42 



NORTH AMERICAN INDEX FOSSILS. 



5. E. consuetum Sardeson. (E. champlainense Rued.) Ordovicic. 

 Small, straight, and very slowly expanding; with elliptical sec- 

 tion; septal concavity about one third diameter of shell, in contact 

 with outer shell and somewhat flattened; filled only in apical por- 

 tion; surface smooth. 



Shakopee dolomyte of Wisconsin, Beekmantown (Div. D) of 

 Lake Champlain region. 



6. E. montrealense Ruedemann. (Fig. 1238.) Ordovicic. 

 Gently expanding, with circular section, siphuncle cylindrical 



with slight interseptal constrictions, and seven sixteenths the diam- 



FlG. 1238. Endoceras montrealense, 

 section showing diameter of siphuncle. 

 (After Ruedemann. ) 



Fig. 1239. Endoceras proteiforme, dia- 

 grammatic section showing extent of septal 

 funnels, endosiphosheaths and endosipho- 

 tube, expanding above in endosiphocone. 

 (After Hyatt.) 



eter of the shell; septal concavity twice the depth of camerse; 

 suture with deep ventral lobe, and small dorsal saddle ( ?) ; sur- 

 face smooth. 



Upper Beekmantown of Fort Cassin, Vermont and Quebec. 



7. E. proteiforme Hall. (Figs. 1239, 1240.) Ordovicic. 



Very large (up to 15 ft. or more) ; section circular; air chambers 

 comparatively shallow ; siphuncle very large, submarginal ; siphonal 

 funnels short, sometimes scarcely reaching next septum. 



Stones River of Minnesota, Tennessee and Cincinnati region; 

 Black River of Ontario-Quebec; Trenton and Utica (?) of same. 

 New York and Minnesota. 



