Vol. IV] ANDERSON AND MARTIN— NEOCENE RECORD 53 



sected triangular interspaces; ambulacral ridges with slight 

 grooved trough and distinct notch on the periphery. 



Dimensions : — Length of the type specimen, 65 mm. ; width, 

 55 mm. ; altitude, 17 mm. 



Occurrence : — This species occurs at various horizons in the 

 Santa Margarita Formation of the Coalinga district, south of 

 Waltham Creek. It is, however, most abundant in the Trophon 

 zone, a little above the base of the Santa Margarita. This 

 species does not appear to be related very closely to A. zvhitneyi 

 Remond. 



Type: — No. 102, Cal. Acad. Sci., Trophon zone. East of 

 Jacalitos Creek, Coalinga, Fresno County, Cal., Lower Santa 

 Margarita Beds. Collector, F. M. Anderson. 



PELECYPODA 

 Genus LEDA Schumacher 

 Leda ochsneri, new species 



Plate 3, figures 8a, 8b and 8c 



Shell small, slightly arcuate anteriorly, excavated behind the 

 beaks, rostrate and acute with valves closed at the posterior 

 extremity; basal margin strongly and regularly arcuate, or 

 sometimes slightly truncated at the rear ; surface marked with 

 strong concentric lines, polished ; posterior ends bearing a shal- 

 low oblique groove extending downward from the beaks. 



This shell resembles Leda taphria Dall, of which it may be 

 the precursor, but it is relatively thicker, less elevated, and less 

 clearly truncated behind. 



Dimensions : — Length, 16 to 20 mm. ; altitude, 9 to 10 mm. ; 

 thickness, 8 mm. 



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

 California, at locality 68. 



Type: — No. 103, and cotypes Nos. 104 and 105, Cal. Acad. 

 Sci., on north bank of Kern River about }i mile west of the 

 power plant and about 3 miles east of the Rio Bravo ranch 

 house, Kern River, Kern County, California. Coll., J. P. 

 Buwalda. 



Named in honor of Mr. W. H. Ochsner. 



