1916] Weaver: Tertiary Faunal Horizons 43 



GENUS SOLEN LINNEUS 

 SoLEN LINCOLNENSIS n. Sp. 



Plate II, Figures 9, 10, 11 and 12 



Description Shell large, rather short, nearly straight and convex ; anterior 

 end obliquely truncated and making an angle with the dorsal margin of 125; basal 

 margin parallel with dorsal; beaks inconspicuous and situated at the junction of 

 dorsal and anterior margin; surface smooth except for well developed lines of 

 growth ; posterior end broadly rounded ; anterior muscular scar elongate and nar-. 

 row and situated half way between dorsal and ventral margin; posterior scar 

 short and quadrangular ; palial sinus broad but short. 



This form differs from Solen parallelus Gabb in that it is much shorter and 

 the anterior end is much more obliquely truncated. 



Dimensions Altitude 19 mm.; longitude 62 mm.; thickness 11 mm. 



Occurrence At locality 256 (University of Washington Palaeontological Col- 

 lection) in railway cuts on the O.-W. R. R. & N. Co. one fourth mile northwest of 

 Lincoln Creek Station in Section 27, Township 15 North, Range 3 West. 



Horizon Lowermost Oligocene ; Molopophorous lincolnensis Zone. 



Gasteropoda 



GENUS EPITONIUM BOLTEN 



EPITONIUM WASHINGTONENSIS n. sp. 

 Plate IV, Figures 46 and 47 



Description Shell long, narrow and conical with nine whorls ; spire high ; 

 whorls moderately convex by about 30 longitudinal ribs which extend over the 

 entire surface of the whorls with the exception of that portion of the area of the 

 body whorl below the basal angle; these ribs are crossed by prominent rounded 

 revolving ribs of which there are 13 upon the body whorl and eight on each of 

 the whorls of the spire; the revolving ribs are commonly arranged in pairs of two, 

 with wide, nearly flat interspaces between each pair. Suture distinct ; base of 

 body whorl flattened and smooth except for presence of eight minute revolving 

 ribs ; a faintly developed revolving keel is developed on the basal angle ; aperture 

 broadly ovate ; inner lip heavily callused. 



Dimensions Altitude of shell 23 mm.; altitude of spire 17 mm.; thickness 9 

 mm.; angle of spire 19. 



Occurrence At locality 256 (University of Washington Palaeontological Col- 

 lection) in railway cuts on the O.-W. R. R. & N. Co. one fourth mile northwest 

 of Lincoln Creek Station in Section 27, Township 15 North, Range 3 West. 



Horizon Lowermost Oligocene; Molopophorous lincolnensis Zone. 



