189 



DESCRIPTIONS OF THREE NEW SPECIES OF OPISTSOSTOMA 

 FROM SARAWAK, NORTH BORNEO. 



By Edgar A. Smith, I.S.O. 



Read Wth November, 1904. 



The three species about to be described were collected by Mr. Sydney 

 Beddome at Picsing, Upper Sadong, Sarawak. Including these, the 

 number of distinct forms now recognized from Borneo amounts to 

 twenty-three. 



Opisthostoma Shelfoedi, n.sp. Fig. 3. 



Testa destrorsa, minima, conica, rufescens ; anfractus 5 convexi, 

 primus Igevis, cseteri liris obliquis, tenuibus, arcuatis, instructi, 

 ultimus primo peculiariter contractus et contortus, deinde arcuatim 

 retrorsus, usque ad apicem spirae ascendens, lamellis fortioribus 

 omatus; apertura circularis ; peristoma duplex, pallidum, margme 

 interno anguste expanso, externo angusto, spirae contiguo. Long.' 2, 

 diam. 1"6 mm. 



Hah. — Picsing, Upper Sadong, Sarawak. 



Eemarkable on account of the way in which the last whorl is 

 curved up the spire, so that the upper edge of the peristome is shghtly 

 above the apex. Under the microscope the surface is seen to be 

 minutely spirally striated. 



1 2 3 



Opisthostoma Sadongense, n.sp. Fig. 2. 

 Testa dextrorsa, rimata, conica, rufescens ; anfractus 6 perconvexi, 

 lamellis numerosis, tenuibus, obliquis, ornati, ultimus constrictus, 

 retrorsus contortus et ascendens, lamellis versus labrum_ validioribus 

 et magis distantibus ; apertura angulatim ovalis, antice leviter canalicu- 

 lata; peristoma duplex, margine interno continuo, porrecto, leviter 

 incrassato, externo anguste expanso, spiram versus interrupto. Longit. 

 2-25, diam. 2-5 mm. 



