Animal. Soft, inarticulated, always fixed in a bivalve shell, without head or eyes, having the mouth naked, concealed, and without any hard parts; a large mantle enveloping the whole of the body, forming two laminiform lobes; the edges detached or sometimes united in front. Gills or respiratory organs external, situated on each side between the body and the mantle; circulation simple, the heart with one ventricle; some few ganglions of the different nerves, but no knotted medullary cord.
Shell. Always bivalve, enveloping the animal entirely or partially, sometimes free, sometimes affixed; the valves most frequently united on one side by a hinge or ligament. Sometimes attached to the shell are testaceous accessory pieces. Twenty families.
Animal. Entirely unknown.
Shell. Oval, somewhat elongated, striated longitudinally, conic, club-shaped, having two valves incrusted on one side of the club, open at its attenuated extremity, and terminated at the other by a convex disk, pierced by a number of small perforations, and encircled by a dilated margin of papyraceous tubes, resembling a plaited ruff—smaller extremity always open. This is a well known, but rare shell, found in sandy places in low water in the Indian ocean. Four species.
Animal. Unknown.
Shell. A tubular sheath, testaceous, attenuated, and open before; terminating posteriorly in an oval, sub-compressed club, roughened by spiniform tubes—one valve fixed in the side of the club, the other free in the tube. Inhabits the Indian seas. Four species.
Animal. Provided with two protuberant calcareous tubes, covering parts of its body at the open end of the tube, each of which is terminated with from five to eight cup-shaped calcareous or corneous appendages. It inhabits the sand, and perforates wood, stones, and sometimes shells.
Shell. Lamarck asserts that the tube and shell of this genus are quite distinct. They have the shell free and detached within the sheath, and neither of the valves fixed into the partition of the tube, which is most generally testaceous, closed, and retort-shaped at the posterior extremity. Inhabits the Indian seas. Four species.
Animal. Unknown.
Shell. A very long testaceous tube, gradually attenuated to its upper end, and divided internally by vaulted divisions seldom complete, the extremity of which is terminated by two slender tubes without interior partitions. Specimens of this genus have been found five feet long. Found in sand on the shores of the Indian seas. Two species.
A fossil genus; consisting of a testaceous cylindrical sheath, the posterior extremity closed, and exhibiting the two valves of the shell it encloses; the anterior end open. Two fossil species.
Animal. Body very much elongated, vermiform: mantle very fine, tubular, opening only at front and below for the issue of a teat-shaped foot; mouth small; very short, distinct tubes; the inferior or respiratory one somewhat larger than the superior; labial appendages short and striated; branchiæ very long, narrow, united, and prolonged throughout the extent of the tubular cavity of the mantle; only one large contractile muscle between the valves; at the point of junction of the mantle and tubes is a muscular ring, in which is implanted a pair of corneo-calcareous appendages.
Shell. Thick, solid, very short or annular, open before and behind; valves equal, equilateral, angular and trenchant before, only touching each other by the opposite edges; no hinge; a considerable spoon-like cavity; only one feeble muscular impression. Tube more or less distinct from the substance in which the animal lives, cylindrical, straight or winding, and closing with age at the buccal extremity so as to envelope the animal and its shell; at the other end it is always open, and divided internally into two syphons by a partition in the middle. Inhabits the European seas in timber. Three species.
Animal. Without a tubular sheath, projecting anteriorly into two united tubes, frequently surrounded by a common skin, and the posterior extremity provided with a short muscular foot, flattened at its extremity.
Shell. Multivalve, equivalve, transverse, gaping at both ends, with various accessory pieces either on the hinge or below it. Inhabits the Indian seas and American shores. Eighteen species.
Animal. Unknown.
Always without accessory pieces, therefore easily distinguished from the Pholas.
Shell. Equivalve, somewhat cuneiform with a very large oval and oblique aperture anteriorly; posterior extremity nearly closed; hinge linear; marginal and without teeth. Three species.
Animal. Body cylindroid, much elongated; the mantle in form of a canal open at both ends, closed in the rest of its extent by a thick epidermis which surrounds it; a cylindroid anterior foot.
Shell. Equivalve, extremely inequilateral, the summits very small, and entirely at the commencement of the dorsal line; one or two teeth in the hinge. Inhabits the seas of America and Europe. Twenty-one species.
Animal. Unknown.
