THEIK GKEAT VAEIETY. 199 



Having traversed the greater part of both Independent* and British 

 -J. Sikhim, and collected over 2,000 specimens of the 



birds of this area, I find that the analysis of my 

 material affords a considerable contribution towards a geographical 

 distribution list for Sikhim, and also some additional notes on several 

 of the species which aid in supplying the want referred to by 

 Mr. Blanford. 



Sikhim owes its great variety of bird-life to its very varied natm-al 



features and its wide diversity of climate, ranging 



SikMm' avifauna! ^ from the torrid heat of the iarai^ skirting the base 



of its outer mountains, up to the arctic cold of its 



everlasting snows. 



The climate of this country, in respect to its flora, has been roughly 

 divided by Sir Joseph Hooker, as noted in a pre- 

 e clunato. vious chapter, into the Tropical, Temperate, and 



Alpine zones. For our purposes, however, it is necessary to make a 

 further subdivision of these zones, and also to recall briefly the geogra- 

 phical position and the leading physical features of Sikhim. 



Sikhim forms a narrow oblong tract in the South-Eastern Himalay- 

 as and Sub-Himalayas, with an area of over 4,000 

 ^, Geographical posi- ^^^^^.^ ^^^^^ wedged in between Nepal on the west, 



and Bhutan on the east, and bounded on the north 

 by Tibet, and on the south by the plains of Bengal. Its position is 

 peculiarly isolated, being separated from Nepal and Bhutan in great 

 part by high wall-like ridges,^ from Tibet by the snows and from 

 Bengal by the dreaded tarai^ jungle. The political division into 

 "British Sikhim" or the Darjeeling district,* and "Independent 

 Sikhim " cannot here be observed. 



Sikhim thus may be viewed as a stupendous stairway leading from 



Ph sical as ects *^^ western border of the Tibetan plateau down to 



ysica aspecs. ^^^ ^l^Jais of Bengal, with a fall of about 17,000 



feet in 150 miles. The surface of this vast incline^ is roughly cut up 



into an innumerable number of rugged peaks and tortuous valleys 



with deep gorges, adown which dash the glacial streams and torrents 



' As an instance of the extent to which Sikhim has been neglected by European travellers. 

 I may note that when Dr. D. D. Cunningham, f.e.8., and myself visited the Tangkar La Pass 

 (16,500) in 1889, it was the second time only that it had been visited by Europeans, the 

 first visitor having been Dr. (Sir Joseph) Hooker in 1849. 



2 The boundary on the western (Nepal) side includes KangchendsSnga, 28,156 feet high— 

 the second highest mountain in the world, and its southern spur the " Single La " range. 



' Hindi tarai = a swamp or marshy tract. 



* The trans-Tista portion of Darjeeling district lately ceded by Bhutan, wa8 formerly a 

 part of the Sikhim State. 



' Gneiss and mica schist are the chief formations ; in the lowest ranges lime, sandstone, 

 and shells are met with, and occasionally cop]ier and iron ores. The surface soil is largely 

 of a lateritic nature. 



