200 CALIFORNIA ACADEMY OF SCIENCES. 



163. Pleurotoma perversa Gabb. 



Pleurolom a perversa GhBB, Proc. Cal. Acad. Sci., Vol. Ill, 1865, p. 183; Pal. Cal., Vol. II, pp. 6, 



73, PI. I, fig. 10, 1869. Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 260. 

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



vShell small, sinistral, elongate, slender; whorls eight to eleven, conve.x; surface smooth 

 except for fine incremental lines which are conve.xly 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. 



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

 16 mm.; defl. 18 degrees. 



Distinguishable from other members of this 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 upper San Pedro series at 

 Deadman Island, San Pedro, and Los Cerritos. Common in upj^er San Pedro series 

 at Crawfish George's. 



Living. — Vancouver Island to Catalina Island (Cooper). 



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



Pliocene. — San Pedro (Arnold). 



Subgenus Borsonia Bellardi. 

 Shell fusilorm; with a plication upon the middle of the coluniellM. 

 Plturotoma pyrennica Roualt is a characteristic species. 



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



Plate V, Fig. 7; Plate IX, Fig. 1. 



vShell small, fusiform, elongate; ape.K 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, ig mm.; lat. 7 mm.; body-whorl 11.5 mm.; aperture, including canal, 

 8.5 mm.; defi. 28 degrees. 



Distinguishable from B. dallii and B. liooceri by the {)rominent nodes on the 

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

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

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

 fos.sils at Berkeley are labeled "Drillin iwjesta." 



