In the Dasypygal division the Orangs (genus Pithecus, Geoffr.) manifest, agreeably with their geographical position, the nearest affinities with the Scleropyga, in the length of the upper limbs and the proportionally small size of the hallux: the Chimpanzees (genus Troglodytes, Geoffr.) show the higher position in the proportions of the upper limbs to the trunk, the large size of the hallux, and other characters set forth in the present and former memoirs on the Anthropoid or Dasypygal Apes.
Source: wiktionary