not now found living in this country. One of them (Hydrodia marginata) is aquatic and inhabits the South of Europe. The other three (viz. Helix fruticum, H. mcarnata, and H. ruderata) are terrestrial and inhabit both the North and South of Europe. H. fruticum and H. ruderata are also Siberian species. It will be seen that, with only two exceptions (viz. 320 TABLE OF DISTRIBUTION. Zonites alliarius and Pupa ringens), all the species which occur in our upper tertiaries are northern forms, and that very few are exclusively northern or southern. In the body of this work the term “ North of Europe” has been used in the ordinary sense, and not with refer- ence to the somewhat arbitrary line of demarcation proposed in the foregoing Table. The authority can be given for every locality ; but to have done this would have taken a great deal of extra space and unnecessarily encumbered the work. 321 ALPHABETICAL LIST OF AUTHORS AND WORKS REFERRED TO OR CONSULTED IN THE PREPARATION OF THIS VOLUME. Apanson, Micuen. Histoire Naturelle du Sénégal. Coquillages. Paris, 1757; 4to, with 19 plates and a map. Ausers, J.C. Die Heliceen nach natiirlicher Verwandtschaft systema- tisch geordnet. Berlin, 1850, 8vo. AuprEr, JosHua. A Catalogue of the Land and Freshwater Testaceous Mollusca found in the vicinity of Newcastle-upon-Tyne, with remarks. In Trans. Nat. Hist. Soc. Northumb., Durh. and Newe. Newcastle, 1850, 4to, pp. 16 (published separately). AupeEr, J. Supplement to the above Catalogue. 1833, 4to, pp. 5. - Annats oF Naruran History from 1838 to 1840; and ANNALS AND MaaazinE or Narurau History, Ist, 2nd, and 3rd Series, from 1841, and still in progress ; containing many interesting contributions on the subject of the British Land and Freshwater Mollusca by Messrs. Gray, Hanley, Thompson, Eyton, Lonsdale, W. Clark, Hincks, Rey. A. M. Norman, and others. Antuony, J.G. On the Byssus of Unio. In Ann. & Mag. Nat. Hist. (1841) vi. p. 77. Arapas e MAcetorr. Catalogo ragionato delle Conchiglie viventi e fos- sili di Sicilia. 1839. Baupon, Aveusre. Catalogue des Mollusques du Département de I’ Oise. In Mém. Soe. Acad. Oise, 1853. Beauvais, 8vo, pp. 20 (published separately). Baupon, A. Essai monographique sur les Pisidies Francaises. Paris, 1897, 8vo, pp. 55, with 5 plates of beautifully executed figures. Becx, H. Index Molluscorum presentis xvi, Musei principis augus- tissimi Christiani Frederici. Hafn., 1838, 4to. Benoit, Lure. LIlustrazione sistematica critica, iconografica de’ Testacei estramarini della Sicilia ulteriore e delle isole circostanti. Napoli, 1857-1860, 4to, quaderni 3 (still in course of publication). Benson, W. H. Occurrence of Clausilia Mortilleti, Dumont, in Kent. In Ann. & Mag. Nat. Hist. July 1856, p. 74. Brrxevey, Rev. M.G. A description of the Anatomical Structure of Cyclostoma elegans. In Zool. Journ. iv. p. 278, pl. xxxiv. Berta, Epoarpo pz. Malacologia terrestre e fluviatile della Valle di Non nel Tirolo Italiano. Parte 1. Molluschi terrestri. Verona, 1852, 8vo, pp. 144, with a plate. . | Pd See LIST OF AUTHORS AND WORKS QUOTED. Binney, A. The Terrestrial Air-breathing Mollusks of the United States (edited by A. Gould). Boston, 1851, 8vo. BuarnviniE, H. pe. Manuel de Malacologie et de Conchyliologie. Paris, 1825, 2 vols. 8vo. Boruase, Witi1aM. The Natural History of Cornwall. Oxford, 1758, folio, with 20 plates. Bovsésr, Nérée. Bulletin d’Histoire Naturelle de France, pour servir a la statistique et a la géographie naturelle de cette contrée. Premicre année, 3° section, Mollusques et Zoophytes. Paris, 1832-5, 8vo, pp. 40. BovcHARD-CHANTEREAUX. Catalogue des Mollusques terrestres et fluvia- tiles observés jusqu’a ce jour a l'état vivant, dans le Département du Pas-de-Calais. Boulogne, 1837, 8vo, p. 142-230, with a plate (in Mém. Soc. d’ Agric. &c. de Boul.). Bovcwarp-CnanTerREAvx. “Ponte de l Ancylus fluviatilis. In Act. Soc. Linn. Bord. v. 1833, p. 210, pl. vi. BovcwaRrD-CHANTEREAUX. Observations sur les Hélices Saxicaves du Boulonnais. In Ann. des Sc. Nat. 4° Série, Zool. 1861, p. 197-218, with a plate. Boureurenat, J. R. Aménités malacologiques. In Guér. Rev. et Mag. Zool. 1853-1860, with plates. Boureuienat, J. R. Monographie des espéces Francaises du genre Sphe- rium. In Mém. Soc. Phys. Bord. 1854 (published separately at Bor- deaux, 8vo, pp. 56, with 4 plates). Boureurenat, J. R. Etude