138 



GEOLOGY OF THE THmD DISTRICT. 



List c^ Fossils from the Reports, etc. of T. A. Conrad, which are found in the Onondaga 

 limestone, and identified and named by him to this period. 



Tbstacea, or Sbell8. 



Delthyxis raricosta. 

 StTophomena gibbosa. 

 — perplana. 



Atrypa nasuta. 



— unisulcata. 



— acutiplJcata. 



Avicula pectenifonnis. 

 Cypricardites inflata. 

 Bellerophon curvilineatus. 

 Pleurotomaria poulsoni. 

 — unisulcata. 



Crustacea. 

 Asaphus aspectans. 



It is possible that D. raricosta may be the same with D. undulatus of the wood-cut ; but the latter is 

 not rare as to number of ribs, having not only the same with D. macropleura and D. pachyoptera, but 

 with an undescribed Delthyris found by Dr. Budd of Lewis county, in the Trenton limestone of that 

 county, and having characters somewhat intermediate to macropleura and undulatus. 



