94 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



end; cardinal margin sloping nearly straight to the posterior 

 extremity, which is narrowly and regularly rounded." An- 

 terior cardinal margin slightly concave and sloping into the 

 broadly convex anterior margin. "Surface ornamented by 

 regular concentric ribs, nearly uniform throughout." Some 

 worn specimens lose these ribs entirely. Found at Locality 6, 

 the figured specimen from the Tejon at Ft. Tejon. L. S. J. U. 

 Pal. Coll. 



Meretrix hornii Gabb 



PI. 15, Figs. 9 and 19 



M. hornii Gabb, Pal. Gal., vol. 1, p. 164; vol. 2, pi. 23, fig. 

 144. 



"Shell subtrigonal, cuneate; beaks anterior, with the cardinal 

 margin sloping convexly to the posterior end, which is narrow ; 

 anterior end prominent above, and curving inwards rapidly be- 

 low towards the base ; lunule small, very narrow, acute below 

 and impressed." Surface marked by prominent, large, band- 

 like concentric ribs with linear interspaces. Locality 6, L. S. J. 

 U. Pal. Coll. 



Pinna lewisi Waring 

 PI. IS, Fig. 24 



Shell thin, pearly, mytiliform, equivalve, truncate and 

 wholly open behind ; hinge line long ; valves triangular, the 

 apical angle being about 45 degrees; convex along the center 

 line and flaring at the margins ; base of shell notched in the 

 middle and convex on either side; surface marked by five in- 

 distinct radiating ribs and concentric lines of growth. Locality 

 8, L. S. J. U. Pal.Coll. 



Named in honor of Mr. J. O. Lewis. Differs from Pinna 

 barrowsi Dickerson of the Martinez formation by having a 

 wider apical angle and fewer radiating ribs. 



Solen parallelus Gabb 



5". parallelus Gabb, Pal. Cal., vol. L p. 146. pi. 22, fig. 117. 

 "Shell elongated, slender, thin; sides parallel, ends rounded; 

 anterior end somewhat more abruptly truncated than the pos- 



