CKETACEOUS FOSSILS. 159 



abrupt anterior end, in the latter species the pallial sinus lies more nearly parallel 

 with the base of the shell. It is narrower and somewhat angular at the base of 

 the notch. 



? T. QUADRATA, 11. 8. 

 PI. 23, Pig. 138. 



Shell inequilateral, subquadrate, about two-fifths longer than 

 wide; beaks prominent, subcentral, nearest the anterior end, 

 which is obliquely subtruncate; posterior end a little the nar- 

 rowest and regularly rounded; basal margin nearly straight. 

 Surface marked by numerous, closely placed, irregular lines of 

 growth. Muscular scars and pallial sinus almost invisible on the 

 cast. 



Pigure, natural size. 



Locality: A single specimen, from Tuscan Springs, Division A., collection of 

 the Academy of Natural Sciences of California ; collected by Dr. Veatch. 



I have only seen a portion of the hinge of this shell, but believe it to belong to 

 the genus Tellina. 



T. ASHBURNERII, 11. S. 

 PI. 23, Pig. 139. 



Shell moderate in size, subequilateral, compressed, nearly 

 twice as long as broad; beaks central, small; cardinal margins 

 sloping nearly equally on both sides ; ends symmetrically round- 

 ed, nearly equal ; base broad, regularly convex. Surface marked 

 only by lines of growth. Hinge small ; lateral teeth, if any, un- 

 known. 



Figure, natural size. 



Locality: Pence's Eanch, north of Orovillc, Butte County (in Division A.). 



Named after Mr. Ashburner, who first made known this prolific locality. 



This species is not unlike T. Mathewsonii (supra), but can be distinguished from 

 young specimens of that by being narrower at all ages. It is slightly more con- 

 vex, and the beaks are not so prominent. 



