Richard Lydekker

“ Between the typical West African chimpanzee and the gorilla (q.v.) there is no difficulty in drawing a distinction; the difficulty comes in when we have to deal with the aberrant races, or species, of chimpanzee, some of which are so gorilla-like that it is by no means easy to determine to which group they really pertain. In height the adult male chimpanzee of the typical form does not exceed 5 ft., and the colour of the hair is a full black, while the skin, especially that of the face, is light-coloured ”

“ The head is rounded and short, without prominent beetling ridges above the eyes, or a strong crest along the middle line of the back of the skull; and the tusks of the old males are of no very great length and prominence. ”

“ Gentleness and docility are specially characteristic of the species, even when full-grown; while in the native state its habits are thoroughly arboreal.
In central Africa the chimpanzees assume more or less marked gorilla-like traits. The first of these aberrant types is Schweinfurth’s chimpanzee (Anthropopithecus troglodytes schweinfurthi) , which inhabits the Niam-Niam country, and, although evidently belonging to the same species as the typical race, exhibits certain gorilla-like features. ”