CANANDAIGUA AND NAPLES QUADRANGLES 65 



this district may be regarded as an indication of the fact that 

 the continental barrier was temporarily down and the western 

 fauna migrated to the east. 



Prattsburg sandstone 



In these beds the fauna, which is fairly profuse in certain 

 layers, does not materially differ from that of the West Hill 

 beds. The lowan species occurring in the High Point fauna are 

 not present or if so are of extremely rare occurrence and certain 

 species are abundant such as 



Spirifer mesastrialis Hall 

 S. miicronatus Kjgnrad var. posterus 

 Hall & Clarke 



Atrypa hystrix Hall 

 A. reticularis Linne 

 Stropheodonta cayuta Hall 



In certain of the beds from the upper part of the division 

 occurs the trilobite Bronteus senescens Clarke, which 

 has also been found as far south as Avoca, Steuben co. in the 

 continuation of the same formation. Associated with it is the 

 spiny crinoid Hystricrinus depressus Wachsmuth & 

 Springer which is known only from these beds. 



