ae ae, Sa It oer ea ae : ne ee es ‘ o*. < * == ae Sen x a a > = SS et - <- _ * “i ang ee Fa RO aD ‘ as SOLAS ee GG, wt F Fog | YX QE (316 Emst Mayr Library CoLy © jmmeuen of Compare’ Hecuard Uneven any HARVARD UNIVERSITY LIBRARY OF THE DEPARTMENT OF MOLLUSKS IN THE MUSEUM OF COMPARATIVE ZOOLOGY Gift of: RICHARD |. JOHNSON : i f ' > & A » Vere, 4 ir eae ase q "he if ; OAD) F i it TPES, Ss \ vay Pt { ; : i ae 5 if ‘a8 ? r , : i , ce » ,t Al, ' ‘ ’ ® F | 4 % HA “d . ; ‘ : 1 a . { aa + ; | : ; eg OPH Ns * / H om a Pe a, ae a i ay P f A SSAC ARNOT OL 22 | Ur ato rs be tig oh Ma i” + /) | P ] Oa Pp ch ‘ I}, ! ] oy’ ’ , i ' } a ' 1 2 5 4 7 ' S ’ ' | ! i eu U 1 t id t ; ‘ el : —D WEN ak ae 4 ' \' Wg: | % 4 ws , ’ f ’ | M ah 1]; a i i mm 0 Fit Ca . or R a nit yen ivy a iu | (tee! mo - aot oo? ae ip i : . ak ii ey i a i} i ae a 1 ? FF 7: i) di W , 1 gee aa t i) \ i 7p 7 Uf) : i Uy ; ‘Al ij y : : I =, A ; sa, | Pen) fl tt arts ft ; mi ane i 1 a iy we: ‘ io i ‘a i} iy : au i 1) uy a i nM 1 iat i 7 ‘dal ; I i! Jj ; i i f { mt are 0 ii U a ; i J =e i i! hy 1 _ : ’ 1 ioe / ; ii! : ae . iat gt Th! i ei) ro i j i I 4 1 y 7 i i el f ; i i 1 : y 1 : ’ ia tt iM { i i u : i i} i ; ; i I i I tpt i , il i i 1 ’ 1 ) : i i J Y ; i 1 7! i! a 1 4 i ri i y 1 iV ! La i i ot et it ; le a 7 i! i i u ie 1 ie fa an 1 , / 1 i : ' \ ny : i! To! H i : mit) evr ti (ty } in i ms f 1 ot i i i iI it a i I ee ae 1 J : ll u 1 i 1 , i i i 1 u j ery Pw ey iS Mo llusk dept Rec. RICHARD J, JOHNSON 1a)iegs THE ELEMENTS OF , CONCHOLOGY: OR NATURAL HISTORY OF SHELLS: ACCORDING TO Che Linnean Spstem, WITH OBSERVATIONS ON MODERN ARRANGEMENTS. BY THOMAS BROWN, ESQ. Captain Forfar Regt. Fellow of the Linnean Society, Member of the Wernerian Natural History Society, Member of the Kirwanian Society of Dublin, and Honorary Member of the Literary and Philosophical Society of Bolton ' > Mlustrated wae nine Engravings. P —a SRD SASS London: PRINTED FOR LACKINGTON, ALLEN, & CO. FINSBURY SQUARE ; LONGMAN, HURST, REES, ORME, AND BROWN, PATER- NOSTER ROW ; JOHN MURRAY, ALBEMARLE STREET 5 ARCHIBALD CONSTABLE AND CO. EDINBURGH 3 AND JOHN CUMMING, ORMOND QUAY, DUBLIN. J, Gleave, Printer. 1816, * aS gee SRO ae ae (eae il sega, ye De sel pono pa de ae ee: 7 TAMAR vieadolt Ae} Leben adele et 92 (“WONG Bhnony re : wal aang eds Ia radon, yy ssisng ARIE: hao hs: wattst tanh shits h aisrie rt ie Aaa eaildyd Ty Madi? cre Oe addy do ga bio Ios Tiarieg >, Oy i. laa 1 pne en Day dealt j 5 “aap spesae hes yeep ay a aha tinh ca em rest. pac re La Re OU ¥¢ ae eee hs Pe paysiyuyy L yais a ig Wathntctth = } ie “ Capes ae” Aaa ‘siodyo.t Se WOE Ve Rago® PN IAAMTE OAR hOrdn, wera AS 20% Gent nH +r as Ode GON rio aa Pan veh Ge ; wy Ba iAl's Une ee A BIA ak PAN AO. 2 WO ATE” isthe a BAGo? Gis Be iwcanes Pe ey ee FAUT GUE NO On Mah ID Hikad dite i Madore aaa Shake pri we. nt So Ob T - ~ i TO SIR JAMES EDWARD SMITH, M.D. F.R.S. PRESIDENT OF THE LINNEAN SOCIETY, Sc. §e. Fe. THE FOLLOWING WORK Is INSCRIBED, WITH ESTEEM AND RESPECT, BY HIS MOST OBEDIENT, HUMBLE SERVANT, The Author. Vga yids Shon FY ‘Sava a | mH eh eh MPROVR peter By Tp, yw oe yah Mee depseri Fina Danis. OO Rage ibang 2): NMRA eS gin aney who: ; vs Aaa BR oS Aisiniseser ware Pike AR Aaliaha te: | , amabe eich: MAA 88 Sarto ty ii > Sh AROVPS BREW ORDO: ta we olan wi Sally “Ne RE NO ik ek ee ee re | cy hae ee an + de ante: utes eye ere eee (ORR yosiak Naver leigh, Atos ashlee Mvigpinat om Mot © oso egret arin ei “4 , Saesseatet oe “ae ‘et eda ah Oe ay sinsiogas ar | ee aban pens chika Lali ionis acieiane * sl Sah ATOY: Siro wal Hae teritoet wie , eh She “ff we er ee a et, % ee dee eee, eh “Asta : aie bie ae patch ‘hear ey” coon: 2 = “shoe Hy) eh er ayes ~ . Z ES NC ae Phas / Pen nine v preface. THE intention of the following work is to lay be- fore the student, in the simplest style, the Linnean arrangement of shells, The author was induced to undertake this simple work, because there was no elementary book on shells in the English language, with the exception of Da Casta’s, whose arrangement is now generally exploded. The work now presented to the public is strictly according to the Linnean System. Several attempts have been made, to overturn the Linnean arrangement of shells, but without effect. And with all its pretended faults no one has been able to supercede it, by a better system. That it is not so complete as the other departments, most people are ready to allow; but its beauties must perpetuate ats pre-eminence. In describing the genera, the author has also pointed out the different alterations of modern ar- vangements, (particularly that of Lamarck ;) and the new genera which they have formed, And it has been his object to illustrate the work, as far as it was possible, by figures of British shells; which will facilitate the study of British Testaceology, and prove equally useful to the study of General Con- chology, * 2p PPD til hf poy yi ree, ay oleae wh Fats arias, oy eos we AY Le Sian ‘atesaih ad ae vilqgnda Olt nt _dubbuta oft we Bytes 11 SEA NSA tusaitogmn ty Sa aa! ay ieee ob Heawbix eos voRlun sh i Qa Rae Ais Hoh wanton’ oot iar oe | oy ale SAN ati oaigntnatny bit irae lle aioe “anor 2h! twemergnivey onan Oe ol Pee ying: hy oh Bolesentg, soit Anon WL. Lgholagea : Be 3s : dt? nbdariht Sai of ‘gaithoin whist ons oft scopbesdocot: shane: stad seni senses iy: | aai Ry atbiiey: Seb alla#s Yo: temo ee : tind ea gee) te abo holiestgnay: at Vy Nite Ra Si re amt ee ab $F oN orenteya. seating A, M ahivassagee of shia | ada sg, ‘vaoure alow venashy sativa silt ety Stalginds 8: SoH) Bee i) bs apni Sen sions Wits “Siells bs Sal WG: Raine i.) | bya oe Sse a am he y fal’ ai” no sane? "ant “ag “oy ‘Shithoat's Pi . ~us; awa Fo anatewess ‘hovel: s chy ie ‘Haken St Wa bi Godot, ey! a Adiplua ign », PSO AME wis avid TY Ow ‘lah Av’ Ssh git Apis ‘M LW wise s et as. Fat a to ost SAY ‘shusiah a Ass. ony 1 a Was Koik 2 Ulla Rakiy ae ye ae WS es ce een ald i ay Ae groovin’ re Wi OCS ws pit: a ahh one i Greist rN sala a oy wegen ‘oe sce Bis idence ee tone F ; F Ps ’ CONTENTS. Page [INTRODUCTION to the science........scsee0eeeereee 1 The animals which have been discovered to inha- Dit sible sé 203262.02" Asad tamicd Meets cece emenes 6 Explanation of the parts of shells. Multivalve........... ee a 0 vibtbe's bate uae semeviaito'e 13 Baler ses cc dceidessee seewsionsaee dea ducoaee eat cenatnad aes 15 Univalve..... eesnreahes ersleia cate a ate doit stale Sralainielaleinae eta e etaie 24, Of genera. Order Ist. Multivalve shells,........ceesceee: satiate) Lo Did EIVAIUE SHBIIS Monae ceoassocceksteentecesesoes 47 —— 3rd. Univalve shells with a regular spire.... 65 Division 2nd. Shells without a regular spire....... 90 Specific description of the plates. Plate 1st. Multivalve shells.......... encxemisteasretdy 98 Bivalvia! SONG cs. ccscaeasuae scaicswsatquaneen 102 9ds, Bivalveshelis. diss odeices cececvordsapeccnes 105 Univalve shellsyiiis. ucsiasedoaeeewaccntws 109 me SIU. lee eee eeee maintotelotie aeimelclatelelete aelelscaeldstlsitehiacisinee FL CONTENTS. To illustrate the genera. Plate 5th. Multivalve shells.............+4 Peewee o GRE Bivalve shells........ eee eee iene blabieros lean ib wa Oth. cveccececdsscevesesceess covsvns PRs ccpaeeyasnnas ib —— 7th. ......006. sesceccecee veveecceecesers decscneeenes 122 Univalve shells.......... Sele P esioeab esta des i ——— Bt. occ ceceeees sae “SBOE EE aep edna eote nes ib a OE. crn nreseccesvecreececsnesesacsscreeccccoeeroeees 123 List of the principal books which treat of Con- CHOLOBY, da nnesisernns ty acpi PPP EER a Ae PE eee 124 Method of cleaning sheils........sscccsseceeseeeeverers 1 129 Simple method of arranging cabinets............... 138 Explanation of terms used in the science of Con- GHOLOSY 0.200002 sceennsessertutoscecess suena venehusas 139 THE ELEMENTS OF CONCHOLOGY. —aea SO) E———- CONCHOLOGY, is the science by which shells, or testaceous bodies, are properly arranged into systematic order. On the face of our globe, the num- ber of Natural Bodies, is so immense, that, on a general view, the human mind recoils from the investigation of them as impossible. But since the invention of systems, the task now appears at once practicable; and, indeed, every object can be traced, with certainty and facility, to its pro- per place in the System of Nature. B 9 THE ELEMENTS In common language, the System of Nature has been divided into three kingdoms, viz. the Animal, Vegetable, and Mineral. 