The situation of the ligament, and the prominency of the apex, are the characters which distinguish it from the Mya.
Shell. Regular oval, elongated, gaping at both ends, equivalve, inequilateral; summit little marked and anterodorsal; hinge complete; similen formed by a conical primary tooth, before a short, compressed, ascending callosity, ligament exterior, attached to the callosity; two muscular impressions. Inhabits the Mediterranean Sea. One species.
Animal. Unknown.
Shell. Oval, elongated, equivalve, subequilateral, with edges nearly straight and parallel, the extremities equally rounded, and, as it were, truncated; summits but little marked; hinge without teeth, or formed by some rudimentary primary teeth, ligament projecting, affixed to thickened callosities; two distinct rounded muscular impressions.—Mediterranean Sea and coasts of America. Ten species.
Animal. Unknown.
The few species of this genus yet known have been blended, by previous authors, either with the Mya or Solen, but from either they are easily distinguished.
Shell. Covered with epidermis, slightly irregular, elongated, gaping at both ends, equivalve, exceedingly inequilateral; summits little marked; hinge toothless; a longitudinal callosity. Ligament exterior, affixed to very projecting callosities on the shortest side of the shell; two distinct muscular impressions. Inhabits the North seas. Two species.
Animal. Subcylindrical, enveloped in a mantle pierced only with one interior and inferior hole for the passage of a very small and conical foot; the tubes very considerable, and completely united; a tolerably large mouth, oval, and with simple lips; very small labial appendages: branchial laminæ inconsiderable; the external very short, the internal united with that of the opposite side.
Shell. Surrounded with a thick epidermis, which is prolonged upon the tubes and the edges of the mantle of the animal; tolerably solid, with fine trenchant edges; the summits very little marked; hinge dissimilar; one or two oblique cardinal folds, divergent, behind a horizontal spoon-shaped hollow upon the left valve, corresponding with a hollow; horizontal and cardinal in the right valve; two distinct muscular impressions. Inhabits the British and American coasts. Eight species.
Animal. Unknown.
Shell. Transverse, subequivalve, gaping at both valves, or in one only; no cardinal teeth; one broad primary tooth in both valves, projecting interiorly; a lateral plate running obliquely under the primary teeth. Sometimes there is a fissure extending from the apex, giving the appearance of a second plate or rib. Inhabits the British and American seas. Twelve species.
Animal. Body oval, much compressed, or subcylindrical; the mantle enclosed only in the half of its inferior side: foot small and projecting but little beyond the abdominal mass, tubes long, distinct or united. This genus is perfectly distinct from the Mactra, to which it formerly belonged, on account of its having no lateral teeth. It is called by De Blainville, Lutricola, from its being found very deep in mud or sand at the mouth of rivers.
Shell. Oval or elongated, regular, equivalve, more or less inequilateral, sometimes but slightly gaping: edges always simple and trenchant; summits feebly marked; hinge subsimilar, formed by two very small divergent cardinal teeth; two very distinct muscular impressions united by a palleal impression profoundly sineous to the rear. Inhabits the seas of Europe and America. Fourteen species.
Animal. Body oval and pretty thick; edges of the mantle thick, smooth, or without tentacular papillæ, augmented behind by two indistinct tubes; mouth small and oval; labial appendages narrow; branchial laminæ very small, and united in their length among themselves and with those of the opposite side; foot oval, trenchant, very long.
Shell. The Mactra has a peculiar hinge distinguishing it from all other genera. It is triangular, with a curved or angular compressed tooth on each valve, with a small oblique cavity on each side, to which is attached the ligament. Two lateral teeth, one near the primary tooth and one near the ligament. The shape of the shell is subtriangular or oblong; exterior smooth, striated, or ribbed transversely; two muscular impressions united by a narrow marginal tongue. Inhabits the British and American coasts. Forty-four species.
Animal. Unknown.
Shell. Close, suborbicular or transverse, striated longitudinally, denticulated, regular, equivalve, inequilateral, summits well marked, and turned to the front: primary teeth somewhat divergent with a hollow at the side; no lateral teeth nor obsolete ones; ligament internal and inserted into a pit in the hinge. It is easily known from the Mactra and Lutraria by the valves fitting exactly. The living species of this genus only exist in the seas of Australasia, while in a fossil state we find at least seven species in France. Eleven species.
Animal. Unknown.
