174 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
ately contracted at the periphery, marked by low, feebly developed axial 
ribs, which are best shown at the angle of the shoulder and scarcely extend 
to the suture. In addition to the axial ribs, the whorls are marked by well- 
incised spiral lines, of which seven occur between the sutures on the 
second and nine upon the third and the penultimate turn. Periphery and 
base of the last whorl well-rounded, the latter somewhat produced, marked 
by the very feeble continuation of the axial ribs and eight spiral lines. 
Aperture ovate, posterior angle squarely truncated; outer lip thin; colum¬ 
ella strongly curved and reflected over the re-enforcing base; provided 
with a strong fold at its insertion. Length of type, 4; diameter, 1.8 mm. 
(Dali and Bartsch.) 
Type in United States National Museum, No. 168716. Type locality, 
San Pedro, California. 
Range. Monterey, California, to Point Abreojos, Lower California. 
Fossil: Pleistocene, San Pedro, California. 
Subgenus Evalina Dali and Bartsch, 1904 
Odostomia americana Dali and Bartsch, 1904 
Proceedings of the Biological Society of Washington, 17:16. 
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 eighteen of which occur upon the second, twenty 
on the third, and eighteen 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 twelve occur 
between the sutures upon the third and penultimate whorls. These spiral 
lirations like the axial ribs appear strongest near the summits of the 
whorls. Periphery and base of the last whorl well-rounded, the latter 
ornamented by about eleven lirations which are similar in character to 
those between the sutures but much less strongly expressed. Aperture 
rather broad, suboval, somewhat effuse anteriorly, posterior angle acute; 
outer lip thin; columella short, somewhat curved, strongly revolute an¬ 
teriorly, having a weak, oblique fold near its insertion. Long., 2.9; 
diam., 1.3 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 168718. Type locality, 
San Pedro, California. 
Range. San Pedro, California, to Coronado Islands. 
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