GASTROPODA— -AKERATIDJE—BULLIDJE. 809 



margin; columella with callus and two to four plicae. Cretacic- 

 Recent. 



648. R. dalli Clark. (Fig. 1 190.) Eocenic. 

 Minute, five-whorled ; suture moderately impressed ; surface with 



regular close-set spirals; outer lip thick, ornamented within; colu- 

 mella with thick callus and two plicae. 



Pamunkey formation of Maryland and Virginia. 



Family Akeratio<e Pilsbry. 

 CCII. Haminea Leach. 

 Thin and brittle shells with concealed spire, oval in contour; 

 surface mostly with spirals. Cretacic-Recent. 



649. H. subcylindrica M. and H. (Fig. 1191.) Cretacic. 

 Subcylindrical, large for the genus (about one inch long) ; very 



Fig. 1 191. Haminea subcylin- FlG. 1 192. Haminea occidentalis, two in- 



drica. (After Meek.) ternal molds. (After Meek.) 



thin ; summit with slight pit over apex ; lip extended below. 

 Pierre of upper Missouri and Black Hills. 



650. H. occidentalis (M. and H.). (Fig. 1 192.) Cretacic. 

 Smaller and less cylindrical than preceding; widest below middle; 



upper end obliquely truncated, with minute, central pit. 



Pierre of Yellowstone, near Platte River, and in the Saskatche- 

 wan region of Canada. 



Family Bullim: Pilsbry. 

 CCIII. Bulla Klein. 



Smooth, involute shells with sunken spire and inflated body 

 whorl; aperture rounded at both ends; outer lip sharp. Juras- 

 sic ( ?) -Recent. 



651. B. macrostoma Gabb. Cretacic. 

 Subglobular, with two or three volutions; aperture very broad, 



