366 Review of the Neio York Geological Reports. 



Fig. 3 occurs also in the hills at Cincinnati. Fig. 6 is, to all 

 appearance, the same as the Caradoc fossil of the same name rep- 

 resented in Murchison's Silurian System. If so, it is one of the 

 few species whose absolute identity on both sides of the Atlantic 

 can be established. 



A Pleurotomaria, considered the same as fig. 2, has also been 

 found both in Iowa and Ohio. Here are some of the bivalves of 

 the Trenton limestone. 



The true S. sericea is a Caradoc fossil ; if this be identical with 

 it, then there is another point of specific identity established be- 

 tween the American and English fossils. A fossil closely allied 



