GASTROPODA. 9 



RiSSOIA FBAUDULENTA. 



(PI. II., fig. 3.) 



Shell small, ovate-elongate, scarcely rimate, thiu, semi-transparent, dull, dirty 

 whitish ; whorls 5, convex, divided by a slightly oblique suture, ornamented with fine 

 spiral striae, crossed by the still more delicate lines of growth ; protoconch large, smooth, 

 globose ; aperture ovate, occupying rather more than a third of the entire length ; 

 outer lip thin ; columella margin very slightly reflexed, united above to the labrum by 

 a thin callus. 



Ijength, 2" 5 millim. ; diani., 1"5 ; aperture, 1 in length. 



Hole 3. 123 fathoms. Stones and gravel. 



The principal features of this shell are the spiral striae, convex whorls, and dull 

 surface. 



RiSSOIA GELIDA. 

 (PI. II., fig. 5.) 



Shell ovate, acuminate above, imperforate, dirty whitish, ornamented with fine 

 spiral liree ; spire obtusely conical ; whorls 5, very convex ; apex smooth ; suture deep, 

 a little oblique ; aperture broadly ovate, rather large, occupying about five-twelfths of 

 the entire length of the shell ; labrum thin, a little eff'use, especially at the base ; 

 columella narrowly reflexed, united above to the labrum by a thin callosity. 



Length, 3 millim. ; diam., 1-75 ; aperture, 1"25 long. 



Operculum normal, paucispiral, thin, without any process. 



Holes 3, 4, 12. In 12f-41 fathom.s. 



The spiral threads are five or six in number on the penultimate whorl, and about 

 twelve on the last. 



RiSSOIA BESERTA. 



(PL II., fig. 1.) 



Shell ovately conical, imperforate or scarcely rimate, dirty whitish, semi-transparent, 

 dull, sculptured only with fine striae of growth ; whorls 5, convex, narrowly margined 

 beneath the suture ; spire conical, blunt at the tip ; suture very slightly oblique ; 

 aperture almost circular ; peristome thin, continuous, outer margin simple, columellar 

 edge narrowly reflexed. 



Length, 2*5 millim. ; diam., 1*75 ; aperture, 1 long. 



Winter Quarters, Feb. 20, 1902, and March 19, 1902, 10 fathoms. 



In form rather like B. yelida, l)ut at once separable on account of its smooth 

 surface. 



RiSSOIA GLACIALIS. 

 (PI. II., fig. 4.) 



Shell ovately conical, narrowly perforated, white, smooth, glossy, exhibiting only 

 fine striae of growth ; whorls 5-6, very convex, and consequently separated by a deep 



VOL. II. X 



