38 BULLETIN 68, UNITED STATES NATIONAL MUSEUM. 



young individual from which our description of the nucleus and 

 early whorls was taken. The other has lost the nucleus, the nine 

 remaining whorls measure: Length 3.7 mm., diameter 1.1 mm. 

 Named for Prof. G. L. liouser. 



TURBONILLA (CHEMNITZIA) ACULEUS C. B. Adams. 



Plate 2, figs. 2, 2a. 



Vhemnitzia acideus C. B. Adams, Ann. Lye. Nat. Hist, of N. Y., vol. 5, 1852, 

 p. 388. 



Shell very slender, elongate-conic, subdiajihanous to milk-white. 

 Nuclear whorls small, two and one-half, forming a small elevated 

 helicoid sj)ire, the axis of which is at right angles to that of the suc- 

 ceeding turns, in the first of which it is about one-third immersed. 

 Post-nuclear whorls slightly rounded, \veakly shouldered at the sum- 

 mit, marked by low, rounded, somewhat sinuous, protractive axial 

 ribs, of -which 14 occur upon the first to third, 16 upon the fourth 

 and fifth, 18 upon the sixth to eighth, 20 upon the ninth, 22 upon the 

 tenth, and 25 upon the penultimate turn. Intercostal spaces about 

 as wide as the ribs, well im])ressed, terminating at the sutures. 

 Sutures well marked. Periphery and base of the last whorl well 

 rounded, smooth, excepting faint lines of growth. Aperture small, 

 rhomboidal; outer lip thin, showing the external markings within; 

 columella oblique, almost straight, strongly reenforced by the base. 



The above description is based upon Professor Adams's types; one 

 a young specimen, of six and one-half whorls, has a little more per- 

 fect nucleus than the adult shell; the latter has twelve post-nuclear 

 whorls and measures: Length 4.4 mm., diameter 1 mm. They come 

 from Panama. 



TURBONILLA (CHEMNITZIA; MURICATOIDES Dall and Bartsch. 



Plate 2, figs. 11, Ua. 



TurboniUa (Chemnitzia) muricatoides Dall and Bartsch, Proc. U. S. Nat. Mus., 

 vol. 33, 1907, p. 495, pi. 14, figs. 2, 2a. 



Shell small, slender, subdiaphanous to milk white; nuclear whorls 

 two and one-half, helicoid but slightly elevated, well rounded, having 

 their axis at right angles to the axis of the post-nuclear turn. Post- 

 nuclear whorls smooth, rather high between the sutures, moderately 

 rounded, marked by strong sublamellar axial ribs, wliich are about 

 half as wide as the spaces that separate them, and extend strongly to 

 the very summit of the whorl where they render the well-marked 

 sutures crenulate. There are 14 of these ribs upon the first, 18 upon 

 the fifth, and 20 upon the penultimate turn. The depressed inter- 

 costal spaces terminate abruptly at the periphery. Base of the last 

 whorl well rounded, smooth, without sculpture. Aperture: (outer 

 lij) fractured), columella slender, slightly twisted. 



