118 [Sewatk 



which produce a faint reticulated appearance under the magni- 

 fier. Surface of the shell, when well preserved in limestone, 

 smooth and shining. Cast strongly and deeply punctate, parti- 

 cularly towards the margins : spines small and nearly vertical 

 to the hinge-line ; number unknown. 



The striae do not extend to the angles of the cardinal extremities ; a 

 considerable space being left smooth, or marked only by concentric striae. 

 In this respect it resembles Chonet.es pusilla, from which it is readily 

 distinguished by its finer and more numerous stride. This species is also 

 distinguished from C. yandellana of the limestone at the Falls of the Ohio^ 

 by its finer and less distinctly defined striae, which do not reach the cardinal 

 extremities, while in that species they are very distinct and well defined on 

 that part of the shell. From C. scitvia, this species is distinguished by 

 its smaller size and less elevated striae, and more gibbous or hemispheric 

 form, and less proportional width. 



This species is usually regarded as the C. 7i.ana ; from which it is di- 

 stinguished by its more gibbous form and much greater number of strise, 

 as well as, frequently, its greater size, though many individuals are not 

 larger than the figures of that species. 



Geological 'position and locality. In the higher beds of limestone of the 

 Upper Helderberg at Oneida falls ; between Jamesville and Manlius, 

 Onondaga county ; in Seneca county ; and on the Indian reservation a 

 few miles southeast of Buffalo. 



1 2 





Chonetes glabra. 



Chonetes yandellana ( n. s.). 



Shell semioval, more or less gibbous ; hinge-line equalling the 



greatest width of the shell ; cardinal spines four or five on 



each side of the beak, apparently nearly vertical to the hinge - 



line. Surface distinctly striated j striae somewhat equal, bifur- 



