CLASS GASTROPODA 
167 
Bartsch from Monterey, but differs from it in being more conic, with the 
whorls more rounded and having the base shorter and more rounded, as 
well as in minor details of sculpture. (Bartsch.) 
Odostomia sapia Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 167; PI. IB, figs. 3, 3a. 
Shell oval semitranslucent. Nuclear whorls small, deeply obliquely 
immersed in the first of the succeeding turns, above which only the tilted 
edge of the last volution projects, which is marked by five slender spiral 
threads. Post-nuclear whorls amply rounded, slightly constricted at the 
sutures and appressed at the summits, marked by six spiral cords between 
the sutures, of which the second and third below the summit are very 
narrow, occupying together about as much space as one of the other 
cords. These cords are separated by grooves which almost equal them. 
Axial sculpture reduced to feeble indications of ribs, which are best shown 
near the summit of the whorls, where they render the spiral keels feebly 
nodulous. About twenty-two of these ribs appear upon the penultimate 
whorl. Periphery and base of the last whorl well-rounded, marked by 
seven spiral keels, which grow successively weaker from the periphery to 
the umbilical area. Channels separating the cords narrow, well-incised, 
crossed by numerous slender axial threads. Aperture large, broadly ovate, 
posterior angle acute; outer lip thin; columella moderately strong, curved, 
slightly reflected; parietal wall glazed with a thin callus. Length, 1.8; 
diameter, 1.1 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 162775. Type locality, 
San Diego, California. 
Range. Known only from type locality. 
Odostomia thalia Bartsch, 1912 
Proceedings of the United States National Museum, 42 :275; PI. 36, fig. 3. 
Shell small, elongate-ovate, bluish-white, semitranslucent. Nuclear 
whorls obliquely immersed in the first of the succeeding turns, above which 
half of the tilted edge of the last volution only projects. Post-nuclear 
whorls well-rounded, feebly shouldered at the summit, marked by very 
slender, poorly developed, decidedly retractive, axial ribs, of which about 
thirty occur between the sutures upon the last two volutions. In addition 
to these axial ribs, the whorls are marked by low, feebly rounded, rather 
broad, spiral cords, of which six occur between the sutures on the second, 
and seven upon the third and fourth whorls; the spaces separating the 
spiral cords are narrow, impressed lines. The intersections of the axial 
ribs and spiral cords from weak tubercles, while the spaces inclosed 
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