328 THE HOLARCTIC REGION. [CHAP. 



istic mammalian genera of the Ethiopian and Oriental regions 

 given above. The total number of genera which can in any sense 

 be considered as peculiar to the eastern half of the Holarctic 

 region does not exceed thirty ; and among these Uropsilus, Scapt- 

 onyx, Elaphodus, and Hydropotes can only be regarded as intruders 

 from the Oriental region ; while Ctenodactylus and Addax are 

 manifestly Ethiopian types. Indeed, if a Mediterranean region 

 were established, the whole of these, and probably also the true 

 Tibetan forms, would have to be removed from the lists. Apart 

 from the absence of peculiar families, the list bears no comparison 

 as regards numbers with that of the mammalian genera distinctive 

 of the Ethiopian region ; while, with the aforesaid deductions, it 

 is also considerably inferior to that of the Oriental region. All 

 this confirms the conclusions already drawn as to the inad- 

 visability of regarding the area under consideration as a separate 

 zoological region. 



The Pliocene and earlier Tertiary faunas of this area having 

 already been considered in connection with Eastern 

 Arctogsea in general in an earlier chapter, we may 



Eastern Hoi- p ass O n to a brief review of the Plistocene mammals 



arctic Region. 



of the eastern division of the Holarctic region, pre- 

 paratory to the consideration of the sub-regions into which the 

 latter is divided. The Plistocene period may be taken in England 

 to commence with the Forest-bed of the Norfolk coast, which 

 overlies the topmost of the Pliocene Crag series, and is itself 

 overlain by the glacial deposits. To a later epoch of the same 

 period belong the brick-earths and gravels of our river valleys, as 

 well as the cavern-deposits ; many of these being either of post- 

 or inter-glacial age. 



During the Plistocene period two very remarkable differences 

 from the existing state of things have to be noticed. In the first 

 place, the eastern Holarctic region was at that time very much 

 less distinctly differentiated from either the Ethiopian or the 

 Oriental than is the case at the present day ; macaques, hyaenas, 

 the lion, rhinoceroses, hippopotami, and elephants abounding in 

 Europe even as far north as England. The second point is the 

 curious mixture of remains of existing species of mammals respec- 

 tively characteristic of hot and cold climates met with in many 



