272 On new Species 0/ Opisthostoma from Borneo. 



rufcscens, ad marginem duplicatam expansam pallida, usque ad 

 suturam tertiam vel quartam sursum porrecta. 

 Longit. 2 millim. ; diam. maj. 2|, min. 1|. 



Hob. Sarawak (C. Hose). 



Five specimens of this species were presented to the 

 British Museum by Mr. Charles Hose, but the particular part 

 of Sarawak where they were collected is unknown. 



0. Hosei and 0. Decrespignyi are the nearest allies of this 

 species. The former is about the same size, but has a more 

 robust spire, smoother and fewer whorls ; but the last is 

 much more strongly lamellated, and has only a single crest, 

 whereas in the present species there are two. 0. Decres- 

 jrignyi has a less conical spire, more rounded volutions, and 

 the body-whorl is scarcely crested at all. 



I have much pleasure in naming this species after the 

 Rev. A. H. Cooke, who has kindly undertaken to figure it 

 in his forthcoming volume on the Mollusca in the l Cambridge 

 Natural History.' 



13. Opisthostoma depauperatum. 



Testa 0. baritense similis, sed minor, minus elongata, lamellis 

 distantioribus ornata, anfractu ultimo valde soluto, antice magis 

 ascendente. 



Longit. 1| millim. ; diam. maj. 2, min. 1 ; apertura § lata. 



Hab. Barit Mountain, North-west Borneo. 



The smaller size, more distant sculpture, and the more 

 uncoiled last whorl distinguish this species from 0. baritense ; 

 also in that form the body-whorl is not produced upward so 

 much anteriorly, the top of the peristome being about on a 

 level with the second suture, whereas in the present species it 

 almost reaches the third. 



14. Opisthostoma Austeni. 



Testa dextrorsa, conica, angustissime perforata, pallida vel plus 

 minus rufescens ; anfractus 6, convexi, regulariter crescentes, 

 sutura profunda sejuncti, liris obliquis tenuissiinis curvatis (in 

 anfr. ultimo sensim crassioribus et distantioribus) instructi ; anfr. 

 ultimus constrictus, ad aperturam valde ascendens et retroversus, 

 baud solutus ; apertura rotunde angulata ; peristoma leviter 

 incrassatum, porrectum, vix expansum, extus lamella tenui angusta 

 circumdatum. 



Longit. 2| millim. ; diam. maj. 2f, min. 1|; apertura cum perist. 

 1| longa et lata. 



Hab. Rumbang, Sarawak. 



