144 TESTACEOUS MOLLUSCA. 



ribs longitudinally striated, the posterior ones subcrenated, the 

 anterior rugulose, the interstices dotted. \^ 9 . 



C. Planicostatum. Sow. Z. P. 1833.— Reeve, t. 77. f. 25.— 

 C. I. f. 25. Subcordate, palish, variegated with brown and 

 fulvous ; posteriorly rounded, anteriorly truncated and obtusely 

 angulated, the centre of the anterior area rather prominent ; with 

 thirty flattened sharp- edged radiating ribs, of which the posterior 

 ones are transversely costellated, the anterior ones anteriorly crenu- 

 lated and all of them closely striated transversely ; the umbones 

 prominent : a deep depression under the umbones is posteriorly 

 conspicuous. C. America. if.-Jf. — Closely resembling Me- 

 dium. 



C. Donaciforme. Schrceter. Ein. 3. p. 68. t. 7 . f. 14. — 

 Brug.p. 214.— W. t. 5.f. 38.— Gmel. 3247.— D. p. U4.— Ch. 

 f. 165. — C. I. f. 27. Subtriangular, thick, posteriorly rounded 

 and attenuated ; anteriorly very short, the slope flattened ; ventral 

 edge strongly arcuated and subincurved anteriorly ; white, marbled 

 with, and the anterior slope almost entirely, livid brown, with 

 radiating grooves, which become obsolete at one end : inside white, 

 the margin strongly dentated. -J . . 1. — Much resembling Donax 

 Cardioides. 



C. Subretusum. Sow. Juix. Z. P. 1840.— C. I. f. 24.— 

 Reeve, t. 86. f. 24. — White, obliquely sub quadrangular, ventricose, 

 anteriorly subcarinated and acuminated, posteriorly subrotund ; 

 before the angle flattened and slightly grooved, behind the angle 

 with six tuberculated ribs, interstices dotted : a heart-shaped 

 cavity close under the umbones, a slight callus within it. 



l io ' • 10* 



CARDITA. 



Shell free, regular, equiualve, inequilateral ; hinge with two un- 

 equal teeth ; primary tooth short, direct, placed under the umbo ; 

 the other oblique, marginal, and produced under the corselet. 



* Subcordiform or oval. 



C. Sulcata. Lam.l. — Philippi.p. 53. Chama Antiquata. 

 Lin. \138.—D.p. 215.— Poll. t. 23./. 11 to 19.— Ch.f. 488, 9. 

 Subcordate, anteriorly longer, white with brown and rufous mark- 

 ings and the beaks white ; longitudinal ribs convex and transversely 

 striated so as to give rise to numerous little tubercles. 1£. — Mediter- 

 ranean. 



C. Ajar. Iirug.Dlct. p. 406. — Lam. 2. — Adans. Seneg. t. 16. 

 /. 2. — Chama A. D. p. 216. Somewhat heart-shaped, slightly 

 produced anteriorly, rufous scarcely spotted with white, with from 

 twenty-one to twenty-six angulated compressed radiating ribs, 

 whose sides arc angulated and backs crowded with rows of scale- 



