shall
find the miniature deer; there certainly existed ancestral wolves and
foxes of similarly small proportions. You have all read your Darwin
carefully enough to know that neither camels, horses, nor deer would
have evolved as they did except for the stimulus given to their limb and
speed development by the contemporaneous evolution of their enemies in
the dog family.

THE MIDDLE STAGE OF EVOLUTION.

A million and a half years later these same animals had attained a very
considerable size; the western country had become transformed by the
elevation of the plateaux into dry, grass-bearing uplands, where both
horses and deer of peculiarly American types were grazing. We have
recently secured some fresh light on the evolution of the American
deer. Besides the _Palaeryx_, which may be related to the true
American deer _Odocoileus_, we have found the complete skeleton of
a small animal named _Merycodus_, nineteen inches high, possessed
of a complete set of delicate antlers with the characteristic burr at
the base indicating the annual shedding of the horn, and a general
structure of skeleton which suggests our so-called pronghorn antelope,
_Antilocapra_, rather than our true American deer, _Odocoileus_.
This was in all probability a distinctively American type.
Its remains have been found in eastern Colorado in the geological
age known as Middle Miocene, which is estimated (_sub rosa_, like
all our other geological estimates), at about a million and a half years
of age. Our first thought as we study this small, strikingly graceful
animal, is wonder that such a high degree of specialization and
perfection was reached at so early a period; our second thought is the
reverence for age sentiment.

THE AFRICAN PERIOD IN AMERICA.

The conditions of environment were different from what they were before
or what they are now. These animals flourished during the period in
which western America must have closely resembled the eastern and
central portions of Africa at the present time.

This inference is drawn from the fact that the predominant fauna of
America in the Middle and Upper Miocene Age and in the Pliocene was
closely analogous to the still extant fauna of Africa. It is true we had
no real antelopes in this country, in fact none of the bovines, and no
giraffes; but there was a camel which my colleague Matthew has surnamed
the "giraffe camel," extraordinarily similar to the giraffe. There were
no hippopotami, no hyraces