254 PKOCEEDINfiS OF THE JIALACOLOGICAL SOCIKTY. 



In speculating on the distribution of land-shells, this casual picking 

 np and transport by man's agency is an element we have always to 

 consider. One means of transport lies in the thatch of the native 

 craft plying on the great rivers of India. Thatched boats coming 

 down from Assam, Cachar, and Sylhet work all through the delta 

 to Chittagong, and even down the coast at times. This was brought 

 home to me very practically on one occasion when crossing the 

 Bhecls of Sylhet during the rains. We were poling througli the 

 high reeds, when I noticed they were covered with Helix {^Planupira) 

 similaris, of which I collected a good number of very fine specimens. 

 In such a place, even if they fall in the water, blown otf by the 

 wind, they would soon get on to the reeds again, and thus survive 

 until the floods abated ; but how easily they would be knocked off 

 into or on to the thatch of a boat, and be carried down to the sea 

 margin ! The species has an enormous range, and this may be one 

 of the means by which that has been brought about. Minute species 

 may have been transported in fruit, such as melons, and especially 

 the banana, and in vegetables, by the same agency of native vessels, 

 which have been navigating the Eastern seas for hundreds and 

 hundreds of years, perhaps long before our knowledge of ancient 

 Egypt begins. 



Coming to the North-East Frontier and Burma, Girasia, and the 

 closely related subgenera Austejiia and Ihymm, have, perhaps, as 

 extended a range as any of the Indian land mollusca. These 

 subgenera are associated in the typical locality, the Khasi Hills, 

 whence Sir Joseph Hooker first sent home Girasia, throughout 

 Assam, the foot of the Eastern Himalaya, westward to Sikkim, and 

 in the North-AVest Himalaya from Gurhwal to Chamba as far as 

 Murree. They are found also from North Burma to Pegu and along 

 the Siam border. The giant of the race, A. magyiificus, was discovered 

 hy Dr. J. Anderson in Yunnan. I have not yet seen any species from 

 Siam proper, nor from the Andaman Islands. 



The slug-like form finds its fullest development in Girasia ruhrum 

 (assuming it to belong to this genus) of the Naga Hills. In this 

 species the shell has become reduced to a minute thin oval disc, and 

 there is truly here as great a difference, comparing it with Girasia, as 

 there is between this last and Austenia. I have no doubt that similar 

 molluscs will be found in other parts of India if only they are 

 sought for.^ 



Species of Girasia are found inhabiting the plain country of Assam, 

 as well as the mountain ranges up to 5,000 and even 8,000 feet ; they 

 are not, like so many other species, tied as it were to rocky ground, and 

 this may account for their very general distribution. I have pointed 

 out that one form of the genus occurs in Peninsular India. They 

 rejoice in damp ; the complete saturation point is the one best suited 



1 In such a series as this Tve are compelled to give the shell greater Tveight in 

 classification than it otherwise would deserve, and supposing by any possibility 

 such forms as thene were preserved in a fossil state, such a course would be 

 strictly right, and prove the most useful for purposes of identification. 