synonymique sur les Mollusques des Alpes maritimes publiés par A. Risso en 1826. Paris, 1861, 8vo, with a plate. Brarp, C. P. Histoire des Coquilles terrestres et fluviatiles qui vivent aux environs de Paris. Paris and Geneva, 1815, 12mo, with 10 co- loured plates. Brown, Tuos. Illustrations of the recent Conchology of Great Britain and Ireland. London, 1845, roy. 8vo, with plates. Brown, T. Description of several new British Shells. In Edinb. Journ. Nat. Hist. i. 1827. Bruauiére, J.G. Encyclopédie Méthodique, tome vi. (Hist. Nat. des Vers). Paris, 1789-1792. Brumati, Leonarpo (Abate). Catalogo sistematico delle Conchiglie ter- restri e fluviatili osservate nel territorio di Monfalcone. Goritz, 1838, 8vo, with a plate. CaituiauD, Fréeperic. Des Clausilies et de leur Clausilium. In Journ. Conch. Paris, iv. 1853, p. 419. CHARPENTIER, JEAN DE. Catalogue des Mollusques terrestres et fluviatiles de la Suisse. Neuchatel, 1837, 4to, pp. 28, with two plates. CHARPENTIER, J. DE.. Essai d’une Classification naturelle des Clausilies. In Journ. Conch. Paris, iii. 1852, p. 357. CHERRES, COLLARD DES. Catalogue des Testacés terrestres et fluviatiles des environs de Brest et de Quimper (Finistére). In Act. Soc. Linn. Bord. 1830, pp. 17 (published separately). CLARKE, Rev. B. J. On the Species of the Genus Limar occurring in Treland. In Ann. Nat. Hist. xii. 1843, p. 302. Cocks, W. P: Contributions to the Falmouth Fauna. 1845. Costa, Emanvet Menpezpa. Historia Naturalis Testaceorum Britannie. or the British Conchology (in English and French). London, 1778, 4to, with 17 coloured plates. LIST OF AUTHORS AND WORKS QUOTED. oee Coxe, WiuurAM. Travels in Switzerland. London, 1789, 3 vols. 8vo. (With an appendix to the third volume, by Studer, under the title of Faunula Helvetica.) oak. Grorces. Legons d’Anatomie Comparée. Paris, 1805, 5 vols. vo. Cuvier, G. (le Chevalier). Mémoires pour servir 4 |’Histoire et a l’ Anatomie des Mollusques. Paris, 1817, 4to. Draparnavp, J. P. R. Tableau des Mollusques terrestres et fluviatiles de la France. Montpellier, 1801, 8vo, pp. 116. Drararnavup, J. P. R. Histoire Naturelle des Mollusques terrestres et flu- viatiles de la France. Montpellier and Paris, 1805, 4to, with 13 plates. Drover, Henrt. Enumération des Mollusques terrestres et fluviatiles vivants de la France Continentale. Paris, 1854, 8vo. Drovet, H. Eléments de la Faune Acoréenne. 1861, 4to, pp. 245. Dumont et Mortinter. Catalogue critique et malacostatique des Mol- lusques de Savoie et du bassin du Léman. Ist part. Geneva, 1857, 8vo, pp. 104. Durvy, D. (l’Abbé). Essai sur les Mollusques terrestres et fluviatiles et leurs Coquilles vivantes et fossiles du Département du Gers. Auch and Paris, 1845, 8vo, pp. 140, with a plate. Duprvy, D. (Abbé). Histoire Naturelle des Mollusques terrestres et d’eau douce qui vivent en France. Paris, 1847-52, 4to, with 51 plates. Favure-Biever. Sur une nouvelle espece de Tes¢acelle. In Bull. Soe. Philom. Paris, 1802, p. 98, pl. v. ' Ferussac, J. B. L. p’AupEBARD Baron pr. Concordance Systématique pour les Mollusques terrestres et fluviatiles de la Grande Bretagne, avec un apercu des travaux modernes des Savants Anglais sur les Mollusques. In Journ. Phys. xc. 1820 (published separately in 4to, pp. 28). Fervssac (pére et fils). Histoire Naturelle générale et particuliére des Mollusques terrestres et fluviatiles, tant des espéces que l’on trouve aujourd’hui vivantes, que des dépouilles fossiles de celles qui n’existent plus; classés d’aprés les caractéres essentiels que présentent ces animaux et leurs coquilles. CEuvre posthume. Paris, 1819, 2 vols. folio, followed by Tables and a Prodromus, and 168 plates. Fiemine, Joun, D.D. A History of British Animals. Edinburgh, 1828. Forses, Epwarp. Malacologia Monensis: a Catalogue of the Mollusca inhabiting the Isle of Man and the neighbouring sea. Edinburgh, 1883, 8vo, pp. 63, with 3 plates. Forses and Hantzy. A History of British Mollusca and their Shells. London, 1853, 4 vols. 8vo, with 64 plates of animals and 152 plates of shells. GasparD, B. Mémoire physiologique sur le Colimagon (Helix pomatia). In Majendie, Journ. Physiol. ii. p. 295 (and an abstract of the above, with notes by Professor T. Bell, in Zool, Journ. i. 1824, p. 93; 11, 1824, hE). Glidéres ae Fiscuer. Monographie du genre Testacelle. Paris, 1856, 8vo, pp. 56, with 2 