AKNOLD — THE PALEONTOLOGY AND STRATIGRAPHY OF SAN PEDKO. 281 



Genus Odostomia Fleming. 



Odostomia Fleming, Edinburgh Encyclopedia, Vol. VII, Pt. I, p. 76, 1817 } {ex parte). 

 Type, Odostomia plicata MoNT. 



Shell with sinistral nucleus, subglobose to broadly conic; spire rarely elevated as in Tiir- 

 bonilla; sculpture varying in the different sections from plain (^Odostomia, s. s.) to highly ornamented 

 [Chrysallida); columella provided with a single fold, which is rarely obsolete. 



Animal as in Turbonilla. The species of this genus are distributed in all seas. 

 The original description of this genus included chiefly small land shells, with dentate 

 a})ertures, but also a few marine species. The land shells had already received 

 names, so the marine species were left to carry Fleming's name, a fact recognized 

 by him in later publications. The rarity of the original edition of the Edinburgh 

 Encyclopedia has made it very difficult to ascertain the facts in regard to this genus, 

 and the true date of its publication, but we believe the facts to be now established as 

 above stated. The species cited in the original publication are 0. inter stincta, 

 0. unidentata, 0. plicata, 0. sandvicensin and 0. insoulpta. 



Section Odostomia Fleming, s. s. 



Odostomia Fleming, Edinburgh Encyclopjedia, Vol. VII, Pt. I, p. 76, i8iy (ex parte). 

 Type, Odostomia plicata MoNT. 



Odostoniias of more or less conical outline, devoid of all sculpture, except incremental lines, 

 and having a more or less prominent columellar fold. 



302. Odostomia tenuis Carpenter. 



Platk I, Fig. 14. 

 Odostomia tenuis Cpr., Cat. Maz. Shells, p. 412, 1856. 



Shell slender, conic, umbilicated, dingy white; nuclear whorls small, immersed; post-nuclear 

 whorls very slightly convex, almost flattened, scarcely contracted at base, and hardly shouldered; 

 suture not very prominent, hardly channeled; base and periphery of the last whorl well rounded; 

 aperture quite large, ovoid, posterior angle acute, outer lip somewhat contracted at its middle; colu- 

 mella very flexuous, slender and revolute; parietal wall covered by a faint callus; columellar fold 

 strong opposite the umbilical chink. 



Dimensio7is. — Long. 5.7 mm.; diam. 2.6 mm. 



The specimen figured is from Santa Rosa Island, California, and has seven 

 post-nuclear whorls. 



The species appears to range in the recent state from Washington to Cali- 

 fornia, and has been found in the post-Pliocene depo.sits of San Diego, San Pedro, 

 and Ventura. 



Section Evalea A. Adams. 



Evalea A. Adams, Ann. Mag. Nat. Hist., 3d Sen, Vol. VI, i860, p. 22. Type, Odostomia (Evalea) 



elegans A. Adams. 

 Ondina De Folin, Fonds de la Mer, p. 214, 1870. Type, Ondina sulcata De Folin, 1. c. 



Odostomias without axial sculpture, having spiral striation or liration. 



( 36 ) March 31, 1903. 



