706 



NORTH AMERICAN INDEX FOSSILS. 



periphery to suture. Body whorl very convex, angulated below 

 as well as above, but less sharply ; surface with coarse, oblique 

 striae of growth ; height i.i in., width 1.42 inches. 

 Eagle Ford formation of Texas. 



Family Neritid.-e Lam. 

 XCVI. Nerita Linn. 

 Semi-globose, non-umbilicate, naticoid shells, with minute spire 

 and large body whorl ; inner lip callous, and 

 with straight, commonly denticulate border. 

 Triassic ?-Holocenic. 

 334. N. nodilirata Cragin. (Fig. 10 16.) 



Jurassic. 

 With strong rounded folds on upper part of 

 whorls. 



Malone formation of Texas. 



335. N. nebrascensis M. and H. (Fig. 1017, a-c.) Jurassic. 

 Small ; inner lip smooth ; surface with zigzag color bands. 

 Upper Jurassic ? of Dakota (Black Hills). 



336. N. (Neretina) naticiformis White. (Fig. 10 17, d, e.) 



Cretacic. 

 Small, surface smooth, inner lip faint. 

 Bear River formation of Wyoming and Utah. 



337. N. crebrilineata White. (Fig. 1017, /,£\) Cretacic. 



Fig. 10 1 6. Nerita no- 

 ■dilirata. (After Cragin, 

 Bull. U. S. G. S., 266.) 



h^&r ^^ e d 



FlG. 1017. a-c, Nerita nebrascensis; d,e,A r . (Neritina) naticiformis ; /, g, N. 

 crebrilineata ; h, i, N. pisum. (After White, U. S. G. S.) 



Larger than preceding ; spire minute ; callus of inner lip strong ; 

 surface with regular fine spirals. 



Laramie of Wyoming and Colorado. 