plates. ; Gerorrroy. Traité sommaire des Coquilles, tant fluviatiles que terrestres, qui se trouvent aux environs de Paris. Paris, 1767, 12mo. GerstreLpT, G. Ueber Land- und Siisswasser-Mollusken Sibiriens und des Amur-Gebietes. Petersburg, 1859, 4to, pp. 44, with a plate. O24 LIST OF AUTHORS AND WORKS QUOTED. Guein, J. F. Caroli a Linné Systema Nature. Leipzig, 1788, 10 vols. 8vo. Govtp, Augustus A. Report on the Invertebrata of Massachusetts. Cambridge (U.8.), 1841, 8vo, with 213 figures. Gras, AtBin. Description des Mollusques fluviatiles et terrestres de la France, et plus particuliérement du Département de l’Isére. Grenoble, 1846, 8vo, with 6 plates. GRATELOUP, DE, Le Dr. Distribution géographique de la famille des Limaciens. Bordeaux, 1855, 8vo, pp. 33. GRATELOUP, DE. Essai sur la Distribution géographique, orographique et statistique des Mollusques terrestres et fluviatiles vivants du Départe- ment de la Gironde. Bordeaux, 1858, 1859, 8vo, pp. 196. GrareLoup et Rautin. Catalogue des Mollusques terrestres et fluviatiles vivants et fossiles de la France continentale et insulaire, par ordre alphabétique. Bordeaux, 1855, 8vo, pp. 56. Gray, Joun Epwarp. New British Species of Mollusca. In London Medical Repository, xv. 1821, p. 239. Gray, J. E. Remarks on the Difficulty of distinguishing certain Genera of Testaceous Mollusca by their Shells alone, and on the anomalies in regard to habitation of certain species. In Philosophical Transactions, exxy. 1835, p. 301. Gray, J. E, A Manual of the Land and Freshwater Shells of the British Tslands (by William Turton, M.D.). Newedition. London, 1840, 8vo, with 12 plates. Gray, J. E, Description of a new species of Spherium found near London (in Ann. & Mag. Nat. Hist., June 1856, p. 465) ; and on a second new species of Spheriwm from the Paddington Canal (in Ann. & Mag. Nat, Hist., July 1856, p. 25). GuerrarD. Observations qui peuvent servir 4 former quelques caractéres de Coquillages. In Mém. Acad. Se. Paris, 1756, p. 145. Hartmann, J. D. W. von. System der Erd- und Fluss-Mollusken der Schweitz und des benachbarten Landes. In Steinmuller, Neue Alpina, Wintherthur, vii. Band i. 1821. 8vo, p. 194. Also in Sturm, Deutsch- lands Fauna, vi. 5 Heft. Nirnberg, 1821, 18mo, pp. 60, with 5 plates. Hep, F. Aufzahlung der in Bayern lebenden Mollusken. In Isis, 1856, p.271; and 1837, p. 304. Herrmannsen, A. N. Indicis generum Malacozoorum primordia, no- mina subgenerum, generum, familiarum, tribuum, ordinum, classium ; adjectis auctoribus, temporibus, locis, systematicis atque litterariis, etymis, synonymis. Cassel, 2 vols. 8vo, 1846-9; and Supplement and Corrigenda, 1852. Hoy, Tuomas. Account of a Spinning Limax or Slug. In Linn. Trans. i. 1790, p. 188. Hurron, Tuomas. On the Land-shells of India. In Journ. Asiat. Soc. Beng. iii. 1834, p. 81, 520. Jerrreys, Joun Gwyn. 2 ate 0 '& ghele © ‘ “ Ali * + i i : fg 44 : Fe a , a Ve ",? 2038 rom setocieadl idm INDEX to VOL. I. The synonyms, as well as the names of spurious species, and of species, genera, and other groups which are ndét described in this volume, are in italics.—The figures in smaller type refer to the page in which the descrip- tion of species, genera, and higher groups will be found. Acuatina, Lam., 149, 150, 287, 288, 289, 295, 296, 297, 302. acicula, Mill., 296, 297, 298, 307. dentiens, Rossm., 289. Acicula, Risso, 295, 307. Acicula, Hartm., 307. Acmea, Esch., 307. Acme, Hartm., 307. fusca, Beck, 309. lineata, Drap., 308. minuta, Brown, 309. Alasmodon, 31. Alea, Jeffr., 265. revoluta, Jeffr., 269. substriata, Jeffy., 261. Alasmodonta margaritifera, F. & H., 37. Ammonite, 78. Amphipeplea, 101, 104. Ainplexus, 174. Ancyuus, Geoffr., 71, 118. Capuloides, Jan, 120. deperditus, Ziegl. (& Dup.), 121. fluviatilis, Mill., 119, 120, 121, 122, 128. gibbosus, Bourg., 120. lacustris, Linn., 120, 122. oblongus, F. & H., 122, 123. spina-rosé, Drap., 123. Anoponts, Lam., 39. anatina, Linn., 43. Cellensis, C. Pfeiff., 43. complanata, Ziegl., 44. cygnea, Linn., 41. cygnea (part.), F. & H., 43. ponderosa, C. Pfeiff., 43. rostrata, Kok., 42. ventricosa, C. Pfeiff., 44. Aplexa, Flem., 98. Aplysia, 78. : | Assiminia Aquatic, 1. Arion, Fér., 126, 150, ater, Linn., 127, 128, 139. Empiricorum, Fér., 127. fasciatus, Nilss., 128. flavus, Fér., 127. hortensis, Fér., 128. Grayana, 65. Auricula, Klein, 5. Auricula, Lam., 299. | Auriculacea, Lam., 299. zeca, Leach, 289. Nouletiana, Drap., 291. tridens, F. & H., 290. | Balea, Leach, 272, 273. Balea, Prideaux, 271, 273. fragilis, F. & H., 278. Sarsii, Phil., 275. Batra, Prid., 149, 150, 271, 272. perversa, Linn., 273. Bithinia, Gray, 59. humilis, Boub., 638. Leachii, 61. tentaculata, 60. ventricosa, Gray, 62. BIVALVES, 1. Buceinum, 297. acicula, Miull., 289, 297. glabrum, Mill., 117. glutinosum, Mill., 102. palustre, Mill., 113. peregrum, Miill., 104. terrestre, Mont., 299. truncatulum, Mull., 115. Bulimi, 174, 282. Buumvs, Scopoh, 114, 149, 150, 231, 232, 241,.253, 276, 289, 291. acutus, Mill., 282, 233. 