Sree Oe a ern pee ee Te cent ne ney nae eeees eS ——— Smeg rm et ear tne oer e eens conn nat see a re - ae > 4 . he > ~ - " : . ian tn ee gh tee tee Then pao : ~~ 2 toe a a ae = es ae rit, _ 4 : oe - 5 = 4 + — ————- rs ~~ Paw) —T n en - te ey a Ay Me y ainda —— ond ee a ce on~! te ail ne ee ee ae ee eS ee hele igs HARVARD UNIVERSITY LIBRARY OF THE MUSEUM OF COMPARATIVE ZOOLOGY Pea. Prey ; K-. Ne AC tt hie _ - a 4 - \ le Be 8m a ow, se ee FY, ee 4 Salk t “ ~~ il 3S ee . Aw of oe p' ‘ ny ag OH 4. « Vii nd yl. yrs UCANMMA, OS £1111 pate latilies ferip lies. Ur tl vig yy, Th. L fan’ ford. CONCHOLOGICAL MANUAL. BY G. B. SOWERBY, Jun. ILLUSTRATED BY UPWARDS OF SIX HUNDRED AND SIXTY FIGURES SECOND EDITION. CONSIDERABLY ENLARGED AND IMPROVED. LONDON: HENRY G. BOHN, YORK STREET, COVENT GARDEN. yy MDCCCXLII. ‘ : iy ie ME {hy a 7 Yadidasssss ey Veiie) \ A | re WATE BUHEE Ce . i 4 i if ‘ & 3 4 . ’ ; at - ; cS aE 0 ' bi we Yee *e ; 7YOOes / ae sue "e rie. teateivgs een if “ A gi r fata! ae a gy ; ba ei “a Ast Ptah as “< Ay ee, RES CYT OH mane eid A ; . Patti edie PREFACE TO THE FIRST EDITION. Iv may be necessary in introducing this little volume, to state, that it is strictly conchological, and that it is compiled for the use not only of those who wish to acquire an elementary acquaintance with the subject, but also of authors and others, who, desirous of extending their knowledge and pursuing their researches, require a book of reference, containing a general outline of what has been done by those who have trodden the same path before them. It has been thought advisable, for general convenience, to arrange the principal part of the information in alphabetical order; adding tables of the sys- tems of Lamarck and De Blainville, to facilitate the systematic pursuit of the science. Persons of the class first alluded to, will find great assistance in the explanation of technical words, their application being further illustrated, in most cases, by a reference to the figures; and, although they might have been multiplied, it is trusted that enough are given for every useful purpose. The definition of the Classes, Orders, Families, and Genera, in the system of De Blainville, and a tabular view, are pre- sented for the use of those who prefer it, or who wish to com- pare it with that of Lamarck. In the explanation of the figures, will be found a systematic arrangement of shells, according to Lamarck, including the names of genera established or proposed since the publication of his system. The descriptions of established genera have 1V PREFACE. been rendered as concise and clear as possible. It is hoped that no essential characters are omitted, and that those living authors, whose proposed generic distinctions have been passed over in a few words, will not have to complain of want of justice in the attempt to interpret their meaning. In most cases the generic name will be found accompanied by its derivation. This has been done, in the hope of assisting the memory by associating the meaning of a term with some peculiarity in the thing described. At the end of each de- scription of a genus, some general observations occur, pointing out the principal character which distinguishes it from others, to which it is nearly allied; and also stating the geographical or geological distribution and habits of the animal. The above descriptions and definitions are illustrated by a series of plates, containing above 500 etchings of nearly as many proposed or established genera, arranged in Lamarckian order, so as to show at a glance all the generic forms of each family. And, although from their number, they could not be very highly finished, it is hoped that they will be found cha- racteristic. The compiler cannot replace his pen without acknowledging, with filial gratitude, the kind assistance of one who has sacri- ficed much of his time in bringing his knowledge and expe- rience to bear upon the correctness and utility of this humble attempt to remove some of the difficulties to which the com- mencement of this, as well as of every other study, is exposed. PREFACE TO THE SECOND EDITION. Tue favourable reception and rapid sale of the first edition of the Conchological Manual having rendered a second neces- sary, the Author takes this opportunity of explaining the nature of the alterations which have been made. In doing this, he has to thank his friends for their suggestions, which, together with his own increased knowledge and experience, enable him to present a more complete and satisfactory work to the scientific public. For the further convenience of those who are studying the rudiments of the science, an entirely new Introduction is given, in which, commencing with the structure and gradual developement of the shell, the author has endeavoured to explain the general principles of Conchology in systematical order. This Introduction is illustrated by 100 wood-cuts, which will be found greatly to assist the Student. The definitions have been rendered more full and complete than before, and the Author has profited by some manuscript notes communicated by a scientific friend, to whom he desires to present his humble acknowledgments. Upwards of four hundred explanations have been given of words which did not appear in the former edition, three-fourths of which are of generic and subgeneric names. A large number of notes, referring to the geographical distribution of the genera, have been added from the pen of Mr. G. B. Sowerby, Senior. vi PREFACK. The plates have been carefully improved ; and three, containing upwards of eighty figures, have been added. On the whole, it will be found that the amount of matter has been nearly doubled; all the defects, as far as they have been discovered, have been removed, and every means used of making the present edition as useful as possible. NAMES OF AUTHORS ABBREVIATED. Adans. Adanson. Author of “ Voyages du Senegal.” Bl. Blainville. Author of “ Manuel de Malacologie et de Conchyliologie,” &c. Brod. W.4J. Broderip, Esq. Author of various descriptions of Shells in the Zoological Journal, &c. Brongn. Brongniart. Author of ‘‘ Memoire sur les terrains du Vicentin, d’Italie, de France, et d’ Allemagne,” &c. Brug. Brugiére. Author of “ Dictionaire des Vers testacés, dans l’Encyclo- pédie,” &c. Cuv. The late Baron Cuvier. Author of ‘‘ Regne Animal,” &c. Defr. Defrance. Contributor to the ‘‘ Annales des Sciences Naturelles,” &c. Desh. Deshayes. Author of “ Coquilles fossiles des environs de Paris,” &c. D’Orb. D’Alcide D’Orbigny. Drap. Dyaparnaud. Author of “ Histoire Naturelle des Mollusques terrestres et fluviatiles de la France,” &c. Fer. De Ferussac. Author of ‘ Histoire Naturelle des Mollusques terrestres et fluviatiles,” &e. Flem. Fleming. Gmel. Gmelin. Author of an edition of Linneeus’s “‘ Systema Nature,” &c. Guild. Rev. Lansdown Guilding. Hiibn. Hubner. Humph. The late George Humphrey. © Lam. Lamarck, Author of “ Animaux sans Vertebres,” &c. Lin. Linneus. Author of “ Systema Nature,” &ce. Mont. Montague. Author of “‘ Testacea Britannica,” &c. Montf. Montfort. Author of “ Histoire Naturelle des Mollusques,” &c. Mill. Miller. Author of ‘ Vermium terrestrium et fluviatilum,” ‘‘ Zoologize Danice,” &e. Ranz. Ranzani. Author of ‘‘ Considerations sur les Balanes,” &e. Schum. Schumacher. Sow. Sowerby. The late James. Author of ‘Mineral Conchology,” &c. George Brettingham, Senr., ‘‘ Genera of Shells,” ‘‘ Species Conchyliorum,”’ &e. G.B.Jun.“ Conchological Manual,” ‘ Conchological Illustrations,” “ Thesaurus Conchyliorum,” Descriptions of New Shells in the Zoological Proceedings, &c. Sw. Swainson. Author of “ Zoological Illustrations,” ‘“ Exotic Conchology,” “ Lardner’s Cabinet Cyclopedia,” &c. > Turt. Turton. Author of ‘“ British Shells.” a FS A ae ett Prat Bae v “eae avin 4 i Hagel Bo sR t gt REP nea of ig iw ea i * acoisieinanis uohale ie aan ae ine alge . Ss eagl i bien Pee wit 3 vate * » elt a INTRODUCTION. Tue Science of Conchology affords a very delightful and in- structive amusement for the leisure hours of those who, retiring occasionally from the gaieties of fashionable life, seek pleasure in the quiet contemplation of some of the smaller, but not less wonderful operations of creative wisdom. And, although the study of shells would be more complete, and rank higher in the scale of philosophical pursuits, were it always accompanied by that of the animal inhabiting them, it nevertheless presents means of intellectual gratification, to many who cannot follow it beyond the cabinet and the boudoir. These may examine with admiration and mental improvement, the beautiful colouring and architecture of these wonders of the deep, they may exercise their taste and judgment in the selection and arrangement of specimens, and their discrimination in detect- mg and appreciating the distinctions upon which the arrange- ment is founded. It is but little that can be known of the subject. without forming a collection of greater or less extent ; for, as it would be uninstructive merely to delight the eye with the bright colours and elegant form of shells, without possessing correct infor- mation respecting them, so it would be insipid and useless to learn technicalities without beimg acquainted by personal obser- vation with the subjects to which they are applied. The first endeavour should, therefore, be to obtain a few shells as examples of the larger divisions, and, when these are understood, to proceed with the smaller groups, until a collection be formed to represent as many generic forms as possible. It may be as £E B 2 INTRODUCTION. well here to advise those who are forming a collection to be very particular in every practicable instance to have the shells properly named at the time of purchasing; as it will save much trouble, and materially assist in the attainment of the desired object. ‘To this end, recourse should be had to those naturalist tradesmen, who unite the attainment and diffusion of real scientific knowledge with their commercial pursuits. Supposing, however, that the person who desires to learn the science, possesses a small parcel of unarranged and unnamed shells, without any previous acquaintance with the subject, the following introductory explanations, are drawn up with the view of enabling him, without further assistance, to obtain a general insight into its principles, equal to that of those who have studied it long and laboriously. To effect this, he must read them, carefully comparing the descriptions with the figures referred to, and with the specimens which he may have at command. After describing the nature of the science and defining its objects, we shall proceed to explain the structure of those objects, and the manner of their growth. We shall then enter somewhat minutely into the principles of classification, the distinctions upon which they are founded, and some of the technical terms used to expressthem. After which we shall pass through the arrangement of Lamarck, defining the general divisions adopted under the terms of ‘‘ Classes, Orders, and Families,” as far as they are capable of definition. ‘The sub- division of the latter into genera will only be entered into so far as to enumerate the principal of them, the more minute de- scriptions being reserved for the alphabetical part of the work. Let none be discouraged by the number of generic dis- tinctions proposed and adopted in modern times; for if well defined, they will be found to facilitate rather than encumber the science. The knowledge of species must be the foundation INTRODUCTION. 3 of every system, and the greater their number, the more necessary it becomes to subdivide them ; if, for instance, all the species now known were to have been included in the 50 genera of Linneus, a single genus would have contained many hundreds of incongruous species, in which case it would be much more difficult to remember them, than if they were to be divided into a far greater number of genera. . Every well marked division, however arbitrary its limits, tends to simplify the subject, and to facilitate the researches of the student. NATURE OF THE SCIENCE. Conchology is the study of shells, viewed and described as to what they are either in themselves, or in relation to the soft, articulate animals which produce them, and of which they forma part. ‘These animals are called Moxiusca, and perhaps the best general description of them will be found in De Blainville’s “Manuel de Malacologie et de Conchyliologie.” The following is a translation, ‘‘ Animal in pairs, the body and its appendages soft, inarticulate (not jointed), enveloped in a muscular skin, commonly called the mantle, which is extremely variable in form, and has developed either within or upon it a calcareous portion, consisting of one or several pieces, commonly called a sHELL.” The term Mollusca was formerly restricted to those soft animals which were destitute of shells, although possessing in other particulars, the characters described above, and it was used in order to distinguish them from the Trstacea, which were covered or internally supported by calcareous parts. In the system of Linnzus, the soft portions are first arranged under the general designation of “ Vermes Mollusca,” and de- scribed without regard to the presence, absence, or character of the shells; and then the shells are separately characterized B 2 4 INTRODUCTION. under the appellation of “ Vermes Testacea,” without any further notice of the animal, than an indication of the genus to which it belongs ; thus the animal of Cypreea is said to be a Limax, and that of Tellina a Tethys. The nearest approach to correctness, and the most philoso- phical method of study will be found in the modern system, adopted by Lamarck and his followers, of observing these animals as a whole, and arranging them according to the assemblage of characters which they present; of course taking into consideration the existence or non-existence, form and structure of the shell, on the same principle, which, in arranging the vertebrated animals would lead us to study the hair, hoof, nails, claws, &c. as well as the other parts. At the same time, it must be admitted that there are many private collectors of Shells who would find it a difficult, if not impossible task to study minutely and successfully the soft parts of the Mollusca. Ladies, for instance, could not be expected to handle with pleasure and perseverance, these fleshy substances, which in order to be preserved from putre- faction, must be kept in spirits; and yet such persons may, with improvement and advantage to their own minds, enjoy the interesting and scientific amusement of studying and arranging the clean and beautiful natural objects which are so easily preserved, and so exquisitely curious in their structure. Let it also be remembered, that if shells had not been rendered commercially valuable, by the zeal and emulation manifested by mere Conchologists for the possession of rare specimens, few travelling merchants and sea captains would have thought them worthy of a corner in their cabins. In this case, few specimens being brought to the country, the more Philosophical Naturalist would have been left without the means of obtain- ing materials to work upon, or of attracting public attention te his favourite pursuit. INTRODUCTION. 