TRIBE CARDIACEA. 129 



VENER1CARDIA. 



Equioalve, inequilateral, suborbicular, generally with longitudinal, 

 radiating ribs: hinge with two oblique teeth in each valve, turned 

 in the same direction. 



V. Australis. Lam. Sow. Tank.—Ast. t. 78. f. 12, 3, 4.— 

 Chama A. W. S. t. 2. f. 4. Rounded and obtusely cordate, 

 posteriorly short and rounded, anteriorly angulated at the ventral 

 edge which is strongly arcuated ; thick, convex, whitish, transversely 

 variegated with chesnut brown on its numerous narrow angulated 

 and crenulated ribs : inside stained with brown anteriorly, margin 

 coarsely toothed. 1. — Australia, fyc. 



V. Megastropha. Gray. Ann. Phil. 25. vignette p. 138. 

 Obliquely heart-shaped, thick, white variegated with rufous, with 

 convex wrinkled ribs : hinge margin very thick. 1. — New Holland ? 



V. Crassicosta. Sow. Tank. Cat. Heart-shaped, tumid, 

 anteriorly angulated, with twenty-two thick depressed ribs which 

 are angulated at their sides, irregularly crenated, variegated with 

 pink orange crimson and dark brown : inside white. 



TRIBE CARDIACEA. 



Primary teeth irregular, either in form or situation ; and 

 accompanied by one or two lateral teeth for the most part. 



CARDIUM. 



Equivalve, subcordate ; beaks prominent ; the interior margins of 

 the valves denticulated or plicated ; hinge with four teeth in both 

 valves ; with two approximate primary oblique teeth, mutually 

 inserted and crossing each other ; two lateral remote teeth. 



* No particular angle on the beaks, and the anterior side at least 

 as large as the posterior. 



C. Costatum. Lin. 1121.— D. p. 109.— Lam. 1. — Wood. G. 

 C. t. 56 f. l.— W. t. 5. f. 34.— List. t. 327. f 164.— Ch.f 151, 

 2.—E. t. 292. f. 1. and t. 293. f. 1. Gibbous, sub-globose, thin, 

 nearly equivalve, with high keeled membranaceous longitudinal 

 white ribs, the interstices reddish tawny ; anterior side gaping ; 

 within white, with grooves corresponding to the exterior ribs. 

 3..3J. — Guinea and Senegal.— (From the straightness of the 

 hinge-margin the shell seems auriculated.) 



C. Indicum. Lam. 2. — C. I. f. 46. Heart-shaped, tumid, 

 sub-equilateral, with obtuse ribs, which at the margin of the an- 

 terior end are covered with spines resembling the teeth of a saw, 

 of the posterior with rather distant trumpet-like scales ; white, 



K 