'That the young stu- dent may more easily understand the meaning of the classes, orders, &c. into which these three kingdoms are divided, we shall compare A Class to an Army ; An Order to a Regiment; A Genus to a Company ; And a Species to a Soldier. When we find a natural body, we must first refer it to a class in the system of Nature, then to an order, next to a genus, and then we endea- vour to ascertain its species. All natural bodies, which agree in every particular, or essential pro- perty, are considered of the same species; for example, all dogs are specifically the same, but the diffe- rence between the hyena, wolf, fox, (though of the same genus as the dog Canis of Linné) and the pointer and : OF CONCHOLOGY. 3 spaniel, is so great as to constitute them of a different species; as is the bull-dog, mastiff, terrier, &c. Dogs taken generally form a genus. So it is with all natural bodies. A plurality of species, constitutes a genus; and many genera, consti- tutes an order; and several orders, a class; and a variety of classes, a kingdom. The term Conchology includes all animals which have a_ testaceous covering, whether they inhabit the sea, land, or fresh-water. By chemical analysis testaceous bo- dies have been found to consist of, carbonate of lime, mixed with gelati- nous matter. Chemists have divided shells into two classes. The first are usually of a compact texture, resembling porce- Jain, and have an enamelled surface, and are in general beautifully varie- gated. Those composing this class 4 THE ELEMENTS | are called porcelanaceous shells. To this class belong various species of conus, cypreea, voluta, &e. The second class consists of shells generally covered with. a strong epi- dermis or skin, below which lies the shell in layers, and composed entirely of the substance well known by the name of mother-of-pearl. In this class are the fresh-water muscles, (the my- tilus cygneus and anatinus of Linné), the haliotts iris. (called the ear-shell), the turbo olearus, and several of the trochus tribe, &c. The porcelaneous. shells, contain a very small portion of soft animal mat- ter; and those of the second class a very large proportion.* It must be clearly understood, that, all shellfish are not included in the science of Testaceology.; The crabs, * See Thomson’s System of Chemistry, vol. v. page 507, &c. + Testaceology, is a modern term for the Natural History of shells, and synonymous with Conchology. OF CONCHOLOGY. a lobsters, sea-urchins, &c. are of the crustaceous order. They differ in their composition from the testacea, the calcareous part of their shell being phosphate of lime, in place of the carbonate of lime. The crustacea differ from the testa- cea in a still more striking point of view: it is well known that crabs, lobsters, &c. cast their shell or eover- ing annually; whereas the testaceous worms retain it as long as they exist. Besides the shells of crustaceous ani- mals, seem to grow all at once ; those of testaceous, evidently are made by the animal, gradually adding to them either annually or at least periodically ; as may be distinctly seen in the com- mon muscle; and all shells are com- posed of layers, which is not the case with crabs, &c. This may be easily proved by taking a shell and filing it slowly, when the different layers are very perceptible; or put a muscle- 6 THE ELEMENTS shell into the fire, it will begin to crackle and divide in separate layers. We have numberless instances of shells, both sea and land, which have been broken, and are firmly mended by the animal; and in almost every collection specimens of mended shells may be found. Shells are only the habitation of soft animals called vermes, or worms, and are the third order of Linneeus’s sixth class of animals. The animals which have been dis- covered to inhabit shells, are ten: 1. Limax, 6. Nereis, 2. Doris, 7. Ascidea, 3. Spio, 8. Tethys, 4. Amphitrite, 9. Triton, 5. Terebella, 10. Sepia. Ist. LIMAX. Body oblong, creeping, with a fleshy kind of shield above, and a lon- gitudinal flat disk beneath; aperture OF CONCHOLOGY. 7 placed. on the right side, within the shield ; feelers four, situate above the mouth, and an eye at the tip of each of the largest ones. This genus is what is generally termed the slug, or snail. 2nd. DORIS. Body, creeping, oblong, and flat beneath ; mouth placed helo: on the fore-part; vent behind, on the back, and surrounded by a fringe; feelers, two and four, seated on the upper part of the body in front, and retrac- tile within their probu receptacles. 3d. SPIO. Body projecting from a tube, joint- ed and furnished with dorsal fibres ; peduncles, or feet, rough with bristles and placed towards the back ; feelers two, long, simple; eyes two, oblong. 8 THE ELEMENTS 4th. AMPHITRITE. Body projecting from a tube and annulate; peduncles, or feet, small, numerous ; feelers two, approximate, feathered ; no eyes. 5th. TEREBELLA. Body oblong, creeping, naked, often inclosed in a tube, furnished with lateral fascicles, or tufts, and branchiz ; mouth placed before, fur- nished with lips without teeth, and protuding a clevate proboscis ; feelers numerous, ciliate, capellary, seated round the mouth. 6th. NEREIS. Body \ong, creeping, with nume- rous lateral peduncles, or feet, on each side; feelers simple, rarely wanting none ; eyes two or four, rarely none. 7th. ASCIDIA. Body fixed, roundish, and appa- rently issuing from a sheath; aper- OF CONCHOLOGY. 9 tures two, generally placed near the upper end, one beneath the other. 8th. 'TETHYS. Body detached, rather oblong, fleshy without peduncles ; mouth with a terminal cylindrical proboscis, under an expanded membrane or lip; aper- tures two, on the left side of the neck. 9th. TRITON. Body oblong ; mouth with an invo- lute spiral proboscis; tentacula, or arms, twelve, six on each side, divided nearly to the base, the hind-ones che- liferous. 10th. SEPIA. Body fleshy, receiving the breast in a sheath, with a tubular aperture at its base ; arms eight, beset with nu- merous warts or suckers, and in most species two pedunculated tentacula ; head short; eyes large; mouth re- sembling a Parrot’s beak. c 10 THE ELEMENTS It is upon the exclusive shape of the shell, and not the animal-inhabi- tant, that the arrangement of Concho- logy is formed. In early periods, naturalists were in much doubt whether to construct the arrangement from the animal, or the shells; and at last it was deter- mined, for the best of reasons, that it should be the latter. Of the great quantities of shells found, how few have had the animal in them? indeed, there are hundreds we shall never be able to ascertain. The greater part of shells in collections, have been found upon the beach, without the animal in them, which have been cast ashore by the agitation of the sea in storms, &c. | Most shells are very different. in their young and adult state, both in form and colour; the student ought, therefore, to make himself well ac- quainted with the generic characters, OF CONCHOLOGY. Lg. to enable him to discriminate the dif- ference. But, indeed, this is often a difficult matter, even to those who have studied the science for many years. In almost all the cypraea, there is considerable difficulty in distinguish- ing them from the voluta, in their young state. The denticulated lip being the last part of the shell which the animal forms. The strombus ge- nus want the expanded lip in the young shell, from which circum- stance it is frequently taken for the bucecinum and murex. The Linnean arrangement of shells, consists of three orders, viz. MMulte- valve, Bivalve, and Univalve. The first order, maultivalve, are shells consisting of more parts than two. Every part of a shell which is connected by a cartilage, ligament, hinge, or teeth, is called a valve of such shell. _. The second order, d¢valve,are shells 12 THE ELEMENTS of two parts or valves, generally con- nected by a cartilage; for example, the cockie and muscle. The third order, wniévalee, consists of shells complete in one piece ; for example, the periwinkle and whelk. This order is subdivided: first, into those with a regular spire, and those without a spire. The first order consists of three genera: Chiton, Lepas, and Pholas. The second order consists of twelve genera: Mya, Solen, Tellina, Cardium, Mactra, Donax, Venus, Spondylus, Chama, Arca, Ostrea, Anomia, My- tilus, Pinna. The third order consists of nineteen genera: Argonauta, Nautilus, Conus, Cyprea, Bulla, Voluta, Buccinum, Strombus, Murex, 'Trochus, Turbo, Helix, Nerita, Haliotis, Patella, Den- talium, Serpula, Teredo, and Sabella. It will now be proper before pro- ceeding to a detail of the Linnean OF CONCHOLOGY. 