Part 3

Elongated, wedge-shaped, covered with regular elevated jagged or scalloped ribs, elegantly disposed; three dorsal accessory pieces; muscular impression almost medial.

_P. crispata._ The curled Pholas.

Somewhat oval, truncated behind, and as if divided into two parts by an oblique furrow from the summit to the base; anterior part reticulated, the other parts plain; muscular impression marginal.

_P. clavata._ The clubbed Pholas.

Short, wedge-form, little gaping, with many accessory pieces.

2. Gastrochæna. Three species.

Always without accessory pieces, and, therefore, easily distinguished from the Pholas.

Shell equivalve, somewhat wedge-shaped, with a very large, oval, oblique, anterior opening between the valves; the posterior extremity nearly close; hinge linear, marginal, without teeth; two distant muscular impressions; sometimes with a kind of tube or calcareous general envelope.

Gastrochæna cuneiformis. G. mytiloides. G. modiolina.

_G. modiolina._ The Modioliform Gastrochæna.

Oval, thin, brittle, gaping at the side; light reddish brown, with a bluish white interior.

_G. cuneiformis._ The wedgelike Gastrochæna. Pl. 3, fig. 1.

Species with a smooth shell, and without distinct tube. (Represented as imbedded in wood.)

FAMILY III. SOLENIDES. Four genera.

1. Solen. Eighteen species.

There are many species belonging to this genus differing considerably in form and appearance. Its name is derived from a Greek word signifying a pipe or tube. It is a bivalve whose breadth sometimes exceeds its length; some species have a resemblance to the sheath of a razor or a knife handle; others are curved like the scabbard of a cimeter.

The Solen is found in the sand of the seashore, which it sometimes penetrates to the depth of one or two feet. Most of the species are covered with an epidermis, which renders their colours more or less obscure. In general they present but little beauty, though some are of a bright pink colour, and some are beautifully and delicately radiated with purple and white.

The principal characteristic of this genus is the hinge, which generally has one subulate tooth, though sometimes two or three.

Shell equivalve, extremely inequilateral, transversely elongated, open at both ends; the apices very small, and entirely at the commencement of the dorsal line; one or two teeth in the hinge; ligament external; two distant muscular impressions; the anterior one very long and narrow, the posterior one sub-angular.

Solen vagina S. corneus. S. ensis. S. pygmæus. S. ambiguus. S. Dombeii. S. Javanicus. S. Caribæus. S. antiquatus. S. vaginoides. S. siliqua. S. cultellus. S. planus. S. minutus. S. constrictus. S. coarctatus. S. rostratus. S. violaceus.

_S. vagina._ The Razor Sheath. Pl. 31, fig. 5.

Valves equal, truncated at both ends; straight or slightly curved; summit terminal.

_S. cultellus._ The kidney-shaped Solen.

Species a little curved lengthwise; summit not terminal.

_S. rostratus._ The violet-beaked Solen.

Species with longer and narrower valves, flatter at the extremities; callosity at the hinge very visible; cardinal teeth or hinge nearer the middle than the anterior side.

_S. ensis._ The Sabre Solen.

Species linear, sabre-shaped; a single compressed tooth in each valve; olive brown at the base, and of a purple hue near the apex.

_S. siliqua._ The podlike Solen.

Species linear, straight; two teeth in one valve and one in the other; covered with a glossy brown epidermis; striated transversely.

_S. antiquatus._ The Antiquated Solen.

Species thin, white, and almost transparent; striated concentrically; ends rounded; hinge near the centre; a tooth in one valve locking into two in the other; the teeth erect and projecting beyond the margin; covered with a dark-coloured epidermis.

2. Panopæa. One species.

Distinguished from the Mya by the prominency of the apex and the situation of the ligament.

Shell regular, elongated oval, gaping at the two extremities, equivalve, inequilateral; summit but little marked, and anterodorsal; hinge very complete, similar, formed by a conical primary tooth before a short, compressed, ascending callosity; ligament exterior, attached to the callosity; two muscular impressions.