5 On account of these and other considerations, it has been thought advisable that the present undertaking should bear a purely conchological character. The peculiarities of the shells alone being detailed for the assistance of those who collect and study them, while at the same time, in deciding upon their affinities and places, in the arrangement, it will be necessary to take advantage of the conclusion to which those have arrived, who have studied the animal in all its parts. And the con- viction must be expressed, that if ever a complete Natural System shall be formed it will result from the labours of the last mentioned class of naturalists. DEFINITION OF A SHELL. Before entering minutely into the description of shells, it will be necessary to distinguish from the true testaceous Mollusca two kinds of animals which have formerly been associated with them. Of these, the first is the class of Crustacea, consisting of crabs, crayfish, &c. These differ from shell-fish, not only in structure and chemical composition, but also in the fact that the animal has jointed limbs, and that the substance of the flesh is inseparable from the hard ex- ternal covering, which invests each particular joint as with a sheath; whereas the Molluscous animal is but partially at- tached to its shell, from which it possesses the power of partly withdrawing and returning. ‘The second class is that to which the sea-urchin, or Echinus, belongs, of which there are many genera and species. The testaceous covering of Echini is composed of a number of small pieces, placed edge to edge, forming a more or less globular external covering to the flesh, which is supported in the centre by a number of bones leaning upon each other in a pyramidal form. The ées¢ is of a fibrous texture, guarded on the outside with moveable spines, which turn on ball and socket joints. 6 INTRODUCTION. A true shell is composed of one or more calcareous pieces, commonly called valves, each piece formed by a series of ‘layers, applied obliquely upon each other, in such a manner that each new layer begins within, and terminates a little in advance of the one before it. STRUCTURE AND GROWTH. We shall now endeavour to describe the manner in which the growth of each separate valve, or each a formed shell, proceeds from the nucleus. ae Before the young animal has left the. egg, if it be an oviparous species, or the body of the parent if viviparous, the nucleus of the shell is generally formed, and specimens are sometimes preserved in which the young shell is seen within the egg, as in the cut, fig. 1, 2; or adhering to the inner sur- face of the full-grown shell by the dried mucus of the animal, as seen in fig. 3 1. Egg of aBulinus. 2.The same broken, shewing the young shell. 3. The young of a Palndina, as seen in the aperture of the shell. In both cases, the nucleus is generally of a more horny and transparent composition than the parts subsequently produced. As soon as the animal is hatched, or, in other words, leaves the ege or body of the parent, of course it begins to increase in size, and to require a corresponding enlargement in the INTRODUCTION. 7 shell. To effect this, a small quantity of mucus substance, secreted by the mantle of the animal, is deposited on the edge of the aperture. When this is dry and become sufficiently hard, it is lined by a more calcareous secretion; and these together form a new layer, which is followed by others in succession ; each new layer being larger than the one that preceded it until the whole being complete, the full-grown animal is invested w'th a shell commensurate with its own proportions. Thus from the apex or nucleus the formation proceeds, as it were, downwards, taking the shape of the part which secretes it, on which it is in a manner moulded. The nucleus, or first formed portion, may for technical pur- poses be considered, mathematically, as the apex of a spiral cone. And here it must be observed, that whether the shell consist of one or several pieces, each piece has a separate nucleus, and the process of formation is separately repeated with each. The word cone is used for convenience, and its meaning extended so as to include all those structures which commencing at a point enlarge downwards. From the apex, the next layer is deposited on its edge, and advancing beyond it necessarily adds to its extent. ‘Thus, suppose for the sake of illustration, the part marked a in the diagram, fig. 4, to represent a nucleus, the cross lines (/) will shew the consecutive layers, which enlarge their circle as they add to their numbers. ‘This disposition of shell “ " P ee ee matter into layers is marked externally by concentric strize, orlines of growth, 4. Imaginary cone. c 1 os a. Apex. while on the inside the edges of the po Babe. laminee are consolidated into a kind of 1. Lines of growth. enamel. If a perpendicular section of a solid portion of a shell were magnified, it would present, in many instances, an 8 : INTRODUCTION. appearance resembling the diagram, fig. 5; a may be taken to represent the horny part of the layers which form the outer coating, named “ Periostaca,” or “ EHyidermis ;” the undula- ting line 6, is formed by the 5- Supposed section of a part of a edges of the calcareous layers, woes and causes the striz, or lines of growth, which are often dis- tinguishable on the surface of the shell; the space ¢ is the middle part of those layers, and at d they are consolidated - into the enamel which lines the interior. In some species the layers are irregularly grouped together, and their edges overlap each other, so that they are easily separable, and advancing beyond each other, give a leafy appearance to the external surface. This structure is termed foltaceous. A very familiar instance of this may be observed in the common oyster. If a specimen of this shell be broken, the substance will be seen to exhibit a degree of looseness, and a magnifying glass will enable the student to trace distinctly the lamine of which it is composed. The accompanying re- presentation of a magnified section (fig. 6) will shew at a, the external surface, with the foliations or leaves; at b, the parcels of layers which EE form them; and at ec, the ———— <= Ss b] pearly structure produced by ikon e Licieconcol dation, sind by ane 6. Section of an oyster shell enlarged. subsequently deposited enamel which covers their external surface. CLASSIFICATION. The classification of shells, that is, their systematic arrange- ment into classes, orders, families, genera and species, cannot INTRODUCTION. 9 be made to depend entirely upon the characters observable in them, viewed by themselves; for this reason, that many simi- larly formed shells form the habitations of animals perfectly distinct, and that many molluscous animals are found to agree with each other in every respect but in the form of their testaceous support. ‘There are, however, many important dis- tinctions to be observed in the shells themselves, leading to the establishment of many of those very divisions, which would afterwards be confirmed by an examination of the soft parts. It is necessary to attend, as far as means and opportunity will allow, to all the points of difference, both in the shell and in the animal, in order to form, and in some instances even to appreciate, a generic or larger distinction. It will therefore be our endeavour to explain the general principles upon which thosé distinctions are formed, and the manner in which they are applied and expressed in detail by scientific writers. NUMBER OF PIECES, OR INDEPENDENTLY FORMED PARTS. The first, most simple and obvious division of shells, is that which results from the number of separate pieces composing them. Hence the distinction implied by the terms UNIVALVE, or consisting of a single piece ; BIVALVE, or composed of two pieces; and MULTIVALVE, or composed of more than two. For an example of univalve, take a common whelk ; for a bivalve, take a muscle or a scallop; and for a multivalve, the barnacle, or balanus, found adhering to the common oyster. But although this arrangement may appear at first sight perfectly easy and plain, some explanation will be necessary in order to guard the student against understanding the above ex- pressions in their strictest sense, without qualification. Thus the 10 INTRODUCTION. univalves are said to consist of a single piece, or spiral cone; but it would be more correct to speak of this piece as forming either the whole or the principal part of the shell : for there is in many instances, a much smaller flattened piece attached to the foot of the animal, which being drawn in when it retires, closes the aperture as with a kind of door, to which in fact the word valve might be very properly applied ; it is called however the OPERCULUM, and the little horny plate, frequently drawn out by means of a pin from the aperture of a periwinkle, will present a familiar example. The same may be said respecting the bivalves; for besisles the principal portions or valves of which the shell is composed, there are in many species, one or two smaller separate portions, named “ accessary plates” by some authors. ‘They are fixed by means of cartilages, on the back of the hinge.— The engraving, fig. 7, represents the accessary valves ofaspecies of Pholas, Accessary valves of a Pholas. which was on this account arranged by Linneeus with the Mul- tivalves. Nearly allied to the Pholades is a set of shells to which De Blainville has given the name “ Tubicole,” or inha- bitants of tubes. In this case, the bivalve shell is connected with a testaceous tube or pipe, to which it is attached either by one or by both valves, or in which it lies attached only by the cartilages of the animal. In the genus Aspergillum, the two small valves are soldered into the sides of the tube in such a manner as to constitute a part of it. One of these shells, called the Water-spout, might be taken up by a person not aware of its real nature, and regarded as a pipe or tube prettily fringed, and nothing more; but upon a closer examination, he would find the two valves, the points of which are visible from the outside of the tube. INTRODUCTION. Il HABITS— Land, Fresh-water, or Marine Shells. Another distinction, leading to important results in classifi- cation, is that which is derived from the nature of the element breathed by the Mollusc. And although this consideration belongs more especially to the study of the animal itself, yet the habits of the animal materially influence the structure of the shell. The TrerrestriAL or Lanp Molluses live on land, breathe air, and feed on plants and trees.—Those who find pleasure in horticultural pursuits will at once call to mind a too familiar example of these Molluscs in the common garden snail. The Land-shells are all univalves, and constitute a family in the Lamarckian system under the name ‘ Colimacea,” or snails, corresponding with the Linnean genus Helix.—They are generally light in structure and simple in form. The Aguatic, or Fresh-water Molluscs, such as the Planorbis, commonly called the Fresh-water Snail; the Unio— known by the name of Fresh-water Muscle, is found in ponds, ditches and rivers. The epidermis of these is gene- rally of a thick, close-grained character, and they are subject to corrosion near the umbones. ‘There are but few genera of fresh-water shells besides the Uniones, among bivalves, and the “ Melaniana” among univalves. Concerning the former it may be observed, that they are all pearly within, and the colour of the thick horny coating embraces all the varieties of brownish and yellowish green. The Marins, or sea-shells, belong to all the classes and orders, and include by far the greater number of species. They vary in the habits of the animal, and consequently in the situations in which they are found. Some are found buried in sand and marine mud, and are named “ Arenicole” or in- habitants of sand; others in holes of rocks and other hard sub- 12 INTRODUCTION. stances, then they are named “ Petricole,’—some of these latter form the holes in which they live by corroding or eating away the stone. A section of these form the family of “ Li- thophagide,” or stone-eaters, of Lamarck. Others, again, take up their parasitical abode in the bodies of animals, and feed upon their substance ; as for instance, the Stylifer, which is found in the vital part of star-fish, and Coronula, and Tubici- nella, found buried in the skin of the whale. LOCOMOTION—Attached, Unattached. A much more subordinate source of distinction arises from the freedom or attachment of the shells. Some of them float or walk freely in their natural element; others are fixed or attached to foreign bodies. Among those which are attached, there is again a difference as to the mode of attachment. Some are united to foreign bodies by means of a glutinating sub- stance, secreted by the animal, and joining part of the surface of the shell to that of the stone, coral, or other substance. In this way shells are fixed to each other in groups ; this is the case with the Spondyli among bivalves, and the Serpulz among univalves. M. de Blainville applies the term “ Fixe” to these shells. Others are kept in a particular place by means of a Byssus or ‘Tendinous fibrous line or bunch of silky hairs, acting as a cable, and allowing the Mollusc to ride as it were at anchor. This Tendon is connected with some part of the animal from which it passes through an opening or hiatus in the shell, as in the Terebratula and the Mytilus. INTRODUCTION. 