no CONCHOLOGY. 



The names I propofe for the chief dif- 

 ferent parts of Univalves are as follow t 



r. The Epidermis, orPeriofleum. This 

 part IS common to Bivalves as Vv^ell as Uni* 

 valves. It is a rough covering or llcin, 

 which many but not all Shells have, only 

 on the outfide, never withinfide the Shell* 

 The Epidermis, perhaps, is a periofle or 

 membrane, that covers the Shells to defend 

 them from exterior accidents, to preferve 

 them, and aid their growth. In that it does 

 the fame office as the periofte or mem- 

 brane that covers the bones of other ani* 

 mals : for the Shells of thefe fifh may be 

 confidered, and indeed are, as analogous 



to the bones of other animals. There 

 are many fpecies of Shells coniiantly have 



the Epidermis ; and there are others that 



never have an epidermis, as the Cowries, 



Olives, &c. 



The Epidermis feems as much a genuine 

 covering of the Shell formed by the fifh 



itfelf. 



