CRETACEOUS FOSSILS. 139 



. DENTALIUM, Linn. 



D. (DlTBUPA ?) PUSILLUM, 11. 8. 

 PL 21, Fig. 99. 



Shell small, gently curved. Section circular. Slightly widest 

 near the mouth; the sides, from the widened portion, running 

 nearly parallel to the aperture, or very slightly approaching. Sur- 

 face polished. 



Length, .38 inch; greatest width, .05 inch. 



Locality : Several specimens found northeast of Martinez (Division B.) ; one at 

 Alizos Creek, near Fort Tejon ; and one, striated longitudinally, from Tuscan 

 Springs. I am not certain that the last may not he distinct ; but, with the pre- 

 sent material, shall not venture to separate it. 



D. Cooperii, n. s. 



PI. 21, Fig. 100. 



Shell growing to a large size ; very slightly curved. Angle 

 of divergence of the sides, about 4.5°. Section usually circular, 

 sometimes slightly elliptical. Surface polished, in ordinary sized 

 specimens; marked by faint longitudinal impressed lines, in the 

 largest. Substance of the shell thin, except in the largest speci- 

 mens, where it becomes unusually thick. 



Figures, natural size. 



Localities : Numerous specimens found by Dr. Cooper at San Diego. Not rare 

 northeast of Martinez, and a few specimens were collected near Fort Tejon (Div. 

 B.) ; and in Divisiorr A. it has been collected at Curry's, south of Mount Diablo, 

 and in the Siskiyou Mountains. 



D. STRAMINEUM, 11. S. 

 PI. 21, Fig. 101. 



Shell moderate in size, slightly curved. Section varying 

 from circular to elliptical. Surface marked by about thirty 



