CEPHALOPODA— CYRTOCHOANITES. 



125 



LXV. OocERAs Hyatt. 



Cyrtoceracones of elongate form, more or less compressed dorso- 

 ventrally; septa rise rapidly on ventral side, and sometimes bend 

 sharply towards the aperture, thus forming a funnel, ridge or 

 shoulder on the convex side. Siphuncle large, nummuloidal in 

 adult, tubular in young, often with actiniform deposits; funnel in 

 typical forms of hook-like section and confined to dorsal side of 

 tube. Ordovicic-Siluric. 



171. 0. seelyi Ruedemann. Ordovicic. 

 Small, breviconic, rapidly enlarging; section slightly compressed, 



oval ; cameras shallow ; septa flat ; siphuncle large ; septal necks only 

 on dorsal side. 



Chazy of Lake Champlain region. 



172. 0.(?) lativentrum Ruedemann. (Fig. 1370.) Ordovicic. 



Fig. 1370. Odceras {?) lativentrum, lateral and ventral view of living chamber 

 with one camera ; septal view showing portion of siphuncle. (After Ruedemann.) 



Slender, strongly curved, large; living chamber about one third 

 length of shell; section depressed, elliptical; siphuncle small, pro- 

 pioventran. 



Chazy of Lake Champlain region. 



