ies easily to a single shot, and does not
seem to afford much better sport than so much rabbit shooting.
The others are the great Kadiak bear (_U. middendorfi_); the
grizzly (_U. horribilis_), and the black or true American bear
(_U. americanus_). The extent to which the last three may
be subdivided remains uncertain, but the barren-ground bear
(_U. richardsoni_) is surely a valid species of the grizzly type.
The grizzlies and the big Alaska bears approach more nearly than
_americanus_ to the widespread brown bear (_U. arctos_) of
Europe and Asia, and the hypothesis is reasonable that they originated
from that form or its immediate ancestors, in which case we have the
interesting series of parallel modifications exhibited in the two
continents, for the large bear of Kamtschatka approaches very nearly to
those of Alaska, while further to the south in America, where the
conditions of life more nearly resemble those surrounding _arctos_,
these bears have in the grizzlies retained more of their original form.
Whether or not the large Pleistocene cave bear (_U. spelaeus_) was a
lineal ancestor is questionable, for in its later period, at least, it was
contemporary with the existing European species. The black bear, with its
litter-brother of brown color, seems to be a genuine product of the new
world.

Many differential characters have been pointed out in the skulls and teeth
of bears, and to a less extent, in the claws; but while these undoubtedly
exist, the conclusions to be drawn from them are uncertain, for the
skulls of bears change greatly with age, and the constancy of these
variations, with the values which they should hold in classification,
we do not yet know.

* * * * *

It is not improbable that the reader may leave this brief survey with
the feeling that its admissions of ignorance exceed its affirmations of
certainty, and such is indeed the case, for the law of scientific
validity forbids the statement as fact, of that concerning which the
least element of doubt remains. But the real advance of zoological
knowledge must not thereby be discredited, for it is due to those who
have contributed to it to remember that little more than a generation
ago these problems of life seemed wrapped in hopeless obscurity, and the
methods of investigation which have led to practically all our present
gains, were then but new born, and with every passing year doubts are
dispelled, and theories