II. FOSSILS FROM THE WATERLIME GROUP NEAR 



BUFFALO, N. Y. 



BY JULIUS POHLMAN, M. D. 



The Waterlime group near the city of Buffalo continues to 

 yield specimens of fossils in various states of perfection. The 

 numbers are few, but as the fauna of the group is very limited, 

 each additional fragment found aids us in a more correct under- 

 standing of the interesting crustaceans which seem to have been 

 the only representatives of animal life at that period of the geo- 

 logical history of our continent. Fragments of Pterygotus have 

 been found at long intervals here, as well as in England, but none 



have been in a satisfactory state of perfection, and it is there- 



* 

 fore with pleasure that I record the finding of the first specimen 



complete enough, to clearly illustrate the different parts and their 



proportions. 



The specimen under consideration presents the dorsal side of 

 the carapace and eleven body segments. At first sight we must 

 admit that it bears a very close resemblance to Eurypterus, 

 and it may be a difficult matter to distinguish between fragments 

 of the bodies of the two genera if the surface markings, which 

 are apparently characteristic of Pterygotus, have been obliterated. 



Viewed as a whole, the most striking difference between 

 Pterygotus and Eurypterus, is the comparatively small carapace 

 of the former. In the latter the average length is equal to the 

 length of four or five of the anterior body segments, but in 

 Pterygotus it is a little shorter than the length of the first three 

 segments. The feet are in every respect considerably smaller 

 in Pterygotus than the corresponding organs of Eurypterus. The 

 whole body of the specimen is covered with small scales, which 

 assume a pustulose character on the two posterior segments. 



