Characters.—A flat crest of blackish-brown hair radiating from the top of the head all round and over the forehead; the entire upper surface covered with long loose fur, the hairs grey at their base, and higher up ringed with greyish-green and blackish-brown; the fore-arms, hands, feet, and the basal three-fourths of the tail blackish-brown; the sides of the head and the whole under surface yellowish; the inside of the limbs yellowish-grey; the hair of the terminal part of the tail lighter than the rest, and ringed with yellow; face, bluish-black.
Distribution.—E. Africa; Mitola, at the mouth of the Osi and Tana rivers.
Habits.—This species was found living in the woods on the coast in small troops of from five to six in number.
THE GUENONS. GENUS CERCOPITHECUS.
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 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 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 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.
Group I. Cercopitheci Rhinosticti.