WEST AMERICAN PYRAMIDELLID MOLLUSKS. 153 



The type (Cat. no. 15730, U.S.N.M.) was collected by Cooper at 

 Santa Barbara, California. It has five post-nuclear whorls and meas- 

 ures: Length 3 mm., diameter 1.5 mm. Cat.no. 162768, U.S.N.M., 

 contains another specimen from San Pedro. Cat. no. 162769, 

 U.S.N.M., one specimen from Pacific Beach, California. 



ODOSTOMIA (CHRYSALLIDA) LOOMISI, new species. 

 Plate 16, fig. 3. 



Shell Yerj small, pupiform, vitreous. Nuclear whorls smooth, 

 deeply obliquely immersed in the first of the succeeding turns, above 

 which only a portion of the tilted edge of the last volution projects. 

 Early post-nuclear whorls well rounded, later ones flattened, some- 

 what excurved at the shouldered and beaded summit, and slightly 

 contracted at the sutures, marked by strong rounded, tuberculated 

 axial ribs, which are decidedly protractive on all but the last whorl; 

 on this they are only moderately protracted. Of the axial ribs, 14 

 appear upon the first, 16 upon the second, 20 upon the third, and 

 24 upon the penultimate turn. In addition to the ribs the whorls 

 are marked between the sutures by four spiral cords, which almost 

 equal the ribs in strength, forming tubercles at their junctions with 

 the axial ribs. On the last whorl and one-half the summit drops 

 below the peripheral keel and leaves this in the suture; the axial 

 ribs, however, terminate at the posterior edge of it, and thus leave 

 it without tubercles. The spaces inclosed by the ribs and cords 

 appear as deep oval pits having their long axis parallel to the cords. 

 Sutures well marked but not channeled. Base of the last whorl 

 long, well rounded, marked by seven spiral cords, the four anterior 

 to the periphery being equal and equally spaced, the other three 

 growing successively smaller; channels between the cords very reg- 

 ular, marked by many slender axial riblets. Aperture oval, some- 

 what effuse anteriorly ; posterior angle obtuse ; outer lip thin, showing 

 the external sculpture within; columella slender, curved, and reflected, 

 not reenforced by the base. 



The type and five specimens were with Prof. C. B. Adams's type of 

 Chemnitzia communis at Amherst College. They come from the 

 Bay of Panama. The type has five post-nuclear whorls and measures : 

 Length 2 mm., diameter 0.9 mm. 



Named for Prof. F. B. Loomis. 



ODOSTOMIA (CHRYSALLIDA) VICOLA, new species. 



Plate 16, fig. 11. 



Shell ovate, vitreous. Nuclear whorls large, deeply immersed in the 

 first of the succeeding turns, above which the tilted edge of the last 

 volution only projects, which is marked by five slender spiral threads. 

 Post-nuclear whorls rounded on all but the first whorl, marked by 

 very broad, strong, retractive axial ribs, of which 16 occur upon the 



