OP CONCHOLOGY. 6 



spaniel, is so great as to constitute 

 them of a different species ; as is the 

 bull-dog, mastiff, terrier, &c. Dogs 

 taken generally form a genus. So it 

 is with all natural bodies. 



A plurality of species, constitutes 

 a genus ; and many genera, consti- 

 tutes an order; and several orders, 

 a class ; and a variety of classes, a 

 kingdom. 



The term Conchology includes all 

 animals which have a testaceous 

 covering, whether they inhabit the 

 sea, land, or fresh-water. 



By chemical analysis testaceous bo- 

 dies have been found to consist of, 

 carbonate of lime, mixed with gelati- 

 nous matter. 



Chemists have divided shells into 

 two classes. The first are usually of 

 a compact texture, resembling porce- 

 lain, and have an enamelled surface, 

 and are in general beautifully varie- 

 gated. Those composing this class 