18 genera, to make the student ac- quainted with the terms used in Tes- taceology, as far as regards the dif- erent parts of shells. EXPLANATION OF THE PARTS OF SHELLS. os MULTIVALVE. Operculum is four small valves on the summit of the lepas, which how- ever is in a certain degree stationary ; and different from the operculum of univalve shells, which will hereafter be described. See plate Ist, fig. Ist, A. Base is that part of the shell by which it is fixed to rocks and other bodies ; plate Ist, figures Ist and 2d, BB B.----H isa piece of stone to which 14 THE ELEMENTS the base is fixed, and G a piece of wood to which the shells of this sec- tion are generally affixed. Ligament is the substance by which the valves or parts of the shell are connected. Some multivalve shells are connected, by the parts of one valve looking into another. Plate Ist, fig. 2d, DDD. Ridges are those cavities in many of the lepas tribe, sometimes lon- gitudinal and sometimes transverse. Plate Ist, fig. Ist, FF. Pedunele.. A sort of stem by which the shells of the second division of lepas are attached to wood, &c. Itis a kind of membranaceous substance, similar to a bladder but materially thinner, and filled with a liquid which evidently affords nourishment to the animal. Plate Ist, fig. 2d,CC. G a plece of wood to which the peduncle is affixed. OF CONCHOLOGY. 15 Feelers are those crenated arms, evolved from the side of the lepas ana- tifera, and other shells of the second division of lepas. While the animal is in the water it continually moves its feelers, evidently for the purpose of entangling minute marine insects, for food. Plate Ist, fig. 2d, EE. BIVALVE. Bivalve shells, consist of two parts or valves, connected by a cartilage, and hinge which is generally com- posed of teeth, those of the one valve looking into a cavity in the other. The valves of some bivalve shells, are formed exactly alike; and others, are very different; the one of some being smooth, the other rugose; one flat, and another convex; and often one is shorter than the other. The shells of the mya, solen, tellina, venus, &c. have in general both valves alike, while those of the spondylus, 16 THE ELEMENTS ostrea, anomia, and pinna, have in general dissimilar valves. The first of these ‘kinds are called equivalve, and the latter inequivalve. Equilateral shells are those whose sides are alike, as in the shells of ostrea, commonly termed scallop- shells in England, or those shells. worn by pilgrims in former times ; “ Aud fix’d the scallop on his hat before.” PARNELL. This is also exemplified in the Arca Glycimeris and Pilosa of Lin- neus. Inequilateral valves are shells whose sides are unequal ; and are of different shapes, as in the mactra, donax, &e. Sumnut is the most elevated point of that part of the shell in which the hinge is placed ; plate Ist, fig. 4 & 8, aa. In naming this the summit, we do not follow the axiom of Linnzeus, but that of a modern author whose autho- OF CONCHOLOGY. a rity we value; and because we consi- der it more properly the summit of the shell, than the opposite extremity. Base, is the reverse of the above, or that part of the shell immediately opposite the summit. Plate Ist, figrs. 6th and 7th, dd. Sides, the right and left parts of the valves; plate Ist, fig. 6th, c. Anterior slope, is that part of the shell in which the ligament is situated. In viewing the anterior slope in front, the beaks of the shell retire from view. Plate Ist, fig. 4th, ¢. Posterior slope, that part of the shell opposite the anterior slope; in viewing it in front, the beaks point to you. Plate Ist, fig. 4th, 4. Disk, the convex centre of a valve, or most prominent part of the valve, suppose it with its inside lying under- most. Plate Ist, fiz. 4th, o. Inside, the concave part of a valve. Plate 4th, fig. 6th, 2. “D 18 THE ELEMENTS Cicatrix, or Tongue, is the impres- sion left on the inside of the valves, by the adhering muscles of the animal. It differs in most shells, according to the shape of the muscle, and is either semi-ovate, round, lunate, elongated, &e. It is often of great use in distin- guishing a species; being, with a very few exceptions, alike in shells of the same species. Some shells have only one cicatrix, as the edible oyster, and muscle; others have two, and some few more ; the Tellina Fusta for exam- ple. Plate Ist, figures 6 and 8, eeee. Lumule. The lunated depressions, situated in the anterior and posterior slopes. In different species of the Venus they are prominent, character- istic marks, often of much service in ascertaining a species. Plate Ist. fig. 4th, 66. Ligament perforation. 'The cir- eular aperture, or perforation, through which the ligament passes ; by which OF CONCHOLOGY. 19 _ the animal of the anomia attaches it- self to stones, and other marine ex- traneous bodies ; it is in general situ- ated in the flat valve, though there are afew exceptions to the contrary. Plate Ist, fig. 7th, m. Hinge, is the point by which bivalve shell are united, it is formed by the teeth of the one valve inserting them- selves between those of the other, or by the teeth of one valve fitting into the cavities or sockets of the opposite valve. It is on the peculiar construction of the hinge that the generic character of Bivalve shells is principally founded, together with the general contour of the shell. Plate 2nd, figures Ist and 3d, 994. Teeth of the Hinge. Upon the number and relative situation of the teeth, principally depend the specific distinctions ; they are of various forms, and very differently placed ; 20 THE ELEMENTS some are single and large, others numerous and small, orbicular, spatuli- form, laminated, &c. Some hinges have no visible teeth, and are termed anarticulate ;* those with few teeth are termed articulate ;} and those with many teeth maltiarticulate.{ Plate Ist, figures 6th and 8th, g g g g. Primary Teeth, are those teeth in general about the centre of the hinge, and are for the most part broad, large, and distinct, and often elevated ; and in general are inserted in a cavity in the opposite valve. They however differ very much in some shells, but may easily be distinguished. Plate Ath, figures Ist, 3d and 7th, aaaaa. Lateral Teeth, are teeth which di- verge from the umbo, and are in gene- ral long and flat, often double, and divided by a groove or hollow. Plate * When a primary tooth has a groove or hollow in its cen- tre, it is called complicated. Plate 4th, fig. 6th, e. t Plate 4th, figures istand12th. + Plate 4th, figures 2nd, Sd, 4th,&c. § Plate 4th, fig. 10th. OF CONCHOLOGY. 21 Ath, figures 2nd, 4th, 6th and 7th, bbb 6. Double Teeth, plate Ath, fig. 1st, ec. - Incurved Teeth are those which are bent round, as in the single tooth of the Solen Siliqua. Plate 4th, fig. 8th, Middle Teeth. Plate 4th, fig. 4th. dd. Numerous Teeth, are those small teeth, of which the hinges of all the Arca are formed, set in rows. Plate Ath, fig. 10th, kk. Cavity of the Hinge. The hollow depression in which the ligament of the Ostrea is situated, generally of a triangular form. Plate 4th, fig. 11th, 2. Ligament of the Hinge, or carti- lage, is that flexible fibrous substance by which the valves are united, and the hinges kept in their proper places; always situated near the beak. Plate 2nd, figures Ist, 3d and 4th, ///; plate 4th, fig. 3d, x. 22 THE ELEMENTS Beak is the extreme point of the summit of bivalves, which for the most part points downwards, or to the one side, as in most species of Venus, &c. Plate 2nd, fig. 5th, rr. . Seam. When the valves are closed, the line between them is so called. Plate 2nd, fig. 6th, ¢ . Umbo. ‘That place situated imme- diately under the beak. Plate Ist, fig. 6th, w ;. and plate 2nd, fig. 4th, w. Kars. Two processes on each side of the beak, in most of that division of Ostrea, called seallops; some have one ear very large, and the other small; and some are searcely observ- able on one side. Plate 2nd, fig. 2nd, Ah. Superior Ear. Plate 4th, fig. 11th, A. Inferior Ear. Do. do. 7. Margin, or Limb. The extreme edge of the whole shell, or either valve, allround. Plate Ist, fig. 4th, p : and plate 2nd, fig. Ist, p. OF CONCHOLOGY. 