RISSOIA. 359 



whorl inflated, apex obtuse ; aperture nearly round, with simple, 

 slightly thickened lip. 



Sicily. 



The spire outline more convex than in the preceding species. 



R. brutia, Tiberi, Ms. has been quoted as a synonym. 



K. TIBERIANA, Issel. PI. 71, fig. 90. - 



Rimate, pellucid, whitish or yellowish, shining, very slightly 

 longitudinally striulate ; whorls 4$, convex, suture impressed, ob- 

 scurely margined ; peristome a little thickened, continuous. 



Length, 1'5 mill. 



Suez. 

 R. GLOBULUS, Moller. PI. 70, fig. 64. 



Whorls rapidly enlarging, convex, with deep suture, apex obtuse, 

 hyaline, whitish or yellowish, shining, smooth. Length, 2*5 mill. 



Norway, Spitsbergen, Greenland, Gulf of St. Lawrence. 



R. GLOBULINA, Monts. (unfigured.) Sicily. 



Unfigured Species of Setia. 



R. PATENS, Gould. Charleston Harbor, S. C. 



R. TRICINCTA, R. CANDIDA, R. BiFASciATA, A. Ad. Japan- 



R. FLAMIA, Beddome. Tasmania. 



R. BIZONATA, Nevill. Mauritius. 



R. SIENNJE, Tenison Woods. = Hydrobiidm. 



R. TORCULARIS, Teuison Woods. Port Jackson, Australia. 



R. GRIEGI, Friele. (Figure inaccessible to me.) Arctic Seas. 



Subgenus RISSOPSIS, Garrett. 1873. 



R. TYPICA, Garrett. PL 69, fig. 52. 



Thin, hyaline, smooth, glossy, white ; whorls 6, flat, suture faintly 

 impressed, margined ; peristome rather thin, sinuous, somewhat ex- 

 panded, columella obliquely arched, slightly callous. 



Length, 10 mill. 



Viti and Samoa Is. 



Subgenus ALVANIA, Risso. 1826. 



R. CIMEX, Linn. PL 65, figs. 11, 12. 



Imperforate, strong, opaque, covered by rounded granules in 

 longitudinal and spiral series, white or light fulvous to chestnut 



