Ervilia. MOLLUSCA. MACTRADiE. 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. 



Mya 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. 

 Lengtli 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. convexum. — Shell convex, transversely ovate, round- 

 ed anteally, truncate retrally. 



Mya decUvis, 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. 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 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 Mi/a declivis of Pennant, 

 Brit. Zool. iv. 79- and the young state of which, seems to be the Tellinafra- 

 gUis of the same author, lb. 86. t. xlvii. f. 26. 



464. A. truncatum. — Convex, wedge-shaped, anteal end 



short, obliquely truncate. 



Anatina truncata, Turt. Biv. Brit. 46. t. iv. f. 6. — In cavities of rocks. 

 — Torbay. 



Length \, breadth fths 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. 