23 Crenulated margin. 'That fine saw- like edge of most of the cockles, which unite into the notch in the opposite valve. It is by no means uncommon in other shells, particularly the Donax. Plate 4th, fig. 6th, mm. Stri@ are fine thread-like lines, eene- rally on the exterior surface of shells, and is sometimes both longitudinal and transverse, and likewise oblique. In some instances the insides of shells are striated; for example, the Murex Tulipa. It is often of much use in distinguishing species. Plate 2nd, fig. 2nd, f/f. Right Valve is that valve which, when viewed with the inside towards you, the anterior slope points to your right hand. Plate Ist, fig. 8th; and plate 4th, figures 5th and 6th, B. Left Valve. The opposite of the above; the anterior slope points to the left hand, when viewed from the 24 THE ELEMENTS inside. Plate 4th, figures 3d, 6th, 7th, 9th, &e. Length of the Shell is taken from the ligament, or the beak, to the opposite margin. Plate Ist, fig. 5th; and plate 2nd, fig. 4th, www wu. Breadth is measured from the most extreme edge of the anterior and posterior slopes, being in a contrary direction from its length. Many shells are broader than long, such as most of the Myze, Solina, Tellina, &c.; and the Mytilus, Ostrea, Pinna, &c. are in general longer than broad. Plate Ist, fig. 5th; plate 2nd, fie. 4th, veve. Byssus, or beard, is an appendage composed of filaments of a silky tex- ture, by which some of the Bivalves fasten themselves to their beds, such as the muscle. Plate 2nd, fig. 6th, s. UNIVALVE. The shells composing this order, are far more numerous than the two OF CONCHOLOGY. 25 preceding, both in genera and spe- cies; and it requires a considerable degree of attention, to discriminate many of the species, as they run into each other so much; and of many of the species there are several varieties. It is by the general outline that the shells of this order are distinguished, together with the formation of the spire, and aperture ; from their having a canal or gutter, the pillar-lip, and the outer-lip being expanded, together with the notches, &c. on the outer surface; the colours also, are of ser- vice in describing species, though it cannot in all cases be depended on, many of them being subject to great variety. Linnzeus divides his Order Univalve into two sections, turbinated shells within a regular spire, and those with- out any regular spire. Apex. The summit or highest part of the spire. Plate 2nd, 4 AA. E 26 THE ELEMENTS . Base is the opposite extremity from the apex, or tip of the spire. In shells with a beak or rostrum, it implies the tip of such beak ; plate 2nd, fig. 11th, B. In shells without a beak, it is understood to be the lower part, as before-mentioned, opposite the apex ; plate 2nd, figures 8th and 9th, BB. In the patella dentalium and teredo, and some others, the base of the shell is that part on which it rests when it is laid on its mouth. Body of the shell. The first or lower whorl of the spire, which is, in gene- ral, longer than the remaining whorls ; and often, the difference is much greater. Plate 2nd, figures 10th and 12th, FF’; and plate 3d, figures 7th and 9th, EVP. Front of the shell, is when the aper- ture faces the observer. Plate 2nd, fig. 7th, Z; and plate 3d, fig. 8th, i. . Back is when the aperture is turned OF CONCHOLOGY. 27 directly from the observer. Plate 3d, figures 5th and 10th, & G. The venter, or belly, is the most prominent part of the lower whorl or body, and generally situated in the vicinity of the lip; and formed by the convexity of the aperture. It is in general only made use of in describing shells, whose body is large in propor- tion to the spire. Plate 3d, figures dth and 10th, H #7. Sides. The extreme edges of the shell, either viewed from the front or back. Plate2nd,fig.11th,kAkkhkkkke : Aperture, or mouth, is that part of the lower whorl, by which the animal protudes itself. This is one of the principal generic distinctions of Unt- valve shells, and differs very much in shape; some apertures being rounded, others semilunar, angular, &c. Plate 2nd, figures 9th and 11th, CC; and * Right side is when the shell is viewed in front, that side next the observer's left hand. Left side, the side with the aperture in it. 28 THE ELEMENTS plate 3d, figures Ist, 3d and 14th, CCC. Canal, or gutter, is a continuation of the aperture, of those shells with a beak, in which it forms a concave gut- ter, running from its commencement in the aperture, to the extremity. Plate 2nd, figures 10th and 11th, Q@ Q; plate 3d, fig. 8th, Q. Beak, or rostrum, is that lengthened process in which the canal is situate ; it commences a little higher up, on the outside, than the insertion of the ca- nal in the inside, which is always dis- tinctly marked by the line of the aper- ture, Plate 2nd, fig. llth, P. Pillar, or columella, is that process which runs through the centre of the shell in the inside, from the base to the apex in most univalve shells, and appears to be the support of the spire ; and, indeed, seems to form that part of the shell; it is in general grooved or folded, and various other shapes ; OF CONCHOLOGY. 29 but, as it is situated in the interior of the shell, a minute description is un- necessary. Plate 2nd, figures 10th and 12th, M@MMMM; and plate 3d, fig. 9th, MM M. Pillar Lip is a continuation of the glossy process with which the aper- ture is lined, expanded on the colu- mella. Plate 3d, figures 7th and 8th, 00. Outer Lip. The expansion, or continuation of the body of the shell, on the left margin of the aperture, and is also lined with the glossy pro- cess of the aperture. Plate 2nd, fig. 7th, N; and plate 3d, fig. 8th, WN NN. The latter is an example of the alated or winged shells. Plaited Columella are those folds, or plaits, which are the distinguishing characteristic of the Voluta genus, Plate 2nd, fig. 7th, z. Operculum, or id. This is only an appendage to the turbinated or spiral 30 THE ELEMENTS shells, affixed to the animal, some- times of a testaceous, in others a car- tilaginous substance. It is. only cal- culated for the protection of the ani- mal, when it retires within its dwell- ing, of which it may be termed its door, and is adapted to the shape of the aperture, which it closes nicely up. Every one must have observed the cartilaginous operculum of the common periwinkle, (the Turbo Litto ratus of Linné,) which has a brown horny appearance, and must in gene- ral be removed, before the animal can be taken out when boiled. Plate 3d, fig. 4th. Spore is all the whorls of the shell, except the lower one, which, as before observed, is termed the body of the shell. Plate 2nd, fig. 12th, D; and plate 3d, figures 7th and 8th, D D. ‘The spire is a prominent feature of the Univalve ; and upon its being ele- vated, depressed, &c. depends much OF CONCHOLOGY OL. of the generic and specific . definition. Adamson in his ‘ Natural History of Senegal,’ printed at Paris, in 1757, says that the external character of the spire, varies according to the plane they turn upon, which, he observes, is either horizontal, cylindrical, conic or ovoid. At the same time, he admits that there are a great many interme- diate forms, which cannot properly be defined. It is a remarkable circumstance, that. many of the young shells, have not the same number of wreaths as the adults; from which circumstance it would appear, that the part of the animal nearest the apex, never in- creases in size. The number of wreaths cannot, at all times, be de- pended upon. - Whorl is one of the wreaths or volutions of the shell. Plate 2nd, fig. 8th, Z; and plate 3d, fig. 10th, ZL. Depressed Spire is