13 In the former, represented by the cut, fig. 8, the tendon passes through a perforation in the upper valve ; and in the latter, Mytilus, fig. 9, the byssus passes out between the valves. Before proceeding to explain the characters of the different groups, according to the modern system of classification, it may be desirable to explain the terms by which the different parts and characters are described, and to shew the manner in which the shells are measured. For this purpose we shall treat of the general divisions separately. We begin with UNIVALVE SHELLS. In considering Univalves merely with reference to their mathematical construction, the first point demanding our attention is, whether they are symmetrical or non-symmetrical, or, in other words, whether a straight line drawn through the shell would divide it into two equal parts. The greater part of univalves are non-symmetrical, being rolled obliquely on the axis; but many are symmetrical, bemg rolled horizontally on- the axis. The Nautilus presents an illustration of the latter ; the Snail is a familiar example of the former. Symmetrical Univalves. In describing these it will be well to commence with the most simple form, such as the Patella,—taking a conical species as an example. In this it will be observed that there 14 INTRODUCTION. is no winding or curvature, but a simple depressed cone, and that the line a, p, divides it into two equal parts. The anterior, a, (cut, fig. 10) is known by the interruption of the muscular impression which surrounds the central disc (d.) ‘This interruption of the muscular impression is in the place where the head of the animal lies in the shell. The im- pression itself is caused by the fibrous muscle which attaches the animal to the shell. The apex (a) in Patella, gene- rally leans towards the anterior (a) part of the shell, and away from the posterior (p); and this circumstance has caused some mistakes, because in Emarginula the apex leans towards the posterior; and students, instead of examining the muscular impression, which is the only criterion, have only noticed the direction in which the apex turned, and concluded that to be the anterior, towards which it inclined. The lines or ribs running from the base to the apex of the shell, in the direction 7, are called radiating lines; and those which encircle the cone in the direction c c, from front to back, are very properly described as concentric. ‘The length is measured from front to back in the line e ; the breadth, from side to side, in the line 6; and the depth from the apex to the base. Let it be observed that patelliform, or limpet-shaped shells are not all symmetrical; Umbrella, Siphonaria, Ancylus, &e. will form exceptions, of which we have yet to speak. And the learner may also be reminded that the Limpets themselves are not all regular in their form: for as they adhere to rocks and other rough surfaces, and are so little locomotive, in many in- stances they partake of the inequalities of the surface, and conform to its irregularities. This adherence is not effected by any agglutinating power in the animal, nor by any tendinous process like that described above; but simply by means of the foot of the animal acting as a sucker. The next variation in symmetrical univalves is to be ob- INTRODUCTION. 15 served in the tubular, curved form, the example of which will be the Dentalium, fig. 12. Dentalium Elephantinum. This has an opening at the anterior termination a, called the aperture. ‘The opening at the posterior end (p) is named a fissure, or perforation. ‘The ribs running along the sides of the shell are longitudinal, or radiating. And the lines round the circumference are lines of growth, or concentric—each one having in succession, at earlier stages of growth, formed the aperture. ‘They are described as concentric, or transverse. Symmetrical Convolute Univalves. The Nautilus, the Spirula, the Scaphite, and the Ammonite are the leading types of this form ; but when we use the term symmetrical, in reference to these, the word must not be un- derstood in its strictest sense, for no shell is perfectly symme- trical: but it means that there is no perceptible difference in the proportion of the two sides; as in the human body, the right side is larger and more powerful than the left, yet toa degree so small that it gives no apparent bias to the figure. CHAMBERED SHELLS. Many of the shells now under consideration are chambered, that is, the internal cavity is divided into separate compart- ments by plates reaching across it, named Septa ; and the only connection between the chambers is formed by the small pipes passing through them,to which the name of Siphon is attached. 16 INTRODUCTION. Septa. The septa are simple in some species, as in the Nautilus, fig. 13. In others they are wndulated, having waved edges, as in some species of Ammonites; in others they are angulated, as in Goniatites, fig. 480 in the plates; and in the greater number of instances, among the Ammonites, they are arbores- cent, or branched. 13. Section of Nautilus.—i4. Undulating Septa.—15. Arborescent Septa. In the above section of a Nautilus, fig. 13, diminished in size, showing the whorls and chambers (c), it will be seen that the edges of the septa (s) are formed in one simple curve. In fig. 14, the upper part of an Ammonite, the undulating line will be seen; and in fig. 15 a specimen is given of the arbo- rescent septa. Siphon. The Siphon is dorsal when placed near the outside of the whorls ; central when near the middle ; and ventral when near the inside of the whorl, or that part which leans against the last volution. When it passes uninterruptedly from one chamber to another, it is described as continuous, as in the case of Spirula; when, on the other hand, it only passes through the septum a little distance, and opens into the chamber, as in Nautilus, it 1s discontenuous. INTRODUCTION. 17 Whorls of Symmetrical Univalves. They are disunited when they do not touch each other, as in the case of Spirula (fig. 471 in the plates); but in the con- trary case they are said to be contiguous. In some species of Nautilus the whorls overwrap each other in such a manner that the early whorls are entirely covered by the last, the edges of which reach to the centre of the disk: the spire is then said to be hidden; as in the Nautilus Pompilius. In Nautilus umbilicatus the spire is nearly hidden, the whorls not quite covering each other; but in the greater number of the Ammonites, the largest part of the preceding whorls is seen. ‘To express the degree in which the whorls overwrap each other, has caused much difficulty in concise descriptions. Perhaps it would be well to apply the term spiral disc to so much of the shell as is seen besides the last whorl, and to describe it as large or small in diameter, compared with the whole: or to say that the whorls of the spire are half, or one-~ third, or one-fourth covered, as the case may be. Aperture of Symmetrical Univalves. In Ammonites Blagdeni and some others the aperture is of an oblong square; it is then said to be sub-quadrated ; in Nau- tilus triangularis it is angulated; in Ammonites Greenoughi it is of an interrupted oval shape, described as elliptical. In the greater number of Orthocerata, it is rounded or circular. The entrance of the last whorl into the aperture of some rounded species of Nautilus causes it to take a semi-lunar form ; if rounded at the sides it is said to be reniform or kidney-shaped: if pointed at the sides it is semi-lunar ; and in some species of Ammonites, it is five-sided or quinque- lateral. Me) > INTRODUCTION. Measurement of Symmetrical Conical Univalves. =s=— =O depth The width is measured across the aperture, which is the widest part of the shell. The length (1) from the dorsal part (d) of the aperture to the dorsal part of the whorl (d) on the opposite part of the shell. The ventral part of the whorls is that nearest to the axis, and the dorsal that which forms the outline of the figure. NON-SYMMETRICAL UNIVALVES. These are conical, irregular, spiral, or convolute. The conical form is when there is no enrolment of the apex. Although the Patellee were described as symmetrical, there are several species of Patelliform shells which are not symmetrical. In Umbrella, for instance, the apex is oblique, the shells being placed obliquely on the animal. In the genus Stphonaria, there is a groove on one side, where the brachia or gills of the animal rest. In the genus Ancylus, it will be observed that the apex bends on one side, and the animal is like the Limnza, which has a spiral shell. The cup and saucer Limpets, or Calyptredz, present a group which requires to be described, differently from the symmetrical or true Limpets. Their structure is very curious, and they vary considerably among INTRODUCTION. 19 themselves, some of them being simply conical, others nearly flat, or discoidal, and others more or less spiral. But their principal peculiarity consists in their having a small internal process or plate variously shaped, commonly named their septum. Septa of Limpets. The septa of Limpets assume a variety of forms, the prin- cipal of which will be seen in the accompanying engravings. The form from which the group derives its generic appella- tion is that of the cup-shaped or Cyathiform species (fig. 17). In the Crepidule, or Slipper-Limpets, the septum is flat, reaching across the opening, like the deck of a vessel; it is then described as transverse (fig. 20). In Calyptraea Eques- tris, it has two prominent points, and is described as. bi-fur- cated (fig. 18). In another species, it is a three-sided plate rather spiral at the apex (fig. 19). Measurement of Cup and Saucer Limpets. The line marked a, p, 1 1, indicates the direction in which c 2 20 INTRODUCTION. the shell is to be measured for length. a indicates the ante- rior, p the posterior. ‘The line d (fig. 23), from the apex to the base, is the depth. ‘The line 6 (fig. 28), is in the direc- tion of the breadth. Irregular non-symmetrical Univulves. Serpuliform shells are irregularly twisted (tortuous) hollow tubes, which were formerly considered to have been secreted by a kind of worm, but now known to be the shells of true Molluscs, of a kind not very widely differing from those which have regularly spiral shells. The greater part of these are attached to foreign bodies, or to each other in groups. Some are attached by the whole length of the shell, they are then said to be decumbent. Some of these are coiled round like the Spirorbis, the little white shell seen on the carapace of the Lobster or on leaves of sea-weeds; they are then said to be discoidal; others again, such as the Vermetus, approach more nearly to the spiral form. The deviation from the regular spire only taking place after the few first volutions. SPIRAL NON-SYMMETRICAL UNIVALVES. Zt ' As these constitute the largest x class, it will be necessary to dwell _ upon them in detail. First as to measurement. The length is measured from the apex, to that part of the aperture a \- (fig. 24), at the greatest distance J i) from it. The breadth is in the oppo- NAN \ y, iin \ . LU aN Z site direction. The anterior, or front part of the aperture, is marked a, where the head of the animal pro- trudes. INTRODUCTION. — 21 Spire of non-symmetrical Univalves. In counting the whorls of which the spire consists, we com- mence at the apex, and reckon downwards to the last, or body whorl. The spire is described as being long or short in rela- tion to the aperture: in which case, all that is above the aper- ture is measured with the spire. Its apex requires particular notice, as the character of the whole shell frequently depends upon the particulars observable in this part. It is sometimes obtuse, or blunt; sometimes acute, or sharp. In the Cones it is frequently flat, and in Planorbis it is concave. It is some- times of a different structure from the rest of the shell, retain- ing the horny and transparent appearance which characterized it when the animal was first hatched. ‘The Tritons present an instance of this, although it is not always observable, owing to the tenderness of the substances which causes it to break or fall away in many specimens. A very remarkable instance also occurs in Bulinus decollatus (cut, fig. 27, 28), so named, because the apex, to the depth of several whorls, falls off, and the shell is decollated. In this, and many more instances, among Pupeform land shells, the occurrence of this cireum- stance seems to be by no means rare or accidental, a provision having been made for filling up the opening by a septum. A Fig. 25, obtuse ; 26, acute; 27,28, decolluted ; 29, concave; 30, papil- lary ; 31, mammellated; 32, discoidal. 