332 Buummus (continued). anatinus, Poir., 66. articulatus, Lam., 235. articulatus, Turt., 225. auris-Mide, 299. clavulus, Turt., 240. decollatus, 61, 240. Jibratus, 299. glans, Brug., 287. Guadaloupensis, Brug., 239. Lackhamensis, F. & H., 235. leucostoma, Poir., 118. lineatus, Drap., 308. Menkeanus, 292. montanus, Drap., 235, 239. INDEX. CLavsiLia (continued). Mortilleti, Dum., 282. nigricans, Mat. & Rack., 278. obtusa, C. Pfeiff., 280. papillaris, Drap., 287. parvula, Stud., 280. plicatula, Drap., 281, 282, 310. Rolphii, Gray, 236, 281, 282, 283, 284, 310. rugosa, Drap., 275, 278, 281, 282. rugulosa, Ziegl., 279. . similis, Charp., 284. solida, Drap., 286, 287. ventricosa, Drap., 284. vivipara, Held, 284. obscurus, Mill., 236, 237,289,248. | Clausilie, 276, 278. octonus, Brug., 289. quadridens, 289. tridens, 289, 292. tuberculatus, Turt., 239. ventricosus, Drap., 232, 234. Bulin, Adans., 5,231. Bulla fluviatilis, Turt., 99. fontinalis, Linn., 98. hypnorum, Linn., 96, 97. rivalis, Mat. & Rack., 100. Bythinella, Moq.-Tand., 63. Bytuinta, §9, 304. Leachii, Shepp., 61. tentaculata, Linn., 60. Cecilianella, Bourg., 295, 296. Anglica, Bourg., 295. Lnesvillei, Bourg., 296. Cecilioides, Beck, 295, 296. Cardium Casertanum, Poli, 24. Carocolla, 174. Carycuip.2, 124, 299, 300. Carycuium, Miill., 299, 300. minimum, Miill., 269, 300, 302. Chilotrema, 174. Cionella, Jeffr., 288, 289. Cocuutcopa, Risso, 149, 150, 287, 288, 289, 297, 302. lubrica, Miill., 289, 292, 294, 295, 297. tridens, Pult., 289, 290, 294. CONCHIFERA, 1. Conovulus, Lam., 5d, 76, 299, 302. Corbicula, 3. Crepidula, 45, Cyclas, Drap. caliculata, Drap., 10. cornea, F. & H., 5. flavescens, Macg., 6. fontinalis, Drap., 20. fontinalis, Nilss., 25. lenticularis, Norm., 22. nucleus, Stud., 6. ovalis, Fér., 8. rhomboidea, Say, 10. rivalis, Dup., 6. rivalis, Drap., 7. rivicola, Leach, 7. Ryckholtii, Norm., 11. Scaldiana, Norm., 6. solida, Norm., 3. CycLosToMA, 303, 304. acutum, Drap., 68. anatinum, Drap., 59, 63, 510. CravsiiA, Drap., 149, 150, 272, 275, contectum, Millet, 56. 276, 277, 287, 289, 291, 292. bidens, Drap., 286. biplicata, Mont., 283, 285, 286. derugata, Fér., 286. dubia, Drap., 279, 282. Everetti, Mill., 279. labiata, 286. laminata, Mont., 284, 286. lineolata, Held, 284. elegans, Miull., 304, 506, 307. ferrugineum, Lam., 307. impurum, Drap., 61. marmorea, Brown, 307. simile, Drap., 62, 64, 310. sulcatum, 303. vitreum, Drap., 68. CyYCLOSTOMATID&, 302. Cyclostome, Lam., 304. Cyrena, 3. fluminalis, 3. Cyrenastrum, Bourg., 3. Delphinula, Lam., 304. DretssenA, Van Bened., 46. polymorpha, Pall., 47. DREISSENID, 45. Elisma, Leach, 282. Hulima stenostoma, 296. GASTEROPODA, 51, 304. Gromaacus, Allm., 129. maculosus, Allm., 129. Glandina, Schum., 287, 297. Gulnaria lacustris, Leach, 105. Helices, 173, 174, 218, 282. Heticipa, 124, 149. Meiix, Linn., -149, 150, 158;- 172, 174, 232, 248, 246, 253, 269, 288, 289. ~ aculeata, Mull., 176. acuta, Miull., 233. albella, Linn., 229. albella, Flem., 229. alliaria, Mill., 161. Altenana, Kickx, 195. aperta, Born, 184, 185. arbustorum, Linn., 186, 188, 190. aspersa, Mull., 178, 181, 182, 184, 185. auricularia, Linn., 108. bidens, Chemn., 172. bidens, Mill., 286. bidens, Linn., 287. Bulimoides, Moq.