when the spire By4 THE ELEMENTS’ is very flat. Plate 2nd, fig. 12th, D; and plate 3d, fig. 5th, 8. Involuted Spire, those shells which have their whorls, or wreaths, con- cealed in the inside of the first whorl or body, as in some of the Nautilus and Cypraxa. Plate 8d, fig. 3d, 7’; plate 7th, fig. 19th; and plate 8th, fig. 21. Suture of the Spire, or whorls, is a fine spiral line, which separates the wreaths or whorls; it is sometimes erenulated, in others sulcated, &c. Reversed, or Heterostrophe Spire. As Mr. Montagu’s definition of a re- versed shell is very distinct, and easily understood, I shall here extract it. “Every Conchologist knows, that most convoluted shells turn one way, and that there are few species which are heterochitical, or invariably turn contrary to the usual manner. Some indeed have doubted, whether this is a permanent character; there OF CONCHOLOGY. os requires, however, no argument to prove it is so, to those who have taken the trouble to examine the common species of heterostrophe shells, which daily present themselves to our notice in Our rural walks. Indeed, it is ra- ther strange that no one of these shells, whose nature is to have their spires turn in the more unusual man- ner, has (to our knowledge) even been met with to vary from that formation ; as such accidental deformities have been found, in a few instances, amongst those which are usually termed dexte- rals, or have the more usual spiral turns, and have become lusus heteros- érophon shells. “In order, therefore, to explain which way the turn of the spiral con- volutions of a reversed shell takes, omitting the vague signification of turning to the right or left, we shall observe, that the more common turn of shells is with me apparent motion o4 THE ELEMENTS of the sun, or as the index or hand of a clock moves. ‘But in order to be more clearly understood, let us compare the spiral volutions of a shell to a common cork- screw, and we shall find that whether the mouth, or apex, is placed up- wards, the spires will turn from the upper to the lower end like acommon screw, which is in the same direction as the index of a timepiece, and what is commonly understood by a dextral or right-handed screw. As a fur- ther definition, such shells have their aperture on the right side, when examined with that end downward ; and is in the direction of the sun’s apparent motion.* * That different authors have described both sides of the shell as the right, is very clear; but it appears to me, Mr. Mon- tagu has himself run into a mistake, concerning the right and left sides of the shell; and I have termed that side of the shell with the aperture in it, when viewed in front, the left side ; contrary to Mr. Montagu. It is admitted by most Concholo- gists, that the apex or tip of the spire, is the top of the shell, and the lower region, in which the aperture is situate, is the OF CONCHOLOGY. 39 “On the contrary, a reversed shell when placed in a perpendicular posi- tion, has its spiral volutions in an opposite direction to the motion of the index of a watch, or a clock, or to a common screw ; and, in fact, resem- bles what is usually termed a sinistral, or left-handed serew. These have their aperture on the left side, or op- posite the left hand of the person, holding the shell with the mouth downward ; and the opening is oppo- site the sun’s apparent motion. Plate 3d, fig. 13th. base or bottom. It is also admitted, that when the shell is placed en its base, with the aperture facing the observer, that this is termed the front—plate 3d, figures 7th and 8th, &c. ; and that placed with the aperture from the observer, it is called the back—plate 3d, figures 9th and 10th. When all this is admitted, it appears to me that the side in which the aper- ture is situated, is unequivocally the le/t side, and the opposite extreme the right. Surely if a man is placed on his feet, with another facing him, the one could not call the side fronting his right side, the right side of him opposite. If any thing, whatever it may be, has a top, base, and proper front, it must also have a proper right and left side; and what I have de- scribed as such, I think will be found to be so. 26 THE ELEMENTS “In order to determine whether a flat shell, whose volutions are laterally placed, is a reversed species, we have only to examine which way the volu- tions turn from the apex, or the centre, towards the mouth; and if we find it contrary to the motion of the index of a watch, it is a heterostrophe, or revers- ed shell; and vice versa.” A flat shell is figured in plate 3d, fig. 14th. : “In some of the more depressed species of Helix, or Nautilus, atten- tion is requisite to be paid to the mouth, in order to determine which is really the upper side of the shell, for it is on that side the spiral turns are to be taken from the centre or apex ; and, in most instances, this is to be determined by the oblique direction of the aperture to the under part, where the lip rarely extends so far as on the upper part. In fixed shells, such as Serpula, there is no difficulty, OF CONCHOLOGY. 8 ¥ | as the side which is sess¢/e must be considered as the base, or under part. Thus in the Serpula Lucidu the fixed part is sometimes very small, and the mouth protends spirally upwards, in a contrary direction to the sun; and therefore must be considered a re- versed or heierostrophe shell, the same as if the volutions nearest the mouth had turned laterally upon the centre or fixed ones. This shell, indeed, is most frequently found with regular lateral volutions ; and though subject to great variety, with respect to con- tortions, it invariably turns the aper- ture one way. “ In some species of Nautilus, how- ever, there can be no rule to ascertain whether it is dextral or sinistral; for when the aperture is exactly lateral, the lip collapses the body equally, and the sides of the shell similar, as in the Natilus Caicar, it cannot be defined. In others of that genus, asin NV. Bec- 30 THE ELEMENTS carit and Seccarit perversus, two shells, the principal distinction of which, is the contrary turn of their volutions, it is easily determined, by the convexity of the upper side; and of course, the aperture being piaced somewhat beneath.” Testacea ri- tannica, page 352, &c. Chambers are the divisions formed by partitions, at regular intervals; as in the Nautilus. Plate 3d, fig. 11th, wwww W. In some of the Serpula there are also divisions, but they are not regular as the preceding; and they differ from the Nautilus, in wanting. a Siphuncu- lus or communication between the chambers; the animal forms a com- plete partition and adds to its shell, which it would appear to be necessi- tated to do, from its body growing too large for its abode. Several of the Patella genus, have. chambers of a laminiform, subspiral, OF CONCHOLOGY. 39 or other form. Plate 3d, fig. 6th, VV. Umbilicus is in general a circular perforation, in the base of the lower whorl, or body, of many univalves ; and common to most of the Trochi, in some of which it runs from the base to the apex; widest at the base, and gradually tapering to the top. Plate 3d, fig. Ist, U. Sub-umbilicated shells, are those which have the umbilicus covered ina greater or less degree by a thin pro- cess; which, in some, almost entirely closes the opening or mouth. Shells which have no umbilicus are termed emperforate. Siphunculus is that small round perforation which forms a communi- cation between the chambers of the Nautil!, which runs through the whole spire of the shell. Plate 3d, fig. 11th, V. Ribs are those longitudinal protu- berances which are in many of the 40 THE ELEMENTS univalve shells. Plate 3d, fig. 12th, RRRR. Teeth of univalves, according to Mr. Montagu, are not properly den- ticles, or tooth-shape protuberances, but are fine white /amine, or ridges, running spirally backwards, in a pa- rallel direction to each other; those on the exterior lip may, in most in- stances, be traced through the outside of the shell, and are nearly alike in length. Plate 3d, fig. 13th, a. Hpidermis is a skin, or cuticle, with which the exterior surface of many of the univalve and bivalve sheils are covered ; and it is destined by nature to protect the surface of their shells from being injured. It is membrana- ceous, or similar to the periosteum, which covers the bones of animals. This skin seems to be formed entirely by the animal, and is uniformly ob- served in some species, and not at all in others; but those shells with a OF CONCHOLOGY. 