WEST AMERICAN PYRAMTDELLID MOLLUSKS. 185 



ODOSTOMIA (MENESTHO) GRAMMATOSPIRA Dall and Bartsch. 



Plate 21, figs. 1,7a. 



Odostomia (Oscilla) grammatospira Dall and Bartsch, Mem. f'al. Acad. Sci., 

 vol. 3, 1903, p. 285, pi. 1, figs. 6, 6a. 



Shell elongate-conic, semitranslucent. Nuclear whorls small, form- 

 ing a depressed helicoid spire, which is a little more than half ob- 

 liquely immersed in the first of the succeeding turns. Post-nuclear 

 whorls moderately rounded, marked by four strong, equal, and al- 

 most equally spaced spiral cords wliich are separated by three well- 

 incised spiral groov.es. Suture subchanneled. Periphery of the last 

 whorl marked by a depressed cord wliich is not c^uite as strong as 

 those between the sutures. Base somewhat attenuated , well rounded, 

 marked by ten spiral cords wliich grow successively weaker and 

 closer spaced from the periphery toward the umbilical area, disap- 

 pearing altogether on the extreme anterior portion. The spaces be- 

 tween the spiral cords on spire and base are marked by slender axial 

 threads. Aperture oval, effuse anteriorly; posterior angle acute; 

 outer lip tliin, showing the external sculpture within, rendered wavy 

 by the keels; columella stout, reflected, reenforced by the base, pro- 

 vided with a weak fold at its insertion; parietal wall glazed with a 

 faint callus. 



The type (Cat. no. 161625, U.S.N.M.) was collected at Cape St. 

 Lucas, Lower California. It has eight post-nuclear whorls and 

 measures: Length 5.3 mm., diameter 2.1 mm. 



ODOSTOMIA (MENESTHO) PHARCIDA Dall and Bartsch. 

 Plate 21, fig. 5. 



Odostomia (Mcncstho) pharcida Dall and Bartsch, Proc. U. S. Nat. Mus., vol. 33, 

 1907, p. 520, pi. 46, fig. 8. Mumiola tenuis Dall, Bull. Nat. Soc. Brit. Col., 

 1897, p. 14, pi. 1, fig. 10; not Odostomia tenuis Carpenter, 1856, nor 

 Odostomia tenuis Jeffrey, 1884. 



Shell small, subcylindric, yellowish- white. Nuclear whorls deeply 

 immersed, a portion of the last and the penultimate only appear when 

 viewed from the side; tliis gives the shell a truncated appearance. 

 Post-nuclear whorls moderately well rounded, rather wide between 

 the sutures, and somewhat shouldered at the summits; ornamented 

 by strong, low, rounded spiral cords, which are separated by moder- 

 ately deep, narrow, depressed channels. wSix of these cords occur 

 upon the first, 7 upon the second to the penultimate whorl between 

 the sutures; the posterior cord is a little broader and less elevated 

 than the rest, while some of those on the penultimate turn show a 

 tendency to divide — that is, a faint spiral line is apparent on the mid- 

 dle of some of these cords. Sutures well impressed. Periphery and 

 base of the last whorl well rounded, the latter ornamented by eight 

 rounded spiral ct)rds similar to those between the sutures. The 



