xxxvi Journal of Proceedings. 



fore, although he might advance in his mind, his bodily structure 

 would remain very constant. The fact that the earliest races of men 

 yet traced out present a type similar to man now existing is rather a 

 proof that the human species is immensely more ancient than we 

 hitherto have had any conception. 



With reference to the Glacial Epoch in Geology, Mr. Wallace said it 

 was a subject which for upwards of fifteen years he had thought and 

 wfitten upon. He was glad to say that he did not differ from their 

 good friend Sir Antonio Brady to the extent he believed. He quite 

 agreed that the period of the Mammoth and the earlier Mammalia was 

 a period close upon or within the Glacial Epoch. In point of fact he 

 considered that the time would come when they would find that changes 

 in climatal conditions have been the principal causes in producing the 

 changes of plants and animals on the earth. He believed that the 

 chief agent in inducing these changes of climate was the geographical 

 alterations in the contours of continents by submergence and upheaval 

 in different stages of the earth's history. He had lately been attempting 

 to show in some detail how it was that these changes in Geography 

 did afford us the means of explaining that hitherto insolvable problem 

 — the mild and luxurious vegetation of the Arctic regions during the 

 Miocene and many earlier Geological epochs. It was quite impos- 

 sible to accept in its entirety Mr. Croll's explanation ; but Mr. Wallace 

 believed he had found the solution in Mr. Croll's own theory of Ocean 

 Currents. Mr. Croll maintained that there had been alternate mild 

 and glacial conditions in the northern hemisphere throughout the 

 Tertiary period ; but the objection to this was that all the Geological 

 evidence showed that before the last Glacial Epoch mild climates alone 

 prevailed in the Arctic regions, whether in the Upper or Lower Mio- 

 cene, the Cretaceous, the Jurassic or the Carboniferous period ; — in 

 fact, every Geological Formation in the Arctic Regions, anterior to the 

 Pliocene, furnished evidence of mild, and in no single instance of cold 

 climates. Now Mr. Croll had himself demonstrated the wonderful 

 power of the Gulf Stream in carrying the warmth of the Tropics into 

 North Temperate and Polar Regions. At present this was the only 

 important body of warm water that reached the Arctic Seas, but there 

 was good geological evidence that in earlier ages the great Northern 

 Continents — Europe, Asia, and North America — were not as now solid 

 masses of land, but were broken up and penetrated by arms of the sea 

 which carried other bodies of warm water northward. When this was 

 the case, the formation of ice in the polar seas would be entirely pre- 

 vented ; and when there was no ice the power of the sun during the 

 long day of the polar summer was amply sufficient to support the vege- 

 tation, the remains of which so astonish us in the Arctic Regions. 

 The last Glacial Epoch was undoubtedly produced by the astronomical 

 conditions which have been so well set forth and illustrated by Mr. 



