CEPHALOPODA— CYRTOCHOANITES. 1 27 



175. P. sauridens Clarke and Ruedemann. (Fig. 1373.) Siluric. 

 Small, fusiform, tapering abruptly and very slightly curved ; 



Fig. 1373. Poterioceras sauridens, two views of inner mold of living chamber, 

 and a nearly complete internal mold. (After Clarke and Ruedemann, Guelph Fauna. ) 



living chamber rather short and strongly contracted, but bending 

 out again at aperture, which has shallow hyponomic sinus and 

 broad, low dorsal saddle. 



Guelph of New York; Upper Monroe of Michigan. 



Fig. 1374. a, b, Poterioceras hyatti, yC^ Yz ', c (center), P. amphora, yC^ ^. 

 (After Whittield.) 



