The ankle (_tarsus_) does not exceed one third of the length of the foot. The stomach is simple, or but very slightly sacculated, in those genera which possess cheek-pouches; but is tripartite--the middle compartment being sacculated--in those that have not store-pockets in their mouths, "a groove with raised edges leading from the gullet-entrance to this middle compartment." The intestine has a cæcum, or blind diverticulum. "When laryngeal air-sacs are developed, they are formed by a single sac, with a median aperture--immediately beneath the epiglottis. This median air-sac is very large, extending down {252}over the front of the neck, and sending [in some genera] processes into the _axillæ_" or arm-pits. (_Huxley._) The main brain (or cerebrum) covers the cerebellum in all the members of the _Cercopithecidæ_; and in them the principal convolutions and fissures found in the human brain are more or less developed. The family _Cercopithecidæ_ includes all the Old World Monkeys except the Anthropoid or true Apes, and Man, these latter constituting the two remaining families of the _Anthropoidea_, namely _Simiidæ_ and _Hominidæ_. The _Cercopithecidæ_ have been again divided into two Sub-families, the _Cercopithecinæ_ and the _Semnopithecinæ_. The first contains the Baboons (_Cynocephalus_), the Gelada Baboons (_Theropithecus_), the Mangabeys (_Cercocebus_) and the Guenons (_Cercopithecus_), all of which inhabit the African continent; and likewise the Black Apes (_Cynopithecus_) from Celebes, and the Macaques (_Macacus_), which are almost exclusively confined to the Asiatic continent. In the second Sub-family are included the Nosed-Monkeys (_Nasalis_) of Borneo; the Langurs (_Semnopithecus_) of India, Malaizia, and the Sunda Islands; and the Guerezas (_Colobus_) of Africa. THE BABOONS, MANGABEYS, AND MACAQUES. SUB-FAMILY CERCOPITHECINÆ. This Sub-family is characterised by the presence, in all its members, of cheek-pouches, and a simple stomach. The tail is variable in length, being long or externally invisible. The callosities on the ischiatic bones are large; in many species they become very turgescent at certain seasons, the enlargement extending sometimes to the tail. The hues of the skin on and round the face also become more vivid periodically. {253}Many of the species of this Sub-family are arboreal; some, however, are found only in barren rocky regions; others in low jungle in the neighbourhood of villages, water-tanks, and cultivated patches. Fruits and insects form their principal diet. THE BABOONS. GENUS PAPIO. _Papio_, Erxleb., Syst. Regne Anim., p. 15 (1777). _Cynocephalus_, Lacép., Mem. de l'Inst. iii., p. 490 (1801). Type, _P. sphinx_ (Geoffr.).