EISSOIDiE. 93 



1 Mauritius [type] ; coll. G. Nevill, Esq. 



One of the most remarkable species of the Genus. 



Section G. — Zebina, H. and A. Adams. 



Oen. Moll. I, p. 328, 1855, type R. coronata, Beduz ; = Group VI, 

 Schwartz, I. c, page 39. 



75. Rissoina tridentata. 



Rissoa tridentata, IlicJiaud, Descr. Coq. noiiv. 1832 ; fide Schioartz, long, 

 8, diam, 4 mil., from lied Sea, Pldlippines, Mauritius and Sandwich I.; 

 Suez, fide M' Andrew ; fide £ease = R, crassilahrmn, Garrett, 1857 ; 

 from Tahiti, fide Grceffe. 



2 N. Caledonia; ex. c. P. Bouvier, Esq. 



1 Roweiah, Red Sea ; coll. J. R. Baxter, Esq. 

 12 Mauritius [9J^, 5], Andamans and Cejlon ; coll. G. Nevill, Esq. 

 4 Sandwich Islands; coll. H. Pease, Esq. [65, 83]. 



76. Rissoina coronata. 



Rissoina coronata, Becltiz, ms., Schwartz, Denies. K. AJc. Wissen, Wien, 

 XlX, 1S60, Mauritius, long. 5'3, diam. 2'3 mil.;l = R. lidentata, Phil., 

 and var, from XJpolu, fide Schmeltz, I. c. V: 



1 Mauritius ; coll. G. Nevill, Esq. 



B. affinis, Garrett, P. Ac. Phil. 1873, Viti Is., long. 5 mil., 

 must be close to this species ? 



77. Rissoina bidentata. 



Rissoa bidentata, Phillipi, Wiegm. Arch. 1845, p. 64, Friendly Isl., 

 long, f , diam. if ; fide Schtoartz, long. 6'5, diam. 2'S mil., Mauritius 

 and Friendly Islands. 



3 Mauritius [5|, 2^ ; coll. G. Nevill, Esq. 



Besides the dentition of the aperture, the differences in the 

 shape of the spire, whorls, &c., easily and certainly distinguish 

 it from R. tridentata. 



