Vol. IV] ANDERSON AND MARTIN— NEOCENE RECORD 63 



Dimensions : — Length of the figured specimen, 25 mm. ; alti- 

 tude, 21 mm. ; thickness of both valves, 8.5 mm. 



Occurrence: — Uncommon in the lower Miocene of north- 

 eastern San Luis Obispo County, California, locality 126. 



Type: — No. 129, Cal. Acad. Sci., in the bed of a small creek 

 near the center of Sec. 34, T. 28 S., R. 15 E., San Luis Obispo 

 County, California. Coll., Bruce Martin. 



Named in honor of Mr. R. B. Moran. 



Genus DONAX Linn. 



Donax triangulata, new species 



Plate 3, figure 9. 



Valves small, thin, trigonal, convex; beaks a little anterior 

 to the middle; dorsal margins nearly straight; anterior ex- 

 tremity rounded ; basal margin nearly straight ; posterior end 

 sharply rounded; an umbonal angulation extending from the 

 beaks to the anterior and posterior extremities, forming areas 

 sculptured with six or seven radial ribs; left valve with one 

 cardinal and two lateral teeth ; ends crenulated within ; muscular 

 impressions indistinct. 



Dimensions : — Altitude of the left valve, 5 mm. ; length, 9 

 mm. ; diameter of the left valve, 2 mm. 



Occurrence : — Lower Miocene of Kern River, Kern County, 

 California, locality 65. 



Type: — No. 130, Cal. Acad. Sci., on west bank of a small 

 canyon P/4 miles northeast of Barker's ranch house, Kern 

 County, California. 



Genus MACTRA Linn. 



Mactra sectoris, new species 



Plate 3, figures 5a, 5b, 5c, 5(1, and 5e. 



Shell small, trigonal, equivalve, inequilateral, almost a quad- 

 rant of a spheno-discoidal solid ; valves convex, inflated ; beaks 

 prominent, elevated, curved inward and forward; the forward 

 dorsal margin slightly concave ; posterior, slightly convex or 

 straight; basal margin circular; ends sharply rounded, the an- 

 terior usually more so than the posterior ; surface showing only 



December 30, 1914. 



