318 RISSOIID7K. 



Subgenus CINGULA, Fleming. 1828. 



Shell thin, smooth or spirally striated, spotted or banded near 

 the suture, outer lip sharp, or slightly thickened. 



R. CINGILLUS, Montg. 

 Oingilla, Monts. 1884, is a synonym. 



Section OINGULA (restricted.) 



Shell elongated, with subacute spire, whorls flatly convex. 



Section ONOBA, H. & A. Adams. 1854. 



Turbiniforrn or somewhat elongated, whorls convex, conspicu- 

 ously spirally striated, sometimes with short longitudinal plica 1 ;it 

 the suture; aperture oval, peristome continuous, thin or slightly 

 thickened. R. STRTATA, Mtg. 



Section CERATIA, II. cv; A. A<lams. 1854. 



Subcylindrical, thin, whorls flatly convex, with obtuse apex : 

 outer lip thin and sharp. 



Animal with flattened, mostly short and clavit'orm tentacles, foot 

 bifurcate behind. R. PROXIMA, Alder. 



Section HYALA, H. & A. Adams. ]<Sf>4. 



Shell elevated conic, thin, hyaline, smooth or spirally striatc ; 

 aperture oval, slightly emarginate anteriorily, outer lip thin, simple. 

 Operculuni snbspiral. 



Tentacles with setaceous .summits. H. VITRKA, Forbes & Han- 

 ley. 



Section IY.\<JIOSTYI,A, Fischer. 187 



Smooth, transparent, apex papillary, last whorl descending; aper- 

 ture semilunar, pillar lip oblique, rectilinear, outer lip not varicose. 



R. AsTriUANA, Fischer. 

 Section SKTFA, II. & A. Adams. 1854. 



Whorls few, smooth, ventricose, spotted, spire short, with obtuse 

 apex, aperture suhorbicular. Animal with pilose tentacles. 



R. PULCHKKRBFA, Jeffreys. 

 Subsection MICROSHTIA, Monts. 18<H4. 



Imperforate or rimate, minute, brightly colored, often fasciate, 

 smooth. 



Pseudosetia, Monts. is a synonym. R. TI ; IK;II>A, Phil 



Subsection C-IN<JI;LINA, Monts. 1884. 



Obtuse or globular, nnicolored, lip thickened, covering the um- 

 bilicus. R. A LDERI, Jeffreys. 



