CRETACEOUS FOSSILS. 113 



perfectly smooth and polished; at other times ornamented hy 

 sharp, impressed lines ; and in still other specimens having square 

 ribs of variable width, with the lines of growth strongly developed 

 in the interspaces, and represented on the surface of the ribs by 

 shallow undulations. 



Figure a, twice natural size ; Fig. b, a magnified view of the surface of the most 

 highly ornamented variety. 

 Locality: Cow Creek, Shasta County, cast of Shasta City. 



NERINEA, Defr. 



K". dispar, n. s. 



PI. 19, Fig. 66, and 66 a. 



Shell slender, elongated ; whorls numerous, very oblique ; 

 apical angle very small ; suture impressed. Surface ornamented 

 by small, longitudinal ribs, which commence below the suture, 

 and end some distance above the lower edge of the whorl ; be- 

 tween the ends of these ribs and the next suture is a large, 

 rounded fold. These are all crossed by fine, revolving lines, and 

 by longitudinal lines of growth. Internally there are no ribs nor 

 folds. The drawing and description of the external surface are 

 taken from a very imperfect impression in the matrix. 



Figures, natural size. 



Locality : North fork of Cottonwood Creek, Shasta County, rare (Division B.). 

 The long, slender form, convex whorls, with the large fold at the base, and the 

 entire absence of internal ribs, will at once distinguish this peculiar species. 



ACTEONINA, D'Orb. 

 ? A. pupoides, n. s. 



PI. 19, Fig. 67. 



Shell small, ovoid ; spire elevated, outline convex ; whorls 

 six or seven ; suture faint. Surface ornamented only by lines of 

 growth. Aperture unknown. 



PAL. VOL. I. — 15 



