CLASS GASTROPODA 
159 
Odostomia eugena Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 147; PI. 14, figs. 1, la. 
Shell elongate-conic, milk-white. Nuclear whorls at least two, small, 
smooth, obliquely half immersed in the first of the succeeding turns. Post- 
nuclear whorls well-rounded, moderately contracted at the suture, well¬ 
shouldered at the summit, marked by strong, very retractive axial ribs, 
of which fourteen occur upon the first, sixteen upon the second, eighteen 
upon the third to fifth, and twenty-two upon the penultimate whorls. In 
addition to these ribs the whorls are marked by four strong spiral cords 
between the sutures which render their junction with the ribs tuberculate. 
The spaces enclosed by the ribs and cords form oval pits, the long axis 
of which coincides with the spiral sculpture. Sutures channeled. Periphery 
of the last whorl marked by a moderately broad groove, which is crossed 
by the continuation of the axial ribs which terminate at the posterior edge 
of the first basal keel. Base of the last whorl well-rounded, marked by six 
spiral keels, which grow successively weaker from the periphery to the 
umbilical region. The broad spaces between these keels are crossed by 
slender, raised, axial threads. Aperture oval; posterior angle obtuse; outer 
lip thin, showing the external sculpture within; columella stout, curved, 
strongly reflected and re-enforced by the base, provided with a strong fold 
at its insertion. Length, 4.3; diameter, 1.5 mm. (Dali and Bartsch.) 
Type in United States National Museum No. 127545. Type locality, 
San Hipolito Point, Lower California. 
Range. San Pedro, California, to San Hipolito Point, Lower Cali¬ 
fornia. 
Odostomia helga Dali and Bartsch, 1909 
Plate 59, figs. 8, Sa 
Bulletin 68, United States National Museum, 166; PI. 17, figs. 8, 8a. 
Shell conic, milk-white. Nuclear whorls smooth, deeply obliquely 
immersed in the first of the succeeding whorls, above which only a portion 
of the last two volutions project. Post-nuclear whorls moderately rounded, 
slightly contracted at the sutures, feebly shouldered at the summits, marked 
between the sutures by four, broad, low, spiral bands which are separated 
by narrow, deeply incised lines. In addition to these bands, the first three 
and one-half whorls are marked by feeble axial ribs, which are best 
developed near the summit of the whorls and scarcely reach the suture. 
The junction of the ribs and cords form weak nodules. Sutures strongly 
impressed but not channeled. Periphery of the last whorl well-rounded, 
marked by a low spiral cord. Base strongly rounded posteriorly, attenu- 
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