MALACOZOA TROPIOPODA. LAMELLIBRANCHIATA. 213 



small; three small, prominent divergent teeth in each 

 valve. Rupes, a rock, and Venus : Rock- Venus. La- 

 marck. 



1 . Ventrupis virgmea. Shell ovato-oblong, consider- 

 ably compressed, concentrically striate, yellowish-white, 

 with radiating bands of florid dots or spots. Named 

 from its beauty. 



2. Venerupis pulldstra. Shell ovato-oblong, mode- 

 rately compressed, divergently and concentrically striate, 

 yellowish or whitish, plain, or patched with brown. 

 Pulldstra, a pullet. 



A. V. Pulldstra arenicola. Living among sand. 



B. V. Pulldstra perf or ans. Boring. 



FAMILY VII. CARDIINA. 



Animal roundish, ovate, or oblong, with the mantle 

 closed, but having an opening for the foot, and two ex- 

 tensile tubes ; the foot large, compressed, tapering. 

 Shell equivalve, entirely closed, generally very convex ; 

 the hinge with central and lateral teeth. Named from 

 the genus Cardium. 



GENUS 1. CARDIUM. Shell subcordiform, roundish, 

 ventricose, equivalve, inequilateral, with radiating ribs ; 

 umbones large ; hinge with two central teeth and two 

 deep pits in each valve. Kap&oz/, the heart. 



1. Cardium echindtum. Shell cordate, obliquely 

 roundish, tumid, with twenty convex, spiniferous ribs. 

 Echindtus, with prickles. 



A. C. echinatum vulgare. Common. 



B. C. echinatum aculeatiun. Prickly. 



2. Cardium edule. Shell cordate, obliquely roundish, 

 or subtriangular, tumid, with twenty-eight flattened, 

 transversely lamellar ribs. Edulis, eatable. 



3. Cardium fascidtum. Shell subcordate, nearly or- 

 bicular, convex, with twenty- six little elevated convex, 

 glossy ribs, marked toward the margins with transverse 

 lamellae, becoming elevated at either end, especially the 

 posterior. Fascidtus, banded. 



4. Cardium exiguum* Shell subcordate, suborbicular. 