_P. Aldrovandi._ The Panopæa of Aldrovandus. Pl. 5, fig. 2.

The type of this genus, transversely elongated, undulated; concentrically wrinkled; of dark green colour, almost black.

3. Solecurtus. Three species.

Shell oval, elongated, equivalve, sub-equilateral, edges almost straight and parallel; the extremities equally rounded, and as if truncated; summits but little marked; hinge toothless, or formed by some rudimentary primary teeth; ligament projecting, affixed to the thick nymphal callosities; two distant, rounded muscular impressions.

Solecurtus radiatus. S. strigilatus. S. legumen.

_S. radiatus._ The radiated Solecurtus.

Species flat, small, with an interior ridge running down obliquely from the summit to the abdominal margin.

_S. strigilatus._ The strigilated Solecurtus.

Species more cylindrical, without interior ridge.

_S. legumen._ The Pease-pod Solecurtus. Pl. 31, fig. 6.

Species still more elongated and sub-cylindrical.

4. Glycimeris. Two species.

Distinguished from the Solen by being without teeth at the hinge.

Shell covered with epidermis, slightly irregular, elongated, gaping at the two extremities, equivalve, inequilateral; the summits but 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.

Glycimeris margaritacea. Glycimeris siliqua.

_G. siliqua._ The podlike Glycimeris.

Transversely oblong, covered with a black epidermis; umbones decorticated; internal disc of the valves white, thick, and callous.

FAMILY IV. MYARIA. Two genera.

1. Mya. The Trough Shell, or Gaper. Four species.

This term is derived from the Greek word μυω, to close, alluding to the animal’s custom of closing the valves. The principal characteristic of the Mya is its gaping at one end; it is likewise distinguished by having a large spoonlike tooth proceeding from beneath the beak. Its form is greatly varied, but generally covered with a greenish epidermis, which may be removed; and the shell, when polished, will display beautiful prismatic colours. The Mya is found on the seashore or on the banks of large rivers, partially concealed in the sand and mud.

Shell transverse, inequilateral, surrounded with a thick epidermis; rather solid; edges thin and sharp; summits but little marked; hinge dissimilar; one or two large, compressed, spoon-shaped teeth rising perpendicularly from the plane of the left valve, and fitting into the entrance of a primary cavity in the right valve; ligament interior, attaching the tooth and cavity; two distant muscular impressions; the anterior long and narrow, the posterior rounded; the mantle impression narrow, with a large sinus or hollow.

Mya truncata. M. arenaria. M. erodona. M. solenimyalis.

_M. arenaria._ The Sand Mya. Pl. 5, fig. 1.

Regular species.

_M. erodona._ The Erodona Mya.

Irregular species, in which the cavity of the right valve is bordered by strong projections.

_M. truncata._ The truncated Mya. Pl. 5, fig. 3.

Sub-oval, truncated; small end gaping; large end rounded; covered with a dark yellowish epidermis; inside white; wrinkled transversely.

2. Anatina. The Duck’s Bill. Ten species.

Shell elongated oval, very thin, fragile, semipellucid; much inflated at one end like a duck’s bill, whence it derives its common name; equivalve, very inequilateral; hinge toothless; the anterior side rounded and much longer than the posterior; ligament interior affixed to a bony spoonlike process in each valve, and sustained by a lateral plate running obliquely into the interior of the shell.

Anatina laterna. A. truncata. A. subrostrata. A. longirostris. A. globulosa. A. trapezoides. A. rugosa. A. imperfecta. A. myalis. A. rupicola.

_A. subrostrata._ The beaklike Anatina.

Species equivalve and regular.

_A. myalis._ The Mya-like Anatina.

Species inequivalve.

_A. trapezoides._ The trapezium-shaped Anatina. Pl. 12, fig. 5.

