CRETACEOUS FOSSILS. 137 



covered between the genera Orypia on one side, and Trochita and 

 Galcrus on the other. 



C. pileum, n. s. 

 PI. 29, Fig. 233, and 233 a, b. 



Shell deep, usually more or less oblique ; whorls about one 

 and a half, increasing very rapidly in size. Surface marked only 

 by very fine lines of growth. Margin of the internal plate concave 

 at the sides, convex in the middle, surface concave ; the upper or 

 right hand edge curved downwards abruptly, and uniting with 

 the side at an acute angle ; the posterior portion of the plate run- 

 ning up spirally into the apex. 



Figures, magnified. The largest specimen is about .6 inch in length. 

 Locality: Not uncommon near Fort Tejon, in Division B. 



NERITA, Linn. 



N. DEFORMIS, U. S. 

 PI. 21, Fig. 96. 



Shell thick, robust, oblique; spire rather elevated; whorls 

 not distinguishable ; body whorl flattened above, rounded on 

 the angle, pretty regularly convex below. Surface smooth, su- 

 tures obliterated. Aperture irregularly quadrate; inner lip in- 

 crusted, not (?) crenulate. 



Figure, natural size. 



Locality : North fork of Cottonwood Creek (Division A.). 



This peculiar shell is the most irregular of all the species with which I am ac- 

 quainted in the genus. In fact, except its distorted outline, it has almost no tan- 

 gible specific characters. 



N. CUNEATA, U. B. 



PI. 21, Fig. 97. 



Shell flattened, euneate; outline elliptical, or sometimes nar- 

 rower atone end than the other; apex nearly terminal, blunt; 



PAL. VOL. I. — IS 



