RIVER-DRIFT GRAVELS. 295 



cation of a cold climate, and the circumstances attending the 

 discovery of the tichorhine rhinoceros in Siberia, the fact that 

 the mammoth of the Lena was enveloped in ice so soon after 

 death, that the flesh had not had time to decay, as well as 

 the manner in which the extinct Pachydermata were pro- 

 vided against cold, clearly show that the Ekphas primigenius 

 and the Rhinoceros tichorhinus, unlike their congeners of to- 

 day, were inhabitants rather of arctic, than of tropical, 

 climates. 



If we were to take the river gravels as a whole, the 

 evidence as to climate would be still stronger, because to the 

 above species we might then add the Norwegian lemming, 

 the Myodes torquatus, and last, not least, the musk ox. These 

 three species, have, however, not yet been found in the 

 upper level gravels. 



Taking the fauna and flora as his guide, Mr. Prestwich 

 assumes that a country where the oak, the yew, the fir, and 

 the bilberry flourished, where the deer, ox, horse, and rein- 

 deer abounded, and where .the rivers froze so as to transport 

 large boulders for considerable distances, " presents conditions 

 which would probably accord with a mean winter cold of not 

 less than 20, while it may have been as low as 10, or even 

 lower. This would be from 19 to 29* below" our present 

 temperature. While, however, the evidence of a more severe 

 climate seems to be conclusive, we are hardly as yet in a 

 condition to estimate with any degree of probability the 

 actual amount of change which has taken place. 



It must always be borne in mind that the temperature of 

 Western Europe is at present exceptionally mild ; if we go 

 either to the east or west, to Canada or Siberia, we find 

 countries under the same latitude as London and Paris, 

 suffering under a far more severe climate. 



The river St. Lawrence, to which I have already pointed 

 * Prestwich, Phil, Trans. 1864, p. 281. 



