686 NORTH AMERICAN INDEX FOSSILS. 



Haliotis- like ; resembling vertically compressed small P. ventri- 

 cosutn with very oblique aperture. 



Waverly of Ohio ; Choteau of Missouri. 



255. P. paralius White and Whitf. (Fig. 969.) Mississippic. 

 Small, apex slightly enrolled, lower portion strongly plicate. 



FlG. 967. Platyceras tribu- FlG. 968. Platyceras halio- Fig. 969. Platyceras 

 losum. (After Keyes.) toides. (After Keyes.) paralius, type. (After 



Keyes. ) 



Kinderhook of Iowa and Missouri ; Waverly of Ohio ; Burling- 

 ton of Missouri. 



256. P. parvum (Swallow). (Fig. 970.) Carbonic. 



Fig. 970. Platyceras parvum, opposite views of a specimen attached to a crinoid stem. 

 (After White, 13th Ind. ) 



Entire shell making about one loose volution ; aperture very 

 sinuous. 



Coal measures of Kansas, Nebraska, Illinois, New Mexico, 

 Indiana, Iowa, Missouri. 



LXXV. Pal^eocapulus * Grabau and Shimer. 

 Symmetrical platyceroids with the beak incurved but scarcely 

 enrolled in the median line or slightly deflected. (Possibly derived 

 from Cyrtolites.) Type P. lodiensis. Devonic-Mississippic. 

 257. P. expansus Hall. (Fig. 971.) Devonic. 



Fig. 971. Paleocapulus expansus. (Pal. N. Y., III.) 



