1872.] DAAVKINS — CLASSIFICATION OP PLEISTOCENE STRATA. 433 



3, The third is that the Hippopotamus could not have traversed 

 vast distauces, say from the south of France to Kirkdale, in York- 

 shire, in one season. So far from holding this view, I have always 

 maintained that in the vast lapse of time represented by the Pleis- 

 tocene, or, as Mr. J. Geikie, speaking merely from the point of view 

 offered by Scotland, terms it, the " Glacial Period," every inch of 

 ground in Middle Europe was fought over by the invading and 

 retreating forms, not at one time, but at successive times. 



4, To the fourth objection (p. 167), that, under the conditions of 

 climate to which I have referred, the vegetation of Britain would have 

 been too scanty and meagre for the support of the animals, and that 

 the destructive floods would reduce the lower grounds to a desert at 

 the break-up of the winter, it is only necessary to refer to Wraugel's 

 ' Siberia,' Middendorf's ' Sibirische Reise,' and Sir John Pranklin's 

 ' Overland Journeys,' to prove the existence of a luxuriant forest- 

 vegetation in the region extending in Middle Siberia south of the 

 Tundras, and in that south of the Barren Grounds, and the fact that 

 large floods in the spring do not destroy the vegetation. 



5, A further objection is based on the presence in some cases of 

 Unio littoraUs and Corhicula consohrina along with the mammalia in 

 the river-deposits. Can we predicate temperature from either of 

 these shells ? The former still lives in the Loire ; and the latter is 

 abundant in the beds of the streams in the region of the Himalayas. 

 The evidence as to the existing range of both these moUusks does 

 not seem to me sufficient to trace any conclusion as to Pleistocene 

 temperature. 



The Temperate Group. 



The third group of Pleistocene mammalia (which still inhabits 

 the temperate zones of Europe, Asia, and America (is far larger 

 than either of the preceding which we have described. It con- 

 tains the 



Musk-Shrew. 



Wild Cat. 



Brown Bear. 



Saiga Antelope 



Beavei*. 



Marten. 



Grizzly Bear. 



Stag. 



Hare. 



Ermine. 



Horse. 



Eoe. 



Eabbit. 



Stoat. 



Bison. 



Fallow Deer. 



Porcupine. 



Otter. 



Urus. 



Wild Boar. 



In the Pleistocene this group of animals had very much the same 

 range over Europe as they have at the present time, although many 

 ef the species have retreated from their ancient homes. Thus the 

 Grizzly Bear, which then ranged from the shores of the Mediter- 

 ranean into Great Britain, Central Germany, and Belgium, has re- 

 treated to its present stronghold in the Rocky Mountains, And al- 

 though, unlike its more arctic associate in France and Britain, the 

 Musk-sheep, it has not been recognized in European Russia or in 

 Northern Asia, there can be little doubt that its line of retreat was 

 eastwards by the Straits of Behring. The Antilope saiga, which then 

 passed as far to the west as Auvergne, and the Musk-shrew, which 

 has been discovered at Bacton, are now only living in the warmer 



