110 PALAEONTOLOGY OF CALIFORNIA. 



panded in advance; columella faintly incrusted; umbilicus imper- 

 forate. Surface marked by irregular and sometimes very distinct 

 lines of growth. 



Figure, natural size. 



Locality: Tuscan Springs, Tehama County (Div. A.). 



A. ALVEATA. 



PL 19, Fig. 59; and PI. 21, Fig. 111. 

 (Natica alveata, Con., Pacific R. R. Report, vol. 5, p. 321, pi. 2, fig. 8, and 8 a.) 



Shell subglobose, elongated; spire high; wborls six and a balf 

 to seven, rounded on the sides, truncated horizontally, or a little 

 obliquely above, and angulated, or sometimes slightly rounded 

 on the edge. Suture linear, usually bordered by a slightly raised 

 margin on the succeeding whorl. Aperture suboval, regularly 

 rounded in advance, biangulate posteriorly; outer lip simple; 

 inner lip thinly incrusted. Umbilicus small, perforate. Surface 

 smooth, or closely striate by fine revolving lines ; smooth speci- 

 mens sometimes show fine lines of growth. 



Figures, natural size. Fig. 59 is from San Diego ; collected by Dr. Cooper. 

 Fig. Ill is from northeast of Martinez. 



This species appears to attain the largest size of any American Cretaceous 

 species in the family, one broken specimen from San Diego having been, at least, 

 two inches high. 



Localities: Found in Division B., at San Diego; Martinez; Clayton; and at 

 Canada de los Alizos, near Fort Tejon (Eocene of Conrad) ; and in Division A., at 

 Curry's, south of Mount Diablo, associated with numerous species of that group. 



The San Diego specimens show none of the revolving lines; while in every case, 

 at the other localities, I have found these lines on, at least, a part of the surface. 

 They are usually most prominent on the upper part of the body whorl, sometimes 

 being visible only on the truncated portion. 



