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POPULAR SCIENCE REVIEW. 
We are carried back in thought to days when the Scottish, 
English, and Welsh highlands were bound in an icy raiment ; 
when large glaciers descended from the mountain flanks into the 
valleys, where the reindeer, the musk ox, the glutton, and the 
arctic fox found a congenial home, and where also the animals 
of warmer climes were constant visitors: days when England 
was united to Europe, and even the hippopotamus could find its 
way, unhindered by ocean barriers, into the rivers of Yorkshire. 
We may perhaps picture to ourselves conditions somewhat like 
those yet prevailing on the western coast of South America, 
where the glacier descends into plains of almost tropical heat ; 
and we can understand how, under such circumstances, the 
severity of an arctic winter would force the animals of the 
northern regions to migrate even as far south as the Pyrenees, 
whilst the returning heat would tempt snch animals as the lion, 
the leopard, the hyaena, and the hippopotamus as far to the 
north as central England. We thus find commingled in one 
common grave, bones in a perfectly similar state of preservation, 
evidently lying where they were first deposited — a clear proof of 
contemporaneity of the representatives of faunas which are now 
so widely separated. Strangely different must have been the 
England of those days. Through the centre of that region now 
occupied by the German Ocean flowed a great river, rising far 
south in the Alps, and receiving among its tributaries the 
Thames and the Humber ; from its banks probably stretched 
extensive forests and grassy plains, whilst on the other side of 
England similar plains and forest tracts occupied what is now 
sea. Through this country the various animals we have spoken 
of all wandered at will — deer and oxen, and horses, rhinoceroses, 
and elephants, and the savage carnivora ; whilst amongst them 
Palaeolithic man hunted and fished, and fought for his life. 
Gradually the conditions of the country changed, may be after 
a period of intense cold, accompanied by physical change, 
during which the Pleistocene men and animals gradually passed 
away, or migrated ; a more genial climate prevailed, and with it 
came also a more civilized race of men, the men of the Neolithic 
period, bringing with them domesticated animals and the 
appliances of a higher culture. Age after age has thus passed 
by, and tribe after tribe has pushed on from far distant homes 
to people new lands, and the newcomers have even displaced the 
earlier ones. Civilization has replaced little by little the rude 
contrivances of old by the varied implements which subserve 
man’s many wants in these more artificial days. The rough 
tools and weapons of stone, bone, or horn gave place to others 
of bronze, and then of iron. The cave was forsaken for the hut, 
in its turn to be left for the house of brick or stone ; the wild 
hunter, fisherman, and shepherd has been followed by the civilized 
