214 



NORTH AMERICAN INDEX FOSSILS. 



Clinton and Niagara of New York, Kentucky, Indiana, Illinois, 

 Wisconsin. 



Fig. 254. Slropheodonta profunda, with enlargement of striae. 



74. S. varistriata (Conrad). (Fig. 255.) Siluric-Devonic. 



Pedicle valve varying from slightly convex to gibbous, with 

 slightly elevated beak. Surface usually with alternations of more 

 or less prominent striae, the sharper ones being separated by several 

 minute ones. 



Manlius and Coeymans of New York, Quebec, New Brunswick. 



Fig. 255. Stropheodonta varistriata. 



Fig. 256. Stropheodonta (Leptostrophia) beckei, interior and exterior of pedicle 

 valves of different sizes ; profile of complete shell. 



