114 NEW YORK STATE MUSEUM 



at home, as in the Shawangunk grit and the Bertie waterlime at 

 Litchfield. This is due to the fact that the greater number of speci- 

 mens are actually shed skins, but shed in the locality itself, and 

 further, as we are quite convinced, to the habit, so clearly observed 

 among the crabs and other crustaceans in the ocean, of eating, with 

 praiseworthy economy, the skins they have shed and further of 

 cutting up and destroying with their pincers all skins and shells that 

 are not any more palatable. In warm seas, where the shore line is 

 alive with crabs, it is on account of these habits of the crabs, impos- 

 sible to pick up whole exoskeletons. Nevertheless we find in the 

 Bertie waterlime, especially at Buffalo, altogether too large a per- 

 centage of splendidly preserved whole exoskeletons of eurypterids 

 which entirely lack the frontal cleft indicating that the skin was 

 shed, to be able to assume that these were drifted into the basin. 

 But Grabau and O'Connell go still further and attempt to 

 make even the fauna of the Bertie waterlime a freshwater fauna. 1 

 It is in view of this assertion that the writer has brought together 

 the following lists of fossils from the Bertie waterlime and Pitts- 

 ford shale and waterlime, our two principal eurypterid-horizons of 

 the Silurian. 



The Pittsford shale at Pittsford contains besides the eurypterids 

 and crustaceans described therefrom (species of Eurypterus, 

 Pterygotus, Hughmilleria, Pseudoniscus, Emmelezoe, Ceratiocaris) : 



Lingula semina Ruedemann cc 



Pterinea poststriata Ruedemann cc 



Leperditia scalaris Jones cc 



Septameroceras sp. rr 



Orthoceras sp. rr 



Toward the east this horizon changes into a waterlime rock, 

 which at Farmers Mills contains besides Eusarcus- van- 

 in g e n i an abundance of 



Lingula alta Ruedemann cc 

 Orbiculoidea molina Ruedemann cc 



The Bertie waterlime contains besides the eurypterids, Pseudo- 

 niscus and Proscorpius 



Inocaulis lesquereuxi (Grote & Pitt) r 

 Lingula testatrix Ruedemann c 

 Diaphorostoma sp. rr 

 Hercynella patelliformis O'Connell rr 



1 Marjorie O'Connell 1 . Description of Some Siluric Gastropods. Buf- 

 falo Soc. of Natural Sciences Bui., v. XI, no. i. 1914. 



