2S8 NEW YORK STATE MUSEUM 



dence of several rather prominent transverse folds. The spiral por- 

 tion of the shell is not preserved. 



Diaphorostoma desmatum Clarke 



One shell from the Upper Oriskany has three volutions; its 

 diameter through the plane of coiling is 17mm, the greatest dis- 

 tance at right angles to this plane is lomm. The concentric striae 

 are pronounced and closely crowded. The revolving striae do not 

 cross the concentric ones and hence only modify the interspaces. 

 This is very similar to the young stages of D . 1 i n e a t u m of 

 the Onondaga and Hamilton above. On the adult shell of this latter 

 species, however, the revolving striae become more and more pro- 

 nounced, producing a cancelation; in the older shells the difference 

 in the development bf the two sets of striae becomes still more 

 marked, and the cancelation becoming scarcely noticeable, the shell 

 appears at a glance to be only longitudinally striated, the very oppo- 

 site of D. desmatum. 



D. nearpassi (Weller) 



One small specimen was found in the Lower Oriskany. It is 8mm 



in greatest diameter and 4mm high. The lines of growth are 



crowded and raised above the surface of the shell. No revolving 



striae are present. 



D. ventricosum (Conrad) 



Shell normal in size and form. It is very abundant in the upper | 

 beds of the Oriskany where it almost invariably occurs as internal 

 molds. It also occurs rarely in the Lower Oriskany beds and in the 

 Lower New Scotland. 



PTEROPODA 



Tentaculites acula Hall 



J 



The characteristic pteropod of the Lower Oriskany where it is 

 quite abundant. ' ^ 



T. elongatus Hall . |f 



Exceedingly abundant in some bands of the Upper Oriskany. It 

 occurs much more rarely in the Lower Oriskany while one specimen 

 was noted in the Upper New Scotland. 



