CEPHALOPODA— ORTHOCHOANITES. 



105 



132. T. Iambi (Whiteaves). (Fig. 1332.) Ordovicic. 



Large, biconvex, with lenticular cross section ; rapidly tapering ; 

 siphuncle subventran and moniliform. 



Trenton (Galena) of Minnesota and Manitoba. 



XLVIII. Edaphoceras Hyatt. 



Gyroceracones and nautilicones with faintly impressed zone in 

 adult. Whorls compressed, biangular; sutures with dorsal and 

 ventral lobes and angular lateral saddles ; V-shaped annular lobe 

 m middle of dorsal lobe in adult. Carbonic. 



Fig. 1333. Edaphoceras niotense, side and dorsal views of a fragment. (After Meek 

 and Worthen, 111. Geol., V.) 



133. E. niotense Meek and Worthen. (Fig. 1333.) Mississippic. 



Smooth; impressed zone appears only in adult; lateral angles 

 sharp, septa deep. Type of genus. 



Keokuk of Illinois. 



XLIX. Remeleoceras Hyatt. 



Discoidal nautilicones with well-developed but shallow contact 

 furrow; wide umbilicus and subquadrangular section in later 



