1922] Fauna from the Eocene of Washington 9 



Occurrence. At locality 324 (University of Washington Palaeontological 

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

 of Vader, Lewis County, Section 29, Township 1 1 North, Range 2 West. 



ARCA (Barbatia) COWUTZENSIS n. sp. 

 Plate VIII, Figure 9 



Description. Shell medium in size, oblong in outline ; inequilateral, beaks 

 situated one-fourth of the distance from the anterior end; dorsal margin 

 slightly curved, anterior end sloping from the dorsal margin at an angle of 40, 

 rounding into the ventral margin which extends obliquely, nearly parallel to the 

 dorsal line; posterior end broadly rounded, sloping from the dorsal line at an 

 angle of 20 ; beaks' low and broad ; valves convex, concave along the posterior 

 and anterior borders ; surface ornamented with numerous, fine, close-set, radiat- 

 ing ribs which cover the entire surface of the shell; interspaces very narrow; 

 about one-third of the width of the rib. 



Dimensions. Length 22 mm. ; height 14 mm. ; thickness 12 mm. 



Occurrence. At locality 329 (University of Washington Palaeontological 

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

 28, Township 11 North, Range 2 West. 



ARCA (Barbatia) I^ANDESI n. sp. 

 Plate VIII, Figure 4 



Description. Shell small, thin and delicate; elongate in outline; inequi- 

 lateral, beaks situated about one-third of the distance from the anterior end; 

 dorsal margin straight; anterior end well rounded, sloping from the dorsal 

 margin at an angle of 35 and rounding into the ventral margin; ventral margin 

 straight, nearly parallel with the dorsal margin ; posterior end rounded ventrally, 

 nearly vertical with the dorsal margin; surface sculptured with fine, radiating 

 ribs which are uniform in character over the whole surface of the shell. On 

 the anterior slope the ribs are separated by interspaces about twice the width of 

 the ribs. Within the interspaces there may be developed threads ; on the middle 

 portion the ribs and the interspaces are narrow. and about equal in width; ap- 

 proaching the posterior slope the ribs alternate in size ; the central ribs are deli- 

 cately beaded ; the posterior ribs from the umbonal slope to the dorsal line are 

 larger, with wider interspaces and are about 14 in number. 



In general outline this species is similar to B. morsel Gabb but differs in the 