-Tand., 232. célata, Stud., 196. candidula, Stad., 211. Cantiana, Mont., 190, 193, 194, 209. caperata, Mont., 213, 215. Carthusiana, Drap., 191. Carthusiana, F. & H., 192. Carthusianella, Drap., 194. Cartusiana, Miull., 191, 192, 231. cellaria, Mill., 159. cespitum, Drap., 218. chersina, Say, 171. cingenda, Mont. 209. INDEX. | HeEwrx (continued). circinnata, Stud., 196. clandestina, Hartm., 196. clara, Held, 169. cochlea, Brown, 92. complanata, Linn., 91, 92. concinna, Jeffr., 196, 198. conica, Drap., 282. conspurcata, Drap., 215. contorta, Linn., 94. cornea, Linn., 93. Corvus, Gmel., 114. costata, Miull., 225. crenella, Mont., 225. depilata, C. Pfeiff., 198. Draparnaudi, Shepp., 84. edentula, Drap., 172. electrina, Gould, 165. elegans, Drap., 216. ericetorum, Miull., 216. ericetorum, Nilss., 217. excavata, Bean, 168. explanata, Mull., 229. fasciolata, Poir., 215. fossaria, Mont., 117. fragilis, Mont., 111. fruticum, Mill., 174. fulva, Mill., 171, 172. fusca, Mont., 204, 205. fusca, Poir., 206. Gibbsiz, Leach, 194. Gigaxit, Charp., 214. glabella, Drap., 196, 310. glabra, Stud., 162. glaphyra, Say, 160. globularis, Jetfy., 202. Goodallii, Mill., 239. granulata, Ald., 202. grisea, Linn., 184. Hammonis, Strom, 165. Helmii, Gilb., 163, 164. 202, 310. hortensis, Penn., 184. hortensis, Miull., 186, 187. hybrida, Poir., 186. instabilis, Ziegl., 217. intersecta, Poir., 215. Itala, Linn., 218. Kirbii, Shepp., 224. Lackhamensis, Mont., 286. lamellata, Jeffr., 175, 2405. 333 hispida, Linn., 196, 197, 198, 200, incarnata, Mill., 174, 202, 206. 334: Hetix (continued). lapicida, Linn., 227. limbata, Drap., 192. limosa, Linn., 108. lineata, Walk., 79. lineata, Olivi, 211, 213. lubrica, Mill., 288, 289, 292. lucida, Pult., 161. lucida, Drap., 161. lucorum, 178. lutea, Mont., 105. maritima, Drap., 211. minuta, Stud., 224. montana, Stud., 196. Morton, Jetir., 171. muscorum, Linn., 248, 249, 251. muscorum, Mont., 248. muscorum, Mill., 252. Naticoides, Drap., 185. neglecta, Drap., 211. nemoralis, Linn., 151, 185, 187, 207. Nilssoniana, Beck, 217. nitens, Gmel., 164. nitens, Mat. & Rack., 164. nitens, Mich., 163, 164. nitida, Drap., 161. nitida, Miull., 167. nitidosa, Fér., 167. nitidula, Drap., 163, 164, 167, 310. obliterata, Hartm., 217. obscura, Miull., 237. obvoluta, Miull., 229, 280, 231, 236, 289. occidentalis, Récl., 204. octanfracta, Mont., 118. octona, Linn., 68, 299. octona, Penn., 299. pallida, Don., 191. paludosa, Da Costa, 227. perversa, Mull., 280. petronella, Charp., 169. picea, Ziegl., 189. Pisana, Mill., 207, 215. planorbis, Linn., 91. plebeium, Drap., 200, 310. pomatia, Linn., 177, 178, 182. Ponentina, Mor., 204. pulchella, Mill., 224, 227. pupa, Linn., 239. pura, Ald., 164. putris, Linn., 151. INDEX. Hewix (continued). pygma, Drap., 223, 310. radiata, Da Costa, 220. radiatula, Ald., 166, 169. revelata, Mich., 202, 204, 206, 207, 310. revelata, Fér.; 202, 204. revelata, Bouch.-Ch., 204, 206. rhodostoma, Drap., 209. rhombea, Turt., 91. rotundata, Miull., 218, 229. rotundata, Turt., 220. ruderata, Stud., 174. rufescens, Penn., 191, 194, 195,196, 197, 198, 2380, 310. rufescens, Gmel., 196. rufescens, Grateloup, 196. rufilabris, Jetfr., 193. rupestris, Stud., 220, 223, 224. Scarburgensis, Ald., 175. seminuluim, Rossm., 175. sericea, Mull., 198, 201, 202, 204. sericea, Ald., 199. sericea, Drap., 204, 310. sericea, Phil., 200. Somershamiensis, Shepp., 229. spinulosa, Mont., 176. spirorbis, Linn., 84. stagnalis, Linn., 111. striata, Mull., 215. striata, Drap., 215. striatula, Linn., 167, 215. striatula, Mull., 167, 215. striatula, Olivi, 167. striatula, Gray, 167. subcylindrica, Linn., 295. submaritima, Rossm., 211. tentaculata, Linn., 60. terebra, Turt., 92. terrestris, Penn., 215. Trochiformis, Mont., 172. Trochilus, Mull., 239. Turtoni, Flem., 219. umbilicata, Mont., 220, 222. umbrosa, Partsch, 198. unifasciata, Poir., 211. variabilis, Drap., 213. ventricosa, Miill., 243. virgata, Da Costa, 210, 211, 212, 2138, 214, 215, 218, 234. viridula, Menke, 168, 169. witrina, Fér., 168, 169. Henix (continued). vitrina, Wagn., 169. vivipara, Linn., 57, 58. vortex, Linn., 88. zonaria, Penn., 209. Hyprosia, Hartm., 63, 304. Ferussina, 69. marginata, Mich., 64, 69. similis, Drap., 64, 310. ulve, 67, 310. ventrosa, Mont., 66. Kelidide, 2: LAMELLIBRANCHIATA, 1. Limacella, Brard, 132. concava, Brard, 134. obliqua, Brard, 136. parma, Brard, 139. unguiculus, Brard, 133. Limacipe, 124, 125. Liiax, Linn., 130. agrestis, Linn., 134, 135, 139. anguiformis, Mor., 129, 130. antiquorum, Fér., 139. arboreus, F. & H., 135. arborum, Bouch.-Ch., 133, 1365, 138. ater, Linn., 127, 182. brunneus, Drap., 139. brunneus, Bouch.