232 BULLETIN 68, UNITED STATES NATIONAL MUSEUM. 



Shell without axial or spiral sculpture excepting microscopic lines 

 of growth. 



Type. — Turbo plicatus Montagu. 



KEY TO THE SPECIES OF THE SUBGENUS ODOSTOMIA. 



Periphery of the last whorl angulated. 



AMiorls overhanging farella, p. 232. 



WTiorls not overhanging. 



Whorls well rounded dinella, p. 232. 



Whorls flattened mammillata, p. 233. 



Periphery of the last whorl well rounded coronadoensis, p. 233. 



ODOSTOMIA (ODOSTOMIA) FARELLA, new species. 



Plate 30, fig. 4. 



Shell small, white. (Nuclear whorls decollated.) Post-nuclear 

 whorls flattened in the middle, shghtly rounded at the appressed 

 summit, strongly contracted at the suture, where they are decidedly 

 overhanging. Suture well impressed. Periphery angulated. Base 

 well rounded, narrowly umbihcated. Entire surface of spire and 

 base marked by fine lines of growth only. Aperture ovate, poste- 

 rior angle acute; outer hp thin; columella very oblique posteriorly, 

 decidedly curved anteriorly, strongly reflected, provided with a weak 

 fold somewhat anterior to its insertion; parietal wall covered with a 

 thin callus. 



The type (Cat. no. 206937, U.S.N.M.) was dredged off Long Beach, 

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

 2.5 mm., diameter 1.2 mm. 



ODOSTOMIA (ODOSTOMIA) DINELLA, new species. 

 Plate 30, fig. 1. 



Shell small, ovate, vitreous, semitransparent. (Nuclear whorls 

 decollated.) Post-nuclear whorls forming a spire with almost 

 straight sides, shghtly rounded, feebly contracted at the suture, 

 appressed at the summit, marked only by fines of growth. Suture 

 well impressed. Periphery of the last whorl obscurely angulated. 

 Base somewhat inflated, well rounded, narrowly umbihcated, 

 marked hke the spire. Aperture ovate, posterior angle acute; outer 

 fip thin; columella slender, almost vertical, slightly revolute, pro- 

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

 strong callus. 



The type (Cat. no. 206938, U.S.N.M.) was dredged near Redondo, 

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

 2.2 mm., diameter L2 mm. 