4i rugged surface have almost always this epidermis. In some it ts lami- nated, velvety, fibrous or rough, and in others very thin and pellucid, and admits the colours of the shell to shine through it. Although many shells are very beautiful, even with this cuticle on them, they are much more so when it is removed; but I would by no means advise the collector of shells to remove it, unless he may have several specimens of the same shell; and then he may do it by way of variety ; but it is always preferable to keep them ina state of nature. All other protuberances, furrows, &e. will be described at the end of the work, in the Glossary of Terms used in the Science. | A shell with epidermis is repre- sented in plate 3d, X ; and the eflect of the epidermis removed at J. G 42 THE ELEMENTS. The next thing to be taken into consideration, is the genera compos- ing the three orders of shells. ee ee OF GENERA. ORDER FIRST. MULTIVALVE SHELLS. Animals soft, of a simple structure, and covered with a calcareous habita- tion or shell. Genus Ist.---CHITON. Animal in- habiting the shell a Doris; shedl con- sisting of several segments or valves, placed transversely on the back of the animal, and lying upon each other at their anterior edge. Linnean Syst. No. 300. OF CONCHOLOGY. 43 The animals of this genus adhere to rocks and stones, in general near low water mark, and are, at first view, very like an oniscus. Plate 5th, fig. Ist. Habitation. The Chitons have only been found to inhabit the ocean. In Turton’s Linné 28 species of Chitons are described. Seven species have been discovered in the British seas. Genus 2nd.---LEPAS. Animal a Triton; shell affixed at the base, and consisting of many unequal erect valves. Linn. Syst. No. 301. The Lepas are termed acorn shells in England. This genus consists of two families or divisions, very different in their form. The first of which is the balanz, or acorn shells, of a sub- conic form, with an operculum or lid, consisting of either four or six valves. The body of the shell has six valves. Plate 5th, fig. 2nd; and plate Ist, fig. 44 THE ELEMENTS Ist. The second family is the anati- ferous, or goose-bearing shells, as they are called, which is connected to, and supported at the base by a tendinous tube or pedicle, which being of a flex- ible nature, allows the animal to writhe about.in quest of food; it has no oper- culum, is wedge-shaped, and consists of five or more unequal valves. Plate Ist, fig. 2nd. Mr. Montagu in his Testacea Bri- fannica, made those two families into two distinct genera. It is singular Linné should have arranged shells so very dissimilar in.the same genus. Habitation. ‘The Lepas have only been found to inhabit the ocean. The shells of this genus adhere in clusters to rocks, shells, floating wood, and other extraneous substances, and being incapable of changing place, are supposed to be true hermaphro- dites. In Turton’s Linné thirty-two. spe- OF CONCHOLOGY. 45 cies of this genus are described ; fif- teen species have been discovered in the British seas. Genus 3d.--PHOLAS. Animal an Ascidea; sheli bivalve, divaricate, with several lesser, differently shaped, ac- cessory ones, at the hinge; hinges recurved, united by a cartilage; in the inside, beneath the hinge, is an in- curved tooth. Linn. Syst. 302. Plate doth, fig. 3d. Habitation. Pholades are found below high water-mark, burrowed in hard clay, lime-stone, or sometimes free-stone, and also wood, which they perforate in their younger state, and as they increase in size enlarge their habitation. The phosphorescent properties of the Pholades are very remarkable ; it contains a liquor which shines with uncommon splendour in the dark, and illuminates whatever it touches, or happens to fall upon. See Memoirs of the French Academy, 1712. 46 THE ELEMENTS ‘There is a remarkable shell-fish called Pholes, which forms for itself holes in different kinds of stone. This fish illuminates the mouth of the person who eats it; and it is remark- ed, that contrary to the nature of other fish, which give light when they tend to putrescence, this is more luminous the fresher it is; and when dried, its light will revive on being moistened either with salt water or fresh ; brandy however immediately extinguishes it.” Priestly’s Optics, page 567. It is to be regretted, that the expe- riments made by chemists on those animals, which have a luminous ap- pearance in the dark, have not been sufficiently decisive, to enable us to state the true cause of it; but it undoubtedly proceeds from phospho- rus, which is abundant in all animal bodies. In Turton’s Linné twelve species are described; five have been found to inhabit the British coasts. OF CONCHOLOGY. 47 ORDER SECOND. BIVALVE SHELLS. Genus 4th.---MYA. Animal an As- cidia; shell bivalve, generally gaping at one end; hinge with broad, thick, strong, patulous tooth, seldom more than one, and not inserted in the oppo- site valve. Linn. Syst. 303. Plate dth, fig. Ath. Habitation. 'The Mye are to be fouad both in the sea and in rivers. The marine kinds generally live under sand or sludge, and the place where they lie is betrayed by a small hole, out of which they occasionally protude their proboscis. ‘Those which inhabit rivers, are generally found in the mud at its bottom. In some places the animals are used for food; but what makes them of considerable import- 48 THE ELEMENTS ance is, the quantity of pearls which they sometimes produce. We are told by Camden, for the value of the — pearls produced by the Mya Mar- gratifera, that Six John Hawkins had a patent for fishing for that shell in the river Irt in Cumberland. The French naturalists divide this genus into three distinct genera: Mya, Glycimeris, and Vulsella. In Turton’s Linné twenty-six species are described; and fourteen have been ascertained to inhabit Great Britain. Genus 5th.--SOLEN. Animal an Ascidia; shell bivalve, oblong, open at both ends; henge with a subulate re- flected tooth, often double, and not inserted in the opposite valve. ann. Syst. 304. Plate Sth, fig. 5th. Razor shell. Habitation. The Solens have only been found to inhabit the ocean ; they are generally found, buried about six inches deep, in the sand; their resi- OF CONCHOLOGY. 49 dence is known by a small dimple on the surface. In some places they are used as food. } The French naturalists have divided the Solens into three distinct genera : Solen, Sanguinalaria, and Corbula. In Turton’s Linné twenty-three spe- cies are described; eleven species have been ascertained as British. Genus 6th.---TELLINA. Animal a Tethys; shell bivalve, generally slop- ing on one side; in the fore-part of one valve a convex, of the other a concave fold; hénge with usually three teeth, the lateral ones smooth on one side. Lann. Syst. 305. Plate 5th, fig. 6th. There are three families of the Tel- line : ovate and thickish,* ovate and compressed,** suborbicular.*** Habitation. The Tellinz are found to inhabit the ocean, rivers and lakes. Those of the ocean lie buried in the sludge, near the shore, and make two H 50 THE ELEMENTS apertures in the sand; when the tide has receded, they may be easily found by looking for these marks. The French writers have divided the Tellina into three genera: Tellina, Cyclus, and Pandora. In Turton’s Linné ninety-four spe- cies are described: twenty-two spe- cies have been discovered in Britain. Genus 7th.---CARDIUM, (acockle.) Animala'Tethys; shell bivalve, nearly equilateral, equivalve, generally con- vex, longitudinally ribbed, striate or grooved, the margin dentated ; hinge with two alternate teeth in the mid- dle, near the beak; one of them com- monly incurved; and larger remote lateral teeth on one side, each looking into the opposite. ann. Syst. 306. Plate 5th, fig. 7th. Habitation. The Cardium, with the exception of one species, have only been found to inhabit the ocean ; this species, the Cardium Fluviatile, has OF CONCHOLOGY. dbl been found, sparingly, at the mouth of the Tees in Yorkshire. Cockles, in general, live just under the surface of the sand, barely covered ; they are necessitated to be near the surface, from the shortness of their tube, by which they draw in and throw out the water. The French have divided the Car- dium into three genera: Cardium, Bucarde, and Cordiformes. In 'Turton’s Linné fifty-two species are described; fifteen species have been found in Great Britain. Genus 8th.