220 CALIFORNIA ACADEMY OF SCIENCES 



Shell small, subcylindrical; spire only slightly elevated; apex subacute; whorls five or six, 

 flat, smooth, except for very fine incremental lines; suture appressed, very distinct; body-whorl 

 convex, but nearly flat near outer lip; aperture elongate-triangular; outer lip thin, nearly straight; 

 inner lip thickly incrusted, the incrustation forming quite a ridge; columella completely incrusted 

 around lower portion, two prominent plications. 



Dime)isions.— "Long. 17.7 mm.; lat. 9.6 mm.; body-whorl 15.7.; aperture 13. i mm.; apical 

 angle 90 degrees. 



This species differs from 0. 2:>edroana in size and comparative width, and from 

 0. intorta in having two plaits, a greater deflection, and in being much larger. 



Common in the lower and upper San Pedro series, and Pliocene of the San 

 Pedro region. Found also in the Pleistocene at Barlow's ranch and the old irri- 

 gating ditch, Ventura; at the bath-house, Santa Barbara, and at Spanish Bight and 

 Pacific Beach, San Diego. 



Living. — Straits of Fuca to San Diego (Cooper). 



Pleistocene. — Santa Barbara to San Diego (Cooper): San Pedro; Santa 

 Barbara; Ventura; San Diego (Arnold). 



Pliocene. — Seven Mile House; Twelve Mile House; Kirker's Pass; San Diego 

 well (Cooper): San Pedro (Arnold). 



200. Olivella intorta Carpenter. 



Olivella ijitorta Cpr., Proc. Zool. Soc, 1856, p. 207. Cooper, 7th Ann. Rept. Cal. St. Min., 1888, 

 p. 255. Keep, West Coast Shells, p. 42, 1892. Williamson, Proc. U. S. Nat. Mus., 

 Vol. XV, 1892, p. 212, PI. XIX, fig. 9. 



Shell small, subovate; spire elevated, solid; whorls five, flat, smooth; suture appressed, very 

 distinct; body-whorl ventricose, smooth; aperture long, narrow, widening anteriorly; outer lip thin; 

 inner lip incrusted, incrustation thick, forming callus on body of middle whorl near aperture; 

 columella with smooth incrustation over lower portion, and one prominent, sharp plait on lower side. 



Dimensions. — Long. 11. 7 mm.; lat. 6 mm.; body-whorl 9.7 mm.; aperture 7.2 mm.; defl. 

 60 degrees. 



Distinguishable from 0. pedroana by breadth, less elevated spire, greater 

 deflection, and larger callus on upper part of inner lip; distinguishable from 

 0. hipllcata by single plait on columella, less deflection and smaller size. 



Quite common in the Pliocene and Pleistocene of the San Pedro region; rare 

 in upper San Pedro series at Los Cerritos. Found in the Pleistocene at Twenty-sixth 

 Street and Pacific Beach, San Diego; and at Barlow's ranch and the old irrigating 

 ditch, Ventura. 



Living. — Santa Cruz to Lower California (Dall). 



Pleistocene. — San Pedro; San Diego (Cooper): San Pedro; Ventura; San 

 Diego (Arnold). 



Pliocene. — San Diego well (Dall). 



