1909.] F. H. Stewart : Aquatic animals from Tibet. 121 



COMPARISON OF THE FISH FAUNA OF THE NORTH 



AND THE SOUTH FACES OF THE GREAT 



HIMALAYAN RANGE. ^ 



By F. H. Stewart, M.A., D.Sc, M.B., Captain, I. M.S. 



In the area of the " North face of the Great Himalayan 

 Range " it is intended to include not only the north face of the 

 great range proper, but the whole area bounded on the south by 

 the crest of the Himalayas, and on the north by the Karakorum 

 range and its continuation eastward. This area is composed of the 

 Trans-Himalayan portions of the catchment-areas of the Brahma- 

 putra on the east and of the Indus on the west, with the Mansaro- 

 war and the Trans-Himalayan Sutlej areas lying in the centre. It 

 extends through twenty degrees of longitude and has an area of 

 about 203,000 sq. miles. 



As far as our present subject is concerned the principal physi- 

 cal characteristics of this region are — 



1. Its great elevation above sea-level (Chaksam ferry on the 

 Brahmaputra, longitude 90° 45' E., ii,55o feet ; Rham-Tso, near 

 the crest of the range, 89° 30' E., 14,700 feet ; Shigatse on the 

 Brahmaputra, 89° E., 12,800 feet; sources of the Brahmaputra^ 

 between 82° and 83° E., 16,000 feet ; Lake Mansarowar, 81° E., 

 14,900 feet ; Gartok on the sources of the Indus, 80° 25' E., 15,100 

 feet ; Leh on the Indus, 78° E., 11,300 feet ; Indus at Skardo, 

 75° 30' E., 8,900 feet). 



2. Its very low rainfall. The greater portion of the water 

 appears to be derived from springs. 



3. The very sparse vegetation. 



4. The rapidity of flow of the streams. 



The south face of the great chain on the other hand includes 

 the catchment-areas of the Manas, Raidak, Tista, Kosi, Baghmati, 

 Rapti, KarnaH, Kah, Ramganga, Ganges, Jumna, Beas, Ravi. 

 Chenab and Jhelum, and the Cis-Himalayan portions of the areas 

 of the Brahmaputra, Sutlej and Indus. 



In regard to the elevation of this area from the zoologist's 

 point of view, it must be remembered that most specimens have 

 been taken from rivers running in the depths of the valleys at 

 probably not more than 3 — 4,000 feet above sea-level. 



In contrast to the north face the south face is, of course, a 

 region of heavy rainfall and abundant vegetation. 



It should be noted that the crest of the Himalayan range does 

 not correspond with the watershed, but that the former lies consi- 

 derably to the south of the latter. As will be pointed out below, 

 we have at present no data which would enable us to decide which 

 of these two lines forms the zoological boundary between the two 

 regions. 



1 For the geographical facts in this note I am chiefly indebted to Burrard 

 andHayden [2]. 



