CEPHALOPODA— ORTHOCHOANITES. 67 



young, proprioventran later. Surface smooth except for growth 

 hnes; hyponomic sinus deep and broad. Ordovicic. 



62. T. seeleyi (Whitfield). (Fig. 1275.) Ordovicic. 



Very slowly expanding tube of subcircular section; impressed 



Fig. 1275. Tarphyceras seeleyi, X Vz- (After Ruedemann, Bull. 90, N. Y. State 



Mus. ) 



zone faint ; small, subcentral siphuncle ; septa closely arranged and 

 strongly concave. 



Beekmantownian (Fort Cassin beds) of Vermont, and Valcour, 

 New York. 



63. T. clarkei Ruedemann. (Fig. 1276.) Ordovicic. 

 Differs from the preceding in its larger size and lateral compres- 

 sion of later whorls, the last being partly free; siphuncle large, 

 tubular, proprioventran. 



Beekmantownian (Fort Cassin beds) of Champlain region, New 

 York. 



64. T. multicameratum Ruedemann. (Fig. 1277.) Ordovicic. 

 Small, with rapidly expanding tube, laterally compressed in later 



whorls, the last being partly free ; camerae numerous, short ; siphun- 

 cle tubular, small and proprioventran. 

 Chazy of Lake Champlain region. 



