223 



Cytherea — continued. 



Scutellaria. . suborbicular, thin, rather flat ; striae distant. . 2^ 



inches. 

 demisulcata. . ovato-trigonal ; on the upper part of the foreside 



transversely sulcated ; sides fiat ; corselet sunk. . Grignon. 

 nitidula. . ovate, inequilateral ; small transverse striae, some- 

 times obsolete. . Grignon. 

 polita. . ovate, rather flat ; beaks very small, recurved, pointed. 

 antiquata. . trigonal, subcordated, transversely striated ; grooves 



beneath the beaks. , \\ inch vv^ide. . Pontcharin. 

 l(Bvigaia. . oblongo-trans verse, smooth, polished ; beak obtuse, 



recurved. . Grignon. 

 iellinaria. . obovato-trigonal, smooth ; lunule ovato-oblong. . 



Grignon. 

 elegans. . ovato-orbiculate ; with transverse, parallel grooves ; 



lunule ovate. . f inch. 

 deltoidea. . ovato-trigonal ; fine transverse striae ; hinder side 



rounded. . small. 

 corhulina. . suborbicular, ventricose ; transverse striae very slight; 



valves very thick and concave. . very small. 



Venus. 



casinoidea. . cordated, oblique, compressed, angulated forwards ; 



transverse, sublamellous grooves, most numerous in the 



upper part of the valves. . Italy. 

 Resembles V. casina. 

 - paphia. . subcordate, subcompressed, oblique, with thick trans- 

 verse rugae. . North Carolina. 

 aratina. . subcordated, trigonoidal ; concentric, transverse striae ; 



inner margin crenulated. . Touraine. 

 obliqua. . long and rounded, rather smooth ; beak obliquely 



recurved. 

 callosa. . orbiculato-cordated, subangulate ; beaks prominent, 



obliquely incurved ; valves callous internally, externally 



striated. . Grignon. 

 text a. . ovate ; cancellated by the intersections of oblique lines ; 



lunule oval. 



Venericardia. 



planicosta. . obliquely cordated, very thick ; transversely ribbed, 



ribs flat ; entire. 

 Chama rhomboidea. . Brocch. 

 petuncularis . . orbicular, subequilateral ; ribs convex, subimbri- 



cated, laterally muricated. . Beauvais. 

 imbricata. . suborbicular ; ribs convex, imbricatedly squamous, 



nodose, rough. . Grignon. 

 acuticosta. . suborbicular ; ribs carinated, squamoso-dentated, 



rather rough. 

 mitis. . suborbicular, numerous, separate, compressed ribs ; back 



smooth, crenulated behind. . Boves. 

 senilis. . obliquely cordated, very inequilateral, with large convex, 



obsoletely crenulated ribs. . Angers. 



