354 THE HOLARCTIC REGION. [CHAP. 



This list includes all the species inhabiting the plateau at 

 elevations exceeding 12,000 feet. Dr Blanford writes that "many 

 of the forms named only inhabit small portions of the area, and 

 whilst Bos grunniens, Pantholops hodgsoni, and Gazella picti- 

 caudata, with several rodents, appear to be peculiar to the high 

 plateaus above 14,000 feet, the two species of Cervus are pro- 

 bably found in brushwood at a rather lower elevation in the more 

 broken region of Eastern Tibet, where the rainfall is heavier and 

 the vegetation more abundant. 



"As was printed in the paper in the Geological Magazine 1 , 

 there is, so far as I am aware, no equally peculiar mammalian 

 fauna to be found in any continental area of equal extent, and for 

 a parallel it is necessary to turn to some island like Celebes, that 

 has long been isolated from all surrounding lands." 



This, however, is not all, for there occur at Hundes, on the 

 Tibetan plateau, mammaliferous strata yielding, among other 

 remains, bones of a rhinoceros, and of an antelope which is 

 apparently generically identical with the chiru (Pantholops), now 

 inhabiting the same area. The isolation and development of this 

 most peculiar fauna is intimately connected with the date of 

 elevation of the Himalaya. After pointing out that both the fossil 

 chiru and the fossil rhinoceros appear to have inhabited the area 

 when it had attained something approaching its present enormous 

 elevation, Dr Blanford 2 writes as follows : " Bearing in mind that 

 the isolation of the Tibetan plateau is far less perfect as regards 

 mammals than that of any island, and that some of the forms 

 the Carnivora especially found in Tibet are evidently very recent 

 immigrants, it is a reasonable conclusion that the peculiar fauna 

 of the Tibetan plateau has been distinct from that of neighbouring 

 countries since middle Tertiary times. 



" But what has caused the isolation of the Tibetan fauna ? 

 Why in this one continental tract is there a generic and specific 

 differentiation of the mammalia, of which no other example 

 exists ? There is only one character in which Tibet is different 

 from other continental areas, its great height. This alone renders 

 the climate of Tibet so different from that of other parts of 



1 Decade 3, Vol. ix. p. 161 (1892). 



2 Geol. Mag. op. cit. p. 165. 



