monkey attacked a _rhesus_, and I saw its face redden as plainly as
that of a man in a violent passion. In the course of a few minutes,
after the battle, the face of this monkey recovered its natural tint.
At the same time that the face reddened, the naked posterior part of
the body, which is always red, seemed to grow still redder; but I
cannot positively assert that this was the case. When the Mandrill is
in any way excited, the brilliantly coloured, naked parts of the skin
are said to become still more vividly coloured.
With several species of baboons the ridge of the forehead projects much
over the eyes, and is studded with a few long hairs, representing our
eyebrows. These animals are always looking about them, and in order to
look upwards they raise their eyebrows. They have thus, as it would
appear, acquired the habit of frequently moving their eyebrows. However
this may be, many kinds of monkeys, especially the baboons, when
angered or in any way excited, rapidly and incessantly move their
eyebrows up and down, as well as the hairy skin of their
foreheads.[515] As we associate in the case of man the raising and
lowering of the eyebrows with definite states of the mind, the almost
incessant movement of the eyebrows by monkeys gives them a senseless
expression. I once observed a man who had a trick of continually
raising his eyebrows without any corresponding emotion, and this gave
to him a foolish appearance; so it is with some persons who keep the
corners of their mouths a little drawn backwards and upwards, as if by
an incipient smile, though at the time they are not amused or pleased.
A young orang, made jealous by her keeper attending to another monkey,
slightly uncovered her teeth, and, uttering a peevish noise like
_tish-shist_, turned her back on him. Both orangs and chimpanzees, when
a little more angered, protrude their lips greatly, and make a harsh
barking noise. A young female chimpanzee, in a violent passion,
presented a curious resemblance to a child in the same state. She
screamed loudly with widely open mouth, the lips being retracted so
that the teeth were fully exposed. She threw her arms wildly about,
sometimes clasping them over her head. She rolled on the ground,
sometimes on her back, sometimes on her belly, and bit everything
within reach. A young gibbon (_Hylobates syndactylus_) in a passion has
been described[516] as behaving in almost exactly the same manner.
The lips of young orangs and chimpanzees are protruded, sometimes to a
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