Species with a moveable tooth or calcareous piece upon the right valve, lodged in the angle formed by the spoonlike process.

FAMILY V. MACTRACEA. Seven genera.

1. Lutraria. Eleven species.

This genus was taken from the Mactra, and is perfectly distinct, as it wants the lateral teeth. It is called Lutricola by De Blainville, from its lurking in sand or mud at the mouths of large rivers.

Shell inequilateral, orbicular, sub-triangular or transversely oval, gaping at the extremities; hinge with one cardinal tooth folded in two, or two teeth, one of which is plain, with an opposite hollow to receive it; no lateral teeth; ligament interior and fixed in the hollow cavity of the primary tooth.

Lutraria solenoides. L. rugosa. L. compressa. L. piperata. L. tellinoides. L. elliptica. L. papyracea. L. plicatella. L. crassiplica. L. complanata. L. candida.

_L. solenoides._ The Solen-like Lutraria.

Species oblong, sub-cylindrical, very gaping, two very strong cardinal teeth; the spoonlike cavity of the ligament vertical.

_L. compressa._ The compressed Lutraria.

Species oval or orbicular, almost equilateral, very compressed, little gaping; hinge similar; internal ligament inserted in the pit of a vertical spoonlike cavity; two distinct tubes, without longitudinal striæ.

_L. rugosa._ The rugged Lutraria.

Species ovate, closed at both ends; striæ from the summit to the base.

_L. elliptica._ The oval Lutraria.

Oblong oval, nearly smooth, having a few concentric striæ, and some diagonal striæ at the ends of the valves; colour yellow or greenish brown; inside white.

2. Mactra. The Kneading-trough. Thirty-three species.

The name given to this genus was derived from the Greek word μακτρα, from its resemblance to a trough used for kneading bread.

In all species of this genus a similarity of colouring and form pervades the whole. In shape they are sub-triangular or oblong, with a smooth, striated, or transversely-ribbed exterior. In some species the valves gape at both ends, and in others at the anterior only. The most general colour is lilac, or white tinged with blue or yellow; some have purple rays on a brown ground.

A singularity in the form of the hinge of the Mactra distinguishes it from all other genera. It is of a triangular form, has a bent or angular compressed tooth on each valve, with a small oblique cavity on each side to which the ligament is attached. There are also two lateral teeth, one near the ligament and the other near the primary tooth. These teeth are thin and fragile; the primary tooth is sometimes indistinct, but the lateral teeth always exist.

The Mactra is found buried in the sand at a little distance from the seashore. Shell generally thin and brittle, covered with epidermis, of a triangular form, transverse, equivalve, inequilateral; beaks prominent; one compressed, folded, cardinal tooth, with an adjoining pit in each valve, projecting inward; lateral teeth thin, lamellous, entering, placed near the hinge; exterior ligament small; an interior ligament inserted in the cardinal pits; two muscular impressions, united by a narrow marginal tongue.

Mactra gigantea. M. Spengleri. M. striatella. M. carinata. M. straminea. M. Australis. M. violacea. M. fasciata. M. turgida. M. plicataria. M. rufescens. M. maculata. M. subplicata. M. triangularis. M. lactea. M. abbreviata. M. Helvacea. M. grandis. M. stultorum. M. maculosa. M. ovalina. M. alba. M. solida. M. castanea. M. rufa. M. squalida. M. Brasiliana. M. donacina. M. depressa. M. lilacea. M. trigonella. M. deltoides. M. crassatella.

_M. gigantea._ The gigantic Mactra.

Species in which the cardinal teeth are almost obsolete, in consequence of the enlargement of the pit of the ligament.

_M. stultorum._ The fool’s Mactra. Pl. 9, fig. 6.

Species in which all the teeth are very large, lamellous, striated longitudinally; colour reddish brown.

_M. solida._ The solid Mactra.

Species thick, solid, without epidermis; lateral teeth finely striated.

