1922] Fauna from the Eocene of Washington 23 



posterior end broader, concave above; line of the escutcheon straight, slightly 

 oblique ; shell thin ; pallial sinus large, rounded in front, reaching beyond the 

 middle of the shell ; ventral .margin straight ; sculpture unknown except for con- 

 centric lines of growth. 



. In outline P. cowlitzensis is more nearly like P. hornii (Gabb) but is more 

 inequilateral than that species and higher in proportion to the length. 



Dimensions. Length 53 mm. ; height 28 mm. ; thickness 12 mm. 



Occurrence. At locality 329 (University of Washington Palaeontological 

 Collection) west bank of Cowlitz River near Vader, Lewis County, Section 28, 

 Township 11 North, Range 2 West. 



PSAMMOBIA OIvEQUAHENSIS n . S p. 



Plate IX, Figures 11, 12 



Description. Shell moderately large, thin ; broad in outline ; anterior end 

 convex, shorter and sloping to a well rounded end ; posterior end broadly rounded, 

 concave above along a post-umbonal slope; posterior dorsal margin straight; 

 ventral margin straight and parallel ; surface with fine concentric lines of growth 

 which on the posterior end become more acute and slightly raised ; obscure radiat- 

 ing lines occur on the posterior margin of the shell. 



Dimensions. Co-types respectively: length 29 mm., 18 mm.; height 26 mm., 

 11 mm. ; thickness 8 mm., 6 mm. 



Occurrence. At locality 324 (University of Washington Palaeontological 

 Collection) on the west bank of Olequah Creek about one-eighth of a mile north 

 of Vader, Lewis County, Section 29, Township 11 North, Range 2 West. 



GENUS SOLEN UNNEAUS 

 SOI^N ClyARKI n. Sp. 



Plate IX, Figure 16 



Description. Shell large and long; valves convex; ventral and dorsal mar- 

 gins parallel; anterior end oblique, rounded at the base; posterior tip unknown; 

 a deep, anterior furrow extends from the umbones to the ventral margin, ver- 

 tically inclined to the dorsal and ventral margins; surface with fine concentric 

 lines of growth which extend parallel with the dorsal and ventral margins for 

 about two-thirds of the length of the shell then turn abruptly and continue to the 

 oorsal margin at right angles to the dorsal line. 



