124 NEW YORK STATE MUSEUM 



mile, to Borst's sawmill, which is 180 feet above the limestone. 

 The upper beds in this section, though retaining their dark blue- 

 gray or blackish color, carry Spirifer and Chonetes and in this 

 respect suggest correspondence with the upper beds in western 

 sections which have latterly been regarded as pertaining to the 

 Marcellus. 



Typical Hamilton sandy shales are exposed just above Borst's 

 mill. No limestone beds were observed in the section above the 

 basal limestone. The distance of the latter above the Onondaga 

 limestone is approximately estimated from levels, to be from 

 10 to 30 feet. The evidence in this section clearly indicates the 

 rapid extinction of the Agoniatites limestone eastward from 

 Otsego county and at points east of that here mentioned no out- 

 crops of the horizon or evidence of its index fossils have been 

 recorded. 



FAUNA OF THE AGONIATITES LIMESTONE 



Most of the species of this horizon have been made known by 

 Conrad and Hall, and the limestone often retains its organic 

 remains in fine preservation. Specially Superior and well known 

 are the great shells of Agoniatites expansus Vanuxem 

 (=G on. v a n u x e in i Hall). To this is to be added a large 

 number (in view of the total faunal list) of other cephalopods. 

 The fauna is peculiar in that it represents a deep water associa- 

 tion introduced briefly in the shallower sea depositing the black 

 shales, and its species are, further, to a notable percentage con- 

 fined to it. Some of the outcrops of this layer in Onondaga 

 county have of late years been carefully exploited by Prin. 

 John D. Wilson of Syracuse, whose investigations have resulted 

 in several additions to the faunal list, and to whom I am indebted 

 for many favors in the study of the species. 



Mesothyra ? (Manlius) 



Proetus haldemani Hall (Cherry Valley) 



Cyrtoceras alternatum Hall (Schoharie) 



C. liratum Conrad (Manlius) 



Cromphoceras conradi Hall (Schoharie, Manlius) 



G. fischeri Hall (Manlius) 



