154 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
of which sixteen occur upon the first, fourteen upon the second and third, 
and eighteen upon the penultimate turn. Intercostal spaces somewhat 
wider than the ribs, strongly impressed. Periphery of the last whorl 
marked by a broad, low keel. Base with a strongly raised tumescence 
about the umbilical area, the space between which and the peripheral keel 
appears slightly concave. The axial ribs continue weakly over the base. 
A strong varix appears on the last whorl, between two axial ribs, and 
extends from the summit to the umbilical chink. Aperture suboval; 
posterior angle obtuse; outer lip thin, showing the external sculpture 
within ; columella strong, straight, and decidedly revolute; parietal wall 
covered by a thin callus. Length, 3 ; diameter, 1.4 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 160484. Type locality, 
San Pedro, California. 
Range. Known only from type locality. 
Subgenus Besla Dali and Bartsch, 1909 
Odostomia callimorpha Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 136; PI. 13, fig. 5. 
Shell very small, pupiform, milk-white. Nuclear whorls completely 
immersed. Post-nuclear whorls flattened, slightly contracted at the 
sutures, moderately shouldered at the summit, marked by strong, de¬ 
pressed, rounded, almost vertical, axial ribs, of which twenty-two occur 
upon all but the first whorl, which is smooth. Intercostal spaces about as 
wide as the ribs, crossed by three slender, spiral lirations on the anterior 
half of the whorls between the sutures. Sutures subchanneled. Periphery 
and base of the last whorl well-rounded, marked by the continuations of 
the axial ribs, which extend almost undiminished to the umbilical area, and 
five equal slender, spiral lirations on the posterior half of the base. 
Aperture broadly oval, posterior angle acute; outer lip thin, showing the 
external sculpture within; columella strongly curved, slightly revolute, 
re-enforced on its posterior half by the base, provided with a strong fold 
at its insertion. Length, 1.5; diameter, 0.6 mm. (Dali and Bartsch.) 
New name for Chrysallida pmnila Carpenter, 1866 ( Proceedings of the 
California Academy of Sciences, 3: 219) ; not Odostomia pumila A. Adams, 
1861. 
Type in United States National Museum, No. 15565. Type locality, 
San Pedro, California. 
Range. Known only from type locality. 
[452 ] 
