CHAP, viii.] THE PREHISTORIC LIMITS. 263 



sented in Britain. The spotted hyaena, lion, lynx, Caffer 

 cat, and hippopotamus, have taken refuge in the southern 

 climates ; the lemming, glutton, pouched marmot, musk 

 sheep, and tailless hare, have retreated either to the north, 

 or to the shelter offered by the forests of Central Europe, 

 or the tops of lofty mountains ; while the cave-bear, 

 woolly rhinoceros, leptorhine rhinoceros, mammoth, and 

 straight-tusked elephant (E. antiquus), have become 

 extinct. - On the other hand, it may be^ concluded from 

 the fact that all the wild Prehistoric mammals were 

 living in the preceding age, that the Prehistoric period 

 is not cut off from that which went before by a line of 

 demarcation such as that dividing the Secondary from 

 the Tertiary periods. The wild fauna and flora of 

 Prehistoric and Historic Europe may be traced back to 

 the Pleistocene age, and therefore the Tertiary period 

 must be looked upon as not ending with the Pleisto- 

 cene, but as extending down to the present day (see 

 Fig. 1). 



Magnitude of Interval between the Pleistocene and 

 Prehistoric Periods. 



Such changes in the mammalia" and in the geography 

 of Britain as those described in the preceding pages, in 

 the interval separating the Pleistocene from the Pre- 

 historic period, could not have taken place in a short 

 time, and when we reflect that comparatively little 

 change has taken place in this country during the last 

 two thousand years, it is obvious that the one period is 

 separated from the other by the lapse of many centuries. 

 Of how many we cannot tell. The sharp line of demar- 

 cation between the two is to be noticed in almost every 



irt*f 



