The teeth are twelve in each jaw; four incisors, two canine, and six molares. In the upper jaw, the canine were placed widely apart from the last incisor, giving an appearance as if a tooth was deficient: this circumstance did not occur in the lower jaw. The teeth were in a very bad condition. In colour, the animal was of a beautiful jet black, being covered with coarse hair over the whole body. The face has no hair, except on the sides, as whiskers, and the hair stands forward from the forehead over the eyes: there is very little beard. The skin of the face is black; the arms are very long, the radius and ulna being of greater length than the os humeri: the hair on the arms runs in one direction, viz. downwards; that on the fore-arm, upwards; the hands are long and narrow, fingers long and tapering; thumb short, not reaching farther than the first joint of the fore-finger; the palms of the hands and soles of the feet are bare and black; the legs are short, in proportion to the arms and body; the feet are long, prehensile, and, when the animal is in a sitting posture, are turned inwards, and the toes are usually bent. The first and second toes are united (except at the last joint) by a membrane. From this circumstance, the animal has derived its specific name. He invariably walks in the erect posture, when on a level surface; and then the arms either hang down, enabling him sometimes to assist himself with his knuckles; or, what is more usual, he keeps his arms uplifted, in nearly an erect position, with the hands pendent, ready to seize a rope, and climb up on the approach of danger, or on the obtrusion of strangers. He walks rather quick in the erect posture, but with a waddling gait, and is soon run down if, whilst pursued, he has no opportunity of escaping by climbing. On the foot are five toes, the great toe being placed like the thumb of the hand: the form of the foot is somewhat similar to that of the hand, having an equal prehensile power; the great toe has a capability of much extension outwards, which enlarges the surface of the foot when the animal walks. The toes are short; the great toe is the longest. The eyes are close together, with the irides of a hazel colour; the upper eyelids have lashes, the lower have none. The nose is confluent with the face, except at the nostrils, which are a little elevated. The mouth large, ears small, resembling the human, except in being deficient in the pendent lobe. He has nails on the fingers and toes, and has hard tubercles on the tuberosities of the ischium, but is destitute of a tail or even the rudiment of one.