DESCRIPTION OF NEW SPECIES 



Pelecypoda v 

 GENUS BARBATIA GRAY 



BARBATIA MERRIAMI n. sp. 

 Plate VI, Figure 1 



Description Shell of moderate size, thick, roughly rectangular in outline and 

 inequilateral ; dorsal margin nearly straight and merging into the posterior margin, 

 which slopes to the posterior end of the umbonal ridge; ventral margin broadly 

 arcuate; beaks situated about one-fourth the length of the shell from the anterior 

 end. A marked umbonal ridge extends from the beaks to the posterior basal 

 extremity; a deep broad umbonal groove situated immediately above this ridge and 

 extending to the dorsal margin. Surface sculpture consists of numerous slightly 

 sinuous radiating ribs with interspaces of about one-half their width. Lines of 

 growth, which become more pronounced near the ventral margin, cross the 

 radiating ribs. 



Dimensions Altitude 19 mm.; longitude 10 mm.; thickness 22 mm. 



Occurrence At locality 36 1 (University of Washington Paleontological Col- 

 lection) situated at the old dam on Porter Creek about two and one-half miles 

 above its junction with Chehalis River in Section 14-, Township 17 North, 

 Range 5 West. 



Horizon Lowermost Oligocene; Barbatia merriami Zone. 



BARBATIA ANDERSONI n. sp. 

 Plate VI, Figure 2 



Description Shell small, roughly rectangular in outline; dorsal margin 

 straight, posterior end truncate and sloping at a low angle from the dorsal margin ; 

 ventral margin straight; anterior end broadly rounded; beaks very close to the 

 anterior end. A poorly developed umbonal ridge extends from the beaks to the 

 posterior extremity; a very slight radial depression extends from the middle of 

 the shell to the ventral margin. The surface is ornamented with numerous radial 

 ribs with interspaces of equal width. 



Barbatia andersoni differs from Barbatia merriami in the constancy of its 

 smaller size, in the absence of a marked umbonal ridge and in the lack of the 

 groove above it. 



[81] 



