CLASS GASTROPODA 
203 
retractive lines of growth and numerous closely spaced spiral striations. 
Aperture oval, posterior angle acute; outer lip thin; columella curved, 
reflected, re-enforced by the base and provided with a moderately strong 
fold at its insertion. Length, 3.6; diameter, 1.6 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 206920. Type locality, 
University of California Station 30, off Catalina Island. 
Range. Known only from type locality. 
Odostomia resina Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 216; PI. 27, fig. 6. 
Shell very small, vitreous, transparent. Nuclear whorls deeply 
obliquely immersed in the first of the succeeding turns, above which only 
the tilted edge of the last volution projects. Post-nuclear whorls inflated, 
strongly rounded, decidedly contracted at the suture, and appressed at the 
summit, where the preceding whorl is reflected through it, and gives the 
summit the false appearance of having a spiral cord. Suture strongly 
constricted. Periphery and base of the last whorl well-rounded. Entire 
surface of the shell marked by lines of growth which are of varying 
strength, and numerous, closely spaced, exceedingly fine, spiral striations. 
Aperture ovate, posterior angle acute; outer lip thin, showing the external 
sculpture within; columella slender, strongly curved, slightly revolute, 
re-enforced by the base, provided with a fold at its insertion. Length, 2.2; 
diameter, 1 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 206925. Type locality, 
Arch Beach, California. 
Range. Known only from type locality. 
Odostomia santarosana Dali and Bartsch, 1909 
Bulletin 68, United States National Museum, 205; Pi. 26, fig. 6. 
Shell elongate-ovate, light olive. Nuclear whorls very deeply obliquely 
immersed in the first of the succeeding turns, above which only the tilted 
edge of the last volution projects. Post-nuclear whorls much broader at 
the moderately constricted suture than at the feebly shouldered summit; 
well-rounded. The first 4 are marked by strongly incised spiral lines, of 
which 7 occur upon the second, 10 upon the third, and 13 upon the fourth, 
of which the 5 immediately below the summit are finer and closer spaced 
than the rest, which are equal. The entire surface of the last whorl is 
marked by numerous very fine, closely spaced, wavy, spiral striations. 
Suture well-impressed. Periphery and base of the last whorl inflated and 
well-rounded. Aperture oval; posterior angle acute; outer lip thin; colu¬ 
mella moderately strong, decidedly curved, somewhat reflected, re-enforced 
[501] 
