CRETACEOUS FOSSILS. 97 



NASSA, Lam. 



N. CRETACEA, 11. 8. 

 PI. 18, Fig. 49. 



Short, fusiform, spire rather elevated; whorls five, rounded, 

 suture distinct. Surface ornamented bv small longitudinal ribs, 

 commencing at the suture and passing nearly across the whorl; 

 these are crossed by fine revolving lines. Canal not very 

 strongly recurved; sinus small, distinct (represented somewhat 

 too small in the figured. Aperture acuminate posteriorly; colu- 

 mella but slightly incrusted. 



Length, usually about half an inch. 



Locality: Not rare at Bull's Head Point, near Martinez (Div. B.). 



N. ANTIQUATA, 11. S. 

 PI. 18, Fig. 50. 



Shell thin, proportionally broader than the preceding species; 

 whorls five, rounded, suture impressed. Surface ornamented by 

 fine longitudinal ribs, almost linear and numerous, crossed by 

 revolving impressed lines, closely placed above, more distant 

 below. Aperture ovate, very narrowly rounded posteriorly; 

 columella very slightly incrusted, broad; canal but slightly re- 

 curved. Length of the specimen, .7 inch; probable length when 

 perfect, .8 inch. 



This species is founded on a single specimen, found by Mr. Mathewson at Bull's 

 Head Point, near Martinez. It is larger than any of the specimens of the pre- 

 ceding species that I have seen. The form is proportionally shorter and broader, 

 and the sculpturing of the surface is markedly different. The shell appears to be 

 minutely cancellate to the naked eye, and the cast, where denuded, exhibits no 

 traces of ribs, while in the other species the cast is distinctly undulated. 



pal. vol. i. — 13 



