148 BULLETIN 68; UNITED STATES NATIONAL MUSEUM. 



ODOSTOMIA (CHRYSALLIDA) TRACHIS, new species. 



Plate 15, figa. 4, 4a. 



Shell small, elongate-conic. Nuclear whorls small, smooth, strongly 

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

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

 moderately rounded, strongly contracted at the sutures, slopingly 

 shouldered at the summit, marked by strong, rounded, decidedly 

 retractive axial ribs, of which 16 occur upon the second, 18 upon the 

 third, and 20 upon the penultimate turp. In addition to the axial 

 ribs the whorls are crossed between the sutures by four spiral cords, 

 which are as strong as the ribs and render them nodulous at their 

 junction. The second of these cords below the summit marks the 

 angle of the shoulder. The spaces inclosed by the ribs and cords are 

 deep, squarish pits. Sutures subchanneled. Periphery of the last 

 whorl marked by a groove, crossed by the spiral ribs, which terminate 

 at the extremity of the first basal cord. Base well rounded, marked 

 by four subequal, distantly spaced, narrow, spiral cords, the broad 

 spaces between wliich are crossed by numerous axial threads. Aper- 

 ture oval; posterior angle obtuse ; outer Up thin, showing the external 

 sculpture within; columella slender, reflected, reenforced by the base, 

 provided with a fold at its insertion; parietal wall covered Avith a 

 thin callus. 



The type (Cat. no. 168619, U.S.N.M.) comes from San Pedro, Cah- 

 fornia. It has five post-nuclear whorls and measures: Length 2.5 

 mm., diameter 1 mm. 



ODOSTOMIA (CHRYSALLIDA) LUCCA, new species. 



Plate 15, figs. 8, 8a. 



Shell broadly conic, milk-white. Nuclear whorls large, obUquely 

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

 edge of the last volution only projects, which shows five strong spiral 

 threads. Post-nuclear whorls well rounded, strongly contracted at 

 the sutures, appressed at the summits with a sloping shoulder that 

 extends from the summit to the second spiral keel, marked by narrow 

 decidedly elevated, retractive axial ribs, of wliich 16 occur upon the 

 first and second, 18 upon the third, and 22 upon the penultimate turn. 

 In addition to the ribs, the whorls are marked between the sutures by 

 four spiral keels, which equal the ribs in strength and render them 

 decidedly nodulous at their junction. The spaces inclosed by the 

 ribs and cords are well impressed rectangular pits whose axis coin- 

 cides with the spiral sculpture. Sutures subchanneled, showing a 

 portion of the first basal keel in the last two volutions. Periphery of 

 the last whorl marked by a broad channel, crossed by the axial ribs 



