WEST AMERICAIS' PYRAMIDELLID MOLLUSKS. 147 



tuberciilate. Of the ribs which are shghtly protractive, 17 appear 

 upon the first to third and 19 upon the penultimate whorl. Sutures 

 strongly channeled. Periphery of the last whorl marked by a sulcus 

 which is crossed by the continuation of the axial ribs. Base moder- 

 ately long, well rounded, marked by six slender spiral threads, the 

 axial sculpture being reduced to mere lines of growth. Aperture 

 oral: posterior angle obtuse; outer lip thin: columella oblique, 

 almost straight, decidedly revolute, marked with a strong fold at 

 its insertion. 



The tj'pe (Cat. no. 162f81, U.S.X.M.) comes from the Bay of 

 Panama. It has five post-nuclear whorls and measures: Length 

 2.3 mm., diameter 1.1 mm. 



ODOSTOMIA (CHRYSALLrOA) EUGENA, new species. 

 Plate 14, figs. 1, la. 



Shell elongate-conic, milk-white. Nuclear whorls at least two, 

 small, smooth, obliquely half immersed in the first of the succeeding 

 turns. Post-nuclear whorls well rounded, moderately contracted 

 at the suture, well shouldered at the summit, marked by strong, 

 very retractive axial ribs, of which 14 occur upon the first, 16 upon 

 the second, 18 upon the third to fiith, and 22 upon the penultimate 

 whorl. In addition to these ribs the whorls are marked by four 

 strong spiral cords between the sutures which render their junction 

 with the ribs tuberculate. The spaces inclosed by the ribs and cords 

 form oval pits, the long axis of which coincides vrith the spiral sculp- 

 ture. Sutures channeled. Periphery of the last whorl marked by a 

 moderately broad groove, which is crossed by the continuation of the 

 axial ribs which terminate at the posterior edge of the first basal keel. 

 Base of the last whorl well rounded, marked by six spiral keels which 

 grow successively weaker from the periphery to the umbilical region. 

 The broad spaces between these keels are crossed by slender, raised 

 axial threads. Aperture oval; posterior angle obtuse; outer Hp 

 tlmi, showing the external sculpture within; columella stout, curved, 

 strongly reflected and reenforced by the base, provided with a strong 

 fold at its insertion. 



The type and three specimens (Cat. no. 127545, U.S.X.M.) comes 

 from San Hipolito Point, Lower California. The type has seven and 

 one-half post-nuclear whorls and measures: Length 4.3 mm., diame- 

 ter 1.5 mm. Cat. no. 168566, L'.S.X.M., one specimen from San 

 Pedro. Two specimens were identified from the same region for 

 Mr. Berry. Cat. no. 168567, L'.S.X'.M, one specimen from San 

 Diego. Another from the foot of Ash street, San Diego, was identi- 

 fied for Mrs. Oldroyd. 



