CRETACEOUS FOSSILS. 197 



AXIN^A, Poli. 



A. Veatchii, n. s. 



PI. 25, Fig. 183, and 183 a. 



Shell thick, subglobose, equivalve and nearly equilateral ; 

 beaks large, incurved, central, approximate, with the sides sloping 

 downwards ; anterior and basal margins regularly rounded ; pos- 

 terior end rounded or subtruncate. Surface marked by from 

 thirty-six to forty radiating ribs, very regular in size, a little the 

 smallest anteriorly and obsolete behind; a faint depression 

 usually exists on the posterior side of the umbones, which passes 

 down and strikes the middle of the posterior margin. Internal 

 margin coarsely crenulated. Hinge robust; teeth arranged ra- 

 diately ; the lateral teeth largest and most widely separated. 

 Area very narrow and short. 



Figures, natural size. 



Localities : Tuscan Springs, Tehama County ; collected by Dr. Veatch ; very 

 abundant. Also found at Texas Flat, Placer County; Pence's Ranch, Butte 

 County; Cow Creek, Shasta County; Orestimba Canon, Stanislaus County; and 

 San Diego. Mr. Re"mond has specimens in his collection, labelled "Antelope 

 Creek," Tehama County. 



A. (LlMOPSIS ?) SAGITTATA, n. S. 

 PI. 31, Fig. 2G7, and 2G7 a. 



Shell subcircular, thin, equivalve, very slightly inequilateral ; 

 base regularly convex, sides unequally so, the posterior being a 

 little the most prominent. Surface marked by numerous faint, 

 radiating lines, which, on weathered surfaces, develop into strongly 

 impressed grooves ; along these lines are small pits, from which 

 proceed downwards fine, impressed, diverging lines. Hinge com- 

 posed of robust, radiating teeth. Inner margin finely crenulated. 

 Area? 



Figures, natural size, and a magnified view of the surface to show the markings. 



