_Cercopithecus_, Erxleben, Syst. Regn. Anim., p. 22 (1777).
The genus _Cercopithecus_ includes a larger number of species than any
other of the _Anthropoidea_. Its members are {42}characterised by their
rather round head, slender but muscular bodies, narrow loins, and long hind
limbs. Their tail is long, though shorter than in the genera next to be
described, viz., the Langurs and the Guerezas. Their face is short, the
muzzle less elongated, the cheek-pouches larger than in the Macaques. The
nose is not prominent, and the nostrils are approximated, while whiskers
are generally developed, as well as a longer or shorter beard. Their
callosities are less extensive than in the Macaques. They have elongated
hands with fingers united by a web at their bases; their thumbs, though
distinct, being less developed in comparison than their great-toes. The fur
is thick and soft, and in most of the species is ringed with differently
and often brilliantly coloured bars.
The _Cercopitheci_ have the skull depressed, presenting no very distinct
brow, for its superciliary ridges are less prominent and angular, and their
outer margin less projecting in comparison with those of the skulls in the
genera already described. The orbits are considerably approximated. Their
molar teeth are strongly cusped, and the posterior lower molar has only
four cusps, and not five, as in the Macaques; but as in these animals, the
two front cusps are united together by a transverse ridge, and the two hind
ones are united together.
The Guenons are entirely confined to the African continent, where they
range from the Gambia to the Congo, and from Abyssinia to the Zambesi; but
the different species are each confined to small restricted areas. Being
essentially arboreal, they live entirely in the forest regions, herding
together in large troops. They can move from tree to tree with great
rapidity, and can climb even on vertical surfaces with surprising
quickness. They are abrupt and energetic in their movements, restless, and
noisy, incessantly chattering and {43}making grimaces. The latter habit is
so characteristic of them that they have obtained from it the name of
_Guenon_, by which they are now so generally known, bestowed on them by the
French. Their food consists of leaves, birds' eggs, and honey, but
pre-eminently of fruits, while they are especially destructive to the ripe
grain-fields of the natives near the woods in which they live. They feed
voraciously, and carry off all that their cheek-pouches can hold, even
after they are satisfied, or if they are called off by the warning cry of
the sentinel, who is said to be always placed on guard on some point of
'vantage when the troop is busy with its depredations. The Guenons are not
only restless, but very inquisitive; they are, therefore, when young, very
easily tamed, and as a consequence they are frequently to be seen as
performers in circuses and exhibitions. When aged they are unreliable in
temper, and often very ill-dispositioned. They are said, also, to repel
with missiles any intruders into the region in which they are established
in any numbers.
The known species--numbering about forty--have for the purposes of
description and easy subsequent discrimination, been arranged into groups
(based on a few of their more or less prominent characters) by different
zoologists. Of these M. Isidore Geoffroy St. Hilaire, of Paris, and
Professor Schlegel, of Leyden, may be specially mentioned; the arrangement
of the latter forming a very convenient key for the determination of the
species. Among the zoologists who have more recently revised this genus is
the well-known Secretary of the Zoological Society of London, Dr. P. L.
Sclater, who has to some extent followed and improved upon Professor
Schlegel's arrangement of the genus. In the present review, therefore, of
the numerous species of this genus, the six groups {44}suggested by Dr.
Sclater have been adopted. These are (I.) The Nose-spotted
Guenons--_Cercopitheci rhinosticti_; (II.) The Green Guenons--_C.
chloronoti_; (III.) The Rufous-backed Guenons--_C. erythronoti_; (IV.) The
Black-limbed Guenons--_C. melanochiri_; (V.) The Tufted-eared Guenons--_C.
auriculati_; (VI.) The Bearded Guenons--_C. barbati_; and lastly, The
Three-cusped Guenons--_C. trituberculati_.