BEEKMANTOWN AND CHAZY FORMATIONS OF CHAM PLAIN BASIN 467 



dorsoventral diameter has become equal to the other one and the 

 conch is subcircular in section. The sutures pass nearly straight 

 transversely in both the nepionic and neanic stages, the lateral lobes 

 being still undeveloped, and the ventral saddle very shallow. They 

 begin, however, in the neanic stage to turn markedly forward near 

 the line of involution, indicating the presence of a high dorsal saddle. 



j&^-v : ; ' : '.y 



Fig 26 Tarphyceras seelyi Whitf. (sp ) Section showing the livin 

 chamber. Natural size 



This forward curvature of the dorsal sutures is in our specimens 

 developed much stronger than either Whitfield's drawings or de- 

 scription would indicate for the type specimen. The latter, however, 

 showed on inspection the same feature. 



