Fig. 272.—Hoolock. Hylobates hoolock. × 1⁄6.
The Gibbons range through south-eastern Asia from Assam and Burmah to Hainan. The number of species is a little doubtful. It is clear that in the first place we may distinguish the Siamang, H. syndactylus, which indeed some regard as a separate genus. It is mainly to be defined by the syndactylous character of the second and third toes; they are united by skin as far as the last joint. The Hainan species, H. hainanus, is probably distinct, and the following names have been given to various other species or races, viz. H. agilis, H. leuciscus, H. leucogenys, H. lar, H. hoolock. These animals can walk erect; and when they do so, the big toe is separated as in unsophisticated or at least unbooted man. The voice is well known to be loud,
and it is a curious fact that the Siamang, which has a large laryngeal pouch, is not excelled in this respect by species in which this sac is not developed.
Fig. 273.—Cerebrum of the Gibbon (Hylobates). (Lateral aspect.) c.c′, c.c″, Anterior and posterior central convolution; fi, interparietal fissure; fr, frontal lobe; f.s, Sylvian fissure; oc, occipital lobe; pa, parietal lobe; s.c, fissure of Rolando; tp, temporal lobe; *, fronto-orbital fissure. (From Wiedersheim's Structure of Man.)
Of Gorillas, genus Gorilla, there is but one species, which must apparently and rather unfortunately be called Gorilla gorilla.
The misfortune is double: in the first place the repetition of the same word as both generic and specific appellation is tiresome to the ears and barbarous in its suggestion; in the second place it is now well known that the "Gorilla" of Hanno, observed by that Carthaginian voyager on an island off the African coast, was not a Gorilla at all as the word is now understood, but probably a Baboon. The external aspect of this great Anthropoid is familiar from many reproductions. The male, as is usual, is larger than the female, and his characters are more pronounced.
The face is naked and black, and the skin generally is deep black, even at birth. The ear is comparatively small, and is adpressed to the side of the head; it is altogether more human in form than that of the Chimpanzee, and this statement applies also to the rudimentary condition of the muscles of the ear, which are more rudimentary than in the Chimpanzee. The nose has an obvious median ridge, and is thus pronounced as an external feature; the nostrils are very wide. The hands and feet are short, thick, and broad; the digits are webbed. In the foot the heel is more apparent than in other Anthropoids. It is not,
however, so marked as in Man, and the phrase "Ex pede Herculem" has been aptly supplemented by "Ex calce hominem." The hair upon the head forms a kind of crest, which can be elevated when the animal is enraged. The neck is thick and short, and the beast has massive shoulders and a broad chest.
