142 BULLETIN eS, UNITED STATES NATIONAL MUSEUM. 



periphery to the umbiHcal area. The grooves on the base are crossed 

 by numerous slender axial threads. Aperture pyriform, somewhat 

 effuse anteriorly; channeled at the posterior angle, which is obtuse; 

 outer lip thin, decidedly arched in the middle, flattened on the side, 

 showing the external sculpture within ; columella stout, reflected very 

 much anteriorly; provided with a strong fold at its insertion; parietal 

 wall covered with a thick callus. 



Professor Adams collected 90 specimens in the Bay of Panama, 

 which he listed under this species; 2S of these are in the Amherst 

 collection which belong to three species. We have taken the finest 

 for our description and figure of Odostomia (Chrysallida) communis, 

 of which there are 15 specimens. The specimen described and figured 

 has seven post-nuclear whorls and measures: Length 3.2 mm., diam- 

 eter 1.2 mm. 



ODOSTOMIA (CHRYSALLIDA) TORRITA, new species. 



Plate 14, fig. 2. 



Chrysallida communis (C. B. Adams) Carpenter, Cat. Mazatlan Shells, 1856, 

 pp. 419, 420; not Chemnitzia communis C. B. Adams, Ann. Lye. Nat. Hist, 

 of N. Y., vol. 5, 1852, p. S90=Odostomia (Chrysallida) communis [C. B. 

 Adams]. 



Shell small, very elongate-ovate, vitreous. Nuclear whorls smooth, 

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

 which the tilted edge of the last volution only projects. Post-nuclear 

 whorls slightly rounded, moderately contracted at the periphery and 

 well shouldered at the summit, marked by strong axial ribs, of 

 which about 20 occur upon all the whorls. Intercostal spaces about 

 as wide as the ribs, marked between the sutures by four slender 

 spiral cords which pass up on the sides of the ribs but do not cross 

 their summits. On the last whorl the first basal keel falls between 

 the sutures; here, too, the ribs are rendered slightly tuberculate by 

 the spiral cords. Sutures strongly marked but not channeled. 

 Periphery of the last whorl marked by a groove. Base somewhat 

 produced, marked by twelve slender, spiral cords which are a little 

 wider than the spaces that separate them and become successively 

 narrower and more closely spaced from the periphery to the umbilical 

 area. The spaces between the cords are marked by numerous 

 slender, axial threads. Aperture pyriform, slightly effuse anteriorly; 

 posterior angle acute; outer lip pinched in posteriorly; thin, showing 

 the external sculpture within; columella stout, strongly reflected 

 anteriorly, reenforced by the base, provided with a weak fold at its 

 insertion; parietal wall covered with a strong callus. 



The type and four specimens are part of the 500 specimens of this 

 species found on Chama and Spondylus at Mazatlan, Mexico. 



The type has five and one-half post-nuclear whorls and measures: 

 Length 2 mm., diameter 0.8 mm. 



