WEST AMERICAN PYRAMIDELLID MOLLUSKS. 233 



ODOSTOMIA (ODOSTOMIA) CORONADOENSIS, new species. 

 Plate 30, fig. 3. 



Shell minute, ovate, vitreous. Nuclear whorls almost vertically 

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

 tilted edge of the last volution projects. Post-nuclear whorls well 

 rounded, slightly contracted at the sutures, with a well rounded 

 shoulder at the summit, marked by retractive lines of growth only. 

 Suture well impressed. Periphery and base of the last whorl 

 shghtly inflated, well rounded, marked like the spire. Aperture 

 ovate; posterior angle acute; outer hp thin; columeha slender, 

 strongly curved, shghtly revolute, reenforced by the base, provided 

 with a weak, deep-seated fold ; parietal wall covered with a thin callus. 



The type (Cat. no. 206939, U.S.N. M.) was dredged by Mr. F. W. 

 Kelsey in 35 fathoms, off Coronado Beach, San Diego, California. 

 It has four post-nuclear whorls and measures: Length 1.7 mm., 

 diameter 0.8 mm. Two topotypes are in Mr. Kelsey's collection. 



ODOSTOMIA (ODOSTOMIA) MAMMILLATA Carpenter. 

 Plate 30, fig. 8. 

 Odostomia mammillata Carpenter, Cat. Mazatlan Shells, 1856, p. 412. 

 Shell ovate, milk-white. Nuclear whorls large, obhque, two-thirds 

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

 decidedly flattened, rather liigh between the sutures, smooth. 

 Suture well impressed. Periphery marked by a slender, raised cord, 

 which renders it angulated. Base rather short, slightly inflated 

 immediately below the umbilical area. Aperture broadly oval; 

 posterior angle acute; outer lip tliin, angulated at the periphery; 

 ' columella short, slender, strongly curved and slightly reflected; pari- 

 etal wall covered by a strong callus. 



A single specimen of this species is known. It is on tablet 1957, 

 Liverpool collection, British Museum, and was taken off Chama at 

 Mazatlan, Mexico. It has four post-nuclear whorls and measures: 

 Length 1.1 mm., diameter 0.7 mm. 



