h conical points which exceed this elevation, affords many places
favorable for its resort. On ascending these mountains, the traveller
scarcely fails to meet with this animal, which, from its peculiarities,
is universally known to the inhabitants of these elevated tracts, while
to those of the plains it is as strange to an animal from a foreign
county. In my visits to the mountainous districts, I uniformly met with
it; and, as far as the information of the natives can be relied on, it
is found on all the mountains."[886]

Now, if asked to conjecture how the Mydaus arrived at the elevated
regions of each of these isolated mountains, we might say that, before
the island was peopled by man, by whom their numbers are now thinned,
they may occasionally have multiplied so as to be forced to collect
together and migrate: in which case notwithstanding the slowness of
their motions, some few would succeed in reaching another mountain, some
twenty, or even, perhaps, fifty miles distant; for although the climate
of the hot intervening plains would be unfavourable to them, they might
support it for a time, and would find there abundance of insects on
which they feed. Volcanic eruptions, which, at different times have
covered the summits of some of those lofty cones with sterile sand and
ashes, may have occasionally contributed to force on these migrations.

_Drifting of animals on ice-floes._--The power of the terrestrial
mammalia to cross the sea is very limited, and it was before stated that
the same species is scarcely ever common to districts widely separated
by the ocean. If there be some exceptions to this rule, they generally
admit of explanation; for there are natural means whereby some animals
may be floated across the water, and the sea may in the course of ages
wear a wide passage through a neck of land, leaving individuals of a
species on each side of the new channel. Polar bears are known to have
been frequently drifted on the ice from Greenland to Iceland; they can
also swim to considerable distances, for Captain Parry, on the return of
his ships through Barrow's Straits, met with a bear swimming in the
water about midway between the shores, which were about forty miles
apart, and where no ice was in sight.[887] "Near the east coast of
Greenland," observes Scoresby, "they have been seen on the ice in such
quantities, that they were compared to flocks of sheep on a common; and
they are often found on field-ice, above