Sir Henry H. Howorth—Geology of the Arctic Lands. 499 
clusion, namely, that if there has ever been a so-called Glacial 
period in the Arctic regions it is now. That the present period is 
the one period in their history when the reign of ice and snow has 
been dominant, that, so far as we can make out, their climate has 
been becoming more and more severe in historic times, and that in 
the Pleistocene age, so far as we have evidence, the climate of the 
Polar area was more and not less temperate than now. All this is 
completely at one with the more recent speculations of the zoologist, 
who sees in the Polar area the centre and focus of a geographical 
region, in which the animal forms are alike in all meridians, namely, 
the so-called circumpolar area, and who further argues that the two 
provinces which are known as Palearctic and Nearctic, in so far as 
they are differentiated from each other, have become so very recently, 
and that in all probability they constituted in Pleistocene times 
one continuous and homogeneous district with the Arctic lands, a 
province marked by a similar fauna and flora. This again is con- 
firmed by such facts as the occurrence of the great sea-cows which 
Steller discovered in Behring’s Island, in a latitude far away from all 
their relatives and congeners. They are essentially animals which 
thrive under temperate or sub-tropical conditions, and this colony, 
so lately occurring in the North Pacific, seems to point very clearly 
to the climate of that region having been recently milder. The 
same conclusion as I have previously argued seems to follow, if 
we are to find any rational explanation of the problem of the 
northern migratory birds—birds which pass their summer in the 
Arctic and sub-Arctic lands and are scattered far and wide during 
the winter. Their types are so essentially northern that we can 
hardly doubt that at no remote time they were living all the year 
round in their present breeding quarters in Greenland and Spitz- 
bergen, no less than in Northern Siberia. The cold which has 
deprived these birds of any suitable food and resting-place in the 
winter is the cold now prevailing, and not a much more severe cold 
dating from the Pleistocene age; and in explaining the difficulties 
and paradoxes of the distribution of animal life in the northern 
hemisphere, we must, as in the case of the vegetable life, invoke not 
a portentous period of ice in the last age of the world, but 
an increasing cold from the time of the Mammoth onwards and 
culminating in our own day. If this be so we may well advance 
another step and enquire what was the cause which has chiefly 
operated to bring about this result. Since it is one which is most 
potent at this moment, and which has been growing in intensity in 
historic times, it ought to be explained without appealing to trans- 
cendental causes, which are so easy to invoke, however hard they 
may be to justify, when we are dealing with a long-departed past. 
In regard to Siberia, I have in previous papers endeavoured to 
offer an explanation of the problem as partially explained by the 
upheaval of the Tibetan plateau, and of the Himalayas and Altai, as 
Humboldt long ago argued, and partly by the stoppage of Behring 
Straits, which prevented the Polar current from reducing the 
temperature of Kamschatka and the Sea of Okhotsk. 
