16 PROCEEDINGS OF THE NATIONAL MUSEUM Vol.70 



separate these cords are almost as wide as the cords and are marked 

 by slender axial threads which give to the spiral grooves a strongly 

 pitted appearance. Aperture large; posterior angle obtuse; some- 

 what channeled at the junction of the columella and basal wall and 

 decidedly flaring at the junction of the outer lip and basal lip ; outer 

 lip thin, showing the external sculpture within by the transmitted 

 light, sinuous at the edge; columella very stout, rather evenly 

 curved, provided with an oblique fold a little anterior to its inser- 

 tion; parietal wall glazed with a thin callus. 



The type, Cat. No. 362447, U.S.N.M., was collected by Dr. R. H. 

 Tremper on rocks at San Clemente Island, California. It has a 

 little more than four postnuclear whorls, having lost the nuclear 

 turns, and measures, length 3.2 mm. ; diameter, 1.9 mm. 



ODOSTOMIA (CHRYSALLIDA) CHACEI, new species 



Plate 3, fig. 3 



Shell elongate-ovate, bluish white. Nuclear whorls two and one- 

 half, well rounded, forming a depressed helicoid spire which is 

 about one-half obliquely immersed in the first of the succeeding 

 turns. The tilted edge of the last volution shows four rather strong 

 spiral cords. Postnuclear whorls stout, separated by a profoundly 

 channeled suture, marked by exceedingly strong axial ribs which 

 on all but the last whorls are slightly protractive ; on the latter they 

 are almost vertical. Of these ribs 16 occur upon the second and 

 third and 18 upon the penultimate turn. The intercostal spaces 

 are about as wide as the ribs. In addition to the axial sculpture 

 the whorls are marked by four strong spiral cords which render 

 their junction with the axial ribs strongly tuberculated. The tuber- 

 cles are almost hemispherical, sloping only very slightly, a little more 

 abruptly posteriorly than anteriorly. The spaces inclosed between 

 the axial ribs and the spiral cords are well-rounded profound pits. 

 The summit of the whorls is tabulated. The summits of the strong 

 ribs render the suture slightly sinuate. Periphery of the last whorl 

 marked by a rather strong spiral cord. Base moderately long, 

 well rounded, marked by five spiral cords which become slightly 

 closer spaced from the peripheral cord anteriorly and also decidedly 

 progressively enfeebled in the same direction. The broad spaces 

 that separate the spiral cords are marked by numerous, slender, 

 axial threads. Aperture oval ; posterior angle obtuse ; outer lip thin, 

 showing the external sculpture within by transmitted light; inner 

 lip slightly curved, appressed to the suceeding whorl for two-thirds 

 of its length, the anterior third only being free; parietal wall cov- 

 ered with a thick callus. 



