74 



CONCHIFERA. 



P. niveus. P. tigi-inus. 



opercularis. Yig. 117 ; ^ ti. s. varius. 

 pusio. 



118 



119 



Anomia (Linn.). Perforate Oyster, Shell round- 

 isli, thin, transparent, pearly ; left valve convex ; 

 right flat, perforated or notched close to the hinge, 

 the muscle passing through this hole to be in- 

 serted into a plate, which is cemented to foreign 

 "bodies. 



A. aculeata. 



ephippium. Fig. 118 ; ^ n.s. 

 patelliformis. 



Ostrea (Linn.). Oyster. Shell very unequal- 

 valved, the left being convex, the right flat ; the 

 left valve is usually cemented to rocks, or to other 

 shells ; surface irregularly plaited, with free edges j 

 hinge toothless. 



0. e dulls. Fig. 119 ; -J- ti. s. 



