blackish tint beneath the eyes, with the upper lip of a delicate blue,
clothed on the lower edge with a thin black moustache; the whiskers are
orange-coloured, with the upper part black, forming a band which
extends backwards to the ears, the latter being clothed with whitish
hairs. In the Zoological Society s Gardens I have often overheard
visitors admiring the beauty of another monkey, deservedly called
Cercopithecus diana (Fig. 78); the general colour of the fur is grey;
the chest and inner surface of the forelegs are white; a large
triangular defined space on the hinder part of the back is rich
chestnut; in the male the inner sides of the thighs and the abdomen are
delicate fawn-coloured, and the top of the head is black; the face and
ears are intensely black, contrasting finely with a white transverse
crest over the eyebrows and a long white peaked beard, of which the
basal portion is black. (47. I have seen most of the above monkeys in
the Zoological Society s Gardens. The description of the Semnopithecus
nemaeus is taken from Mr. W.C. Martin s Natural History of Mammalia,
1841, p. 460; see also pp. 475, 523.)
In these and many other monkeys, the beauty and singular arrangement of
their colours, and still more the diversified and elegant arrangement
of the crests and tufts of hair on their heads, force the conviction on
my mind that these characters have been acquired through sexual
selection exclusively as ornaments.
A SUMMARY.
The law of battle for the possession of the female appears to prevail
throughout the whole great class of mammals. Most naturalists will
admit that the greater size, strength, courage, and pugnacity of the
male, his special weapons of offence, as well as his special means of
defence, have been acquired or modified through that form of selection
which I have called sexual. This does not depend on any superiority in
the general struggle for life, but on certain individuals of one sex,
generally the male, being successful in conquering other males, and
leaving a larger number of offspring to inherit their superiority than
do the less successful males.
There is another and more peaceful kind of contest, in which the males
endeavour to excite or allure the females by various charms. This is
probably carried on in some cases by the powerful odours emitted by the
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