refore, outside the range of controversy in science; we are concerned
only to retrace the stages of that evolution, and the agencies which
controlled it. Here, unfortunately, the geological record gives us
little aid. Tree-dwelling animals are amongst the least likely to
be buried in deposits which may preserve their bones for ages. The
distribution of femur and ape remains shows that the order of the
Primates has been widespread and numerous since the middle of the
Tertiary Era, yet singularly few remains of the various families have
been preserved.

Hence the origin of the Primates is obscure. They are first foreshadowed
in certain femur-like forms of the Eocene period, which are said in some
cases (Adapis) to combine the characters of pachyderms and femurs, and
in others (Anaptomorphus) to unite the features of Insectivores and
femurs. Perhaps the more common opinion is that they were evolved from
a branch of the Insectivores, but the evidence is too slender to justify
an opinion. It was an age when the primitive placental mammals were just
beginning to diverge from each other, and had still many features in
common. For the present all we can say is that in the earliest spread
of the patriarchal mammal race one branch adopted arboreal life, and
evolved in the direction of the femurs and the apes. The generally
arboreal character of the Primates justifies this conclusion.

In the Miocene period we find a great expansion of the monkeys. These in
turn enter the scene quite suddenly, and the authorities are reduced to
uncertain and contradictory conjectures as to their origin. Some think
that they develop not from the femurs, but along an independent line
from the Insectivores, or other ancestors of the Primates. We will not
linger over these early monkeys, nor engage upon the hopeless task of
tracing their gradual ramification into the numerous families of the
present age. It is clear only that they soon divided into two main
streams, one of which spread into the monkeys of America and the other
into the monkeys of the Old World. There are important anatomical
differences between the two. The monkeys remained in Central and
Southern Europe until near the end of the Tertiary. Gradually we
perceive that the advancing cold is driving them further south, and
the monkeys of Gibraltar to-day are the diminished remnant of the great
family that had previously wandered as far as Britain and France.

A third wave, also spreadin