1922] Fauna from the Hoccne 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. cowlitsensis 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 OLEQUAHENSIS n. Sp. 



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 LINNEAUS 



SOLEN CLARKI 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. 



