124 THE NAUTILUS. 



'< Amnicola egena" of Gould being a spineless Pofamopyrgus from New 



Zealand. 



Descriptions of New Species. 

 Faludestrina imitator, u. sp. 



Shell narrowly perforate or nearly closed, narrowly ovate, thin, 

 light corneous, subtranslucent, nearly smooth, not glossy; whorls 4$, 

 the first planorboid, causing the apex to be decidedly obtuse, the rest 

 quite convex, separated by a deep suture. Spire slender, conic. 

 Aperture somewhat less than half the shell's length, ovate, angular 

 posteriorly, the parietal margin somewhat flattened; peristome thin, 

 the inner margin adnate to the preceding whorl for a short distance 

 above. Alt. 3, diam. l.tt, greatest axis of aperture 1.28 mm. 



Counties near San Francisco Bay, California. Types from Santa 

 Cruz. 



This species, though corneous and subtranslucent, resembles a young 

 Bythinella nicklinlanu in form. It is evidently a common shell in the 

 region mentioned above. In a lot from Oakland the shells are larger 

 length 4$ mm , with five whorls This is analagous to the attenuata 

 form of nickliniana, in the East. The same large form is before me 

 from Petaluma Creek, Sonoma county (J. B. Davy) and Santa Cruz in 

 brackish water (VV. J. Raymond); and I have seen similar but 

 deeply eroded specimens, the earlier whorls wholly removed, from San 

 Pedro. It may be that the types and other specimens before me of 

 small size, perhaps some 200 shells in all, arc only half grown, and all 

 would attain a length of 4 to 5 mm. when adult. It is conspicuously 

 unlike ^Bythinella intermedia" Tryon and Pomatlopsisbinneyi Tryon. 

 and is less attenuated than the smooth ''seemani" form of " Tryonia" 

 protea. P. stearnsiana is not attenuated above, but stout spired, more 

 on the style of P. longinqua Gld. (intermedia Tryon), while in imi- 

 tator the spire is slender above, though the apex itself is quite obtuse. 

 P. stearnsiana, n. sp. 



Shell narrowly perforate, ovate, thin, corneous, nearly smooth, some- 

 what glossy, whorls nearly 4^, convex, separated by rather deep sutures, 

 the !-pire with convexly conic lateral outlines, stout. Apex rather 

 obtuse. Aperture half the shell's length or somewhat less, ovate, the 

 posterior angle blunt and rounded, peristome continuous, the inner 

 margin well defined, generally quite free at the edge from the adjacent 

 whorl. Alt. 2.6, diam 1.7, or larger up to 3.'- mm. alt. 



Near Oakland (type locality); Marshall's, Marin Co. ; Tuolumnie 

 Co. (Hemphill). San Francisco Peninsula? (G. W. Dunn.) 



