720 



NORTH AMERICAN INDEX FOSSILS. 



Colorado formation of Colorado, Utah, etc. 

 385. G. conradi Meek. (Fig. 1044, b t c.) Cretacic. 



Low spire, broadly rounded body whorl with a subsutural angu- 

 lation and a narrow flattened or concave band between this and 

 the suture ; strongly carinate in the central basal portion, while a 



I 



further angulation margins the broad funnel-shaped umbilicus ; 

 aperture subrhombic, about twice as wide as high. 



Colorado formation (Benton, and Pugnellus sandstone), of South 

 Dakota and Colorado. 



386. G. crenata Conrad. (Fig. 1045.) Cretacic. 

 Like the former but with the carination below the suture crenu- 



lated or nodulated, generally not shown in the internal mold. 

 Ripleyan of New Jersey, Alabama, Mississippi. 



387. G. abyssina (Morton). (Fig. 1046.) Cretacic. 



Gyrodes abyssina. (After Whitfield. 



Like the preceding, but without the basal carination. 



Ripleyan of New Jersey, Alabama, Texas. 

 388. G. petrosa (Morton). (Fig. 1047.) Cretacic. 



Like G. abyssina but smaller and with the space below the 

 suture flat instead of concave. 