----MACTRA. Animal a Tethys; shell bivalve, with unequal sides, equivalve ; middle tooth of the hinge complicated, with a small hol- low on each side, lateral teeth, remote, and inserted into each other. Sinn. Syst. 307. Plate 6th, fig. 8th. Habitation. Shells of this genus have only been found to inhabit the ocean. These shells lurk in the sand 62 THE ELEMENTS or sludge, most commonly at the mouths of rivers, or near them. The French naturalists divide the Mactra into two genera: Mactra and Lutraria. In Turton’s Linné twenty-seven species are described ; twelve have been discovered in the British seas. Genus 9th.---DONAX. Animal a Tethys; shell bivalve, with generally a crenulate margin, the frontal margin very obtuse; henge with two teeth, and a single marginal one placed a little behind, rarely double, triple or none. Linn. Syst. 308. Plate 6th, fig. Sth. The shells of this genus are in ge- neral triangular, inequilateral, flatten- ed, treuncated before, and wedge- shaped. Habitation. The Donax has only been found to inhabit the ocean; lurking in the sand of the shore, and OF CONCHOLOGY. 53 may be found on the reflux of the tide. In Turton’s Linné nineteen of this genus are described ; and six species have been found in the British seas. The French conchologists have di- vided this genus into two: Donax and Petricola. Genus 10th.--VENUS. Animala Tethys ; shell bivalve, the frontal mar- gin flattened, with incumbent lips; hinge with three teeth, all of them approximate, the lateral ones diver- gent at the tip. Linn. Syst. 309. Plate 6th, fig. 10th. This genus is divided into two sec- tions: pubentes* and impuberes.** This latter section is divided into three families: subcordatz,} orbiculate,}+: and ovalis.;}; Dr. Turton has not followed Linné in the above arrangement, but has divided them into three sections; A somewhat heart-shaped, B orbicular, 54 THE ELEMENTS C oval, alittle angular near the beaks. Habitation. 'The shells of this ge- | nus have only been found to inhabit the ocean. They in general lurk in the sand; and many of the larger spe- cies are only to be found in very deep water. The shells composing this numerous tribe, are perhaps the most elegant, and beautifully diversified, of all the bivalve shells. In Turton’s Linné, no Jess than 154 species are described ; and 25 species have been discovered to inhabit the seas around Great Britain. Genus Iith--SPONDYLUS. Ani- mala'Vethys: shell hard, solid, and ridged, with unequal valves; one valve in general convex, and the other ra- ther flat: Ainge with two recurved teeth, separated by a small hollow. finn. Syst. 310. Plate 6th, fig. 11th. flabitation. This genus has only been found to inhabit the ocean. They OF CONCHOLOGY. 55 adhere to rocks in deep water, and require considerable force to tear them from their retreats. Some of the Spondyli have ears, and others not; they are in general strong, rugose shells. ‘This genus re- quires considerable attention, as some of the species vary exceedingly, so much so that many have been taken for distinct species. The French writers divide the Spon- dyli into two genera: Spondylus, and Plicatula. The valves of the last are in general rude, thick, uneven, and uncouth. In Turton’s Linné only four spe- cies are described ; no species of this genus have been found to inhabit the British seas. Genus 12th.---CHAMA. Animala Tethys; shell bivalve, rather coarse ; hinge with a callous gibbosity, ob- liquely inserted into an oblique cavity ; 56 THE ELEMENTS anterior slope closed. Linn. Syst. 311. Plate 6th, fig. 12th. . Habitation. The shells of this ge- nus have only been found to inhabit the ocean ; they live only in very deep water. The Chama Gigas is the largest and heaviest shell yet discovered, be- ing sometimes of the amazing weight of 532 pounds, and the animal inhabi- tant so large as to furnish one hun- dred and twenty-two men with a meal ; and is said to be very palatable: and such is its strength that it is able to cut asunder a ship’s cable. This spe- cies inhabits the Indian Ocean. The French writers divide this ge- nus into five, Chama, Tridacna, Hip- possus, Cardita, and Isocardia. In Turton’s Linné twenty-five spe- cies are described. Only one of this genus has been found in the British seas, the Chama Cor, discovered by Captain Laskey, off St. Abb’s-head in OF CONCHOLOGY. 57 Scotland. To that gentleman the British Conchologist is indebted for the discovery of many new species. Genus 13th---ARCA. Animal a Tethys; shell bivalve, equivalve; hinge with numerous sharp teeth, alternately inserted between each other. Zann. Syst. 312. Plate 6th, fig. 13th. Linné divides this genus into two families: *with the margin entire ; **with margin crenulated; and has subdivided each into two sections, Ttbeaks recurved; and {t{beaks in- flected. Habitation. Some of the Area are affixed by the foot of the animal to rocks ; and others lurk in the sand or mud near the shore, generally be- tween high and low water mark. The Arca have only been found to inhabit the ocean. This genus takes its name from the strong resemblance the Arca Noe, and some others, 4 to the hull of a 58 THE ELEMENTS vessel when the valves are united. Many of the Arks are, however, void of this character, but are sufficiently united to the genus, by the number and construction of their teeth. The French Conchologists have made two genera of the Arca: Arca and Nuclia. The Arca Now is an example of the former, and the Arca Nucleus of the latter. In Turton’s Linné forty-two species are described; and six species have been found on the British shores. Genus 14th.--OSTREA, (or oyster.) Animala Tethys: shell bivalve, gene- rally with unequal valves, and slightly eared ; hinge without teeth, but fur- nished with an ovate hollow, and mostly lateral transverse grooves. Linn. Syst. 313. Plate 7th, fig. 14th. The Ostrea is divided into three families: *valves radiated and eared, as in scallops ; “rugged or rough, as in the oyster; ““hinge with a perpen- OF CONCHOLOGY. 59 dicular furrowed line, as in the spe- cies of Perna. The first family is again subdivided into three sections: {valves equilateral, and ears equal; }fears unequal, and having one of them generally ciliated with spires within ; Titvalves gibbous on one side. Habitation. The Ostrea have only been found in the ocean; some lurk in the sand in large beds, others ad- here to rocks, and some to trees on the shores of the West Indies, &e. The Ostrea might with great pro- priety be divided into two species, scallops and oysters, as those sections are yery dissimilar. The French Naturalists have formed this genus into seven: Ostrea, Pec- ten, Malleus, Perna, Lima, Pedum, and Gryphus. In Turton’s Linné 137 species are described; nine species are found in the British seas. 60 | THE ELEMENTS Most of the foreign, and a few of the British Pectens, are very beauti- | ful shells. Genus L5th.---ANOMIA. Animal an emarginate ciliate strap-shaped body, with bristles or fringe affixed to the upper-valve ; arms two, linear longer than the body, connivent pro- jecting, alternate on the valve and ciliate on each side, the fringe affixed to each valve; shell bivalve, inequi- valve, one of the valves flattish, the other gibbous at the base with a pro- duced beak, generally curved over the hinge; one of the valves often perforated near the base ; Aznge with a linear prominent cicatrix and a late- ral tooth placed within, but in the flat valve on the very margin; two bony rays for the base of the animal. Lann. Syst. 314. Plate 7th, fig. 15th. Habitation. The Anomia have on- ly been found to inhabit the ocean. The animal attaches itself to fuci, OF CONCHOLOGY. 