208 AN ANCIENT HAUNT OF THE CERVUS MEGACEROS ; 
Islands Europe presented a condition similar to that of Greenland at 
the present time ; and during the prevalence of this period of extreme 
cold the glacial drift, boulder clay, and stratified sands and gravels, 
were deposited over the whole of Northern Europe, and over North 
America, as far south as the 39th parallel, during prolonged sub- 
mergence under an arctic sea. Then followed the changes of that 
subsequent period, during which the physical geography acquired its 
latest development, and the present continents gradually assumed 
the characteristics fitting them for existing conditions of life. 
Of nearly a hundred species of mammals recognized in the post- 
glacial deposits of Europe, fifty-seven still occupy the same localities ; 
whilst others, such as the reindeer and the musk-sheep have with- 
drawn to northerly areas. A continuous chain of life, however, is 
indicated by the prolongation of about twelve pliocene species into 
the post-glacial fauna of Great Britain. But, along with those, 
numerous new species appear; and changes of an altogether novel 
character are inaugurated by the presence among them of man. 
The revolution wrought in physical geography, in climate, and in 
all the accompanying conditions of life, during the pleistocene age are 
most clearly illustrated by the character and distribution of the 
mammalia, of which fifty-three species are represented in the remains 
found in the gravels and cave deposits. The Hlephas primigenius, or 
mammoth, common both to Europe and America, has become 
extinct in the old world, subsequent to the advent of man. It is still 
an open question whether in the new world man coexisted with the 
mastodon ; but in the eastern hemisphere at least, more than one 
species of proboscidian abounded, and in vast herds overspread the 
northern plains of Europe and Asia. Along with those there were 
three or four species of rhinoceros, a large hippopotamus, and other 
forms of animal life pointing to a condition of things widely differ- 
ing from anything known within the historic period. The herbivora 
included both deer and oxen, some of which still survive in more 
limited northern areas ; and those, along with the mammoth, woolly 
rhinoceros, Irish elk, and reindeer, were preyed upon by numerous 
carnivora, including the extinct cave lion and great cave bear, the 
ursus ferox, or grizzly bear,—now the strongest and most ferocious of 
all the carnivora of the American continent,—and the cave hyzna, 
which has still its living representatives in South Africa. 
