Ch. xvil] fossils of uppp:ii cretaceous rocks. 



247 



of which are distinguished by a fibrous texture, and are often met with in 

 fragments, having probably been extremely friable. 



Fi?. 271. 



Fis. 272. 



Fisc. 273. 



Pecten b-cosiatus. 

 White chalk, upper and 

 lower arreensands. 



Plagiostoma IToperi, Sow. 



Syn. Lima Uoperi. 



"White chalk and upper 



grcensand. 



Plagiostoma spinosum. Sow. 



SyD. Spondylus spinosus. 



Upper white chalk. 



Of the singular family called Rudistes^ by Lamarck, hereafter to be 

 mentioned as extremely characteristic of the chalk of Southern Europe, a 



Fig:. 274. 



Fig. 275. 



Inoceramus Lamarekii. 



Syn. Catillus Lam<irckii. 



"White chalk (Dixon's Geol. Sussex, Tab. 28, 



fig. 29). 



Ostrea msicularis. Syn. GrypJicea gloiosa. 

 Upper chalk and upper greensand. 



single representative only (fig. 218) has been diseovered in the white 

 chalk of England. 



Fig. 276. 



Fig. 27T. 



Ostrea columha. 



Syn. Gryphma colicmba. 



Upper greensand. 



Ostrea earinata. Chalk marl, upper and 

 lower greensand. 



