MOLLUSCA OF INDIA. 335 



of the genus Ah/cceus, the number being nearly if not quite equal 

 to all the other known truly Indian species of that singular form. 

 It is highly probable that many more forms may yet be procured 

 from this region. As already mentioned, there are several species 

 of my own collection as yet undcscribed, and the general distri- 

 bution of shells is so excessively local that any diligent collector 

 may add largely to the number. All the hills and valleys of 

 Independent Sikhim are completely unexplored so far as the 

 moUusca are concerned, and the neighbouring regions of Xepal and 

 lihotan are yet a terra incognita.'^ 



This was written some 50 years ago, and although Sikhim has 

 been since well worked, the two neighbouring areas still remain a 

 blank as respects the land mollusca. 



William Blanford, writing when on his first visit to Darjiling 

 and after collecting there, says: "There seems in very many indeed 

 of the Sikhim species of shells to be a tendency to occur in two 

 varieties, one conspicuously smaller than the other. This has been 

 already remarked in the case of Helix pJedostoma, H. trignrium, 

 and Achatina tenuispira, and it is equally true of Strej)taulus 

 hlanfordi, Alyccexis otipliorus, and Achatina crassilahris or crassula, 

 and some others." It is most marked in some of the Khasi Hill 

 shells, notably in Spiraculum Msjiidum at Teria Ghat. 



In the 'Journal of the Asiatic Society of Bengal' (1874) I 

 wrote: "The Alycaei particularly seem to be inexhaustible; the 

 different species are very local but very persistent in character over 

 comparatively small areas, and as they are generally abundant 

 where they occur, the idea that they are accidental varieties is not 

 supported. Very few have a wide vertical distribution, and some 

 common forms of the Khasi Hills, at a distance of some 120 miles 

 east in the Naga country, are absent or become very rare indeed. 

 The whole section is a most interesting one, and illustrates admi- 

 rably the many changes that nature will ring on any particular 

 form of life where confined to particular habitats suitable for their 

 development, and again subjected to all the slow alternations in 

 climate, soil, &c. that time produces." " Several species of Alycaei, 

 when taken in a fresh state, are found covered with a coating of 

 earthjr matter, sometimes black, rendering them very indistinct and 

 difficult to find, especially as they are to be generally found below 

 the surface and beneath the dead leaves and decaying bark and 

 sticks that cover the ground so thickly in virgin forest. Dead 

 shells maybe sometimes seen in hundreds in the clearings after the 

 cut jungle has been fired, when the surface vegetable mould is 

 burnt and the ground heated to a great depth. In this way many 

 local forms of land-shells must be destroyed off manj' a large area 

 as the country becomes cleared, and many of the more local species 

 have no doubt thus died out." 



