744 NORTH AMERICAN INDEX FOSSILS. 



464. G. sublaevis M. and H. (Fig. 1078, k.) Cretacic. 

 Larger and somewhat more slender than G. gracilenta and suture 



slightly impressed. 



Laramie (Judith River) of Upper Missouri River region. 



465. G. subtortuosa M. and H. (Fig. 1078, /, m.) Cretacic. 

 Small, low-spired, strongly angulated near the middle, shoulder 



nearly flat ; no ribs or spirals. 



Laramie of Upper Missouri River region and the Bow and Belly 

 River regions of Canada. 



466. G. tenuicarinata M. and H. (Fig. 1078, n, 0.) Cretacic. 

 Angulated, short and thick-set, shoulder flat, limited by sharp 



carina, below which are two or three sharp spirals. 



Laramie of Montana, the Upper Missouri River region, Col- 

 orado, east of Rockies, Utah and various localities in Canada. 



467. G. simpsoni Meek. (Fig. 1078, p.) Eocenic. 

 Smooth, whorls convex, suture impressed. 



Bridger Eocenic, Wyoming. 



468. G. tenera Hall. (Fig. 1078, q.) Eocenic. 

 Like the preceding but with faint ribs extending part way below 



the suture, and with faint spirals. 

 Eocenic, Utah. 



469. G. nodulifera Meek. (Fig. 1078, r-t.) Eocenic. 

 Ribs mostly replaced by faint nodulations on the median angu- 

 lation. Shoulder flat. 



Fresh-water Eocenic of Rocky Mountain region. 



470. G. carteri Conrad. (Fig. 1078, u, v.) Eocenic. 

 Nodules strong, ribs not altogether obsolete. 



Fresh-water Eocenic of Rocky Mountain region. 



471. G. columinis White. (Fig. 1078, w.) Eocenic. 

 Strongly angular, nodes large and sharp and continued in ribs 



nearly to sutures ; spirals strong. 



Fresh-water Eocenic of Rocky Mountain region. 



Family Nerineim: Zittel. 

 CXXXI. Nerinea Defrance. 

 Like Turritella in form, but aperture with short anterior notch, 

 columella with simple folds which are also commonly found on 

 both inner and outer lip. Jurassic-Cretacic. 



