d in that year!

The "migration of the squirrels" is still an unexplained fact. It is
among the grey squirrels it takes place; hence the name given to that
species, _Sciurus migratorius_. There is no regularity about these
migrations, and their motive is not known. Immense bands of the
squirrels are observed in a particular neighbourhood, proceeding through
the woods or across tracts of open ground, all in one direction.
Nothing stays their course. Narrow streams and broad rivers are crossed
by them by swimming, and many are drowned in the attempt.

Under ordinary circumstances, these little creatures are as much afraid
of water as cats, yet when moving along their track of migration they
plunge boldly into a river, without calculating whether they will ever
reach the other side. When found upon the opposite bank, they are often
so tired with the effort, that one may overtake them with a stick; and
thousands are killed in this way when a migration has been discovered.

It is stated that they roll pieces of dry wood, or bark, into the water,
and, seating themselves on these, are wafted across, their tails
supplying them with a sail: of course this account must be held as
apocryphal.

But the question is, what motive impels them to undertake these long and
perilous wanderings, from which it is thought they never return to their
original place of abode? It cannot be the search of food, nor the
desire to change from a colder to a warmer climate. The direction of
the wanderings forbids us to receive either of these as the correct
reason. No light has been yet thrown upon this curious habit. It would
seem as if some strange instinct propelled them, but for what purpose,
and to what end, no one can tell.

CHAPTER TWENTY.

TREEING A BEAR.

The doctor was the only one not taking part in the conversation. Even
the rude guides listened. All that related to game interested them,
even the scientific details given by the hunter-naturalist. The doctor
had ridden on in front of us. Some one remarked that he wanted water to
mix with the contents of his flask, and was therefore searching for a
stream. Be this as it may, he was seen suddenly to jerk his spare horse
about, and spur back to us, his countenance exhibiting symptoms of
surprise and alarm.

"What is it, doctor?" inquired one.

"He has seen Indians," remarked another.

"A bear--a bear!" cried the doctor, panting for breath; "a grizzly bear!
a terri