225 



Cardita. 



yallicana. . roundedly rhomboidal, oblique ; ribs radiating, sub- 



sqaamose ; upward, the squamae more distant. . Angers. 

 rudista. . obliquely cordated, transverse ; ribs round, separated; 



squamously echinated in the forepart. . Sienna. 

 Etrusca. . obliquely cordated ; ribs nearly flat and smooth. . 



Sienna. 

 crassa. . oblong, rather winding backwards ; ribs thick, rounded, 



imbricatedly squamose ; squamae obtuse. 



Cypricardia. 



coralliophaga. . thin, oblong, rather cylindrical ; decussatedly 



striated ; compressed before ; marginal striae prominent in 



laminae. . Italy. 

 modiolaris. . oval-oblong ; tumid ; transverse, bowed striae ; 



lunule ovate, impressed. . Caen. 

 obliqua. . obliquely cordated, convex, rather smooth; upper 



border rounded ; no transverse striae. . Mouliers. 

 trigona. . cordato-trigonal, short ; with very small transverse 



striae. 



Isocardia. 



Cor. . cordato-globose, smooth. . Italy. 



arietina. . oblongo-cordate, with deep longitudinal grooves ; 

 bases large, terminating in two contorted turns. . Italy. 



Cucullaea. 



crassatina. . subcordated, ventricose, with interrupted longitu- 

 dinal grooves, sometimes none; a very short internal 

 auricle. . Beauvais. 



Area. 



scapha. . transversely oblong, ventricose, many ribbed; the ribs 

 flat ; umbos oblique. . Demifossil. . Timor. 



diluvii. . ovato-transverse, ventricose, many ribbed ; ribs thirty- 

 two to thirty-six, flat, transversely striated ; area sloping ; 

 margin crenated. . 2 inches wide. . Plaisance. 



biangula. . transversely oblong ; decussated, with granulato- 

 squamous striae, the foreside produced, with two angles. . 

 lj inch wide. 



scepulina. . oblongo-ovate ; transverse, windingly contracted in 

 the middle ; with longitudinal grooves closely granu- 

 lated. . Grignon. 

 Area barbatula, Annales du Mus. 



interrupta ovato-oblong ; transverse, depressed, longitudinally 

 grooved ; hinge interrupted, with few teeth ; beaks con- 

 tiguous. . Parnes. 



clathrata. . ovato-transverse, depressed, finely cancellated; 

 foreside oblique, beaks approximated. . f inch. .Angers. 



angusta. .transversely oblong ; narrow, rather depressed ; decus- 

 sated; beaks approximated. .Grignon. 



quadrilatera. . transverse, oblongo- quadrate, windingly depressed 

 in the middle, decussating striae ; the long striae most con- 

 spicuous. 



Gg. 



