CEPHALOPODA— CYRTOCHOANITES. 



123 



living chamber slightly contracted ; siphuncle slightly nummuloidal ; 

 surface smooth. 



Chazy of Lake Champlain region. 



166.0. lycus (Hall). (Fig. 1365.) Ordovicic. 



Larger, more arcuate, and more compressed than preceding; 



living chamber very slightly contracting, somewhat abrupt just 



Fig. 1365. Oncoceras lycus, body chamber and a few carnerae are preserved. 

 (After Clarke, Pal. Minn.) 



below slightly flaring lip ; venter subacute ; lip with dorsal and 

 ventral sinus. 



Stones River beds of Wisconsin and Minnesota. 



167. 0. carveri Clarke. (Fig. 1366.) 



Ordovicic. 



Fig. 1366. Oncoceras carveri, living chamber and a few camerse. 

 (After Clarke, Pal. Minn.) 



More strongly compressed than preceding; dorsoventral and 

 lateral diameters as 3:2. 



Stones River beds of Minnesota and Illinois. 



168. 0. pandion (Hall). (Fig. 1367.) Ordovicic. 



Strongly arched venter and less curved dorsum, the latter broad, 

 the former narrow ; suture with broad ventral saddle. 



