WEST AMERICAN PYRAMIDELLID MOLLUSKS. 149 



which terminate at the posterior edge of the first basal keel. Base 

 of the last whorl well rounded, marked by five subequal and subequally 

 spaced spiral lirations, separated by broad spaces which are marked 

 by numerous prominent axial threads. Aperture broadly oval; pos- 

 terior angle obtuse; outer lip tliin, showing the external sculpture 

 within; columella moderately strong, curved, reenforced by the base, 

 provided with a weak fold at its insertion ; parietal wall covered mth 

 a thin callus. 



The type (Cat. no. 206898, U.S.N.M.) comes from San Diego. It 

 has five post-nuclear whorls and measures: Length 4 mm., diameter 

 1.4 mm. The University of California has one specimen from station 

 30, off Santa Catalina Island, and four from station 47, off San Diego. 



Tins species is closely alHed to Odostomia (Ohrysallida) oldroydi. It 

 chffers in having a comparatively larger nucleus wliich is more promi- 

 nently sculptured, in being more attenuated and having more slender 

 ribs and spiral cords and in having the axial sculpture on the base 

 much stronger. It is likewdse much smaller. 



ODOSTOMIA (CHRYSALLIDA) CLEMENTINA, new species. 



Plate 15, figs. 5, 5a. 



Shell elongate-conic, vitreous. Nuclear whorls obhquely immersed 

 in the first post-nuclear turn, above wliich only the tilted edge of the 

 last volution projects, which is marked b}^ five slender spiral threads. 

 Post-nuclear whorls well rounded, moderately contracted at the 

 sutures, strongly slopingly shouldered at the summit, marked by 

 strong, somewhat retractive axial ribs, of which 14 occur upon the 

 first and second, 18 upon the tliird and the penultimate turn. In 

 addition to the axial ribs, the whorls are marked by four spiral cords 

 between the sutures, of wliich the second one anterior to the summit 

 marks the angle of the shoulder. On the last two whorls the first 

 basal is apparent in the strongly contracted sutures. Periphery of 

 the last whorl marked by a spiral groove. Base well rounded, some- 

 what attenuated anteriorly, marked by five distant spiral cords wliich 

 grow successively weaker from the periphery to the umbilical region. 

 The broad spaces that separate these cords are marked by numerous 

 fine, raised, axial threads. Aperture broadly oval; posterior angle 

 obtuse ; outer lip thin, showing the external sculpture within, rendered 

 sinuous by the spiral cords; columella moderately strong, shghtly 

 reflected, reenforced by the base, pro\aded with a slender fold at its 

 insertion. 



The type (Cat. no. 162043, U.S.N.M.) comes from San Clemente 

 Island, California. It has five post-nuclear whorls and measures: 

 Length 2.3 mm., diameter 1.1 mm. 

 2565— Pull. 08—09 11 



