CEPHALOPODA— HOLOCHOANITES. 45 



9, N. noveboracum Ruedemann. Ordovicic. 

 Nepionic bulb (preseptal cone) plump; apex obtusely rounded, 



length 19 mm. 



Ghazy of Lake Champlain region. Rare. 



10. N. aulema Clarke. (Fig. 1242.) Ordovicic. 



Fig. 1242. Nanno aulema, part of shell showing preseptal sipho and camerae 

 and siphuncle ; also mold of siphuncle. (After Clarke, Pal. Minn.) 



Type of genus; preseptal cone thinner and less plump than in 

 preceding, with sharply pointed apex, and rather abruptly con- 

 tracted at camerated end. 



Black River of Minnesota. 



VII. PiLOCERAS Salter. 



Breviconic cyrtoceracones, siphuncle very large ; endocones well 

 defined; septa strongly concave and camerse empty. Ordovicic. 



II. P. explanator Whitfield. (Fig. 1243.) Ordovicic. 



Large (over 10 inches long) with a short preseptal cone; 

 siphuncle with oblique interseptal annuli; surface smooth. 



Upper Beekmantown (Cassian) of the Lake Champlain region; 

 a closely related or identical form {P. triton Bill.) occurs in the 

 Upper Beekmantown of Newfoundland. 



