CLASS GASTROPODA 
219 
than one and two-thirds turns, smooth, and moderately convex. The por¬ 
tion following the nepionic part is crossed on the upper surface by quite 
regularly spaced, sublamellar riblets, which become weaker as the shell 
increases in size, and disappear completely after one and one-half turns; 
the remaining part of the upper surface being marked by weak incremental 
lines only. Sutures well-marked. Periphery of the last whorl well-rounded, 
the first half showing continuations of the ribs, the rest being smooth. 
Base moderately rounded with a fairly strong spiral keel which is situated 
about one-third of the way toward the umbilical angle from the periphery. 
Umbilicus much narrower than V. stearnsi, its outer edge terminating in a 
blunt angle. Columellar wall decidedly concaved, the inner half marked by 
a series of strong riblike nodules as in V. stearnsi. Aperture decidedly 
oblique, subcircular; outer lip thin; columella very thick, concaved, pro¬ 
vided with a moderately strong callus, which bends back into the umbilicus. 
Greater diameter, 2.2; lesser diameter, 1.7; altitude, 1 mm. (Bartsch.) 
Type in United States National Museum, No. 192686. Type locality, 
off Del Monte, Monterey Bay, California. 
Range. Monterey to San Diego, California. 
Vitrinella Columbiana Bartsch, 1921 
Proceedings , Biological Society of Washington, 34:39. 
Shell moderately large, depressed, helicoid, semitranslucent, bluish- 
white. Nuclear whorls decollated. Postnuclear whorls gently rounded, 
almost appressed at the summit, marked by rather strong incremental 
lines which extend over both the upper and lower surface; the lower 
surface is a little more convex than the upper; the umbilical wall is 
marked by strong notches. Aperture decidedly oblique, almost circular; 
parietal wall marked by a thin callus, which renders the peristome almost 
complete. Altitude, 1.5; greater diameter, 3.1 mm. (Bartsch.) 
Type in United States National Museum, No. 340848. Type locality, 
Departure Bay, British Columbia. 
Range. Departure Bay, British Columbia. 
Vitrinella smithi Bartsch, 1927 
Proceedings of the United States National Museum, 70: Art. 11, 33: PI. 4, figs. 6, 8, 9. 
Shell minute, pale brown. Nuclear whorls one and a half, smooth. 
Postnuclear whorls two, well-rounded, with well-impressed suture, marked 
by strongly curved lines of growth only. Under surface widely, openly 
umbilicated, marked by lines of growth only. The last whorl strongly 
curved. Aperture slightly oblique, subcircular; peristome thin, rendered 
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