we know nothing, for the only related forms which have yet come to light
are of no great antiquity, being confined to the Pleistocene of Europe
as far south as France, and are not distinguishable from existing
species. Until recently it has been supposed that one species was found
in northern Europe and Asia, and two others, a northern and a southern,
in North America, but lately the last two have been subdivided, and the
present practice is to regard the Scandinavian reindeer (_Rangifer
tarandus_) as the type, with eight or nine other species or
sub-species, consisting of the two longest known American forms, the
northern, or barren-ground caribou (_R. arcticus_); the southern, or
woodland (_R. caribou_); the three inhabiting respectively
Spitzbergen, Greenland and Newfoundland, and still more lately four more
from British Columbia and Alaska. The differences between these are not
very profound, but they seem on the whole to represent two types: the
barren-ground, small of size, with long, slender antlers but little
palmated; and the woodland, larger, with shorter and more massive
antlers, usually with broad palms. There is some reason to believe that
both these types lived in Europe during the interglacial period, the
first-named being probably the earlier and confined to western Europe,
while the other extended into Asia. The present reindeer of Greenland
and Spitzbergen seem to agree most closely with the barren-ground, while
the southern forms are nearest to the woodland, and these are said to
also resemble the reindeer of Siberia. It is, therefore, not an
improbable conjecture that there were two migrations into America, one
of the barren-ground type from western Europe, by way of the Spitzbergen
land connection, and the other of the woodland, from Siberia, by way of
Alaska.

Little more can be said, perhaps even less, of the other circumpolar
genus, _Alces_, known in America as "moose," and across the