No. IV. 



Description of Six New Species of the Genu* Uhio, embrac- 

 ing the Anatomy of the Oviduct of one of lhcn>. together 

 with snini Anatomical Observations on the Genu*. Jiy 

 Isaac Leo. — Read before Ike American Philosophical Society 

 November 2d 1827. 



}JrcUiuiuan> lttmavhs. 



FN the present contribution to the science of Concholoey, 1 

 ■have endeavoured to be as brief as I thought the subject 

 would permit 



I have often fell the great inconvenience sustained from 

 too short and indefinite descriptions; and am therefore fully 

 sensible of the necessity, for the proper distinction of the spe- 

 ci( 9, of a more minute notice of their characters than i> usu- 

 ally given. In ihix Mr Barneshasshewna laudable example, 

 and he deserves the acknowledgments of the conchologist*. 



It will be observed I have followed his plan of dividing the 

 margin of the disk into eight parts, reversing hi> posterior and 

 anterior margins. 



3wamson says, "Although Lamarck has described so many (Uniones),lhe 

 short descriptions he has given, and the want of figures to elucidate them, rendei il 



impossible to determine accurately one half the species which he has enumerated 



