150 TESTACEOUS MOLLUSCA. 



truncated and carinated with its slope more or less concave : teeth 

 and anterior end often tinged with purple internally : anterior dorsal 

 edge rather incurved. — Variety. C. Rostrata. Lam. 3. With 

 the anterior side produced attenuated and slightly heaked. 1|^. — 

 New Holland. 



C. Coralliophaga. Lam. 4. — Bl. t. 76. f. 3.— Chama C. 

 Gmel. 3305.— D. p. 220. — W. t. 9. /. 17.— Ch. f. 1673, 4. 

 Obloug, rounded at both extremities, cylindraceous, thin, white 

 tipped with purple at the beaks, diaphonous, compressed anteriorly ; 

 marked with decussated striae which at the margin are raised into 

 low ridges. 2. — In Madrepores at St. Domingo. (Bears some 

 resemblance to Mytilus Lithophagus.) 



HIATELLA. 



Equivalve, very inequilateral and transverse ; gaping at the ventral 

 margin ; hinge with a small tooth in the right valve ; and two 

 oblique somewhat larger ones in the left valve; ligament 

 external. 



H. Arctica.* Lam. — Turt. Biv. t. 2.f. 12. — Solen Minu- 

 tus. Lin. 1115.— W. t.3. f. 33.— D. p. 69.— Mont. t. l.f.4. 

 — Ch.f. 51, 2.— Saxicava A. Phil.t.3.f.3. Oblong, produced 

 and truncated anteriorly, white with transverse wrinkles, ligamental 

 edge subincurved, anterior slope with two oblique ridges usually 

 armed with spines. — Variety. Without the spines. (H. Ob- 

 longa. Turt. Biv. t. 2. f 13.) f . — Atlantic and Mediter- 

 ranean. 1 



ISOCARDIA. 



Equivalve, heart-shaped, ventricose ; beaks distant, divergent, and 

 spirally turned to one side ; hinge with two primary flattened, 

 teeth, one of them recurved and under the beak ; an elongated 

 lateral one under the ligament which is external and forked on 

 one side. 



I. Cor.* Lam. 1. — Bl. t. 69. f. 2. — Chama Cor. Lin. 

 U37.—D. p. 212.— Ch. f. 483.—^. t. 232. /. 1.— Bon. 4. 

 t. 134. — W. t. 9. f. 1. Heart-shaped, globose, smooth, fulvous 

 and the beaks clouded with white ; epidermis reddish. 3 . . 2f . — 

 Europe. 



I. Moltkiana. Lam. 3.-— Chama M. D. p. 213.— Ch. 

 f 484, 5, 6, 7.—E. t. 233. /. 1.— Cardita M. Brug. Die. 

 p. 404. Heart-shaped, subtriangular, inequilateral, yellowish white, 



1 Compare Mytilus Pracisus of Montagu, t. 4. f. 2. — (W. 

 t. 12./ IK) 



