GASTROPODA— NERINEID&. 



745 



472. N. goodelli Cragin. (Fig. 1079, a, b.) Jurassic. 



Sides of whorls concave, strongly carinated at base, with three 

 to four rather marked spirals ; outer wall with one prominent, 

 thin, acute fold internally, extending scarcely half way across the 

 chamber (well seen in longitudinal sections). Columella partly 



Fig. 1079. a, b, Nerinea goodelli; c-e, Nerinella stantoni, with enlargement and 

 section. (After Cragin, Bull. U. S. G. S., 266.) 



hollow and with a smaller fold, while a third one occurs near the 

 middle of the upper side of the chamber. 



Malone formation of Texas ; a related, if not identical form ap- 

 pears in the Upper Jurassic (Sequanien ?) of the Mazapil region of 

 Mexico. 



473. N. austinensis Roemer. (Fig. 1080, a.) Comanchic. 

 Large, apical angle about 20 , whorls gently concave, smooth, 



basal angulation nodose. Columella with two or three sharp folds, 

 the middle one, if present, smallest, outer lip with one sharp fold 

 directed downwards. 



Edwards limestone of Texas. 



474. N. cultrispira Roemer. (Fig. 1080, b.) Comanchic. 

 Much more slender than preceding ; whorls smooth, strongly 



concave ; basal carina a sharp, blade-like keel. Columella with a 

 single fold and outer lip with a faint one, obsolete in the adult shell. 

 Edwards limestone of Texas. 



