200 CALIFORNIA ACADEMY OF SCIENCES. 



163. Pleurotoma perversa Gahb. 



Pleicrotoma perversa Gabb, Proc. Cal. Acad. Sci., Vol. Ill, 1865, p. 183; Pal. Cal., Vol. 11, pp. 6, 



73, PI. I, fig. ID, 1869. Cooper, 7th Ann. Rept. Cal. St. Min., i888, p. 260. 

 Snrcula perversa, Gabb, Tryon, Man. Conch., Vol. VI, p. 239, PI. VI, fig. 79, 1884. 



Shell small, sinistral, elongate, slender; whorls eight to eleven, convex; surface smooth 

 except lor fine incremental lines which are convexly angulated posteriorly a little above middle of 

 whorl; suture deeply impressed, distinct; aperture elongate-ovate; outer lip arcuate anteriorly; inner 

 lip incrusted; columella smooth; posterior sinus prominent; anterior sinus long, narrow. 



Dimensions. — Long. 42 mm.; lat. 11.5 mm.; body-whorl 21 mm.; aperture, including canal, 

 16 mm.; defi. 18 degrees. 



Distinguishable from other member.-? of thi.s family by being sinistral. 



Common in the Pliocene and lower San Pedro series at Deadman Island; in 

 lower San Pedro series at San Pedro; and rare in the npper San Pedro series at 

 Deadman Island, San Pedro, and Los Cerritos. Common in upper San Pedro series 

 at Crawfish George's. 



Living. — Vancouver Island to Cutalina Island (Coojser). 



Pleistocene. — Santa Barbara to San Pedro (Coojier) : San Pedro (Arnold). 



Pliocene. — San Pedro (Arnold). 



Subgenus Borsonia Bdlardi. 

 Shell fusiform; with a plication upon the middle of the columt'll.i. 

 Pleurotoma j^yrenaica Roualt is a characteristic species. 



164. Pleurotoma (Borsonia) bartschi, sp. nov. 



PL.4TE V, Fig. 7; Plate IX, Fig. 1. 



Shell small, fusiform, elongate; apex obtuse, mammilliform; whorls seven, angulated near 

 middle; body-whorl less angulated than those of spire; anterior portion of whorl ornamented with 

 about twelve oblique, transversely elongated nodes, which reach their greatest prominence on the 

 angle of the whorl; body-whorl sometimes smooth and sometimes nodose; posterior portion of whorl 

 flat and smooth except for incremental lines; incremental lines fine, oblique, and angulated convexly 

 posteriorly on upper portion of whorl; suture deeply appressed, distinct; aperture elongate-elliptical; 

 outer lip thin, arcuate anteriorly below posterior sinus; inner lip incrusted; columella nearly straight, 

 incrusted, with one sharp plication in middle of aperture; posterior sinus shallow; anterior sinus 

 prominent. 



Dimensions. — Long. 19 mm.; lat. 7 mm.; body-whorl 11. 5 mm.; aperture, including canal, 

 8.5 mm.; defi. 28 degrees. 



Distinguishable from B. dallii and B. hooveii by the prominent nodes on the 

 whorls. Looks very much like Drillin tnrosa, but is easily distinguishable by the 

 plication on columella and more angulated body-whorls. Pronounced a new species 

 by Dr. Dall. Specimens of Borsonia bartschi in the State Museum collection of 

 fossils at Berkeley are labeled "Drillia mutsta." 



