tropic; but in Africa, some baboons range to the southern extremity of
the continent.

But this extreme restriction of the order to almost tropical lands is
only recent. Directly we go back to the Pliocene period of geology,
we find the remains of monkeys in France, and even in England. In the
earlier Miocene, several kinds, some of large size, lived in France,
Germany, and Greece, all more or less closely allied to living forms of
Asia and Africa. About the same period monkeys of the South American
type inhabited the United States. In the remote Eocene period the same
temperate lands were inhabited by lemurs in the East, and by curious
animals believed to be intermediate between lemurs and marmosets in the
West. We know from a variety of other evidence that throughout these
vast periods a mild and almost sub-tropical climate extended over all
Central Europe and parts of North America, while one of a temperate
character prevailed as far north as the Arctic circle. The monkey tribe
then enjoyed a far greater range over the earth, and perhaps filled a
more important place in nature than it does now. Its restriction to the
comparatively narrow limits of the tropics is no doubt mainly due to the
great alteration of climate which occurred at the close of the Tertiary
period, but it may have been aided by the continuous development of
varied forms of mammalian life better fitted for the contrasted seasons
and deciduous vegetation of the north temperate regions. The more
extensive area formerly inhabited by the monkey tribe, would have
favored their development into a number of divergent forms, in distant
regions, and adapted to distinct modes of life. As these retreated
southward and became concentrated in a more limited area, such as were
able to maintain themselves became mingled together as we now find them,
the ancient and lowly marmosets and lemurs subsisting side by side with
the more recent and more highly developed howlers and anthropoid apes.