180 



BULLETIN 68, L^NITED STATES NATIONAL MUSEUM. 



rounded, the latter somewhat produced, marked by the very feeble 

 contimiation of the axial ribs and eight spiral lines. Aperture ovate, 

 posterior angle squarely truncated; outer lip thin; columella strongly 

 curved and reflected over the reenforcing base; provided with a 

 strong fold at its insertion. 



The type and 34 specimens (Cat. no. 168716, U.S.N.M.) were col- 

 lected at San Pedro, California. The type has five post-nuclear 

 whorls and measures: Length 4 mm., diameter 1.8 mm. 



The following additional specimens have been examined: 



U.S.N.M. 

 cat. no. 



No. of 

 speci- 



Locality. 



Disposition of 

 material. 



168716 

 207128 



168717 



46176 

 105499 



San Pedro, California 



do 



do 



do 



Catalina Island, California 



Arch Beach, California 



Todos Santos Bay, Lower California. 

 Point Abreojos, Lower California 



U. S. Nat. Mus. 



Do. 

 Oldroyd coll. 



Do. 

 U. S. Nat. Mas. 

 Univ. Cal. coll. 

 U. S. Nat. Mus. 



Do. 



One specimen (Cat. no. 73999, U.S.N.M.) not quite perfect, comes 

 from Monterey, California, and is provisionall}^ referred to the species. 



Subgenus EVALINA Dall and Bartsch. 



Evalina Dall and Bartsch, Proc. BioL Soc. Wash., voL 17, 1904, p. 12. 



Odostomias having feebly developed axial ribs which are usually 

 only indicated near the summit of the whorls; spiral sculpture con- 

 sisting of many fine lirations; summit of the whorls not tabulated. 



Type.^—Odostomia (Evalina) americana Dall and Bartsch. 



KEY TO THE SPECIES .OF THE SUBGENUS EVALINA. 



Spiral lirations on the body whorl 23 americana, p. 180. 



Spiral lirations on the body whorl 15 intermedia, p. 181, 



ODOSTOMIA (EVALINA) AMERICANA Dall and Bartsch. 



Plate 20, figs. 7,7a. 



Odostomia {Evalina) americana Dall and Bartsch, Proc. Biol. Soc. Wash., vol. 

 17, 1904, p. IG. 



Shell elongate-conic, subdiaphanous to milk-white. Nuclear whorls 

 quite large, at least two about three-fourths obliquely immersed. 

 Post-nuclear whorls rather broad between the sutures, well rounded, 

 faintly shouldered at the summit, ornamented with depressed, 

 rounded, rather broad axial ribs, about 18 of which occur upon the 

 second, 20 on the third, and 18 upon the penultimate whorl. The 

 ribs are best developed near the summits of the whorls and scarcely 

 extend to the periphery. Spiral lirations low, rounded, subequal, 

 about 12 occur between the sutures upon the third and the penulti- 

 mate whorls. These spiral lirations like the axial ribs appear strong- 

 est near the summits of the whorls. Periphery and base of the last 



