Ervjlta. MOLLUSCA. MACTRAD^. 
431 
Gen.CXVII. ERVILIA.^Shell oval, equi valve, inequilateral, 
closed ; hinge with a single strong erect cloven tooth in 
one valve, closing into a deep cleft between two small la- 
minar divergent elevations in the other, 
461. E. nitens. — Beaks prominent, rounded at both extre- 
mities, regularly and finely striated concentrically. 
IMya nitens, Laskey^ Wern. Mem. i. 375, t. viii. f. 4. Mont. Test. Brit. 
Sup. 165 — Ervilia nitens, Turt. Biv. Brit. 56, t. xix. f. 4 — At Dun- 
bar, Mr Laskey. 
Length nearly a quarter of an inch, a little more in breadth ; flattish, a 
little tapering at the longest side ; colour glossy pink ; margin entire. 
Gen.CXVIII. AMPHIDESMA.— Shell inequilateral; hinge 
with a projection for the support of the internal cartilage 
in each valve, and one or two small adjacent teeth. 
* No lateral teeth. 
462. A. conveociim. — Shell convex, transversely ovate, round- 
ed anteally, truncate retrally. 
My a declivis, Don. Brit. Shells, t. Ixxxii — Anatina con. Turt. Biv. Brit. 
44. t. iv. f. 1, 2 — Sandy bays, rare. 
Length 1|, breadth nearly 2^ inches ; very convex, thin, and brittle, of a 
rusty white colour ; irregularly wrinkled concentrically, with two or three ob- 
solete longitudinal folds ; support for the ligament narrow. 
463. A. fuhescens. — 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 cover- 
ed with minute tubercles, giving it a rough aspect ; slightly wrinkled by the 
lines of growth, ventral margin and the dorsal one behind the beaks nearly 
straight, 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. 79* and the young state of which, seems to be the Tellinafra- 
gilis of the same author, Ib. 86. t. xlvii. f. 26. 
464. A. fruncatum. — - Convex, wedge-shaped, an teal end 
short, obliquely truncate. 
Anatina truncata, Turt. Biv. Brit. 46. t. iv. f. 6. — In cavities of rocks. 
— Torbay. 
Length breadth |ths of an inch ; rough, striate transversely ; anteally, 
the dorsal margin slopes rapidly, the retral margin is truncate ; the retro- 
dorsal and 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 remain- 
ing species, the point of attachment is on the flat surface of the tooth, which 
is parallel with the mesial plane. 