99 INTRODUCTION. papillary apex is one which is swelled at the extremity into a little rounded nob, or nipple; and a mammellated apex is one which is rounded out more fully into the shape of a teat. Whorls. The spire is described as consisting of numerous or few whorls, and sometimes the number of them is particularly stated. A whorl consists of one turn of the spiral cone. The whorls are described as flattened, when the sides are not bulged out so as to cause the outline of the spire to deviate considerably from straightness: when the contrary is the case, the whorls are said to be ventricose, and either rounded or angulated. The degree of rapidity with which the whorls become enlarged presents an important source of distinc- tion. ‘The suture, or seam, which separates < whorl from another is also noticed as being distinct r otherwise ; canaliculated, or grooved; or covered by an enamel, which in some instances is swelled into a ridge or fumid. Fig. 33, few ; 34, numerous ; 35, rounded, ventricose ; 36, angular, ven- tricose ; 37, flattened. Suture. Fig. 88, canaliculated ; 39, enamelled. INTRODUCTION. 23 Varices. Varices are caused by periodical rests or stoppages in the growth of the shell, when the edge of the aperture thickens, and renders the shell as complete as when full grown. Again, after an interval, another check takes place, and another thickened edge is formed, and so on in succession, until the animal arrives at maturity, and the shell is full-grown, The thickened edges successively forming the aperture, remain visible on the outside, through all the subsequent stages. When these rests take place at frequent periods, the varices will of course be numerous as in Harpa and Scalaria. They occur at regular or irregular distances, varying in shape and other characters. When the varices occur at regular intervals, and form a connected ridge from whorl to whorl up the spire, they are said to be continuous, as in Ranella; when on the contrary, the varix on one whorl does not come in con- tact with that on the other, they are described as discontinuous. In order to distinguish a regular varix from a mere external ridge, it will be sufficient to notice whether its edge overlaps the external surface, and whether it resembles the open edge of the aperture, which true varices do. Fig. 40, numerous; 41, few, continuous ; 42, few, discontinuous. Aperture. The aperture or opening of the spiral tube, was formerly described as the mouth; a term calculated to convey an DA. INTRODUCTION. erroneous impression, when applied to a part of the shell which has no correspondence with the mouth of the animal. The word aperture is used by modern writers in a general sense, including the cavity, its edge, and the canals. The cavity itself is distinguished in various shells as to its shape, which depends much upon the degree of modification produced by the last whorl. In some cases, as in Cyclostoma, where the aperture stands apart from the last whorl, the shape is round, or nearly so. ‘The Scalaria presents a good example of this. In others, where the inner edge or lip, wrapping over the body whorl is nearly straight, the aperture is semi-lunar, or half-moon shaped: this is remarkable in the “ Weritacea” of Lamarck, named, on that account, ‘‘ hemi-cyclostomata” by De Blainville. In a great number of instances, the lower part of the body whorl enters obliquely into the upper part of the aperture, the result being a pyriform, or pear-shaped open- ing. ‘The aperture is described as long when it is largest in the direction of the axis, and wide, in the contrary case. The anterior is the part at the greatest distance from the apex, and the body whorl; the posterior, the part nearest to the apex. Thus some apertures are described as posteriorly contracted and anteriorly widened, or the reverse. A linear aperture is one contracted in its whole length, as in Cypraea. When the whorls are angulated, a trigonal aperture is the result, as in many species of Trochus. Some are transversely oval, that is in an opposite direction to the axis, and others longitudinally oval. When the whorls are formed with two outer angles, a somewhat quadrated aperture is formed. ‘There are other variations too numerous to mention. iS) or INTRODUCTION. Apertures. i Fig. 43, Helicina, semilunar ; 44, Pirena, pyriform ; 45, Cyprea, linear ; 46, Trochus, trigonal; 47, Cyclostoma, rounded; 48, Chilina, poste- riorly contracted ; 49, Stomatia, transversely oval; 50, Murex, longitu- dinally oval. The entire edge of the aperture described generally, is named the Peritréme, but this term can only be conveniently applied in cases where, in some at least of its characters, it is the same all round, so that one descriptive term is applicable to the whole. As, however, this is of rare occurrence, it is found convenient in descriptions to separate the rim from the outer lip. In a great number of instances, this is done natu- rally, by a canal, or notch at the anterior or lower extremity, and by the posterior union of that part which overlays the body whorl with the other portion. At these two points the outer and inner lips separate from each other: we therefore describe the Canals of the Aperture. When there is neither notch nor canal, anteriorly or poste- riorly, interrupting the edge of the aperture, it is described as entire. When there is a notch or sinus at the anterior 296 INTRODUCTION. extremity, it is said to be emarginated. When the edge of this notch is expanded, and drawn out in the form of a beak, it is said to be canaliferous, or to have a canal. When, in addition to this, the lips are thickened and contracted poste- riorly near their junction, and drawn out so as to forma groove, it is said to be bt-canaliculated, or to have two canals. The anterior canal is said to be long or short, according to the proportion which it may bear to the rest of the shell. Thus the canal of Ranella ranina (fig. 393 in the plates), may be described as short; while that of Murex haustellum, (fig. 396, pl.) is ong. When it is wide near the aperture, and becomes gradually contracted towards its termination, it is said to be tapering, as in Pyrula (fig. 388, pl.) ; when the termi- nation is sudden, it is described as truncated. If, on placing the shell upon a plane, with the aperture downwards, the canal is seen to rise upwards, it is recurved. In Buccinum and Nassa it is turned suddenly over the back, and forms a short, curved elevation; it is then described as recurved and vari- cose. If the edges meet, so as to form a tube, it is said to be closed, as in some species of Murex and Typhis. The pos- terior canal is, in some cases, free, or standing out from the spire, as in some species of Ranellee; while in others it is decumbent, running up the sides of the spire, as in Rostellaria (fig. 402, pl.). Canals. Fig. 51, Fasciolaria, truncated ; 52, Nassa, recurved, varicose ; 53, Cerithium, recurved ; 54, Typhis, closed. INTRODUCTION. P47), Lips, or edges of the Aperture. The part of the edge of the aperture next to the body whorl is named the inner, or columellar lip. Posteriorly it com- mences at the point of union with the outer lip, where that touches the body whorl, the junction being generally marked by an angle, and sometimes by a canal. Anteriorly it terminates where there is generally seen a notch or canal, or sudden angle, from which the outer lip proceeds. ‘The part which setting out from the body whorl, and proceeds outwards at a distance from the axis, till it reaches the anterior canal or notch (or its place in case of absence) is named the outer lip. In many cases the edges are united in such a manner, that it is difficult to distinguish where the inner lip terminates, and the outer lip commences: when this is the case, it is usual to describe the margin or peritréme, as a whole, without distin- guishing the parts. The outer lip, sometimes called the right lip, or labrum of continental writers, is sometimes acute, not being of thicker substance than the remainder of the shell. In other cases it is obtuse, or thickened and rounded at the edge. When thickened and turned backwards it is described as reflected ; when, on the other hand, it is turned inwards towards the axis, as in the Cypreede, it is inflected, or invo- lute. When it is toothed, a distinction must be observed as to whether the dentations are external or internal. If the teeth are small and numerous, it is denticulated ; if larger, it is dentated ; when expanded into a kind of wing, as in some species of Strombus and Rostellaria, it is described as alated ; and a family in Lamarck’s system is named “ Alate,” from this very circumstance. In some of those which are expanded, the expansion is divided into separate, attenuated portions, they are then said to be digitated. 28 INTRODUCTION. Outer Lips. Fig. 25, Helix, reflected ; 56, Cypraa, involute, denticulated ; 57, Sera alated ; 58, Murex, digitated ; 59, Rostellaria, dentated. The inner lip, sometimes named the columellar lip, or ‘< labium,” is subject to similar variations as to thickness, dentition, &e. That portion of it which lies upon the body- whorl is frequently distinguished from that which intervenes between it and the notch or canal. De Blainville, restricting the term lip ‘‘ bord gauche” to the former portion, applies the term “columella” to the latter; and in some instances this may be the more convenient method of describing the part in question. ‘The columellar lip is sometimes detached entirely from the body of the shell, asin Murex haustellum ; in others it is decumbent, or lying over the last whorl, although quite distinct, and in some cases, thickened, callous, or tumid. At the lower or anterior part, sometimes called the columella, there are in many instances flattened, laminated folds; these are particularly conspicuous in the genera Cymba and Melo, where, being obliquely spiral and laminar, they are extremely elegant, presenting to the eye graduated repetitions of the line of beauty. In other cases, as in the Turbinelle, they are more horizontal and thickened. INTRODUCTION. 99 In some cases the columella is swelled into a varicose mass ; as in Oliva, Ancillaria, &c.; it is then described as tumid or varicose. It is sometimes tortuous, and sometimes straight, and.is susceptible of many variations, too minute and par- ticular to be described in this part of the work. Columellar Lips. Fig. 60, Melo, obliquely platted; 61, Turbinellus, horizon- tally plaited ; 62, Ancillaria, varicose, tortuous; 63, Na- tica, straight. OPERCULUM. The aperture of many species of shells remains constantly open ; but in a great number of species it is occasionally closed, whenever the animal is retracted within the shell, by a calca- reous or horny piece called the operculum. This must be dis- tinguished in the first instance from another kind of calcareous covering, which in some univalve shells serves to close the aper- ture during a certain portion of the year. This piece, named the epiphragm, although hardened and shelly in appearance, is no real part of the animal or of the shell ; being only a secretion temporarily hardened, for the purpose of defending the animal from external influences during the hibernating or torpid season, to be dissolved when that season is at an end. On examining this piece, it will be observed that it is not formed 30 INTRODUCTION. in regular layers like the rest of the shell; while the true operculum is of a regularly laminated structure, having a nucleus and receiving obliquely deposited additions, either in a lateral spiral or concentric direction. It is attached to the posterior part of the foot on the upper surface; and when the animal retires within its shell, that part of the foot enters last, drawing the operculum after it, and thus closing the aperture. The opercula of various shells differ in the first place as to their chemical composition. ‘They are calcareous when formed principally of calcareous matter, like the rest of the shell, as in Neritina, Nerita, and some others. They are corneo- calcareous, when upon an internal lamina of horny consistency there is a thickened layer of shelly matter. This is the case with shells of the genus Turbo and Phasianella, which are on this account distinguished from those of the genus Trochus; the opercula of the latter being horny or corneus. The size of the operculum is distinguished by comparison with the rest of the shell; thus, those of Strombus, Cassis, &c. are small; while those of Cyclostoma and others are large, filling up the cavity at its outer edge. The direction in which the successive layers are deposited, forms another ground of distinction. ‘The disc is formed in some instances of a series of whorls, the apex or nucleus being more or less central ; if these whorls are numerous, the oper- culum is described as multispiral, as in shells of the genus Trochus; if few, as in Cyclostoma, it is paucispiral. In some instances the flattened spire consists of but one whorl, it is then unispiral ; and when scarcely one turn is completed, it is described as subspiral. When the layers are applied upon each other in such a manner that the nucleus is central, and the edges of the subsequent layers are extended beyond INTRODUCTION. 31 each other all around, so as to form rims, the operculum is described as concentric ; if the nucleus is lateral, or at one side without being spiral, it is Jammellated ; and when it forms a terminal point, enlarging in the form of a finger-nail or claw, it is wnguiculated. In the operculum of a Neritina, there is a lateral process, by means of which it is locked into the columella, the term articulated is then applied. In that of Navicella, there is also a process which appears to radiate from the nucleus, it has therefore been described as a radiated operculum. Opercula of Spiral Univalves. Fig. 64, multispiral ; 65, paucispiral ; 66, concentric; 67, articu- lated ; 68, radiated ; 69, lammellated ; 70, unguiculated. BIVALVE SHELLS. Bivalve shells, named Conchacea by Lamarck, are those which consist of two principal portions united to and folded upon each other by means of a hinge. The pieces united compose the shell, while each piece separately is called a valve. Considering the bivalve shell as a whole, it will be necessary, 32 INTRODUCTION. in the first instance, to describe the position in which it is to be observed, in order to give the student a clearly defined notion of what is intended, when terms expressive of height, depth, length, breadth, &c. are used, as well as when the anterior and posterior extremities are spoken of. For this purpose, we must suppose the animal to be living and creeping along the bed of the sea by means of its foot ; where this foot protrudes, will be the ventral margin, and the opposite part the dorsal margin of the shell. ‘There will then be a valve on each side ; and if we further suppose the animal to be walking forward with its back to the observer, the right and left valves will correspond with his right and left sides. Measurements. The length will be measured from anterior (a) to poste- rior (p),and the lines of growth running in the same direction will consequently be longitudinal or concentric ; transverse of some authors. The height will be from the umbones (w), to the ventral margin, and lines or bands in that direction are termed radiating ; longitudinal, according to some authors. INTRODUCTION. 