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



ornamented by regularly and closely spaced concentric ribs. 

 Locality A, L. S. J. U. Pal. Coll. 



Named in honor of Dr. T. W. Stanton of the U. S. Geolog- 

 ical Survey. 



Miltha parsonsi, new species 



PI. 12, Fig. 13 



Shell sub-circular, convex, rather thick; beak small, pointed, 

 depressed and turned forward; anterior cardinal margin 

 straight and sloping, making a sharp angle with the broadly 

 rounded anterior margin; posterior cardinal margin convex 

 and sloping into broadly rounded posterior margin; surface 

 marked by six major concentric lines of growth and fine con- 

 centric ribs. Locality 4, L. S. J. U. Pal. Coll. 



Named in honor of Mr. B. F. Parsons of Taft. 



Opis virginalis, new species 

 PI. 14, Fig. 4 



Shell small, oblique, cordate in profile, triangular; valves 

 equal, higher than long; beaks submedian, prominent, incurved, 

 and approximate ; surface divided by a sharply angular umbonal 

 ridge into two areas, the posterior of which is flattened and 

 narrow, while the anterior is broadly convex and about twice as 

 wide as the posterior area ; anterior margin broadly rounded ; 

 base of margin broadly curved and extending to end of um- 

 bonal ridge where it makes an angle of about 80 degrees with 

 the truncated and deflected posterior end ; surface marked by 

 flattened, equally spaced concentric ribs, which are separated by 

 fine interspaces. Locality 4, L. S. J. U. Pal. Coll. 



This species is very similar to O. triangulatus (Cooper),*^ of 

 the Chico, but is broader at the base, more full anteriorly, has a 

 longer beak, and is less angulated. 



Ostrea idriaensis Gabb 

 PI. 13, Fig. 10 



O. idricensis Gabb, Pal. Cal., vol. 2, p. 203, pi. 33, fig. 

 103b, c, and d., pi. 34, fig. 103, 103a. 



«' Proc. Cal. Acad. Sci., Second Series, vol. 6, p. 332, pi. 47, fig. 7, 1896. 



