1895.] liOLLUSCA OP THE ANDAMAN AND NICOBAB ISLANDS. 449 



Genus Durgella. 



2. DuBGELLA ANDAMANiciTS, NeviU MS. (p. 442). 



I have not seen this species. It is entered in the 'Hand-list.' 

 10 in the Calcutta Museum (10 in spirit), type Andamans from 

 de Eoepstorff, " has been taken for the young of Dmvjclla christi- 

 ance," which is not unlikely to be the case. 



Genus Gibasia. 



GiEASiA, sp. inc. (p. 442). 



My brother described having found, when he made the ascent 

 oE Saddle Peak on North Andaman with Col. Hobday of the G. T. 

 Siu'vey, a large slug-like form resembling this genus. It was done 

 up in leaves, but was accidentally lost before they got into camp. 

 This genus may therefore be sought for by future collectors. 



Genus Planispiba. 



4, Planispiba wimbebleti, n. sp. (p. 442). 



Locality. Nicobars (de Roepstorff). 



Shell depressedly orbiculate, narrowly umbilicated, very fiuely 

 hirsute ; sculpture, when this is abraded the surface is covered 

 with minute regular papillatiou, which is much coarser than that 

 of H. helferi ; colour horny grey ; spire rounded ; apex rounded ; 

 suture impressed ; whorls 4, not fully developed, slightly convex ; 

 aperture and peristome probably slightly expanded and reflected. 



Size : maj. diam. 10'2, min. 8"9 ; alt. axis 5'7 mm. 



This species is nearest to H. helferi, but may be distinguished by 

 its narrower umbilicus and the great difference in sculpture, and 

 the whorls above are not so flat. This is probably no. 102 of 

 Nevill's 'Hand-list' (p. 76), collected by Ferd. Stoliczka. 



Planispira helfen, Benson, has only hitherto been found in the 

 Andamans ; the young shell of four whorls and banded I found in 

 Mr. de Eoepstorff's collection from the Mcobars ; but it might have 

 got among them accidentally, and therefore this new habitat has 

 to be confirmed. 



Genus Sivella. 

 1. Sivella castba, Blandf. 



A variety is recorded by Nevill, ' Hand-list,' p. 56, from the 

 Andamans and a single specimen is in my collection from Mr. Wood- 

 Mason. 



The umbilicus is vsdder than in castra and the apex far flatter. 

 Sculpture quite smooth below, with transverse striae ; whereas 

 castra from typical locality, of same size, has close spiral striation 

 most distinct. There is also a remarkable difi'erence in the suture, 

 the Andaman shell has a fine beading running into it, produced by 

 the sharply defined carinate edge of the shell. I believe this to 

 be only an immature Discus sanis. 



Pboc. Zool, Soc— 1895, No. XXIX. 29 