33 The points from which the growth of the shell commences, are called the wmbones ; these usually turn towards the anterior part of the shell: if this circumstance fails to point out the anterior, it may in many cases be distinguished by the mus- cular impressions of the mantle. If this has a sinus or winding, it is always near the posterior muscular impression ; and in all cases where there is an external ligament, it is on the pos- terior side. There is sometimes an impression near the front of the umbones, which forms a semicircle on each valve; the space within this semicircle is called the lunule (wood-cut, fig. 71 and 72, J. J. 1.); a corresponding depression, when it exists on the posterior margin near the umbones, is named the escutcheon. Fig. 73, lt, lateral teeth ; c £, cardinal teeth; c, cartilage under the ligament ; 7, ligament; f. fulcrum of the ligament. The hinge of the shell is on the dorsal margin, and is com- posed of the various apparatus by which the two valves act upon each other in opening and shutting. It consists of a ligament, which is placed on the dorsal margin, just at the back of the umbones, and unites the two valves together ; the cartilage or thick gristly elastic substance, sometimes found close to the ligament, to which it then forms an inner coating, and sometimes received into a pit within the shell. It serves the purpose of keeping the shell open when not forcibly closed by the adductor muscles. An inner layer of shelly matter upon D 34 INTRODUCTION. which are placed teeth, and pits to receive them on the two valves reciprocally. Each of these it will be necessary to treat of more at large; observing, at the same time, that in some species of Bivalves these parts may be wholly or partially wanting. Thus we meet with some shells, such as the Muscle, without teeth; and there is the group containing Pholas, &c. the hinge of which is destitute of teeth and ligament, the two valves being kept together by loose cartilages, and by the con- tracted space in which they are confined. Ligament and Ligamentary Cartilage of the Hinge. These two distinct substances have been described by many writers as though, composing the same mass, they were of one substance; but the difference may very easily be explained. The true ligament is external, being fixed on the edge of one valve behind the umbones, and passing over in an arch to the corresponding edge of the other, very correctly retaining the name of ligament, because it serves the purpose of binding the two together. ‘The thick, elastic substance, which Mr. Gray names the cartilage, is sometimes found in connexion with the ligament, so as to form one mass with it, although it is always separable and placed within it: it is sometimes placed quite within the shell, and separated from the ligament, in a pit or hollow formed for its reception in the hinge lamina, near the centre. It is found in both valves, and being elastic, the portion in one valve presses against that in the other, so as to keep the valves apart, unless voluntarily closed by the adductor muscles of the animal. ‘The ligament is sometimes spread over an external area, as in Arca, while the cartilage is placed in several grooves of the same area, beneath the outer covering. INTRODUCTION. 35 Hinge lamina, Teeth and Fulcrum of the Ligament. In a great variety of cases, there is a thickening of the sub- stance of the shell within, under the dorsal margin; this is named the hinge lamina. It is sometimes merely callous ; but in many cases it has raised teeth in both valves, those in one valve entering into corresponding cavities in the other. Those which are placed immediately below the umbones, and seem to take their rise from beneath them, are called cardinal teeth ; those at a distance from the umbones, which are seen to lie along the upper margin of the shell are named lateral teeth. When the cardinal teeth terminate in a double point, which is not unfrequently the case, they are said to be bifid. The lateral teeth, in various species, are distinguished as termi- nating near to, or at a distance from the umbones. In the Nucule and Arce there is a row of teeth placed across the hinge lamina. In which case, the lateral cannot be distin- guished from the cardinal teeth. Muscular Impression. % ge ey \ Plkah j ip ro fsie™ _ ~ o Za The Fig. 74. a, anterior ; p, posterior ; m %, muscular impressions. Lamarck divides the Bivalve shells into two general orders ; p 2 36 INTRODUCTION. the first is named ‘“‘ Dimyaria,” having two adductor muscles ; and the second, “ Monomyaria,”’ having but one. ‘These adductor muscles are used for the purpose of drawing the valves together, being composed of contractile fibrous gristle, fastened firmly to the inner surface of each valve. The place where they are thus fixed may be seen when the animal is removed, by depressed areas, which are generally pretty well defined, and are named muscular impressions. Where there is but one adductor muscle, there will be but one of these im- pressions near the centre of each valve, but in the Dimyaria, where there are two, the impressions areseen, one on the ante- rior, and one on the posterior of each valve, just below the hinge lamina. ‘They are sometimes complex, that is composed of several portions in a group; but in general, they are simple _and well defined. They are also described as large or small, in proportion to the size of the shell; regular or irregularin form. The animal is attached to the inner surface by the fibrous portions of the mantle, which creates a linear impression or cicatriz, commonly described as the palleal impression, or muscular impression of the mantle. It runs near the ven- tral margin from one muscular impression to the other, some- times in a smooth continuous line or band, and sometimes in an interrupted series of small impressions. Near the point of union with the posterior muscular impression, there is some- times a more or less considerable winding inwards towards the centre of the shell, and back again towards the point of union. This is named the sinus, and is distinguished as being angular or rounded, large or small, according to the species. When it enters towards the centre of the shell in a tongue-shaped outline it is said to be ligulate. Where it exists it affords a certain index to the posterior side of the shell; as it is the region through which the excretory tubes pass. INTRODUCTION. 37 Umbones. These are the prominent points of the dorsal edge, where the growth of the shell commenced, and are called beaks, by some English writers. In some instances they are close to each other; in others they are rendered distant from each other by the intervention of areas in the hinge, as in Spondyli, &e. In Pectunculus they are straight; im Venus curved towards the anterior margin; in Isocardia, spiral ; in Chama, decumbent ; in Diceras, free. In shells subject to external corrosion, the process commences at the umbones. Fig. 75, distant ; 76, straight ; 77, curved ; 78, spiral; 79, decumbent ; 80, free ; 81, close. GENERAL CHARACTER OF BIVALVES. When the breadth is spoken of, the distance between the most convex parts of both valves, when closed, is intended ; but when an expression implying thickness is used, it refers to the substance of each valve: it is important to bear this in mind, as many persons have been misled by descriptions in which the distinction has not been attended to. Glycimeris (fig. 67 in the plates) is a thick shell, but Anatina (fig. 69 in the plates) is a broad one. 38 INTRODUCTION. Regularity. A great number of Bivalves are extremely regular in their form. These are generally locomotive, and consequently free from those obstructions in growth occurring to stationary shells, which being confined in a particular position, or to a parti- cular spot, modify their shape according to the substance with which they come in contact, and thus become irregular. This is generally the case with shells which are attached to sub- marine substances, such as Spondyli, Oysters, &c.; and the degree of irregularity will depend upon the extent of surface involved in the attachment. In the case of fixed shells, the attached valve is usually termed the under valve, and the other which moves freely upon the hinge, is termed _ the upper valve. Form and Proportions. Bivalves are said to be equivalve when the two valves cor- respond in extent, breadth, and thickness; and of course inequivalve in the contrary case. ‘They are equilateral when a line drawn from the umbones to the ventral margin would divide the shell into two nearly equal parts; and of course inequilateral in the opposite case, which occurs in the great majority of instances. A Bivalve is said to be compressed, when the distance is small from the most prominent part of one valve to that of the other. It is cylindrical when lengthened, and more or less rounded in its breadth, as in Lithodomus (fig. 161 in the plates). It is cordiform when the shape presents a resem- blance to an imaginary heart, as in Cardium cardissa (fig. 122 in the plates), andin the Isocardia (fig. 126 in the plates). It is linguiform when it resembles a tongue in shape, as in Vulsella (fig. 185 in the plates); rostrated when it protrudes INTRODUCTION. 39 at either extremity, and terminates in a kind of point, as in Sanguinolaria Diphos (fig 99 in the plates); ¢runcated when it ends in a square or angle, as if cut off; an example of which may be seen in Solen (fig. 60 in the plates). Other Bivalves are distinguished as being auriculated, having processes flattened and expanded on either side of the umbones, as in Pecten (cut, fig. 82). When there is one of these on each side of the umbones, it is bi-auriculated ; when only on one side, it is wnt-auriculated. When the expansion is very broad, as in Unio alatus (fig. 142 in the plates), and in the Hammer Oyster (cut. fig, 83), the term alated is used. Fig. 82, auriculated ; 83, auriculated, alated. With regard to these alated species of Uniones, it is neces- sary to observe that they are also “ adnate,” as it is termed ; the two valves being joined to each other by the dorsal edge of the expanded parts, and united so completely in substance with each other, that they cannot be separated without being broken. Many other terms are used to express difference in Bivalves, but being generally applicable to Univalves and Multivalves, as well as to them, they will be found explained at large in the alphabetical part of the work. MULTIVALVE SHELLS. These are of three different kinds; first, the ‘ dorsal,” as they are termed by Linneeus, because they form a ridge in the back of the animal. They are composed of eight pieces, or 40 INTRODUCTION. separate valves, placed in a longitudinal series, being joined to each other by inserted lamina, and named Articulata by De Blainville, on that account. ‘The genus Chiton is the only example of this kind of Multivalves. 4 Ww 7 \/ 3S < Fig. 84, 85, Chiton. a, anterior; p, posterior ; d, dorsal ridge; J 7, lateral areas of the valves; cc, central areas; 77, inserted lamina; m, margin. The second kind, M. De Blainville terms the lateral bivalves, the pieces being placed in pairs on each side of the animal; these compose the “ Pedunculated Cirripedes.” Fig. 86, Anatina. They differ considerably in the number and arrangement of the valves ; the small ones, which are found near the peduncle in some species, are sometimes termed accessary valves ; those which form the edge through which the bunch of Cilia pro- trude, are termed ventral, and those on the opposite side dorsal. The extremity joining the peduncle is the basal, or anterior; and the upper extremity is the apsiral, or posterior. The peduncle is the medium of attachment to submarine sub- stances, to which this well known tribe of shells adhere. The third kind are termed coronular by De Blainville, and INTRODUCTION. 