102 G O N C H O L O G Y« 



Univalves, let me note the five following 

 ftandard or effential ch^radters for the 

 clafles or flimilies. 



Thefe are, i, Simple or not turbinated. 

 2. Turbinated, with a fingle continued 

 cavity. 3. Turbinated and chambered, or 

 with many compartments or cavities. 4. 

 The total (hape : and, 5. The aperture^ 

 mouth, or opening of the Shell. 



The fubordinate characlers for genera 

 and fpecies, I reckon to be only five 

 for Univalves, viz. i. The num.ber of 

 fpires, convolutions, rounds, or wreaths^ 

 2. Whether opercuiated, or covered with 

 a lid, or not opercuiated. 3. The ihelly 

 fubftance, whether opake, horny, pearly, 

 &c. 4. The Epidermis : and, 5. The head 

 and end or tip. 



As thefe characters include the principal 

 parts of all Univalves, they of courfe 

 conftitute the rudiments of the fyftem. 



It 



