Two gibbons are climbing a tree while a chimpanzee and two orang-utans are playing with thr branches of the tree on the ground. Coloured etching by S. Milne.

Licence: Public Domain Mark

Credit: Two gibbons are climbing a tree while a chimpanzee and two orang-utans are playing with thr branches of the tree on the ground. Coloured etching by S. Milne. Wellcome Collection. Source: Wellcome Collection.