-Ch., 159. carinatus, Risso (& Leach), 183. cinctus, Mull., 129. cinereo-niger, Nilss., 138. cinereus, Mill., 137, 138. filans, Hoy, 136. flavus, Linn., 133, 1490. flavus, Mull., 127, 134. fuscus, Miull., 129. gagates, Drap., 131, 153, 145. Livonicus, Schrenck, 136. marginatus, Miull., 132. maximus, Linn., 137, 138. parvulus, Norm., 189. Sowerbii, Fér., 132, 135. tenellus, F. & H., 189. tenellus, Mill., 140. variegatus, Drap., 134. Limnaa, Brug., 1o1. auricularia, Linn., 108, 109, 110, | 115; Burnetti, Ald., 108, 104. cornea, 115. INDEX. 335 Linn&a (continued). glabra, Miull., 112, 117, 299. glutinosa, Mull., 102, 108. involuta, Thomps., 103. palustris, Mull., 108,113. peregra, Miull., 104, 107, 111, 112, 117, 119: stagnalis, Linn., 111, 112, 118. truncatula, Mull, 114, 115. 119. LIMN#IDA, 77, 300. Limneus auricularius, F. & H., 108. Burnetti, F. & H., 104. glaber, F. & H., 117. glutinosus, F. & F., 102. anvolutus, KF. & H., 108. lineatus, Bean, 106. palustris, KF. & H., 118. pereger, BF. & H., 104. stagnalis, F. & H., 111. truncatulus, F. & H., 115. Limnea intermedia, Fér., 105, 107. Limneus acutus, Jeffr., 109. elongatus, Drap., 118. minutus, Drap., 117. ovatus, Drap., 105, 106. tinctus, Jeffr., 114. Lithoglyphus Naticoides, Fér., 70. Lntiopa bombyx, 68. Intea, 101. Lymnea, Brug., 101. Mangelia nivalis, 296. | Margarita, 71. Margaritana, 31. Melampus, Montf., 55, 76, 299, 306 Murex, 300. Mya margaritifera, Linn., 37. ovalis, Mont., 33 pictorum, Linn., 34. Mysca Batava, Turt., 37. _ Mytilide, 29, 46. Mytilus, 29, 46. anatinus, Linn., 403. 336 Mytilus (continued). avonensis, Mont., 40, 45. eygneus, Linn., 41. dentatus, Turt., 42. incrassatus, Shepp., 42. paludosus, Turt., 42. polymorphus, Pall., 47. radiatus, Miull., 42. stagnalis, Ginel., 42. Zellensis, Gmel., 42. Myzas, 101. Natica Kingiti, F. & H., 70. Nautilus, 80. lacustris, Lightf., 81. Nerita, 53, 638. elegans, Mill., 304. fasciata, Mill., 57. fluviatilis, Linn., 53. obtusa, Stud., 74. piscinalis, Mull., 72. NERITIDA, 52. Neritina, Lam., 52, 63. Betica, Lam., 54. fluviatilis, Linn., 53. Neritostoma, Klein, 5. Onchidium Celticum, 300. Otina, 76, 299. Paludestrina, D’ Orb., 64. Pautvupina, Lam., 55, 304. anatina, 62. contecta, Millet, 56. diaphana, Mich., 68. Listeri,F. & H., 56. marginata, Mich., 69. meridionalis, Risso, 65. muriatica, Lam., 68. similis, 62. ventricosa, Menke, 60. viridis, 62. vivipara, Linn., 58. Paludinella, Pfeiff. & Lov., 64. PALUDINIDA, 55. Parmacella, 141. Patella, 119, 308. fluviatilis, List., 121. lacustris, Linn., 121, 122, 123. PECTINIBRANCHIATA, 51. Pedipes, Adans., 306. INDEX. Puysa, Lam., 95. acuta, Drap., 98, 100. alba, Turt., 100. contorta, Mich., 100. elongata, Say, 97. fontinalis, Linn., 98, 99. hypnorum, Linn., 96. Sowerbyana, D’Orb., 100. subopaca, Lam., 100. Pinna fluviatilis, Sander, 49. Pisrpium, C. Pfeiff., 16. amnicum, Mill., 20. arceforme, Malm, 28. australe, Phil., 22. cinereum, Ald., 21. conicum, 4. fontinale, Drap., 20. Henslowianum, Jen., 20, 21. nitidum, Jen., 25. obtusale, C. Pfeitf., 24. pallidum, Gass., 22. pulchellum, Jen., 21. pusillum, Gmel., 23. Recluzianum, Bourg., 4. roseum, Scholtz, 26. sinuatum, Bourg., 26. tetragonum, Norm., 28. ventricosum, Prime, 24. PLANoRBIS, Guett., 78, 228. albus, Miill., 83, 85, 86. carinatus, Miull., 89, 92. complanatus, Linn., 91. compressus, Mich., 89, 90. contortus, Linn., 94. corneus, Linn., 93. cristatus, Drap., 82. disciformis, Jeffr., 90. Draparnaldi, Jeffr., 84. glaber, Jeffr., 85, 88. gyrorbis, v. Seck., 86. intermedius, Charp., 93. lacustris, F. & H., 79. levis, Ald., 86. leucostoma, Mich., 88, 151. lineatus, Walk., 79, 82. lutescens, Jeffr., 90. marginatus, Drap., 84, 91, 92. Nautileus, Linn., 82. . nitidus, Mill., 80, 81. Rossmiissleri, Auersw., 86. rotundatus, Poir., 88. similis, Miull., 94. INDEX. PLANORBIS (continued). spirorbis, Miill., 87, 89, 93. spirorbis, Moq.-Tand., 87. spirorbis, Drap., 84. submarginatus, Crist. & Jan, 93. turgidus, Jeftr., 93. turritus, Miull., 98. umbilicatus, Mill., 92. vortex, Linn., 38, 90, 93. PNEUMONOBRANCHS, 76. Polyphemus, Montf., 287, 288. PULMOBRANCHS, 76. PULMONATES, 76. PULMONIFERS, 76. PULMONOBRANCHIATA, 76. PULMONOBRANCHS, 76. Pura, Lam., 149, 150, 240, 241, 243, 251, 252, 258, 264, 272, 276, 279. Anglica, F. & H., 244. Anglica, Moq.