LAMELLIBRANCHIATA. 



123 



No. 341. Gervillia socialis. Lye. and Mor. 



This genus is entirely fossil, ranging from the Carboniferous to the Creta- 

 ceous; 37 species being known. From the Muschelkalk, Munchingen, Wur- 

 temberg. 



No. 342. [667, Cast]. Qervillia anceps, Deshayes. 



A characteristic bivalve fossil, from the 

 Lower Greensand of Atherfeld, Lsle of 

 Wight, England. Size, 8 x 2. 



No. 343. Lima rigida, Deshayes. 



The type genus of the Limidae; 300 species fossil, ranging from the Car- 

 boniferous. From the Calcareous Grit (Jurassic), Oxford, England. 



No. 344. Pecten opercularis, Lam. 



This genus, the type of the Scallop family (Pectinidse), has 450 extinct 

 species, beginning in the Devonian, and 200 still living. Quaternary, Palermo, 

 Sicily. 



No. 345. Pecten expansus, Dall. 

 Tertiary, San Diego, California. 



No. 346. Pecten (Neithea) quadricostata, Sow 



This typical Cretaceous shell, from College Hill 

 Texas, closely resembles Janira Neocomiensis of d'Or 

 bigny, from the Low^er Cretaceous of France. 



No. 347. Ostrea Marshii, Sow. 



The family Ostreidte have shells unequivalved 

 and unequilateral, and one muscular impression. 

 They are commonl}^ regarded as the lowest of the 

 Lamellibranchs. This type genus began in the 

 Carboniferous and has supplied 200 extinct species 

 and 70 living. From the Lias, Stilfenberg, Wur- 

 temberg. 



No. 348. Ostrea larva, Lam. 

 From the Rotten Limestone (Cretaceous), Alabama River. 



No. 349. Ostrea, 



From the Raised Beaches (Quaternary), Gebel Zeit, Gulf of Suez. 



