CLASS GASTROPODA 
165 
Odsotomia pulcia Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 160; PI. 16, figs. 10, 10a. 
Shell small, ovate, vitreous. Nuclear whorls deeply, very obliquely 
immersed in the first of the post-nuclear whorls, above which only the 
tilted edge of the last volution projects, which is marked by five slender 
spiral threads. Post-nuclear whorls well-rounded, strongly contracted at 
the sutures and shouldered at the summits, marked by very strong, 
decidedly retractively curved, axial ribs, of which sixteen occur upon 
the first, eighteen upon the second, and twenty upon the penultimate turn. 
In addition to the axial ribs, the whorls are marked between the sutures 
by four very broad, low, spiral bands, which are separated by mere 
impressed lines, and which render the axial ribs feebly tuberculated. 
Suture subchanneled. Periphery of the last whorl marked by a narrow 
deep groove, which is not crossed by the axial ribs. Base well-rounded, 
crossed by six spiral cords, which grow decidedly weaker and closer 
spaced from the periphery to the umbilical area, the spaces between them 
being crossed by numerous, slender, axial threads. Aperture oval; pos¬ 
terior angle acute; outer lip thin, showing the external sculpture within; 
columella stout, strongly reflected anteriorly, provided with a weak fold at 
its insertion. Length, 2.2; diameter, 1.2 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 162763. Type locality, 
San Pedro, California. 
Range. Known only from type locality. 
Odostomia ritteri Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 146; Pi. 14, figs. 8, 8a. 
Shell elongate-conic, milk-white. Nuclear whorls at least two, smooth, 
deeply obliquely immersed in the first of the succeeding turns, above 
which only a portion of the last two turns project. Post-nuclear whorls 
moderately rounded, strongly constricted at the sutures, slopingly shoul¬ 
dered at the summit, ornamented by strong, retractive, axial ribs, of 
which fourteen occur upon the first, sixteen upon the second to fourth, 
eighteen upon the fifth, and twenty upon the penultimate turn. In 
addition to the axial ribs, the whorls are marked by spiral cords between 
the sutures, which are a little more than half as strong as the ribs and of 
which three occur upon the first three whorls and four upon the succeed¬ 
ing turns; the second one below the summit marking the angle of the long 
sloping shoulder. Junction of ribs and cords strongly nodulous; the 
spaces enclosed between them are deep squarish pits. Sutures strongly 
channeled. Periphery of the last whorl marked by a broad groove that 
is crossed by the continuations of the axial ribs which terminate at the 
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