CEPHALOPODA— ORTHOCHOANITES. 69 



and are laterally compressed in adult. Aperture with prominent 

 lateral crests. Ordovicic. 



65. E. kelloggi (Whitfield). (Fig. 1278.) Ordovicic. 



Large, rather closely coiled, rapidly enlarging; living chamber 



free in old age ; whorls slightly compressed laterally ; impressed 



zone marked, but not deep ; sutures with broad lateral lobes in 



Fig. 1278. Eurystot7iites kelloggi, iyipt sp&cxmtn, y^ ^2- (After "Whitfield, 

 Am. Mus. Bull.) 



adult; siphuncle tubular, subventran in earlier, extracentroventran 

 in adult stages. 



Beekmantownian (Fort Cassin beds) of Lake Champlain region. 



66. E. virginianus Hyatt. Ordovicic. 

 More cylindrical whorls than preceding, with more numerous 



and straighter sutures, and siphuncle nearer the venter. 



Beekmantownian of Lake Champlain region (Fort Cassin), and 

 near Lexington, Va. 



67. E. undatus (Emmons). (Fig. 1279.) Ordovicic. 

 With fewer whorls than E. kelloggi; strongly compressed in 



adult, the last whorls not embracing and loosing impressed zone. 



