ARNOLD — THE PALEONTOLOGY AND STKATIGKAPHY OF SAN PKDKO. 219 



Genus Admete Mdlkr. 



Shell oval, thin, diaphanous, covered by a thin epidermis; spire sharp; last whorl ventricose; 

 aperture oval, feebly channeled in front, columella arcuated, obliquely truncated, with rudimentary 

 plications; outer lip sharp. 



Admete viridula Fabr. is a characteristic species. 



198. Admete gracilior Carpenter. 



Plate VII, Fig. 4. 



Cancel/aria gracilior Cpk., Pal. Cal., Vol. II, p. 50, 1869. Coopek, 7th Ann. Rept. Cal. St. Min., 

 1888, p. 23. 



Shell small, ovate, thin; spire elevated, subacute; whorls si.K, rounded to subangular, crossed 

 by numerous prominent, rounded ridges which reach their ma.ximum prominence on the angle of the 

 whorl; these ridges become nearly obsolete on the anterior part of the body-whorl; spiral sculpture 

 consists of numerous fine ridges and furrows; suture deeply depressed, giving shouldered appear- 

 ance to whorls; aperture ovate; outer lip thin, smooth; inner lip only slightly incrusted; columella 

 obliquely truncated, and having two plications on inner side; slight umbilical slit; no canal. 



DmietisioHS. — Long. 11 mm.; lat. 6.3 mm.; body-whorl 7.5 mm.; aperture 5.5 mm.; defl. 

 50 degrees. 



A unique form, looking something like a small Fusus robustm with the canal 

 gone. It is quite a variable species, one specimen showing a narrower spire and 

 fewer, but more prominent ribs than the type, while still another showed more 

 rounded whorls and less prominent ridges. 



Found in the lower San Pedro series at Deadman Island. Also obtained from 

 the Pleistocene at the bath-house, Santa Barbara; and at Port Los Angeles, near 

 Santa Monica. The specimen figured is from the lower San Pedro series at Dead- 

 man Island, and is now in the United States National Museum. 



Pleistocene. — San Pedro (Oldroyd; Arnold): Santa Barbara (Carpenter; 

 Arnold): Santa Monica (xVrnold). 



Family LIV. OLIVID^. 



Genus Olivella Sivainson. 



Shell small, polished; spire produced, acute; suture canaliculated; aperture narrow behind; 

 enlarged anteriorly; columella plicated in front, callous posteriorly. 



Olivella undatella is a characteristic species. 



199. Olivella biplicata Souerby. 



Olivella biplicata Sby., Tank. Cat., App., p. 33, 1825. Cpr., Brit. Assn. Rept., 1863, p. 661. 

 H. & A. Adams, Gen. Rec. Moll., p. 146. Gabb, Pal. Cal., Vol. II, p. 75, 1869. 

 Tryon, Man. Conch., Vol. V, p. 87, PI. XXXIV, fig. 58, 1883. Cooper, 7th Ann. 

 Rept. Cal. St. Min., 1888, p. 255. Keep, West Coast Shells, p. 40, fig. 20, 1892. 

 Williamson, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 212 (and varieties). 



