History of British animals - University of Guam Marine Laboratory

Ervii.ia. MOLLUSCA. MACTRAMJ. 431Gen.CXVII. ERVILIA.— Shell oval, equi valve, inequilateral,closed ;hinge with a single strong erect cloven tooth inone valve, closinginto a deep cleft between two small laminardivergent elevations in the other,— 461. E. nitens. — Beaks prominent, rounded at both extremities,regularly and finely striated concentrically.Mya nitens, Laskey, Wern. Mem. i. 375, t. viii. f. 4. Mont.Sup. 165 Ervilia nitens, Turt. Biv. Brit. 5C, t. xix.bar, Mr Laskey.Test. Brit.f. 4—At Dim-Length nearly a quarter of an inch, a little more in breadth ; flattish, alittle tapering at the longest side ;colour glossy pink ; margin entire.Gen.CXVIII. AMPHIDESMA.—Shell inequilateral; hingewith a projectionfor the support of the internal cartilagein each valve, and one or two small adjacentteeth..*No lateral teeth.— 462. A. comvexum. — Shell convex, transversely ovate, roundedanteally,truncate retrally.Mya declivis, Don. Brit. Shells, t. lxxxii—Anatina con. Turt. Biv. Brit.44. t. iv. f. 1, 2— Sandy bays, rare.Length l£, breadth nearly 24 inches ; very convex, thin, and brittle, of arusty white colour ; irregularly wrinkled concentrically, with two or three obsoletelongitudinal folds ; support for the ligament narrow.— 463. A. pubescens.— Shell slightly compressed, transverse,anteally rounded, retrally broadly truncate ; surface rough.Mya pubescens, Pult. Dorset. 27- Mont. Test. Brit. 40—Anatina pub.Turt. Biv. Brit. 45. t. 4. f. 3—Southern shores of England.Length 2, breadth 2^ inches ; white, the surface of the shell closely coveredwith minute tubercles, giving it a rough aspect ; slightly wrinkled by thelines of growth, ventral margin and the dorsal one behind the beaks nearlystraight, the latter with a contiguous ridge ; support for the ligament broad,with an elevated retral margin. This is probably the Mya declivis of Pennant,Brit. Zool. iv. 7'J. and the young state of which, seems to be the Tellinafragilisof the same author, lb. 86. t. xlvii. f. 26.464. A. truncatum. — Convex, wedge-shaped,short, obliquely truncate.— Torbay.anteal endAnatina truncata, Turt. Biv. Brit. 46. t. iv. f. 6.— In cavities of rocks.Length J, breadth fths of an inch; rough, striate transversely; anteally,the dorsal margin slopes rapidly, the retral margin is truncate ; the retrodorsaland ventral margins nearly straight.In the three preceding species, the support for the ligament is triangular,and the point of attachment is the centro-umbonal margin ; in the remainbigspecies, the point of attachment is on the flat surface of the tooth, whichis parallel with the mesial plane.