The American monkeys consist of two chief families,--the Cebidae, and
the Midas or Marmosets--which are again separated into thirteen genera,
consisting of about eighty-six species, greatly diversified among
themselves. In America neither Pithecidae or Lemurs are found: they
exclusively inhabit the Old World.
The Cebidae have thirty-six teeth; the Marmosets possess but thirty-two:
three of them, however, are pre-molar, as are three of those of the
Cebidae, thus distinguishing them both from all the forms of the Old
World.
The Marmosets are a low type of apes--their brain being smooth, and they
having claws instead of nails; but from their intelligent-looking
countenances, and their gentle, playful disposition, they appear to have
as much sense as the larger apes.
The American monkeys differ greatly in size and form. The largest--the
savage black howler--is nearly two feet and a half in length of trunk;
while the beautiful timid marmoset is so small that it may be inclosed
in the two hands. Some have tails twice the length of their bodies; the
caudal appendages of others appear to have been docked, or are
altogether absent. The long tails of some are prehensile, and have a
smooth surface, which enables them to employ it as a fifth hand; others
are covered with thick bushy hair, and are employed apparently only in
balancing the animal. When night comes they roll themselves into a
ball, huddled together as close as may be, to keep themselves warm.
Sometimes it happens that a few little monkeys have not been alert
enough to get into the ball, and are left shivering outside. They keep
up a pitiful howling the whole night through.
One family--the Marmosets--have, as has been remarked, claws instead of
nails. Others are covered with short, coarse hair; while others, again,
have coats of a long, soft silky texture.
Some sport among the branches, seeking their food in the daytime;
others, again, only come forth from the hollows of trees, where they
have their beds during the night season--their eyes being formed, like
those of owls, incapable of meeting the glare of day.
It is remarkable that the smallest of all--the Hapali pygmaeus,
measuring only seven inches in length of body--is among the most widely
dispersed, having found its way into Mexico: the only monkey known to
have wandered far from the great river-plain.
All the monkeys of the New World are arborial; as, indeed, are many of
the animals which, in other parts of the world, live entirely on the
ground. They are mostly furnished with long, prehensile tails. Some
have the under part of the extremity perfectly smooth, so as to serve
the purpose of a fifth hand, by which the creatures can swing themselves
from bough to bough, and hold on securely while their four hands are
actively employed. On passing through an Amazonian forest, sometimes
the branches of the trees are seen alive with active little creatures
swinging backwards and forwards, climbing up the sipos with the agility
of seamen on the rigging of a ship, scampering along the boughs, playing
all sorts of antics, or engaged in plucking the juicy fruit or hard nuts
to be found in ample abundance, even on the tallest monarchs of the
woods.