_M. trigonella._ The three-cornered Mactra.

Species in which the lateral teeth are almost obsolete; exterior surface smooth.

_M. triangularis._ The triangular Mactra.

Species very small, strong, opaque, white; inside white; margin strongly crenated.

_M. crassa._ The thick Mactra.

Species very thick, solid, striated longitudinally; the cardinal teeth obsolete, or almost so; the lateral very thick, very close, and reflected; an external ligament as well as an internal one.

3. Crassatella. Eleven species.

May be easily known from the Mactra and Lutraria, as the valves, when closed, fit exactly, and do not gape. It is remarkable that all the living species contained in this genus only exist in the seas of Australasia, while at least seven species in a fossil state are found in France.

Shell inequilateral, sub-orbicular, close, equivalve, sometimes attenuated at one end; two divergent primary teeth, with a cavity at the side; lateral teeth obsolete; ligament internal, inserted in the cavity of the hinge.

Crassatella Kingicola. C. donacina. C. sulcata. C. subradiata. C. contraria. C. cuneata. C. rostrata. C. glabrata. C. erycinæa. C. cycladea. C. striata.

_C. sulcata._ The furrowed Crassatella. Pl. 6, fig 4.

Shell ordinarily thick, striated transversely, denticulated, sub-triangular, equivalve, inequilateral, summits well marked and evidently turned forward; hinge very large, subsimilar, formed by two diverging cardinal teeth, separated by a large pit; ligament almost entirely interior, and inserted in the pit.

_C. Kingicola._ The King’s Island Crassatella.

Ovate, orbicular; yellowish white, with obsolete rays; very minutely striated transversely; the umbones somewhat plicated.

4. Erycina. One species.

The only living species of this genus is found on the sand in New-Holland, but there are many fossils in France. It is so equivocal in character that it is difficult to judge of their hinge.

_E. cardioides._ The cardium-shaped Erycina. Pl. 6, fig. 5.

Shell rather longer than high, sub-triangular, regular, equivalve, inequilateral, rarely gaping; the summits well marked and a little anteriorly inclined; hinge subsimilar; two unequal cardinal teeth, converging at the summit, and leaving a pit between them; two lateral teeth, not distant, lamellous, inserted; ligament interior, fixed in the cavity between the primary teeth.

5. Ungulina. Two species.

This genus is very remarkable for having the pit or cavity divided into two parts, the one at the end of the other; the ligament is partially seen from the outside.

Ungulina oblonga. Ungulina transversa.

_U. transversa._ The transverse Ungulina.

Shell vertical or longitudinal, rather irregular, not gaping, equivalve, inequilateral, with summits little marked and decorticated; hinge dorsal, formed by one short, primary cleft tooth, before an oblong pit, divided by a small ligament, in which is inserted a sub-interior ligament; colour yellowish brown.

6. Solenimya. Two species.

This genus, which at first sight is confounded with the Solens, differs from them particularly by the singular disposition of the ligament placed at the short side of the shell.

Solenimya Australis. Solenimya Mediterranea.

_S. Australis._ The Australian Solenimya. Pl. 6, fig. 2.

Shell covered with a thick brownish epidermis, regular, thick, elongated oval, edges straight and parallel, equally rounded at both extremities; valves equal, very inequilateral.

_S. Mediterranea._ The Mediterranean Solenimya.

Transversely oblong; dark brown, ribbed longitudinally, with imbricated projecting foliations; inside white.

7. Amphidesma. Sixteen species.

This genus was constituted by Lamarck on account of the peculiar characters which distinguished it from those genera which it most resembles; particularly in having the valves connected by two ligaments.

Shell generally small, transverse, sub-oval or rounded, occasionally a little gaping at the sides; hinge with one or two cardinal teeth, and a narrow cavity for the interior ligament; exterior ligament short.

