GASTROPOD A—STROPHOSTYLWM. 



683 



Like P. ventricosum with apex only coiled. 

 Oriskany of Maryland, etc. 



FlG. 961. Platyceras magnificum, a small individual. (Pal. N. Y., III. 



243. P. reflexum Hall. (Fig. 962.) 



Like P. gebhardi, but only coiled apically. 

 Oriskany of Maryland, etc. 



244. P. arkonense Shimer and Grabau. 



Devonic. 



Devonic. 



Fig. 962. Platycerasrejlexum, opposite views of two individuals. (Pal. N. Y.,III.) 



Similar to the next, but with scattered slender spines. 

 Hamilton of Ontario, Michigan, and Iowa, Charlestown, Indiana. 



245. P. erectum Hall. (Fig. 963, a.) Devonic. 

 Like Diaphorostoma lineata, with last whorl free, and margin 



oblique and sinuous. 



Hamilton of New York, Ontario, etc. 



246. P. carinatum Hall. (Fig. 963, b.) Devonic. 



