86 University of Washington Publications in Geology [Vol. 'I. 



Occurrence At locality 330 (University of Washington Paleontological Col- 

 lection) situated at the Greece ranch, four miles east of Vader, on the east bank of 

 Cowlitz River, in Section 25, Township 11 North, Range 2 West. 



Horizon Lower Oligocene; lower phase of Molopophorous lincolnensis Zone. 



GENUS NATICA SCOPOLI 



NATICA OLIGOCENICA n. sp. 



Plate VII, Figure 23 



Description Shell small with five whorls the surfaces of which are evenly 

 rounded except the posterior which is somewhat flattened; spire a little elevated 

 for the genus ; shell smooth except for faintly developed longitudinal lines of growth ; 

 suture distinct and appressed. The lower portion of body whorl merges into the 

 base with a rounded angulation; surface of base below the angulation is deep and 

 broad with the umbilical opening at its center. 



Dimensions Altitude of shell 5 mm.; altitude of spire 1.5 mm.; maximum 

 diameter 4.5 mm.; angle of spire 90. 



Occurrence At locality 352 (University of Washington Paleontological Col- 

 lection) in railway cuts on the line of 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 Lower Oligocene; Molopophorous lincolnensis Zone. 



GENUS RISSOA FREM 

 RlSSOA LETTANA n. sp. 



Plate VII, Figure 13 



Description Shell minute, thick and moderately robust; whorls five and 

 broadly convex; suture distinct and linear; surface ornamented by 21 well developed 

 longitudinal ribs which extend over the upper two-thirds of the surface of the body 

 whorl and become obsolete below; on the body whorl these are crossed by 18 

 equally spaced and equally developed revolving ribs; between each of these is an 

 interspace of about one-half the width of the ribs; aperture approximately oval but 

 incurving slightly posteriorly; inner lip thickened but not calloused; outer lip entire 

 and moderately thick. 



Dimensions Altitude of shell 1.5 mm.; altitude of spire, .75 mm.; maximum 

 diameter of shell 1 mm.; angle of spire 35. 