Amphidesma variegata. A. donacilla. A. lactea. A. cornea. A. albella. A. flexuosa. A. prismatica. A. phaseolina. A. corbuloides. A. glabrella. A. lucinalis. A. Boysii. A. tenuis. A. purpurascens. A. nucleola. A. physioides.

_A. glabrella._ The smooth Amphidesma. Pl. 6, fig. 9.

Species lenticular or oval, with or without a lunated depression.

_A. lactea._ The milky Amphidesma.

Sub-orbicular, sub-pellucid, compressed, reticulated; yellowish white.

FAMILY VI. CORBULACEA. Two genera.

1. Corbula. Nine species.

This genus approximates the Crassatella and Ungulina, but is distinguished from them by the inequality of the valves and the strong primary tooth.

Shell rather solid, a little irregular and triangular, inequivalve, more or less inequilateral, rounded and enlarged before, attenuated and prolonged behind; summits well marked, one projecting behind the other; hinge anomalous, formed by a large, conical, recurved cardinal tooth, with a cavity at its base for the reception of the tooth of the other valve; ligament very small; two muscular impressions little distant.

Corbula Australis. C. sulcata. C. erythrodon. C. ovalina. C. Taitensis. C. nucleus. C. impressa. C. porcina. C. semen.

_C. nucleus._ The kernel Corbula.

Strong, sub-triangular, under valve larger than the upper one; transversely striated; covered with a thick brownish epidermis.

_C. ovalina._ The ovate Corbula. Pl. 6, fig. 6.

Regular species.

_C. Australis._ The Australian Corbula.

Irregular species, living in stone.

2. Pandora. Two species.

Closely allied to the Corbula.

Pandora rostrata. Pandora obtusa.

_P. rostrata._ The beaked Pandora. Pl. 6, fig. 3.

Shell white, regular, elongated, inequivalve, inequilateral; right or upper valve entirely flat, with a plait or fold; much produced towards the beak; hinge anomalous, formed by a transverse cardinal tooth on the right valve, entering into a corresponding cavity on the left; ligament internal, oblique, triangular, inserted in a pit rather deep, with edges a little projecting on each valve; two rounded muscular impressions.

FAMILY VII. LITHOPHAGI. Three genera.

1. Saxicava. Five species.

This genus is taken from the Mytilus, and, like the Pholas, possesses the faculty of penetrating calcareous rocks, from which it cannot be extracted without breaking the substance in which it is imbedded.

Shell bivalve, thick, covered with epidermis, rather irregular, elongated, sub-cylindrical, obtuse at the two extremities; summits little marked; hinge toothless, or with a very small rudimentary tooth; ligament external, a little inflated.

Saxicava rugosa. S. Gallicana. S. pholadis. S. Australis. S. veneriformis.

_S. Australis._ The Australian Saxicava. Pl. 7, fig. 6.

Answers to the above description.

_S. Gallicana._ The Gallic Saxicava.

Oblong, wrinkled, truncated at the posterior extremity, one valve larger than the other; pale horn colour.

2. Petricola. Thirteen species.

This genus possesses the same faculty of boring rocks as the Saxicava; it is distinguished from the latter genus by the hinge having one or two teeth in each valve.

Shell sub-trigonal, transverse, inequilateral; upper side narrowed and a little gaping; lower side rounded.

Petricola lamellosa. P. ochroleuca. P. semilamellata. P. lucinalis P. striata. P. costellata. P. rocelaria. P. exilis. P. ruperella. P. chamoides. P. pholadiformis. P. labagella. P. linguatula.

_P. lamellosa._ The lamellous Petricola. Pl. 7, fig. 3.

Species oval, trigonal, radiated; two teeth on one valve, and one on the other.

_P. pholadiformis._ The Pholas-shaped Petricola.

Species transversely elongated.

3. Venerirupis. Seven species.

Another lithophagous shell, taken from the genus Venus, from which it is distinguished by the different disposition of the teeth, having three primary in one of the valves at least.