6) shells, stones, and other extraneous bodies at the bottom of the sea: they are generally affixed by a ligament which passes through the perforation in the flat valve. A species called the Squamula is often found adhering to the Pecten Opercularis, and is very common at Aberlady Bay in Scotland ; it resembles the seale of a fish, and partakes of the form of the furrows and strie of the Ostrea, which makes it very beautiful. Lamarck has divided the Anomia into three genera: Anomia, Calceola, and Crania. ; The Anomia Sandalium of Linné, is an example of the Calceola, and the Anomia Craniolaris of the Crania. In Turton’s Linné fifty-one species are described ; and six have been dis- covered on the British shores. Genus 16th.---MYTILUS, (or mus- cle.) Animal allied to an Aseidia ; shell bivalve, rough, generally affixed 62 THE ELEMENTS by a byssus or beard of silky filaments ; hinge mostly without teeth, with gene- rally a subulate, excavated, longitudi- nal line. Linn. Syst. 315. Plate 7th, fig. 16th. The Linnean Mytili are divided into three families: *Parasitici, &c. parasi- tical, affixed as it were by claws, as exemplified in the Mytilus Cristi Galli; **Plani, &e. flat or compressed into a flattened form, and slightly eared; as in the Mytilus Margratiferus; ***Ven- tricosiusculi, &c. ventricose or convex, as in Mytilus Edulhs. Habitation. The Mytili are found to inhabit the ocean, lakes, rivers and ponds. Marine Muscles adhere to rocks or beds by a thin byssus, and some to the Gorgoniz by claws. Some penetrate calcareous rocks, &c. where. they reside without changing place, some of them adhere to rocks on the shore, and are either used for bait or food, and as such they are esteemed OF CONCHOLOGY. 63 by many; but it is dangerous to eat plentifully of them, unless they are known to be wholesome, as many of them produce very bad effects after they are taken into the stomach. The fresh water muscles are generally found on the surface, or a little way under the mud. Some muscles pro- duce pearls. Lamarck divides this genus into three species: Mytilus, Modiolus, and Anodonta. ) In Turton’s Linné sixty-four species are described; and thirteen have been found to inhabit the seas, lakes, &c. of Great Britain. Genus 17th.---PINNA. Animal a Limax; sheli sub-bivalve, fragil, up- right, gaping at one end, and fur- nished with a byssus or beard: hinge without teeth, the valves united into one. nnn. Syst. 316. Plate 7th. fig. 17th. 64 THE ELEMENTS Fiabitation. The Pinnz, which fre- quently grow to a large size, are only found to inhabit the ocean. They are generally found standing erect in the smoother water bays, with the broad end or base of the shell uppermost. And they are sometimes found affixed by their byssus to rocks. In Italy the byssus of the Pinna is woven into a sort of silk. The fibres or filaments of which it is composed, are very tough, and of a fine glossy brown colour. The ancient Romans highly esteemed articles made of this byssus; and at Naples and Palermo there are still manufactories of it. This genus forms an excellent inter- mediate link between the bivalve and univalve shells, being in truth what Linné defines it---a sub-bivalve shell ; it being immoveably fixed, by a calca- reous process, at the hinge. | The Pinnee are wedge-shaped shells, or somewhat of a triangular form, id " OF CONCHOLOGY. 65 widening from the top, which is nar- row and pointed, to the base which is wide and extended. In Turton’s Linné eighteen species of Pinne are described; and three only have been found to inhabit the British seas. ORDER THIRD. UNIVALVE SHELLS With a regular Spire. Genus 18th.--ARGONAUTA. Anz- mala Sepia or Clio; shell univalve, spiral, involute, membranaceous, and unilocular, or consisting of a single apartment or cell. Zann Syst. 317. Plate 7th, fig. 18th. Habitation. The Argonaute have only been found g inhabit the ocean, 66 THE ELEMENTS and are found among the rocks near the shore, in the Mediterranean and | Indian Ocean. The Argonauta argo is the Nauti- lus so famous amongst the ancients, and often mentioned in the writings of Pliny and others. I[t-is supposed that in the earliest ages of society, this shell suggested to men the first idea of using sails. In calm weather it rises to the surface of the water, (which it does by discharging a quan- tity of fluid, that rendered it specifi- cally heavier than the sea-water,) and spreads its arms ever the shell, which answer the purpose of oars; it then throws out and expands a double membrane, which it can oblique in any direction at pleasure, this answers the purpose of a sail, and by this it is im- pelled forward by the breeze, like a ship under sail; two of its arms hang over the shell, and serve as rudders or oars, to direct its course. In the OF CONCHOLOGY. 67 event of danger it immediately with- draws within its cell, and sinks to the bottom. Lamarck proposes two distinct ge- nera of the Argonauta. The first is exemplified by the Argonauta Argo of Linné; the second is constituted by the Argonauta Vitreus of Gmelin, and he terms it Carinaria. It is some- what remarkable, that the great Linné should have been completely at a loss where to place this shell; and in the twelfth edition of the Systema Natu- re, we find it placed among the Pi- tillee, under the title of Patella Cristata, to which tribe it bears no resemblance. It was by Gmelin, with more propri- ety placed among the Argonauta; but even in this situation it seems mis- placed, and I concur with Lamarck in the propriety of forming a new genus with it. Lamarck terms it the Carinaria. 68 THE ELEMENTS In Turton’s Linné five species of this genus are described; none of which have been found to inhabit the British seas. Genus 19th.---NAUTILUS. 90 THE ELEMENTS DIVISION SECOND. Shells without a regular sptre. Genus 32nd.---PATELLA. Animal a Limax; shell univalye, subconic, shaped like a bason; without a spire. Linn. Syst. 331. Plate 9th, fig. 32. Linné divides this genus into five families : *Labiate, &c. furnished with an internal lip; shell entire; **Den- tate, Kc. with the margin angular or irregularly toothed ; ***Mucronate, &e. with a pointed recurved tip or crown; ****Integerrime, &c. very entire, and not pointed at the tip or vertex ; *****Perforate, &c. with the crown perforated. Habitation. 'This tribe of shells have been found to inhabit the sea, lakes, and rivers. Those of the sea in general adhere to rocks and stones OF CONCHOLOGY. 91 on the shore; and are so tenacious, that they cannot be removed without breaking the shell, unless taken by surprise. Those inhabiting fresh wa- ter are generally found adhering to aquatic plants. The Patelle are called limpets in England. The Patella is a very good genus, though there are several authors who dispute this point. We cannot see that the distinctive characters Lamarck has chosen, are sufficient reason for the formation of new genera; their division into sections appears to us quite sufficient ; for with the excep- tion of the chambered limpets, they are all perfectly simple shells, and very like each other. . Lamarck forms the Patellz into six genera: Patella, Fissurella, Emargi- nula, Concholepas, Crepidula, and Calyptrza. 7 In Turton’s Linné no less than 240 species of Limpets are described ; 92 THE ELEMENTS and fourteen species have been ascer- tained to be indigenous to Britain. Genus 33d.--DENTALIUM. Ani- mala 'Terebella; shell univalve, tubu- lar, straight or slightly curved, with cavity undivided, and open at both ends. Linn. Sysi. 332. Plate 9th, fio. 33d. Habitation. ‘The shells of this ge- nus are only found to inhabit the ocean. ‘They are solitary, and are to be found immersed in the mud, in an oblique or perpendicular position.--- And the shores are those which have flat extended beaches, and on which a quantity of seft mud is collected, commonly known by the name of sludge. This genus is unquestionably simple, and very distinct and perfect. Continental Testaceclogists have also endeavoured to overturn this genus, but without effect. It is defined with too much precision and simplicity to’ be altered. OF CONCHOLOGY 95 The shells of this genus are known in England by the name of tooth-shells, or sea teeth. In Turton’s Linné 22 species of Dentalium are described ; and seven have been found to inhabit the British coasts. Genus 34th.---SERPULA.