Shell. Somewhat longer than high, subtrigonal, regular equivalved, inequilateral, gaping but little or not at all; summits well marked and a little inclined to the front; hinge subsimilar; two unequal cardinal teeth converging to the summit; two oblong, compressed, short, and inserted lateral teeth; ligament internal and situated in a pit. Owing to the equivocal character of this genus it is somewhat difficult to judge of the hinge. Inhabits the Indian and American seas. Two species.
Animal. Unknown.
Shell. Vertical or sublongitudinal, a little irregular, not gaping, equivalve, subequilateral, with summits a little marked; hinge dorsal, formed by a cardinal tooth; two long muscular impressions, one short primary cleft tooth in each valve, with an oblong groove divided in the middle of the margin, ligament internal inserted in a pit. Two species.
Animal. Unknown.
Shell. Covered with a thick epidermis, enclosing it entirely except at the extremities, regular, somewhat thick, oval, elongated, straight and parallel edges, also rounded at its two extremities, valves equal, very inequilateral; the anterior side much longer than the posterior; summits feebly marked; hinge subsimilar, formed by a cardinal tooth, dilated, compressed, and a little reflexed above; subexterior ligament inserted upon the tooth, and nearly at the posterior extremity of the shell; two small, rounded, widely separated muscular impressions, without any visible abdominal impression. Four species.
Animal. Very imperfectly known.
Shell. Transverse, inequilateral, somewhat rounded or suboval; sides slightly gaping; hinge with one or two cardinal teeth, and a narrow groove for the internal ligament; ligament double, the external one short, the internal one fixed in the internal grooves. The two ligaments distinguish this genus from all other bivalves. Inhabits the West Indian and American seas. Forty-five species.
Animal. Unknown.
Shell. Tolerably solid, regular, inequivalve, inequilateral with a conical, flexed, ascending, primary tooth in each valve; a cavity at the side; no lateral teeth; ligament interior, placed in the cavities; two neighbouring muscular impressions. Inhabits the British and American seas. Ten species. Four fossil.
Animal. Body much compressed, somewhat elongated, in form of a furrow, in consequence of the union of the edges of the mantle, and its continuation with the tubes, which are united and short; foot small, thickest in front, and issuing through a tolerably large cleft in the mantle.
Shell. Regular, white, elongated, much compressed, inequivalved, inequilateral; right or upper valve quite flat, with a fold; summits feebly marked; hinge anomalous, formed by a transverse cardinal tooth on the right; valve entering a corresponding cavity in the left; ligament internal, oblique, triangular, inserted in a somewhat deep pit, with edges a little projecting on each valve; two round muscular impressions. Inhabits the Mediterranean, British, and American seas. Four living species, and two fossils, according to Defrance.
Animal. Long, subcylindrical, the mantle closed in all parts, prolonged behind by two long tubes, thick and close together externally, pierced interiorly and in front with a round orifice, for the passage of a very small foot; mouth very large; labial appendages small; branchial laminæ free, the external pair much shorter than the internal.
Lamarck has thought proper to remove this genus from the Mytilus; it possesses the faculty, like the Pholas, of penetrating rocks and substances, and cannot be extracted but by breaking the substance in which it is imbedded.
Shell. Thick, with an epidermis, a little irregular, elongated, subcylindrical, obtuse at both ends; summits feebly marked; hinge toothless, or with a very small rudimentary tooth; ligament external, somewhat inflated; two round muscular impressions distinct, and several others irregular. Inhabits the British and American seas, in cavities, which they bore in rocks or wood. Nine species.
Animal. Unknown.
Shell. Subtrigonal, more or less irregular, transverse, inequilateral; upper side narrowed and a little gaping; lower side rounded; hinge with two teeth in each valve, or in one valve only. Inhabits the Australian seas, boring into wood and rocks. Thirteen species.
Animal. Unknown, but probably resembling the Venus.
Another lithophagous shell, taken from the genus Venus, and distinguished from it by the different disposition of the teeth.
Shell. Transverse, inequilateral, posterior side short, the anterior gaping slightly. Hinge with two teeth on the right valve, three on the left, and sometimes three on both—these are small, near together, and parallel. Ligament exterior. Inhabits the British seas, boring into rocks and clay. Eight species.
This family is divided into N. Solenaria and N. Tellinaria, from their resemblance to the Solen and Tellina.
