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



rostrum ; ventral margin very broadly rounded ; escutcheon 

 lanceolate, distinct ; lunule indistinct. This species has less 

 thickness than L. gabbi Conrad and quite a different shape. 

 Its ribbing is somewhat finer. Figure 1, Plate 1 illustrates 

 L. gabbi well and brings out the differences at a glance. 



Dimensions : — Height of broken type, 10mm. ; length, 

 18mm. ; convexity, 2mm. 



Type: — No. 250, and cotype. No. 251, Cal. Acad. Sci. Lo- 

 cality 244, Tejon Quadrangle, Kern County, California, Tejon 

 group. In east bank of Live Oak Creek about three-fourths 

 of a mile from its mouth or from the edge of the San Joaquin 

 Vallev. and about three miles due east of the mouth of Canada 

 de las Uvas (Grapevine Creek). Coll., Bruce Martin. 



Named for its occurrence in the vicinity of Caiiada de las 

 Uvas. 



Leda vaderensis, new species 

 Plate 1, figure 3 



Shell robust, thick, with prominent, central beak ; anterior 

 dorsal margin slightly convex, sloping toward a well rounded 

 anterior; posterior dorsal margin concave; ventral margin 

 convex resembling that of L. gabbi closely ; decoration consist- 

 ing of very fine, round concentric ribs. This species differs 

 from L. gabbi in its finer ribbing, in its greater convexity, and 

 in the central position of its beak. 



Dimensions: — Height, 7mm.; length, 13mm.; convexity, 

 2mm. 



Type: — No. 252, Cal. Acad. Sci. Locality 183, in the west 

 bank of the Cowlitz River, about one and three-fourths miles 

 southeast of Vader, Washington. Coll., Bruce Martin. 



Named for its occurrence near Vader, Washington. 



Glycimeris ruckmani, new species 

 Plate 1, figures 5a and 5b 



Shell of moderate size with acutely pointed beaks ; dorsal 

 margins sloping steeply to join a broadly rounded ventral 

 margin; the posterior dorsal margin slightly convex and with 

 a gentler slope than the straight anterior dorsal margin; deco- 

 ration consisting of about 28 rounded radial ribs crossed by 

 concentric growth lines ; area semilunar and marked by im- 

 pressed lines curving outward from the altitude line. 



