A Hand-book to the Primates, Volume 2 (of 2)

by Henry O. Forbes

The food of the Semnopithecinæ—of which they consume a large bulk at a time—consists chiefly of leaves and young shoots of trees. For this purpose their sacculated stomach forms a necessary receptacle and store for their food during their hasty collection of it.

The Sub-family practically consists of but two genera—Colobus and Semnopithecus. One species, forming a third genus (Nasalis), is closely related to the latter. The Colobi are confined to Africa, and the Semnopitheci—of which there are a large number of species—inhabit the mainland of India, the Malayan Peninsula, and the neighbouring Archipelago as far east only as Wallace's line, which runs between the islands of Bali and Lombock, and northwards to the east of Borneo.

THE GUEREZAS. GENUS COLOBUS.

Colobus, Illiger, Prodr. Syst. Mamm., p. 69 (1811).

The Guerezas are a group of Monkeys entirely confined to the African continent. The character which especially distinguishes them from the Langurs, which (with the exception of the monotypic Nosed Monkeys of Borneo) form the remaining members of the Sub-family, is the condition of their thumbs. In these animals the thumb is practically absent, being either quite invisible externally, or presenting merely a tubercle, which may or may not have a nail upon it. The hands are long and straight, and the nails of the fingers are compressed and pointed. In these animals the body is slender, though somewhat more robust than in Semnopithecus. The face is naked or covered only with a sparse and soft down, the nostrils being separated by a wide division. From this feature these Monkeys have been described by some naturalists as Platyrrhine or Megarrhine. The ears are rounded above, with the posterior upper angle pointed or square, and generally naked, but they are sometimes haired or tufted inside. All the Guerezas have a specially elongated tail, which is often tufted at the end. Their fur is long and slightly harsher than that of the Langurs, but it is not ringed with differently coloured bands. Their callosities are large and naked.

The skulls in Colobus and Semnopithecus are very similar in shape; but those of the former are often longer, larger, and have a greater cranial capacity than those of the Semnopitheci. The muzzle is short, and the hind molar of the lower jaw has five tubercles. The thumbs, even when apparently absent, are represented under the skin by a single bone, the ungual phalanx, which articulates directly with the metacarpal bone. The Guerezas differ from the Guenons in having very small cheek-pouches and no laryngeal sacs. Their stomach is transversely sacculated like the upper part of the great intestine in the human body.

The Guerezas, which represent the Langurs in Asia, inhabit Tropical Africa, ranging from Abyssinia and Zanzibar in the east, to Senegambia, Angola, and perhaps the island of Fernando Po on the west—between about 15° N. lat. on the eastern and 12° on the western side, to 10° S. lat. They live in small troops in the forest, both on the plains and on the mountains, their food consisting of fruits, but principally of leaves, which they eat in large quantities, as the peculiar and capacious form of their storehouse-like stomach, in lieu of cheek-pouches, would indicate.

Of their habits in their native state very little indeed is known, for they prefer to keep to the great trees of the forests far from human habitation; while, owing to their very delicate constitution enabling them to resist for a very short period the rigours of a climate cooler than their own, scarcely anything has been learnt of them in captivity. The beautiful skins of many of the species form a considerable article of commerce in Europe and America to adorn the costumes of the most refined and cultivated ladies, who vie for their possession with the semi-nude and barbarous warriors of Equatorial Africa, by whom they are also used as ornaments for their persons and for decorations for their weapons.

I. VAN BENEDEN'S GUEREZA. COLOBUS VERUS.

Colobus verus, Van Bened., Bull. Acad. Sc., Brux., v., p. 344, pl. 13 (1838); Less., Spec. Mamm., p. 70 (1840); Martin, Mammif. Anim., p. 503 (1841); Geoffr., Cat. Méth. Primates, p. 17, no. 4 (1851); Wagner, in Schreber, Säugeth. Suppl., v., p. 37 (1855); Gray, P. Z. S., 1868, p. 182; Schl. Mus. Pays-Bas, vii., p. 28 (1876).