224 

 Venericardia continued. 



concentrica. . suborbicular, rather depressed ; concentric, ele- 

 vated, lamellose striae, with grooves. . Chamont. 



decussata. . suborbicular ; longitudinal ribs cancellated by trans- 

 verse striae ; hinge teeth divaricated. . Grignon. 



elegans. . suborbicular ; numerous elevated, compressed ribs ; 

 backs squamosely serrated. . Grignon. 



Cardium. 



distans. . tumid, subequilateral ; sixteen ribs, obtuse, smooth, 



and distant. . England. 

 echinatum. . tumid ; ribs flat, grooved, with thick ear-formed 



papillae. 

 burdigalinum. . gaping forwards, ribs smooth in the middle, 



serrato-spinose before, and crenato-squamous in the hinder 



part ; border of the opening deeply serrated. . Bourdeaux. 

 porulosum. . margin serrated with ligulated teeth ; ribs carinated, 



crenulated, and porulous at their base. . Grignon. 

 sulcatinum. . longitudinally sulcated ; corselet and lunule smooth. 

 rhomboides. . subtransverse ; sixteen distant ribs, transversely 



sulcated. 

 diluvianum. . angulated in the fore part ; fourteen ribs, distant, 



convex ; corselet raised, subcarinated. . Sienna. 

 serrigerum, . thirty ribs, with serrseform teeth ; sharpest on the 



foreside. . Grignon. 

 Telluris. . shaped somewhat like cardium cardissa ; the carinated 



back of the valves sulcated ; the anterior side flat ; back 



part convex ; with obtuse entire keels. . Mons and St. Jean 



d'Asie. 

 lithocardium. . subtrilateral ; valves with carinated ribs on the 



back, diminishing upwards, very sharp. 



cymbularia. . long, subtrilateral ; valves with carinated ribs, di- 

 minishing to points upwards ; longitudinally sulcated. . 



Valogne. 

 umbonare . . obliquely cordated ; seventeen ribs, transversely 



striated ; base large. . Sienna. 

 Hillanum. . obliquely cordated ; transverse, close, concentric 



striae ; longitudinally sulcated on the foreside. . England. 

 hibernicum. . rounded ; valves sulcated and carinated ; sides 



transversely produced, pervious at the extremity, hinder 



part shortest, truncated, projecting in the middle. . England. 

 discors. . subcordated, thin, rather smooth ; with longitudinal 



strise anteriorly, and transverse ones posteriorly. 

 porulosum. . subcordated ; edge serrated ; ribs raised, crenulated, 



carinated, thin, porulous at the base. 

 asperulum. . roundish, cordated, subechinated ; numerous sub- 



squamous convex ribs, about thirty-two ; with erect for- 

 nicated squamae. 

 calcitrapoides. . roundish, cordated ; fore part echinated ; convex 



ribs, twenty to twenty-two, mostly smooth, but sharp in 



the fore part. 



