166 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
posterior margin of the first basal keel. Base of the last whorl well- 
rounded, marked by six spiral cords which are of unequal strength, sepa¬ 
rated by grooves of different widths, which are crossed by fine axial 
threads. Aperture oval, effuse anteriorly; posterior angle obtuse; outer 
lip rendered sinuous by the cords, thin, showing the external sculpture 
within; columella slender, strongly reflected, provided with a fold at its 
insertion. Length, 4.5; diameter, 1.6 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 206896. Type locality, 
University of California, Station 30, off Catalina Island. 
Range. Catalina Island to San Diego, California. 
Odostomia cumshewaensis Bartsch, 1921 
Proceedings of the Biological Society of Washington, 34: 34. 
Shell broadly elongate, conic, milk-white. Nuclear whorls, at least two, 
obliquely immersed in the first of the postnuclear whorls, above which 
about two-thirds of the nuclear spire projects. Postnuclear whorls strongly 
rounded, constricted at the periphery, marked by strong, retractively slant¬ 
ing axial ribs, of which sixteen occur upon the first, eighteen upon the 
second, twenty-two upon the third, and the penultimate turn. These ribs 
are crossed by four strong cords which are a little wider than the ribs and 
render the axial ribs tuberculated, the first row of tubercles at the summit 
being decidedly smaller than the two that succeed it. All three of these 
have the tubercles strongly, evenly rounded. The fourth, immediately 
above the periphery, however, has the spiral cord stronger than the axial 
ribs, and appears as an almost uninterrupted cord with feebler tubercles. 
The pits enclosed between the ribs and spiral cords are strongly impressed 
and rounded. Suture strongly constricted, a part of the first basal cord 
showing at the suture of the last two turns. Periphery well rounded, 
marked by a strong spiral cord. Base moderately long, marked by five 
spiral cords on the anterior three-fourths, which become succeedingly nar¬ 
rower and feebler, the last two being indicated merely by the incised lines 
that separate them. The anterior fourth of the base is smooth, excepting 
incremental lines. The spaces between the spiral cords on the base are 
crossed by fine axial threads. Aperture very broadly oval; posterior angle 
obtuse; outer lip thin, showing the external sculpture within; inner lip 
strongly curved, reflected over and appressed to the base, a very narrow 
chink remaining behind the lip, indicating a very slight umbilicus; parietal 
wall covered by a thick callus. Length, 2.7; diameter, 1.2 mm. (Bartsch.) 
Type in United States National Museum, No. 340860. Type locality, 
Cumshewa Inlet, British Columbia. 
This species suggests Odostomia (Chrysallida) astricta Dali and 
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