178 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



of equally spaced nodes, the uppermost, the most prominent 

 and lowermost, the weakest; further decoration consisting of 

 numerous spiral threads cut by growth lines; aperture oval; 

 columella slightly incrusted; canal twisted, short. 



This form differs from Strepsidura washingtonensis Weaver 

 and 6". oregonensis Dall in that it is more elongate and its 

 shoulders on its whorls are more sloping above and less prom- 

 inent. 



Dimensions: — Length of type, 29 mm. ; width of body whorl, 

 18 mm. 



Type:— No. 425, cotype 424, Cal. Acad. Sci. Locality 181, 

 near Vader, Lewis County, Washington, on east bank of the 

 Cowlitz River, just back of the Greeco ranch house, about four 

 miles east of Vader. Colls., F. M. Anderson and Bruce Martin. 



Named for Mr. Robert Pack, Paleontologist, U. S. Geolog- 

 ical Survey. 



Littorina oligocenica, new species 



PI. 31, Fig. 1 



Shell minute with five whorls ; whorls nearly flat, suture dis- 

 tinct, linear; body-whorl about two-thirds the shell length; 

 mouth rounded ; outer lip thin. 



Dimensions: — Length, 3 mm. ; width of body-whorl, 1 mm. 



Type: — No. 426, Cal. Acad. Sci. Locality 181, near Vader, 

 Lewis County, Washington, on east bank of the Cowlitz River, 

 just back of the Greeco ranch house, about four miles east of 

 Vader. Colls., F. M. Anderson and Bruce Martin. 



Marginella pacifica, new species 

 PI. 31, Fig. 2 



Shell minute, egg shaped, smooth ; whorls four ; spire nearly 

 immersed ; suture obscure ; body-whorl thickest in middle ; outer 

 lip slightly thickened ; inner lip bearing five sub-equally spaced 

 plaits, of which the last two are the strongest; canal, short, 

 wide. This form is very numerous at the type locality. 



Dimensions: — Length, 3 mm. ; width of body-whorl, 1.7 mm. 



Type: — No. 427, Cal. Acad. Sci. Locality 181, near Vader, 

 Lewis County, Washington, on east bank of the Cowlitz River, 

 just back of the Greeco ranch house, about four miles east of 

 Vader. Colls., F. M. Anderson and Bruce Martin. 



