158 LITTORINIDJJ. 



Very probably belongs to the Lltiojjince, near Alaba^ Dlalaj 

 &c. 



1. Plesiotrochus, n. sp. 



An interesting form, of this very distinct new Grenus wTiicb 

 I have for several years intended to describe. The whorls are 

 characteristically concave. 



10 Maurithis ; coll. G. Nevill, Esq. 



1 Audamaus; coll. Dr. F. Stoliczka. 



2. Plesiotrochus [?] n. sp. 



2 Persian Gulf ; coll. W. T. Blanford, Esq. 



Sub-family FOSSABIN^, Stoliczka. 



Genus RISELLA, Graij, 



Syn. Brit. Mus. 1S40, type Trochus melanostoma, Qm. ; ^Bemhiciumy 

 Fhilippi, Zeits. Malac. Ill, 1845. 



1. Risella plana. 



Trochus plana, Quoy, Toy. Astrol. 1832, " Port Western'' Bass's Strait ; 

 =Littorina australis. Gray, Beechey's Voy. 1839; var.=R. grisea, 

 Fhil., Zeits. Mai. 1851, Hah. 1 



7 Australia; ex c. Asiat. Soc, Bengal [coll. Strange]. 

 4 South Australia ; ex c. British Museum and Miss Pelly. 



Agree with figure, in Conch. Cab. II, of JB. grisea, Phil. 



1 Port Mactay ; ex Mus. Godeffroy [as " var. jff., Crosse "]. 

 30 Port Jackson ; coll. Dr. J. C. Cox and G. Nevill, Esq. 



2. Risella imbrioata. 



Littorina imbricata, Oray, Beechey's Voy., 1839 [_sine Hab.] ; = Risella 

 Melmannseggi, Frauenfeld, 1866, N. Zealand. 



1 Australia j ex c. G. Nevill, Esq. 



