CLASS GASTROPODA 
153 
is not apparent at the aperture. The sculpture varies from smooth to 
lamellar axial ribs and spiral keels. (Bartsch.) 
Of the forty subgenera now recognized under Odostomia nineteen 
have been found represented on the west coast of America. (Bartsch.) 
Type. Turbo plicatus Montagu. 
Distribution. Universal, from low water to deep water. Fossil: 
Eocene to Pleistocene. 
Subgenus Salassiella Dali and Bartsch, 1909 
Odostomia laxa Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 133; Pi. 13, fig. 8. 
Shell pupiform, milk-white. Nuclear whorls at least two, small, form¬ 
ing a depressed helicoid spire, whose axis is at right angles to that of the 
succeeding turns, in the first of which it is about two-thirds immersed. 
Post-nuclear whorls inflated, contracted at the suture, and strongly 
roundedly shouldered at the summit, marked by lamellar, flexuose axial 
ribs, which are only feebly expressed on the first. On the second there 
are eighteen, on the third twenty, twenty-two upon the fourth, and twenty- 
eight upon the penultimate turn, upon which there is a strong varix. 
Intercostal spaces about one and one-half times as wide as the ribs, well- 
impressed. Sutures constricted. Periphery and base of the last whorl 
well-rounded, marked by the continuations of the axial ribs. Aperture 
broadly oval; posterior angle obtuse; outer lip thin, showing the external 
sculpture within; columella slender, strongly curved and slightly revolute, 
provided with a weak fold at its insertion. Length, 4.3; diameter, 1.7 mm. 
(Dali and Bartsch.) 
Type in United States National Museum, No. 106512. Type locality, 
Scammons Lagoon, Lower California. 
Range. San Diego, California, to Scammons Lagoon, Lower Cali¬ 
fornia. 
Odostomia richi Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 133; Pi. 13, figs. 6, 6a. 
Shell small, broadly conic, white. Nuclear whorls three, forming a 
depressed helicoid spire, whose axis is at right angles to that of the suc¬ 
ceeding turns, in the first of which it is about one-third immersed. Post- 
nuclear whorls strongly rounded, moderately contracted at the suture, 
broadly tabulated at the shoulder, marked by strong, lamellar, axial ribs, 
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