V.] SIWALIK FAUNA. 209 



from tropical Africa of deer and bears ; for these are both groups 

 which live in fertile or well-wooded countries, whereas the line of 

 immigration from Europe to Africa was probably always, as now, 

 to a great extent a dry and desert tract, suited to antelopes and 

 large felines, but almost impassable to deer and bears." The 

 Siwalik chimpanzee, however, indicates most unmistakably that 

 the communication by way of Arabia or Syria between the Ethio- 

 pian and Oriental regions must have embraced a forest-area, and 

 accordingly have been of considerable width. 



With regard to the question why so many genera which existed 

 in India and southern Europe during the Pliocene should have 

 disappeared from those areas to live on in Africa, all we can say is 

 that it is quite evident that a southern migration of the fauna has 

 certainly taken place, and that this was probably induced by the 

 cold heralding the approach of the glacial period. Although we 

 have few, if any, decisive physical evidences of a cold period in 

 India, yet the existence of a goat (Hemitragus) nearly allied to a 

 Himalayan species in the ranges of southern India seems to indi- 

 cate that such must have occurred, as it would be quite impossible 

 for the ancestral form to have crossed the intervening plains under 

 present conditions of temperature. It is further noteworthy that 

 many of the animals which have disappeared from India, such 

 as chimpanzees, hippopotami, giraifes, water-chevrotains, and 

 ostriches, are precisely those which are now restricted to very hot 

 climates ; whereas the lion, tiger, rhinoceroses, elephants, and 

 monkeys, which both now or during the Plistocene are known 

 to be capable of existing in cold climates, have persisted. 



Leaving these exceedingly difficult questions, two other points 

 may be noticed in connection with the Siwalik fauna. In the 

 first place, since the Siwalik hills themselves form ranges of con- 

 siderable height on its southern flank, it is evident that the 

 Himalaya was much lower during the lower Pliocene epoch than 

 it is at present ; Dr Blanford l stating that the movement which 

 led to its elevation "has been distributed over the Tertiary and 

 post-Tertiary period, and a great portion in post-Plistocene." 

 This will account for the community between the lower Pliocene 



1 See Geol. Mag. Decade 3, Vol. ix. p. 166, note (1892). 

 L. 14 