4] compose the order Sessile Cirripedes of Lamarck; they consist of a number of valves placed against each other side by side in a circle, supported on a plate, or tube, or cup, and closed by an operculum composed of two or more valves. The basal support is sometimes thick and flat, sometimes forming an elongated tube, and sometimes hollowed out into acup. In other species it is altogether wanting. The oper- culum always consists of more than one piece, generally of two pairs: they are either articulated to each other by serrated edges, and placed against each other conically, as in Balanus, or they lie flat in two pairs against each other. Through the ventral pair the cirrhi protrude. The parietal valves, composing the principal part of the shell, vary in number, form and position. The anterior valves are placed on the same side with the cirrhi; the posterior, those on the opposite side; and those which remain between on each side are the lateral valves. In many cases, parti- cularly in Balanus, each valve is separated into the prominent and depressed areas, and the inserted lamina, In some instances, the parietal portion is formed by a single rounded piece. In the accompanying cut (87), the prominent areas are dis- Cy \ A SD 4 Y MUN PTE OH Rats AN) \N 4 49 INTRODUCTION. tinguished by the letters pr, and the depressed areas by r ; the posterior valves of the operculum are marked p. o., and the anterior a. 0. The basal valve (fig. 88) belongs to a Balanus. Fig. 89 is an Acasta, the cup-shaped base of which is represented at fig. 90. In the foregoing explanations we have omitted many of those general terms which, relating to external characters, are applicable to shells in almost every division of the system. It may be as well, however, to enumerate a few of them in this place, although they are explained under their respective letters in the alphabetical part of the work. When bars or ribs, or large strie are crossed by others radiating from the umbones, shells are said to be cancellated, as represented in cut, fig. 91. When there is a series of nodules or spines on the upper part of the whorls, they are coronated, as shewn in cut, fig. 92. When a series of pro- jecting parts overlay each other, in the manner of tiles, as in the cut, fig. 98, the word imbricated is applied. When marked by a regular series of ridges, radiating from the apex, they are pectinated ; the species of Chiton, a single valve of which is represented in cut, fig. 94, has received the specific name of pectinatus, in consequence of this character. Shells are said to be plicated when characterized by angular bendings or fold- ings in their surface, as shewn in cut, fig. 95. A strong instance of this is seen in the Ostrzea Crista-Galli. When the margin of any shell has a series of minute notches, resembling the teeth of a saw, it is said to be serrated ; when covered with raised points or spines it is aculeated ; and when striated in both directions, it is decussated ; when covered with a num- ber of raised rounded points, it is granulated; and having a series of these points placed in a row, near or upon the edge, it is denticulated, as already explained in reference to the outer lips of Spiral Univalves. When the external surface is INTRODUCTION, 43 rendered uneven by raised knobs, it is said to be tuberculated ; and if rendered rough and prickly by sharp points it is muri- cated, as in the cut, fig. 97. The term reticulated is applied to fine raised lines, crossing each other, and resembling fine net-work. External surface. Fig. 91, cancellated; 92, coronated ; 93, imbricated ; 94, pectinated; 95, plicated; 96, decussated; 97, muricated ; 98, foliated. By the foregoing general observations and explanations, it is trusted that the reader will be prepared for the following exposition of the general arrangement of Lamarck, and the principles upon which it is founded. GENERAL ARRANGEMENT ACCORDING TO LAMARCK. In Lamarck’s ‘‘ Histoire Naturelle des Animaux sans Ver- tebres,” he divides the invertebrata into classes, the 9th, 10th, and 11th of which include animals possessed of shells properly so called. ‘These are the AnneELIpEs, the Crrripepes, the ConcuHIFERA, and the Motiusca. The class ANNELIDES constitutes the 9th, and is divided into three orders, namely, the ‘‘ Apodes,”’ ‘‘ Antennees,” and “* Sedentaires ;” the last of which, Sedentaria, alone contains testaceous animals. This order includes tubular shells, which, 44 INTRODUCTION. with the exception of Dentalium, are irregularly twisted, and attached to each other, or to extraneous substances. The first family Dorsalia, contains the genus Siliquaria (plates, fig. 1), known from the Serpulz, by the slit which passes through the whole length of the shell on the upper surface of the tube. The second family, MJaldania, has the genus Dentalium (plates, fig. 2), a species of which are commonly known by the name of “ tooth shells;” these are regularly formed, curved conical tubes, open at both extremities. The third family, Serpulacea, includes the genera Serpula, Spirorbis, Galeolaria, Vermilia, Spiroglyphus, and Magilus. The only shell that a learner would be likely to place among these incorrectly, according to the system, is the Vermetus (plates, fig. 345), which being regularly spiral at the apicial extremity, has been placed among the Mollusca; to which situation the whole of the shells under consideration have a better title than is gene- rally supposed. It should be mentioned that the Serpulacea are provided with opercula. Class CirRIPEDES. This class constitutes the tenth of invertebrated animals, and receives its name from the jointed and ciliated branchia which protrude between the opercular valves. ‘They are Mul- tivalve shells, and were all included in the single genus Lepas in the system of Linneus, and are commonly known by the name “ Barnacles.” Lamarck has, however, divided them into two distinct orders. First, the Sessile Cirripedes, or those which being composed of several valves, joined to each other, side by side in a circle, are attached to each other, or to sub- marine bodies by the basal portion of their own substance, and form a hollow, irregular cone, with the aperture above closed by an operculum consisting of two or more valves. Secondly, the Pedunculated Cirripedes, which are composed of INTRODUCTION. 45. valves placed in pairs against each other, so as to form a flattened disc attached by means of a tendinous tube called a peduncle. The first of these orders includes the genera Tubicinella, Coronula, Platylepas, Clitia, Conia, Elmineus, Catophragmus, Octomeris, Balanus, Creusia, Nobia, Savig- nium, Pyrgoma, Adna, Megatréma. ‘The second contains the genera Pentelasmis, Scalpellum, Smilium, Pollicipes, Bisnzeus, Lithotrya, Ibla, Octolasmis, Cineras, Otion. Conchological writers are not agreed as to the propriety of allowing the above to enter into the present science. Class CoNCHIFERA. The shell of a conchiferous animal is always bivalve, com- posed of two pieces placed opposite to each other, joined at the dorsal margins by an elastic hinge. All true bivalve shells belong to animals of this class; and the correspondence between the shell and the animal is so true that on examining an empty bivalve shell we can not only determine that its inhabitant belonged to this class, but also decide on the par- ticular order and family in which it should be placed, without seeing the soft parts. The first general division of Conchifera is that which results from observing the muscular impressions, or marks made on the inner surface of the valve by the insertion of the adductor muscles. All Conchifera are divided into two orders, as fol- lows: First Order, Conchifera Dimyaria. Having two adductor muscles, and consequently two im- pressions in each valve. ‘They are separated into the follow- ing families : 1. Tubicole (plates, fig. 44 to 54), having shelly tubes be- sides the valves. This family contains the genera Asper- 46 INTRODUCTION. gillum, Clavagella, Teredina, Teredo, Xylophaga, Fis- tulana, and Gastrocheena. . Pholadaria (plates, fig. 55 to 59), cylindrical, living in holes in rocks pierced by the animals. Lamarck places in this family the genera Pholas and Gastrochena, the last of which belongs more properly to the family ‘Tubi- col, as placed above. ‘olenacea (plates, fig. 60 to 68), longitudinally (trans- versely, Lam.) elongated, open at the anterior and pos- terior extremities. This family contains the genera Solen, Pholadomya, Panopza, Glycimeris (Solecurtus) and Solenimya. . Myaria (plates, fig. 69 to 76), ligament internal. A spoon-shaped ligamentary pit in one or both valves. Shell generally gaping at one or both extremities. This family includes the genera Anatina, Mya, Anatinella, Lyonsia, Myochama, Cleidotherus. . Mactracea (plates, fig. 77 to 88), the cartilage placed in a trigonal pit, with a small external ligament. The genera Lutraria, Mactra, Crassatella, Erycina, Ungu- lina, Amphidesma, and Solenimya. belong to this family, the last of which ought to have been placed among the Solenacea, as above. . ‘Corbulacea (plates, fig. 89, 90), inequivalve, with an in- ternal ligament resembling the Mactracea, but differing in having one valve deeper than the other, although regular shells. This small family contains only the genera Corbula and Pandora. . Lithophagide (plates, fig. 91 to 97), irregular, terebrating, living in holes of rocks. The genera are Saxicava, Petricola, and Venerirupis. . Nymphacea (plates, fig. 98 to 110), ligament external, generally placed upon a prominent fulerum, which INTRODUCTION. 47 passes from the inside to the outside of the hinge; valves generally gaping at the extremities. This family contains the genera Sanguinolaria, Psammobia, Psam- motzea, Tellinides, Corbis, Lucina, Donax, Capsa, and Crassina. 9. Conchacea (plates, fig. 111 to 121), regular, having several cardinal teeth and sometimes lateral teeth. The Conchacea constitute one of the most beautiful and numerous families of the class; they present equivalve shells, which are always regular, unattached, and in general closed, especially at the sides; they are always more or less inequilateral. They are divided into the fluviatile and marine Conchacea, the first containing the genera Cyclas, Cyrena, and Galatheea, found in rivers ; and the second, Cyprina, Cytherea, Venus, and Vene- ricardia. 10. Cardiacea (plates, fig. 122 to 180). This family, which resembles the last in some general characters, are also regular and equivalve, and are generally provided with radiating ribs, which are seldom seen in the Conchacea. The genera enumerated in this family are Cardium, Cardita, Cypricardia, Hiatella, and Isocardia. 11. Arcacea (plates, fig. 131 to 138). These are known by having a row of numerous small teeth on the cardinal hinge in each valve. The genera included are, Cucullea, Arca, Pectunculus, Nucula. 12. Trigonacea (plates, fig. 189 and 140). It is doubtful whether this family should remain distinct. As of the two genera placed in it, the first, Trigonia, is thought by some naturalists to have strong affinities with Nucula, in the family of Arcacea; and the latter, Castalia, cer- tainly belongs to the Nayades. 13. Nayades (plates, fig. 141 to 152). These are fresh-water AS INTRODUCTION. -shells, covered on the outside by a thick horny epidermis, and pearly within. ‘They include the genera Unio, Hyria, Anodon, Iridina. 14. Chamacea (plates, fig. 153 to 155), Seqeivalss, irregular, foliaceous, attached; containing the genera Diceras, Chama, and Etheria. Second Order, Conchifera Monomyaria. Having one adductor muscle, and therefore only one im- pression in each valve. ‘They are separated into the following families :— 1. Tridacnacea (plates, fig. 156 & 157), transverse, equivalve, with an elongated muscular impression, near the centre of the ventral margin; margin undulated at the termi- nation of the radiated large ribs. The genera Tridacna and Hippopus are included. 2. Mytilacea (plates, fig. 158 to 162), generally regular, with the hinge linear, without teeth, occupying the greater part of the dorsal margin. ‘This family includes the genera Modiola, Mytilus, Pinna. . Malleacea (plates, fig. 163 to 170), shell generally thin, inequivalve, irregular, foliaceous, with the hinge linear. This family contains the genera Crenatula, Perna, Mal- leus, Avicula, Meleagrina. 4. Pectinides (plates, fig. 171 to 178). ‘The Pectinides are generally regular or nearly so, with the shell solid; the greater part of them are auriculated at the dorsal mar- gin, and generally characterized by ribs radiating from the umbones. ‘The genera are Pedum, Lima, Plagio- stoma, Pecten, Plicatula, Spondylus, Podopsis. 5. Ostracea (plates, fig. 180 to 192). The shells of this family are irregular, generally attached and foliaceous. ee) INTRODUCTION. 49 They compose the genera Gryphea, Ostrea, Vulsella, Placuna, Anomia. 6. Rudistes. (plates 195 to 200). This family is composed of a particular association of shells, which appear on one side to be connected with the Ostracea; and on the other to approach the Brachiopoda. They differ from Ostracea in having no hinge or ligament, and only re- semble them in their irregularity and foliaceous struc- ture. The following six genera are placed by Lamarck in this family: —Spherulites, Radiolites, Calceola, Birostrites, Discina, Crania. Of these, Calceola, Dis- cina, and Crania are shewn to belong to the Brachio- poda. 7. Brachiopoda (plates, fig. 201 to 219). The shells of this family are inequivalve, equilateral, and attached to marine bodies by a tendon passing through one of the valves. The animals have, near their mouth, two elon- gated, ciliated arms, which are spirally rolled when at rest. ‘The following genera are enumerated by Lamarck, Orbicula, Terebratula, Lingula. MOLLUSCA. Lamarck applies, or rather restricts, this name to those in- vertebrated animals, which while they are inarticulate in all their parts, have the head sufficiently advanced at the anterior part of the body to be distinguished ; which is not the case with the Conchifera. All the shells are univalve, and are divided into six orders, namely, the Preropopa, which have wing-shaped natatory organs or fins, and have light, thin transparent, nearly symmetrical shells; the Gasrrropopa, with the foot not distinguishable from the rest of the body, E 50 INTRODUCTION. have patelliform, open, and scarcely spiral shells ; the TRACHE- LIPODA with the foot distinct and attached to the neck of the animal, have spiral, non-symmetrical shells. ‘The CEPHALO- Popa, with arms covered by suckers surrounding the head of the animal, have generally symmetrical convolute shells. ‘The Cephalopoda are divided into C. polythalamia, which have the internal cavity divided into chambers by septa, as in the Nautilus ; and the C. Monothalamia, which are not so divided, as the Argonauta. ‘The order Heteropoda contains the genus Carinaria alone. Order Pteropoda. This order,containing hyaline, symmetrical, non-spiral shells, as above described, is not divided into families, but contains the following genera, Hyaleea, Cleodora, Limacina, Cymbulia ; the first of which, although composed of a single piece, resem- bles a bivalve so nearly, that Linneus actually placed it in his genus Anomia. Order Gasteropoda. With the exception of the genus Bulla and Vitrina, the last of which forms a passage into the next order, the shells con- tained in this order are patelliform, open, and scarcely spiral. They are divided into the following families :— 1. Phyllidiana (plates, fig. 227 to 231), containing the genera Chiton, Chitonellus, and Patella, the two former of which present the only exception to the statement above made, that all the shells of Mollusca were uni- valve. 