N. Solenaria. Three genera.
Animal. Unknown.
Shell. Oval, compressed, a little elongated, gaping but little, equivalve, subequilateral, rounded at both extremities; no mark of posterior keel; summits feebly marked; hinge formed by one or two contiguous cardinal teeth upon each valve; ligament projecting, two round muscular impressions, distant and joined by a narrow palleal impression strongly sinuous behind. Inhabits the sea at Jamaica and shores of America. Nine species.
Animal. Unknown.
Resembling the Tellina, from which it was taken, but not having an irregular plait on the anterior part.
Shell. Transverse, oblong-ovate, or elliptical, flattened, slightly gaping at one side; summits projecting; hinge formed by two primary teeth in the left valve, and one in the opposite one Inhabits the European and American seas. Twenty-one species.
Animal. Unknown.
Shell. Of the same form as the Psammobia, but differing in the number of teeth, the left valve of the Psammotæa having only one tooth; and sometimes one valve is without teeth, while the other has two; ligament exterior, attached to callosities at the hinge, and without an irregular plait. Inhabits the Australian seas. Seven species. One fossil species.
N. Tellinaria. Seven Genera.
The two last of these genera have no lateral teeth, the rest have one or two.
Animal. Body triangular, much compressed: the free edge of the mantle furnished with a row of tentacular, largest and longest in the rear; foot very large, compressed and pointed to the front; buccal appendages nearly as large as the bronchial laminæ, of which the external pair are much smaller than the internal; the anterior contractile muscle larger than the other; tubes very distinct.
Shell. Of a somewhat variable form, generally striated longitudinally and much compressed, equivalved, more or less inequilateral; the anterior side almost always longer and more rounded than the posterior, which constantly presents a flexuous fold, at least at its inferior edge; summits feebly marked; hinge similar; one or two cardinal teeth; two lateral teeth, far apart with a pit at their base in each valve; ligament posterior, large; round muscular impressions. The finest species of this beautiful shell are found in the pearl fisheries of Ceylon; and numerous species on the American shore. Sixty-eight species.
Animal. As above.
This genus is very nearly allied to the Psammobia, Tellina, and Lucina, but upon close examination it will be found to be distinct from either.
Shell. Equilateral, transverse, somewhat elongated, nearly without the flexuous plait; two divergent cardinal teeth, of which the anterior is but little distant from the summit. Inhabits the Bay of Naples. Two species. One species is found on the shores of America.
Animal. Differing slightly from the Lucina.
This genus was classed by Lamarck with the Lucina, but the great difference in the organization of the animals discovered by Cuvier, has made this a distinct genus.
Shell. Equivalve, transverse, without any irregular fold on the anterior margin, having the beaks flexed inward and opposite; two cardinal teeth; two lateral, the posterior of which is nearest the hinge; muscular impressions simple, ligament external. Inhabits the Indian Ocean.
Animal. Very imperfectly known.
Shell. Inequilateral, suborbicular, beaks small, pointed, and oblique; two divergent cardinal teeth, one of which is bifid, and which vary or disappear with age; two lateral teeth sometimes obsolete, the posterior approaches nearest to the cardinal teeth; two muscular impressions far apart, the posterior in shape of a band, sometimes very long; ligament external. Inhabits the British and American seas. Twenty-six species.
Animal. As in Tellina.
Shell. Transverse, inequilateral, equivalve; anterior side short and obtuse; two primary teeth in one or both valves; one or two lateral teeth varying in distance; two round muscular impressions; ligament, external, short, and inserted at the posterior impression. Inhabits the seas of Europe and America. Thirty-one species.
Animal. As above.
Shell. Transverse, equivalve, valves approximate and close; three primary teeth in the right valve, and a single bifid tooth in the left, inserted into a cavity in the opposite one; no lateral teeth; ligament external and on the short side, as in Donax, from which it was separated by Lamarck, on account of the peculiarity of the hinge, inhabits the Indian Ocean. Three species.
Animal. As above.
Shell. Distinguished from the Venus by having only two teeth on each valve, and from the crasatella by the position of the ligament; solid, suborbicular, thick, hinge with two strong diverging primary teeth in the right valve, and two unequal ones on the other; ligament external. Inhabits the Scottish and Devonshire coasts. One species.
This family is divided into Conchæ Marinæ, and Conchæ Fluviatiles.