of Secular Changes of Climate. 369 



Europe the same remarkable commingling of northern and 

 southern forms — of forms that demand a humid climate and 

 are capable of enduring considerable cold, together with species 

 which, while seeking moist conditions, yet could not survive 

 the cold of our present winters. The testimony of the mam- 

 mals and plants is confirmed by that of the land and freshwater 

 mollusca — all the evidence thus conspiring to demonstrate 

 that the climate of Pleistocene Europe was, for some time at 

 all events, remarkably equable and somewhat humid. The 

 summers may not indeed have been warmer than they are 

 now; the winters, however, were certainly much more genial." 

 (< Prehistoric Europe/ p. 540.) 



This, be it observed, is a description of a condition of things 

 which existed during an Interglacial Period belonging, not to 

 the close, but to the very climax of the Glacial Epoch. For 

 immediately preceding and succeeding this Period almost the 

 whole of Northern Europe was enveloped in one continuous 

 sheet of ice. " But if," continues Prof. J. Geikie, u the 

 evidence of such a climate having formerly obtained be very 

 weighty, not less convincing are the proofs, supplied by the 

 Pleistocene deposits, of extreme conditions. Think what must 

 have been the state of Middle and Northern Europe when 

 Paleolithic man hunted the reindeer in Southern France, and 

 when the arctic willow and its congeners grew at low levels 

 in Central Europe. Reflect upon the fact that in the very 

 same latitude in France, where at one time the Canary laurel 

 and the fig-tree flourished, the pine, the spruce, and northern 

 and high-alpine mosses at another time found a congenial 

 habitat. Bear in view, also, that the land and freshwater 

 molluscs testify in like manner to the same strongly contrasted 

 climate. Besides those that tell of more equable and genial 

 conditions than the present, there are species now restricted 

 to the higher Alps and northern latitudes that formerly 

 abounded in middle Europe, and their shells occur commingled 

 in the same deposits with the remains of lemmings, marmots, 

 reindeer, and other northern and mountain-loving animals." 

 (P. 541.) 



But more convincing still is another range of facts, some of 

 which have been adduced by Mr. Wallace himself. In a sec- 

 tion on alternations of warm and cold periods during the 

 Glacial Epoch (' Island Life/ p. 114), he says: — 



" The evidence that such was the case " (alternate warm and 

 cold periods) " is very remarkable. The ' Till/ as we have 

 seen, could only have been formed when the country was en- 

 tirely buried under a large ice-sheet of enormous thickness, 

 and when it must therefore have been, in all the parts so 