2. Semiphyllidiana (plates, fig. 232 and 233). Of the two genera contained in this family, Pleurobranchus is broad, thin, and slightly spiral at the apex, and Umbrella is flat, circular, with a central apex. INTRODUCTION. 51 a 3. Calyptracea (plates, fig. 234 to 246). The patelliform shells of this family, although united by no other general characters, are brought together by the characters of the animals which produce them. ‘The genera are Parmo- phorus, Kmarginula, Siphonaria, Fissurella, Pileopsis, Calyptraa, Crepidula, Ancylus. 4. Bulleana (plates, fig. 247 to 253), contains the genera Bulla and Bullea. . Aplysiacea (plates, fig. 254 and 255). ‘The genera Aplysia and Dolabella are both expanded, somewhat or flattened shells, with the apex placed at one extremity, and slightly spiral. . Limacinea (fig. 256 to 263). Many of the animals (slugs) are without shells; some, as the Limax, or common i=) garden slug, have a slightly developed calcareous piece, hidden beneath the mantle, and of others the shells are scarcely spiral. The genera included in this family are, Parmacella, Limax, Testacella, Vitrina. Order Trachelipoda. All the remaining spiral non-symmetrical shells are arranged in this order, which is divided into the following families :-— 1. Colimacea (plates, fig. 264 to 307). With the exception of the few contained in the family of Limacina, which ought not to be separated from this order, the whole of the land-shells are contained in this family, and although it is difficult to notice any one character by which terres- trial shells may be distinguished from others, few at all conversant with the subject are liable to mistake them. There is a general lightness and simplicity of form, which, though not clearly definable, is generally under- stood. The following distribution of genera by Lamarck, is generally acknowledged to require numerous modifi- E 2 Or bo INTRODUCTION. cations; the genera are Helix, Carocolla, Anostoma, Helicina, Pupa, Clausilia, Bulinus, Achatina, Succinea, Auricula, Cyclostoma. . Lymneana (plates, fig. 308 to 312). The shells of this family are found in fresh water, wells, ditches, and ponds. ‘They are of a light horny structure, and simple form. ‘The genera Planorbis, Physa, and Lymnea are placed in this family by Lamarck. . Melaniana (plates, fig. 318 to 317). ~These are also found in fresh water, principally in rivers; they are thicker than those of the last family; and the greater part of them have elevated spires composed of numerous whorls. ‘This family contains the genera Melania, Melanopsis, Pirena. . Peristomata (plates, fig 318 to 322). These are also fresh-water shells, having opercula, and covered by a smooth green, or greenish-brown epidermis. ‘They differ from the last family in having the peritreme entire. The genera are Valvata, Paludina, and Ampullaria. . WNeritacea (plates, fig. 323 to 333). The peculiarity of the shells of this family consists in the inner lip being flattened and rather straight at the inner edge. ‘The genera are Navicella, Neritina, Nerita, Natica, and Jan- thina, the last of which forms an exception to the general character, and is placed by De Blainville in a family by itself. . Macrostomata (plates, fig. 334 to 341), so named, on account of the large open aperture which they present in comparison to the spire. ‘The shells of this family, which contains the genera Stomatia, Stomatella, and Haliotis, are pearly within. . Plicacea (plates, fig. 342 to 344), contains the genera Tornatella and Pyramidella. . Scalariana (plates, fig. 345 to 352). The genera Ver- 10. 11. 12. 13. INTRODUCTION. 53 metus, Scalaria and Delphinula, seem to have been placed in this family by Lamarck, on account of the whorls being distinct from each other. . Turbinacea (plates, 353 to 371). The shells contained in this family are all more or less globose, or angular, thickened and pearly within. The following genera are included in this division by Lamarck, Solarium, Rotella, Trochus, Monodonta, Turbo, Planaxis, Phasianella, and Turritella. Canalifera (plates, fig. 872 to 401). The numerous genera of which this family is formed, namely, Ceri- thium, Pleurotoma, Turbinella, Cancellaria, Fasciolaria, Fusus, Pyrula, Ranella, Murex, Triton, are distin- guished by having at the anterior termination of the aperture, a more or less elongated canal. Alate (plates, fig. 402 to 406). These are known by having the outer lip more or less expanded and gene- rally a posterior canal leaning towards the spire. ‘The generaare Rostellaria, Strombus, and Pteroceras. Purpurifera (plates, fig. 407 to 429). In these, the canal, if such it may be called, is extremely short, and. turning abruptly backwards, produces a kind of varix at the lower part of the whorl. The genera enumerated in this family are Cassidaria, Cassis, Ricinula, Purpura, Monoceras, Concholepas, Harpa, Dolium, Buccinum, Eburna, Terebra. Columellata (plates, fig. 430 to 483). The shells of. this family are emarginated at the anterior extremity of the aperture, and the inner lip is characterized by plates or folds, which, with the exception of those on Columbella, are distinct. The genera are Mitra, Voluta, Margi- nella, Volvaria, Columbella, the latter of which would be better placed among the Purpurifera. 54 INTRODUCTION. 14. Convolute (plates, fig. 444 to 462). The well-known shells contained in this family are distinguished for the small proportion of the spire, if any, which remains un- covered by the last whorl. ‘They might be well divided into two groups, the first containing the genera Ovulum and Cyprea, under the name of Cypreade, which are truly convolute, having the spire entirely hidden; and the second containing the genera Oliva, Ancillaria, and Conus. Order Polythalamous, or Chambered Cephalopoda. The greater part of the shells belonging to this order are symmetrical, and the internal cavity is divided into separate compartments, by plates called Septa. It is divided into the. _ following families :— 1. Orthocerata (plates, fig. 463 to 470), containing the genera Belemnites, Orthoceras, Nodosaria, Hippurites, and Conilites. Hippurites certainly has no affinity with the Cephalopoda, but is ascertained to be a bivalve shell, properly belonging to the family Rudistes; the other genera are straight, elongated, and conical. . Lituacea (plates, fig. 471), containing the genera Spirula, Spirulina, and Lituola, the two latter of which are microscopic. bo 3. Cristacea, containing the microscopic genera Renulina, Orbiculina, and Cristellaria. 4, Spherulacea, containing the microscopic genera Miliola, Gyrogona, and Melonia. 5. Radiolacea, containing the microscopic genera Rotalites, Lenticulina, Placentula. 6. Nautilacea (plates, fig. 472 to 476). ‘This family con- tains the following genera—Discorbites, Siderolites, Polystomella, Vorticialis, Nummulites, and Nautilus ; INTRODUCTION. 55 the two latter of which alone are now received in cabinets of shells, the four former belonging to that class of microscopic fossils, now termed Foraminifera ; the genus Nummulites, although large, may probably belong to the same class, and perhaps it would have been better to have included the remaining genus, Nautilus, in the next family, from which it differs in having the septa which divides the chambers simple at their edges. 7, Ammonacea (plates, fig. 477 to 484). The edges of the septa of these are all more or less smuous and com- plicated. ‘This family contains the following genera, Ammonites, Ammonoceras, Baculites, and Turrilites, the latter of which presents a singular anomaly in having an oblique spire, like that of the order Tracheli- poda, while it is divided into chambers by sinuous septa. Order Monothalamous Cephalopoda. The only shells included in this order belong to the genera Argonauta (plates, fig. 485), placed here by Lamarck, and Bellerophon (plates, fig. 486 and 487), a fossil genus subse- quently added. Order Heteropoda. The singular and beautiful transparent shell contained in this order, under the generic name Carinaria, forms a cover- ing to a small portion of an animal, equally remarkable and equally distinct from those of all other orders. The above arrangement, although far from perfect, and requiring numerous modifications, is perhaps liable to as few objections as any other yet proposed, and will certainly be more easily understood by those who have not the opportunity of studying the soft parts of the animal. rete ohbed iss BAL RT OT enti En ORC aa f a cap aiR Ine : CONCHOLOGICAL MANUAL. ABIDA. Leach. A genus founded ona species of Pura, which has the peristome slightly reflected, and numerous plaits in the aperture. Pupa Juniperi, Pupasecale, Draparnaud. Great Britain; also Central and Southern Europe. ABRA. Leach. A genus composed of AMPHIDESMA tenue, pris- maticum, and other small thin species. British Channel and * Mediterranean. Fam. Mactracea. ABSIA. Leach. Lirnorrya, Sowerby. Fam. Pedunculated Cir- ripedes. ACAMAS. Montfort. Brtemnrres multiforatus, Blainville. A species described as being perforated at the apex, by a stellated perforation. No species of Belemnite at present known agreeing with the description ; it is supposed to have been taken from a broken specimen. ACANTHOCHETES. A name given toa species of Chiton having bunches of bristles at the sides of the valves. ACARDO. Commercon. Described from a pair of bony plates, taken from the vertebree of the Whale, and mistaken fora bivalve shell, destitute of a hinge. ACARDO. Swainson. A generic term applied by Swainson to the nearly toothless species of Cardium, named C. edentulum by some authors ; C. Greenlandicum by others: fig. 123*. ACASTA. Leach. Order, Sessile Cirripedes, Lamarck. BaLANus Montagui, Sowerby. A small genus separated from Balanus, on account of the cup-shaped base, but re-united by Sowerby, who shews, in his Genera of Shells, that this is a merely accidental circumstance, resulting from the situations in which the shells ac- quire their growth. If, for instance, the Balanus be attached to 58 ACHATINA. a flat surface, in an open situation, the base will be short and flat; if it be placed in a hollow among other growing substances, it will be lengthened out in order that the aperture of the shell may be even with the outer surface of the surrounding mass ; and if, as in the Acastz, it be imbedded in a soft and loose substance, the base, being left to itself, will take a regular form. The Acastee are found imbedded in sponges. Hz. Balanus Montagui, of Great Britain, fig. 26. Also found in the Pacific ocean and Philippines. ACAVUS. Montfort. Fam. Limacinea, Blainville ; Colimacea, Lamarck. A division of the genus Helix, which may be con- sidered synonymous with De Ferrusac’s sub-genus Helicogena. De Montfort has given H. Heemastoma, asan example. Fig. 267. ACCESSARY VALVES, are the smaller or less important testaceous plates, found on the hinge or dorsal margins of the true valves of some shells. Example, the small plates on the hinge of Pholas, fig. 55, a. ‘The Pholades were placed by Linnzus and Bruguiere among multivalve shells. ACEPHALOPHORA. Blainville. (a, without ; xedade, head.) The third class of the type Malacozoaria, Bl. including all bivalve shells, the animals of which have no distinct head This class corresponds with the Conchifera of Lamarck, and is divided into the orders Palliobranchiata, Rudistes, Lamellibranchiata, and Heterobranchiata, the last of which contains no genera of testa- ceous Mollusca. ACHATINA, Auctorum. Fam. Colimacea, Lam. (from Achates, anagate.) am. Limacinee, Bl. Gen. PouypuHEemus, Montf.— Descr. Shell oval or oblong, sub-turrited, light, thin ; aperture oval, or pyriform; outer lip sharp; columella smooth, tortuous, truncated, so as to form a notch at its union with the outer lip. —Obs. It is from this notch that we are enabled to distinguish Achatinee from Bulini, which, moreover, generally have a reflected outer lip, The Polyphemi of Montfort have an undulation in the centre of the outer lip. Achatina Virginea, fig. 286. Poly- phemus Glans, fig. 288. These land shells are found in various ADESMACEA. a9 parts of the globe, but attain the greatest size and richness of colouring in tropical climates ; particularly in the West India Islands. ACHATINELLA. Sow. A small group of shells, differing from Achatina in having the inner edge of the outer lip thickened, and a slight groove near the suture of the spire. Fig. 287. Sand- wich Islands. ACHELOIS. Montf. Coniuites Achelois. Knorr. Supp. T. 4, fig. 1. ACICULA. Nilson. Acnwatina Acicula, Auct. CIONELLA, Jefireys. ACIONA. Leach. A genus described by De Blainville as consisting of those species of Scalaria, the whorls of which do not touch each other. If this account be correct, the genus proposed by Leach will inelude the typical species of Scalaria, such as S. pretiosa. ACME. Hartmann. A genus formed of Turzo fuscus, Walker. Avricuta lineata, Drap. thus described —‘‘ Shell sub-cylindrical, with a blunt tip; mouth ovate, simple, thin, slightly reflected over the pillar, forming a slight perforation.’’ The animal is said to resemble a Cyclostoma, but has no operculum. Auricula lineata, Drap. Hist. 57, t. 3, fig. 20, 21. Southern Europe. ACTEON. Montf. Tornatexwa, Lam. ACTINOCAMAX. Stokes. A genus of Belemnitiform Fossils. ACULEATED. Beset with sharp spines, as the margin of Chiton aculeatus, fig. 227. ACUMINATED. Terminating in a point, as the apex of Melania subulata, fig. 313. ACUS. Humphrey. Treresra of Lamarck. ACUTE. Sharp, pointed, or sharp-edged. ADDUCTOR MUSCLE. That which draws the two valves of a shell together, and leaves a mark on the inner surface of each, called the MuscuLar Impression. ADELOSINA. D’Orb. A genus of microscopic Foraminifera. ADESMACEA. BI. (a, without; Aecpa, desma, ligament.) The 10th family of the order Lamellibranchiata, Bl. composed of Mollusca which either bore tubular dwellings in rocks, wood, Xe. or live in testaceous tubes, their shells beimg consequently desti- tute of the hinge ligament. ‘The action of opening and shutting 60 AKERA. the valves being limited to the narrow space to which they are confined, or else the valves themselves being soldered into the tube, renders it unnecessary for them to have a ligament to keep them in their places. The genera Pholas, Teredina, Fistulana, and Septaria, belong to this family, which corresponds in part with the families Tubicolaria and Pholadaria, of Lamarck. ADNA. Leach. One of the genera separated by Leach from Pyrgoma, and characterized as consisting of an upper valve, supported on a funnel-shaped base, which is not buried in the coral to which it is attached, like Pyrgoma, but is seen externally. The operculum consists of four valves. Adna, fig. 32. British Channel and Mediterranean. ADNATE. A term applied by some authors to those shells belong- ing to the family of Unionidee, which have the valves. joined together at the dorsal margin, not like other bivalves, by a distinct ligament, but by the substance of the shell itself, the vaives appearing to grow together in such a manner that they cannot be separated without one cf them being broken as will be seen in our figure of Dipsas plicatus, fig. 142. This circumstance has been made the foundation of specific and even generic dis- tinctions, for which however it is insufficient, because many species which when young are ‘‘ adnate,’ when fully grown have their valves joined together only by a ligament. ABGLIA. Say. A division of ‘‘ Unionidee,”’ described as having the ‘¢shell cuneate ; bosses prominent ; cardinal teeth much com- pressed, placed on one side of the bosses. Adglia ovata, Say. Occidens Lea. Am. Tr. ii. pl. 10.” lLardner’s Encyclopedia of Malacology. AGANIDES. Montf. Orsvurres, Lam. AGATHIRSES. Montf. Sirtievarta, Auct. AGINA —-—— ? Belongs to Saxicava, Auct.' AKERA. Bl. The fourth family of the order Monopleurobran- chiata, Bl. containing the genera Bulla, Bullzea and Bellerophon, which, excepting the last, constitutes the family Bulleeana, Lam. AKERA. A genus of extremely light, horny shells, resembling Buuva, from which it differs, in the outer lip being separated AMICULA. 61 from the body whorl, which is elastic. Hv. Bulla fragilis, fig. 247. ALAA. Jeffrey's. A genus of minute land shells, resembling Vertigo, but separated because they are dextral, while Vertigo is sinistral. Hx. fig. 292. A. marginata, Pupa marginata, Drap. found in marshy ground, roots of trees, moss, &c. Britain and Southern and Central Europe. ALASMODON. Say. A division of the genus Unto, Auct. con- sisting of those species which have cardinal, but no lateral teeth. Hv. A. complanatus, fig. 141. North America and Europe. ALATA, Lam. A family of the order Trachelipoda, Lam. con- taining the following genera which may be thus distinguished. 1. RosteLuaria. Sinus close to the canal ; including Hip- pochrenes, and Aporrhais, Fig. 402 to 404. 2. StrromsBus. Sinus not close to the canal. Fig. 406. 3. Preroceras. Same, digitated. Fig. 405. ALATED. (From Ala, a wing.) Winged, a term applied to shells, when any portion of them is spread out in any direction, as in fig. 403. Hippochrenes, Montf. and fig. 147, Unio Alatus. ALCADIA. Gray? (B. M. Syn. p. 134) Helicinze which have a notch in the aperture.. .A distinction which it is impossible to maintain. See HeLicina. ALATUS. Humphrey. Stromsus, Auct. ALECTRION. Montf. Buccinum Papillosum, Auct. fig. 422. ALEPAS. Rang. A genus of Pedunculated Cirripedes without a shell. ALVEOLINA. D’Orbigny. A genus of microscopic Foraminifera. AMALTHUS. Montf. A. margaritaceus, Montf. is a species of AmMonirEs described as very flat, keeled, with an angular aper- ture. It belongs to the family Ammonacea, Lam. AMARULA-—-— ? A genus composed of Mrxania Amarula, Auct. and similar species. AMBIGUA. Lam. The fourth section of the order Conchifera Dimyaria, containing the family Chamacea, fig. 153 to 155. AMICULA. A genus formed for the reception of Cuiron amicu- latus, Auct. the valves of which are covered by an integument ; so as to be completely hidden externally. 62 AMMONOCERATITES. AMIMONUS. Montf. Coninires ungulatus, Knorr. A species distinguished only by being slightly curved ; Mam. Orthocerata, Lam. AMMONACKEA. Bl. The fourth family of the order Polythalamia, Bl. or chambered shells, described as thin, chambered, discoidal, convolute, symmetrical, generally compressed, with visible whorls. This last character is used in De Blainville’s System to dis- tinguish the Ammonacea from the Nautilacea. This family contains the genera Discorbites, Scaphites, Ammonites, and Simplegas. AMMONACEA. Lam. The seventh family of Polythalamous Cephalopoda, Lam. containing the genera Ammonites, Orbulites, Ammonoceras, Turrilites and Baculites, to which may be added Amalthus, Simplegas, Ellipsolites, Nautellipsites, Hamites, Icthy- osarcolites, and other genera mentioned in the list of figures 477 to 484. AMMONITES. Auct. (from Jupiter Ammon.) fam. Ammonacea, Lam. and Bl.— Deser. Symmetrical, convolute, discoidal, orbicular; chambers numerous, divided by lobated, branched or sinuous septa, perforated by a Siphon ; aperture generally more or less modified by the last whorl. The fossils of the secondary strata which compose this genus are numerous and well known ; they are vulgarly termed ‘‘snake-stones,’ and some of them are extremely beautiful, particularly when the internal structure is exhibited by a section. There is some difficulty in distinguishing them from the Fossil Nautili, for although the whorls, being visible and the Septa sinuous, may be taken as the characteristics of the Ammonites, yet there are several species which partake the characters of both. The Orbulites of Lamarck (fig. 479) for instance, have sinuous septa like Ammonites, but the last whorl covers those which precede it as in Nautilus. Simplegas Montf. and Bl (fig. 475) has the whorls visible externally and the septa simple. Ammonites is figured in the plates (478). AMMONOCERAS, © or AMMONOCERATITES. The shells described under this Lamarckian genus present an ¢ Lam. (from Ammon & Kepac, ceras, horn.) AMPLEXUS. 63 anomaly which is considered by Mr.G. B. Sowerby, sen., as merely accidental. They resemble the Ammonites in internal structure, but instead of being spirally convolute they are merely curved like ahorn. zw. fig. 477, copied from De Blainville. AMNICOLA. The name of a genus mentioned in the family of Melaniana in the conchological part of the Synopsis of the British Museum, but unexplained. AMPHIBOLA ———-? The same as Ampuuiartia, Auct. AMPHIBULIMA. Lam. Succinea Patula, Auct. (fig. 266.) was first published in the Ann. du. Mus. D’Hist. Nat. under the name Amphibulima cucullata. The generic name was afterwards aban- doned by its author, and the species stands in his system as Suc- cinea cucullata. West Indies. AMPHIDESMA. Lam. (from Apow, ampho, ambo, Aecpoc, desmos, ligamentum). Fam. Mactracea, Lam.—Descr. Equivalve, oval or rounded, sub-equilateral, sometimes rather gaping at the sides, with slight posterior fold ; hinge with one or two cardinal teeth in each valve, and two elongated lateral teeth, distinct in one valve, nearly obsolete in the other ; ligament short, separated from the cartilage, which is elongated and couched obliquely in an exca- vation of the hinge.—Obs. In most bivalve shells, the cartilage and lgament are unitedin one mass, or placed close to each other; the contrary in this case gives rise to the name, which signifies double ligament. This circumstance distinguishes the genus Amphidesma from Tellina, which in other respects it greatly resembles. From Lutraria it may be known by its distinct lateral teeth, and also by its valves being nearly close all round, while the Lutrarize gape anteriorly. The species do not appear to be numerous, no fossil species are known. A. Reticulatum, fig. 85. West India Islands, Brazil, Coast of Pacific, &c. AMPHIPEPLEA. Nilson. The type of this proposed genus is Limnea glutinosa, Auct. Gray’s edition of Turton, page 243, plate 9. fig. 103. The shellis polished and the inner lip expanded. AMPHISTEGINA. D’Orb. A genus of microscopic Foraminifera. AMPLEXUS. J. Sowerby. A. Corralloides, fig. 463. A singularly formed fossil, described as nearly cylindrical, divided into cham- 64 ANALOGOUS. bers by numerous transverse septa, which embrace each other with reflected margins. It occurs in the Dublin limestone, and re- sembles & coral or madrepore. AMPLEXUS. A generic name proposed by Captain Brown for Heurx pulchella, Drap. 112, tab. 107-134. Zurama, Leach. AMPULLARIA. Auct. (Ampulla, a rounded vessel). Fam. “ Peris- tomiens,” Lam. Ellipsostomata, Bl.—Descr. Spiral, globular, some- times discuidal, frequently umbilicated, covered with a rounded, horny epidermis ; spire short; whorls rapidly enlarging ; aper- ture elliptical, rounded anteriorly ; peristome nearly or quite entire, thickened and slightly reflected ; operculum, testaceous, annular, with a subcentral nucleus. —Obs. This genus of fresh- water shells of which a few fossil species occur, is easily distin- guished from other genera, by obvious characters, particularly by a thick, horny, greenish-brown epidermis, and the rotundity in form. One species, the A. Cornu-arictis which forms the type of Lamarck’s genus I'lanorbis, requires notice on account of its flatness, but may be known by the aperture which in the Ampul- laria is longer than wide, and in Planorbis the contrary. Lanistes, Montf. is described from a reversed species of Ampullaria. The Ampullaria is vulgarly called the Idol Shell, and is said to be held in great veneration by the South American Savages. The animal has a large bag, opening beneath, placed on the side of the res- piratory cavity. It is supposed that the animal has the power of filling this bag with water, and that it is thus enabled to live a long time out of water. They have been brought as far as from Egypt to Paris alive, packed in saw-dust. Ez. fig. 318. East and. West Indies, North Africa, South America, &c. AMPULLARINA UewA genus formed for the reception of AmPpuuuaRIA ayellana. Fig. 538. From Australia. AMPULLINA - ? Part of the genus Hexicrna, Auct. ANALOGOUS. A term applied to certain species of fossil shells, which present a certain degree of resemblance to recent species; but which are not sufficiently similar to warrant the use of the term ‘identical,’ or any other implying that they are of the same species. ANATINA. 65 ANASTOMA or ANOSTOMA. Fischer. (from Ava, ana, back- wards ; Sroya, stoma, mouth) Fam. Colimacea, Lamark. A genus of land shells so named from the singular circumstance of the last whorl taking a sudden turn and reflecting the aperture up- wards, so as to present it on the same plane with the spire; so that the animal walks with the spire of the shell downwards resting on the foot. In other respects, the two species of which this genus is composed, resemble other Helices; and belong to ’ De Ferrusac’s division ‘‘ Helicodonta.’’ Tomogerus is De Mont- fort’s name for this genus. 4. depressum is represented in the plates figs. 271, 272. The nearest approach to this genus will be found in the fossil shell named Strophostoma, by Deshayes, which, however, has no teeth in the aperture and is provided with an operculum like Cyclostoma. South America. ANATIFER. Brug. Anatira, Lam. This name, which signifies Duckbearing, has been given to the shells commonly called Bar- nacles, on account of an absurd notion entertained among the ancients, that they inclose the young of the Barnacle duck, in an embryo state. The beautiful bunch of jointed arms, the ciliz of which serve the purpose of agitating the water, so as to draw in food by the current, were supposed to be the feathers of the future bird. For a description of these shells, see PenTE- LASMIs ; and fig. 34. ANATINA. Lam. (That which belongs to a duck) Fam. Myaria, Lam. Pyloridea, Bl.—Deser. Thin, transparent, generally equi- valve, inequilateral, transverse, marine; hinge with a spoon- shaped process in each valve, containing the cartilage.—Obs. Some species included in the genus Anatina of authors, A. striata, for instance, have not the spoon-shaped prominence, but in its place a small, testaceous, moving appendage, connected with the interior of the hinge. These are now separated, and form the genus Lyonsia. The genus Neara, Gray, is composed of Anatina longirostrum, and similar species, which have neither the bony appendage nor the spoon-shaped prominence. Mya is distin- guished from Anatina, by the thickness of the shell, and also by having the prominence only in the hinge of one valve. Fig. 69. F 66 ANCULOSA. A. rostrata. The Anatinze are found in the East Indies and South Sea Islands. ANATINELLA. G. B. Sowerby. (Dimunition of Anatina). A genus so named from its resemblance to Anatina, from which it differs in being destitute of the internal appendage, and having no sinus in the palleal impression. One species having been brought from Ceylon, received the name of Anatinella Sibbaldii. Another has lately been found in the Philippine Islands. Fig. 70. ANATOMUS. Montf. Tom. 2, plate 279. A microscopic shell, appearing from the figure to resemble ScisSURELLA. ANAULAX. Brogn. Anciutarta, Auct. ANCILLA. Lam. Awncriiuarta, Auct. ANCILLARIA.