1881.] SUMATRA AND BORNEO. 633 



33, CoRBicuLA GRACILIS, Prime. 



Abundant in all the lakes in Sumatra, especially Lake Singkarah. 

 The shell is fished in quantities, and used for making lime for betel- 

 chewing. 



34. Unio dimotus, Lea. 

 Abundant. 



IL Shells collected in Koetei and in the Amontai and Bandjermasin 



Districts of Borneo. 



Hklicid^. 



1. Nanina (Rhyssota) brookei, Adams & Reeve. 



I found dead specimens in Koetei. The Dyaks use them as orna- 

 ments in the top of the lids of their arrow-cases. Six live specimens 

 at Mindai (in Amontai district). It is, however, rare, hiding in 

 layers of decayed leaves. 



2. Nanina (Xesta) consul, Pfeiffer. 

 Found at Mindai. Two specimens. 



3. Helix mindaiensis, nov. sp. (Plate LV. fig. 7.) 



Shell very slightly umbilicated, sinistral, convexly conoid, semi- 

 transparent, of a reddish brown colour, with a white-tipped lip. 

 Spire conical, with somewhat convex outlines and the apex obtuse. 

 Whorls 6, but slightly convex, sculptured with finely granulated 

 radiating striae, regularly increasing ; the last acutely keeled. Aper- 

 ture oblique, lunate. Peristome sharp, slightly thickened ; upper 

 margin short, oblique, the basal (seen from beneath) rather sinuous. 

 Greatest diam. 30 millim., axis 13 inillim. 



Hab. Mindai (Amontai district), very abundant amongst the de- 

 caying leaves in the forest. 



This species is of a darker colour than Helix maarseveeni, has one 

 whorl less, has more convex outlines to the spire, is not so sharply 

 keeled around the last whorl, and more narrowly umbilicated. Its 

 sculpture, too, is rather more coarsely granular. 



4. Helix (Videna) metcalfei, Pfeiffer. 

 One specimen, collected at Mindai. 



5. Helix (Videna) planorbis. Lesson. 

 From Mindai. Scarce. 



6. BuLiMus (Amphidromus) interruptus, Miiller. 



This shell was very abundant in Bandjermasin, both the dextral and 

 sinistral forms, and variously coloured ; of the rare pure white variety 

 only one specimen was obtained. After heavy rains the trees were 

 quite spotted with them. 



Proc. Zool. Soc— 1881, No. XLI. 41 