-Tand., 257. antivertigo, Drap., 253. arctica, v. Wall., 257. - avena, 248. avenacea, 243. bigranata, Rossm., 250. borealis, Mor., 261. Callicratis, Scacchi, 271. Charpentieri, Shuttl., 257. columella, v. Mart., 269. costulata, Nilss., 271. cylindracea, Da Costa, 249. Desmoulinsiana, Jeffr., 257. doliolum, 241. edentula, Drap., 268. fragilis, Drap., 275. énornata, Mich., 269. marginata, Drap., 241, 248, 249, 252, 253. milium, Gould, 262. minuta, Stud., 271. minutissima, Hartm., 251, 270. Moulinsiana, Dup., 255. muscorum, F. & H., 249. muscorum, Drap., 271. obtusa, Flem., 271. ovata, Say, 255. pusilla, Biv., 254. pusilla, F. & H., 263. pygmea, Drap., 257. ae Jeffr., 241, 244, 246, 248, D1. ringens, Mich., 246. 337 Pupa (continued). rugosa, Drap., 310. secale, Drap., 238, 241, 242, 246. Sempronit, Charp., 248. Shuttleworthiana, Charp., 261. substriata, F. & H., 26]. tridens, 241. triplicata, Stud., 271. umbilicata, Drap., 222, 241, 245, 246, 248, 251, 252. Venetzit, F. & H., 265. Pupe, 240, 255. Pupula, Agass., 308. Rissoa anatina, F. & H., 64. castanea, Jeffr., 69. ventrosa, F. & H., 66. Rissoe, 68. Scalaria, Lam., 304. Segmentina, Flem., 80. Solarium, 220. SPHARIID®, I. SpH2£RivuM, Scop., 4. Brochonianum, Bourg., 11. citrinum, Norm., 6. corneum, Linn., 5. lacustre, Mill., 10. ovale, Fér., 8. pallidum, Gray, 8. Pisidioides, Gray, 6. rivicola, Leach, 7. Stagnicola elegans, Leach, 112. Styloides, Fér., 288. Succinea, Drap., 149, 150, 156. abbreviata, Mor., 155. arenaria, Bouch.-Ch., 155. elegans, Risso, 153, 154. gracilis, Ald., 154. oblonga, Drap., 153, 154, 150. Pfeiferi, Rossm., 154. putris, Linn., 150, 151, 153, 154. Tellina amnica, Mill., 20. cornea, Linn., 95. Henslowana, Shepp., 21. lacustris, Mill., 10. pusilla, Gmel., 22, 23. rivalis, Miull., 7. Teredo, 49, 229, 276. 008 Terrestrial, 124. TESTACELLA, Cuv., 140 é¢ seq. Alte-ripe, 147. Deshayesti, 147. Europea, De Roissy, 147. Haliotidea, Drap., 145, 147. Maugei, Fér., 144, 147, 148. Medii-Templi, Tapp., 146. scutulum, Sow:, 145, 147. Testacelle, 144, 156. TrsTACELLIDA, 124, 140, 149. Testacellus, Faure-Big., 141. Theba, Risso, 209. Tichogonia fluviatilis, Erichs., 46. Trochus, 71. . perspectivus, 220. sylvaticus, List., 248. Truncatella, 304. Turbo bidens, Mont., 280. biplicatus, Mont., 283. chrysalis, Turt., 252. fasciatus, Penn., 235. glaber, Da Costa, 295. Helicinus, Lightf., 227. juniperi, Mont., 243. laminatus, Mont., 284. Leachit, Shepp., 61. Nautileus, Linn., 82. nigricans, Mat. & Rack., 280. Offtonensis, Shepp., 269. perversus, Linn., 273. seadentatus, Mont., 255, 259. stagnorum, Baster, 68. : thermalis, Gmel., 68. tridens, Pult., 289, 290. ulve, Penn., 66. ventrosus, Mont., 66. vertigo, Mont., 267. Turtonia minuta, 4. Unto, Philipps., 31. amnicus, Ziegl., 37. Batavus, 31. curvirostris, Norm., 39. littoralis, 31. margaritifer, Linn., 37. margaritiferus, F.& H., 37. nand, Lam., 37. nanus, Dup., 37. Philippi, Dup., 36. INDEX. | | Unio (continued). pictorum, Linn., 34. rhomboideus, 31. Roissyi, Mich., 38. sinuata, Lam., 38. tumidus, Philipps., 32 Unionipa&, 28. UNIVALVES, 51. . Vallonia, 174. Vatvata, Mill., 72. antiqua, Morr., 73. cristata, Mull., 74. depressa, C. Pfeiff., 72. minuta, Drap., 75. piscinalis, Mull, 72. planorbis, Drap., 75. spirorbis, Drap., 75. VALVATID&, 70. Vertico, Miull., 149, 150, 251, 252, 253, 256, 260, 264, 272, 289. alpestris, Ald., 258, 259. alpestris, Fér., 261. Anglica, Fér., 246. angustior, Jeffr., 265. antivertigo, Drap., 253, 256, 257, 259, 264. curta, Held, 262. cylindrica, Fér., 271. edentula, Drap., 264, 268, 270. hamata, Held, 267. heterostropha, Leach, 264. minutissima, Hartm., 270. Moulinsiana, Dup., 255, 257, 258, 259. nana, Mich., 267. nitida, Fér., 269. octodentata, Stud., 255. palustris, Leach, 255. plicata, A. Mill., 267. pusilla, Miull., 252, 253, 263, 266, 267, 268. pygmea, Drap., 252, 255, 256, 257, 259, 260, 261. rupestris, 255. septemdentata, Fér., 255. substriata, Jeffr., 255, 261, 264. Venetzii, Rossm., 567. Vitrina, Drap., 150, 155, 159. depressa, Jeffr., 157. diaphana, Drap., 156, 158. Dillwynii, Jeffr., 157. Draparnaldi, Cuy., 157. INDEX. ViTRINA (continued). Draparnaldi, Setfy., 157. major, Fér., 157. pellucida, Miill., 156, 158. semilimax, Fér., 141. Vitrine, 143, 158. Zonites, De Montf., 143, 150, 156, 158, 160, 220. alliarius, Mill., 161, 162, 168. cellarius, Mill., 159, 160, 161, 162, 164, 230. erystallinus, Mull., 170. 