270 MALACOZOA. TKOPIOPODA. LAMELLIBRANCHIATA. 



Ed. 2. iT. 210.— Venus Senegalensis. Gniel. Syst. Nat. i. 3282.— 

 Venus pullastra. Lamk. Syst. v. 598; Ed. 2. vi. 357. — Venerupis 

 pullastra. Flem. Brit. Anim. 451. 



Venus perforans of Montagu differs from Venus Pullastra 

 only in being abbreviated or distorted. Specimens presenting 

 this character are often brought up from deep water off Aber- 

 deen, and have been found by Mr. Alexander Murray at Fra- 

 serburgh, and intermediate gradations occur, there being in- 

 dividuals which one could not with certainty refer to the one 

 or the other so-called species. 



Venus perforans. Mont. Test. Brit. 127. — Venerupis perforans. 

 Turt. Brit. Biv. 29. PI. 2. f. 15, 16, 17, 1 8.— Venerupis perforans. 

 Flem. Brit. Anim. 451 . — Venerupis perforans. Lamk. Svst. v. 506 ; 

 Ed. n. vi. 163. 



Family VII. — Cakdiina. 



Animal roundish, ovate, or oblong ; with the mantle 

 closed, but having a considerable anteroinferior opening 

 for the foot, and presenting behind two extensile tubes, 

 the lower for respiration, the upper for the fceces ; the 

 foot large, compressed, tapering ; two adductor muscles, 

 distant and nearly equal. 



Shell regular, equivalve, entirely closed, often longitu- 

 dinally ribbed, generally very convex ; the hinge with 

 central and lateral teeth ; the ligament rather short, 

 external, prominent ; the muscular impressions large, 

 roundish, submarginal. 



Genus 1. Cardium. Cockle. 



Animal roundish. The lobes of the mantle bordered 

 with papillae, and forming behind two short siphons. 

 Foot very large, subcylindrical, with a subcorneal, com- 

 pressed termination, Dent above the middle, and directed 

 forwards. Branchiae short, unequal. Mouth trans- 

 verse, funnel-shaped, with small triangular appendages. 

 Adductor muscles nearly equal. 



Shell subcordiform, roundish, ventricose, equivalve, 

 inequilateral, with radiating costse. Umbones large, 

 prominent, curved inwards and a little forwards, or 

 direct. Hinge strong, with two conical central teeth 



