168 James Geikie — On Changes of Climate, 



the Pleistocene hippopotamus differed very much from its living 

 representative (and so far as we know it did not), there is no 

 likelihood of such a bulky brute having performed the wonderful 

 migrations which this hypothesis assigns to it.^ 



I have referred to the hippopotamus alone, but at least three 

 of the other southern forms met with in English " Pleistocene " 

 deposits seem to come under the same category. Elephas antiquiis 

 and the two rhinoceroses [B. leptorhinus, Owen, and B. megarhinus) 

 would certainly have fared as badly as the hippopotamus if they had 

 ventured into Britain at a time when our high grounds were covered 

 with snow and ice. Nor, judging from what we know of their 

 present representatives, can we suppose that these animals were 

 migratory. Again, I think it hardly possible that the cave-lion, 

 the hy^na, and the sabre-toothed machairodus could have visited 

 this country under the conditions assumed. It is quite true that the 

 lion infested Grreece within historical times, and that, as Mr. Dawkins 

 remarks, "the temperature of the mountains of Thrace was un- 

 doubtedly infinitely more severe than that of any region in which it 

 now lives." But the temperature of " Pleistocene " Britain, ac- 

 cording to this theory, must have been " infinitely more severe " 

 than that of the mountains of Thrace ; and the question we have to 

 consider is whether the lion could live under conditions still more 

 trying than those that mark the bleak " barrens " of British America 

 or the treeless tundras of Northern Asia. I say " still more 

 trying," because the summers of such a Britain, as is thought to 

 have existed in Post-glacial times must have been far cooler than 

 those of Northern Asia and America are at present. With the poor 

 and meagre vegetation which a country of this kind would be able 

 to support, the herbivora could not have been abundant. Indeed, 

 only a very few of the mammalia enumerated by Mr. Dawkins could 

 possibly have existed under the conditions supposed, and probably 

 none of these would belong to his second group, which consists 

 of such species as still inhabit the temperate zones of Europe and 

 America. If, therefore, we eliminate the whole of this second 

 group, we have left only the true Arctic mammalia — the glutton, 

 the reindeer, the musk-sheep, the pouched marmot, the tail-less hare, 

 and the Lemming — to form provaunt for the lion and his congeners, 

 the Machairodus and the hyaena. But how can we suppose it 

 possible that these carnivora would leave the temperate zone (which, 



^ Sir Charles Lyell says (1863) geologists may freely speculate on the time when 

 the hippopotamus "may have swum in a few summer days from rivers in the south of 

 Spain or France to the Sorame, Thames, or Severn, making timely retreat to the 

 south before the snow and ice set in." But, according to this theory, the natations 

 and peregrinations of our old river-horse must have extended even further north than 

 the Thames, as certain valley gravels at Leeds bear witness. In the discussion above 

 I have not referred to the evidence of a mild condition of things afforded by the 

 presence of Cyrena fluminalis and Utiio littoralis. If the evidence of these shells is 

 to be trusted, however, it would furnish an additional reason why we should reject 

 the "migration" theory, and maintain, as the more probable hypothesis, the alterna- 

 tive explanation suggested by Lyell, "that when the temperature of the river water 

 was congenial to the Cyrena above mentioned, it was also suited to the hippopotamus." 

 (Principles, 10th edit., vol. i., p. 194.) 



