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



Genus YOLDIA Moller 



Yoldia temblorensis, new species 



Plate 3, figure 3 



Shell small, oblong ovate, thin, arcuate on lower margin, 

 nearly straight above; beaks central, inconspicuous; hinge 

 margin bent only six degrees from a straight line ; anterior end 

 well rounded; posterior end rostrate, almost pointed, slightly 

 open, angulated by an impressed line extending from the beaks 

 downward to the posterior end below the siphonal opening; 

 anterior end similarly crossed by an impressed zone extending 

 from the beaks obliquely downward and forward; surface 

 sculptured by regular lines of growth. 



Dimensions: — Length, 18 mm.; width, 7.5 mm. 



Occurrence : — Lower Miocene of Kern River, California, 

 locality 68. 



Type: — No. 106, 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 County, California. 

 Coll., J. P. Buwalda. 



Yoldia newcombi, new species 

 Plate 3, figure 2 



Shell small, thin, compressed, ovally elongated ; valves equal, 

 very inequilateral, greatly attenuated behind; beaks small, 

 slightly raised, near the anterior extremity; escutcheon lan- 

 ceolate, very long, bordered by a narrow groove ; lunule indis- 

 tinct; anterior dorsal margin short, nearly straight; anterior 

 end well rounded ; base ovately rounded ; posterior extremity 

 tapering to a narrow, rounded end, gaping; posterior dorsal 

 margin broadly concave, with the opposed margins projecting 

 above the escutcheon ; posterior dorsal area flattened ; umbones 

 inconspicuous; interior inaccessible. 



Dimensions: — Length, 14 mm.; length of rostrum, 10.5 

 mm. ; altitude, 5 mm. ; thickness of both valves, 2.2 mm. 



Occurrence: — Lower Miocene of Clallam County, Wash- 

 ington, locality 213. 



This species can be easily recognized by its small size and 

 long rostrum. 



