MALACOZOA TROPIOPODA. LAMELLIBRANCUIATA. 213 



small; three small, prominent divergent teeth in each 

 Talve. Riipes, a rock, and Venus : Rock-Venus. La- 

 marck. 



1. Venerupis virghiea. — Shell ovato-oblong, consider- 

 ably compressed, concentrically striate, yellowish-white, 

 with radiating bands of florid dots or spots. Named 

 from its beauty. 



2. Feneriqns puUdstra. — Shell ovato-oblong, mode- 

 rately compressed, divergently and concentrically striate, 

 yellowish or whitish, plain, or patched with brown. 

 PuUdstra, a pullet. 



A. V. PuUdstra arenicola. Living among sand. 



B. V. PuUdstra perforans. Boring. 



Family VIL — 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. ILapbiov, the heart. 



1. Cardium echindtum. — Shell cordate, obliquely 

 roundish, tumid, wdth twenty convex, spiniferous ribs. 

 Echindtus, with prickles. 



A. C. ecJunatum vidgare. Common. 



B. C. ecJunatum acideatum. Prickly. 



2. Cdrdmm eduJe. — Shell cordate, obhquely 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 httle elevated convex, 

 glossy ribs, marked toward the margins with transverse 

 lamellae, becoming elevated at either end, especially the 

 posterior. Fascidtus, banded. 



4. Cardium exifftium. — Shell subcordate, suborbicular. 