339 ZONITES (continued). excavatus, Bean, 168, 169. fulvus, Mull, 171. glaber, 162. nitidulus, Drap., 163, 165. nitidus, Mull., 165, 165, 167, 170. purus, Ald., 164, 166, 169, 310. radiatulus, Ald., 166, 168, 310. Zospeum, Bourg., 296. Zua, Leach, 289. lubrica, F. & H., 292. Zurama, 174. EXPLANATION OF PLATES. ea ee FRONTISPIECE. Unio margaritifer, and pearl. PLats I. Figure 1. Spherium rivicola, showing the double tube and foot. 2. Hinge of the shell. 8. Pisidium amnicum, showing the single tube and foot. 4, Hinge of the shell. 5. Unio pictorum, showing both orifices and the foot. 6. Hinge of the shell. PuatTE II, Figure 1. Anodonta anatina, showing both orifices and the foot. 2. Hinge of the shell. 3. Dreissena polymorpha, showing the two orifices and tubes in an inverted position and the byssus attached to the fragment of a valve of an Anatina. 4. Shell. 5. Inside of hinge. PuatTeE ITI. Figure 1. Neritina fluviatilis, showing the snout, tentacles, position of the eyes, and the foot. 2. Shell. 3, 4. Operculum. 5. Paludina vivipara. 6. Shell, showing the operculum in situ. 7. Bythinia tentaculata. 8. Shell, showing the operculum in situ. 9, Back view of shell. 10. Hydrobia similis. 11. Shell, showing the operculum im situ. 12. Natural size. 13. Valvata cristata, showing the branchial plume and fila- ment. 14, Shell of V. piscinalis. 15. Operculum of same. PuateE IV. Figure 1. Planorbis corneus, showing the body and attachment of the foot. 2, 3. Shell. 4,5. Physa fontinalis, showing the digitated lobes of the mantle. 6, 7. Shell. 8. Limnea peregra, showing the respiratory opening to the right. 9, 10. Shell of i. shitpia eae oT 11, 12. Ancylus fluviatilis, showing the front and under side. 13, 14. Shell. EXPLANATION OF PLATES. 341 PuaTe V. Figure 1. Arion ater, showing the tentacles, eyes, shield, position of the respiratory opening, and slime-gland at the tail. 2. Same at rest. 3. Geomalacus maculosus (from Brit. Moll. pl. F. F, F*. f. 5). 4, Limax maximus, showing the position of the respiratory opening. 5. Shell or Limacella. 6. Testacella Haliotidea, showing the labial palps (below the tentacles) and the position of the shell. 7. Shell. 8. Ege. PLatTE VI. Figure 1, Succinea putris. 2. Shell. 3. Vitrina pellucida. 4. Shell. 5. Zonites cellarius. 6. Shell. 7. Helix aspersa. 8. Shell. Puate VII. Figure 1. Bulimus acutus. 2. Shell of var. inflata. 3. Pupa umlilicata. 4. Shell. 5, Natural size. 6. Vertigo pygmea, showing the two tentacles. 7. Shell. 8. Natural size. 9. Bala perversa. 10, Shell. 11. Natural size. 12. Clausilia laminata. 13. Shell. 14. Clausilium. 15. Cochlicopa lubrica. 16. Shell. 17. Natural size. 18. Achatina acicula. 19. Head and tentacles. 20. Shell. 21. Natural size. PuatsE VIII. Figure 1. Carychium minimum, showing the position of the eyes. 2. Shell. 3. Natural size. 4, Cyclostoma elegans, showing the snout and position of the eyes. 5, Shell. 6. Operculum. 7. Acme lineata, showing the position of the tentacles and eyes. 8,9. Shell. 10. Natural size. 11. Operculum magnified. THE END. 3 aecun i aah SiS tat ntonee solani -— é pot odd Io.moltizog odt aaitrode vain ensanh Boe +0 Le s sole i | ee ee Leal 1 4 vs ee 1. Fister “Hyer ™ , by heise ‘ ry i ; | ) fair : % Hinge ot a a i oats surat 3 i: i ; : BES, ee ii nai eit te ifr gl res bea sale Bas see , f) q At ot hes’ 3 ate win DoT toh gacr5 ‘ae? eat a &. sa nee | ani td Ss cet | ae a 4 : 4 + tny To Tsde | 2 astan sneha Jf ae pia Ey lap Be ss tag anole Ri) font. oye Aisle Oe el a i Hasli AL es 8880 piiadote BL. ; Pays heeotis teh) Losie loraal Bower r alain nds oy " pa . Pisnm & Ree 3, Bas we the ic ef c eae oo, ey Oh the See ghee Pure A 3 coils eS sil is uae 64 | sie ; : . < BAe stl m ‘ fas : Be a8 \o ated dla 4 ; Mh ia Se had diet by ye _ ; TeAih aa Lee ae *- =A » + ’ “bipee Ws. DGarm., We a creat trah MAP es . 7 7 tl if ate, oe4 rare 2 Pinar hs. perirvs - ahr aie, he bs bay: aad, wtteluiyen te ‘ “Sehe iu a “4 iF “RRs |S 5 a S i Ais Physa fittiess , we bivwing de, ig aie Anliow.: ur al "Sitti Fy ee THT a 8, SAnieee i ie: own uf fae papirttes orp xe to the fy gli, Mp hi 1 of 2. eerie + ON ; thy is Air sesh Ruts Hos » Blow kage hee thet ror ais. 13). Shval. Pian big a Plate I u a Lv) Ns ~, SS) NS, NS ~ ~ Me, “¢ ~™ 1.2. Spherium de! Lh Coa the eae * peta SE rh a ee | , 2) ID. Plat e I-45) Dreitssena LHOAOnNTA. wok o> Pee” 11, LE LZ /-7. Nerrtina 5.6.faliudiwne 7-2 Brythinia lO0-~12?. [1 vdrobia 15215. Valvata Dy tha He ee ef Planorbts. Pf FA9'. Lhvsa Hl=/4 Inevlias. 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