CCELOSPIKA OF THE COKNIFEROUS LIMESTONE. 32» 



CcBlospira concava. 



PLATE LIIL 



Ltptocalia concava : Hall, Pal. New-Tork, Vol. iii, pa. 245, pi. xxxviii, figs. 1-7. 1861. 

 Calotpira concava : Hall, Sixteenth Report on the State Cabinet, p. 60, with figure. 1863. 



The specimens from the Upper Helderberg limestone at Caledonia, 

 New- York, and those from the upper portion of the Lower Helderberg 

 group in Oneida and Herkimer counties, do not show any differences of 

 specific importance, and I am therefore constrained to regard this species 

 as passing upwards from the Lower Helderberg formation ; unless indeed 

 we may infer that some of the sediments of that epoch may have exten- 

 ded farther to the westward and this species have there existed, while 

 the superincumbent formations of limestone, in the absence of the Oris- 

 kany sandstone, have directly succeeded the older beds in such a manner 

 as to have become incorporated with them, or to have left no line of 

 demarcation. 



A single specimen from Stafford in Genesee county is considerably 

 larger than any of those from other localities of the Corniferous lime- 

 stone or of the Lower Helderberg group, while the sinus of the dorsal 

 valve is narrower and less depressed. The material at present possessed 

 is insufficient to characterize it as a distinct species. 



Geological fonnation and localities. In the Corniferous limestone at Caledonia 

 and other places in Western New- York, and also in the same formation in Canada 

 West. 



[ Palaeontology IV.] 42 



