SPECIES OE LAND-SHELLS FROM BORNEO. 347 



produced into semitubular short spines, forming a spiral series 

 around the middle of the penultimate and one or two preceding 

 volutions. The spines of the lower series on the body-whorl 

 are longer than those above, curve backward, and form a crest 

 around the base. Tlie aperture, which is trumpet-shaped, is 

 directed backwards. 



18. Opisthostoma jucundum. (PI. XXV. figs. 1-3, 13 a.) 



Testa umbiUcata, conica, plus minus rufescens ; anfractus 7, apicales 

 Iseves, rotundati, cseteri lamellis nutnerosis tenuibus obliquis in medio sub- 

 productis instructi, ultimus contortus, retrorsus, antice solutus; peristoma 

 tenue, anguste reflexum. 



Alt. 2| millim., diam. maj. 3, min. 1|. Apertura 1 lata. 



Mab. Mantanani Island, jS". Borneo. 



This species is a little smaller than 0. Everetti, consists of a 

 whorl more, has more numerous lamellae, which have a wavy 

 appearance upon the body-whorl, and are a little produced about 

 the middle of the upper volutions, so that they have a somewhat 

 angular appearance. 



14. Opisthostoma Wallace:, ^«cey. (PI. XXV. figs. 14, 14a.) 

 Plectostouia Wallacei, Ancey, Bull. Soc. Mai. France, 1887, p. 276 = 



Opisthostoma cristatum, Smith, MSS. 



Hab. Busau, N.W. Borneo. 



This species is a trifle less robust than 0. jiicundum, much 

 more closely lamellated, has a more expanded peristome, and a 

 distinct basal crest or ridge upon the body-whorl. 



Specimens of this species have been distributed under the name 

 of 0. cristatum, Smith. Eorgetting that FJectostoma was syno- 

 nymous with Opisthostoma I overlooked the description of this 

 species by M. Ancey under the name of Pled. Wallacei. 



15. Opisthostoma baritense. (PI. XXV. figs. 15, 15 a.) 

 Testa elata, ovato-conica, rufescens, angustissime perforata ; anfractus 



6, perconvexi, sutura profunda sejuncti, primus Isevis, cseteri oblique 

 subconferte tenuissime lamellati, ultimus retrorsum et sursum contortus, 

 breviter solutus; peristoma leviter expansum. 



Alt. 2^ millim., diam. maj. 2J, min. 1^. Apertura § lata. 

 Sab. Barit Mountain, N.W. Borneo. 



This species is about the same size as 0. Wallacei, but is more 

 pupiform, redder, more distantly lamellated ; the body- whorl has 

 no basal crest, and the aperture and peristome are smaller. 



