297 Crown Point Section 31 



the Mohawk valley. He found the hemispheric form above the 

 Black River onh\ 



The lowest member of the Trenton in this secflion is the 

 Raphistoma lenticularc zone, 4 feet 9 inches in thickness. This 

 fossil is common in this zone, but only one specimen was found 

 above.* 



Above this is the Parastrophia hemiplicata zone of Theo. G. 

 Whitef. Although not abundant, this fossil is characfteristic of 

 20 feet 9 inches (C 31-34). C 39-43 are marked by the presence 

 of Trinudeus concentriciis Eaton, which is not found lower in the 

 strata. It will be seen that trilobites are a much more prominent 

 part of the fauna after C 37. Asapluis platyccphaliis Stokes, 

 which has not before been common, becomes abundant in C 46 

 and 47. 



Dahnanella testudinaria, Rafinisquina alteniata, Pleflam- 

 bonites sericeics, Bellerophon bilobatus, Asaphus platycephalus, and 

 Calymene senaria are found all through the Trenton here, as at 

 the type locality, Trenton Falls, N. Y. Platystrophia biforata is 

 not found in the lowest part, either in this se(5lion or at Trenton 

 Falls. Lamellibranchs are not common at either place. 



LIST OF SPECIES 



A 1-8. Basal 52 feet of Chazy. 



B I- 1 6. Upper 146 feet of Chazy. 



C I- 1 7. Upper 2ig feet of Chazy. 



C 18-29. Black River. 67 feet. 



C 30-47. Trenton limestone. Lower 88 feet. 



*Since the Trenton at Crane'.s Point and Norton's Bay on the Vermont 

 side of the lake, about two miles distant, is 314 feet in thickness, the .strata 

 shown on this Point represent less than one-third of a complete section. 



fTrans. N. Y. Acad. Sci., XXV, p. 20 (1895). 



