erect posture when on a level surface; and then the arms either hang
down, enabling him 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, while pursued, he has no opportunity of escaping by
climbing.... When he walks in the erect posture, he turns the leg and
foot outward, which occasions him to have a waddling gait and to seem
bow-legged."

Dr. Burrough states of another Gibbon, the Horlack or Hooluk:

"They walk erect; and when placed on the floor, or in an open field,
balance themselves very prettily by raising their hands over their
head and slightly bending the arm at the wrist and elbow, and then run
tolerably fast, rocking from side to side; and, if urged to greater
speed, they let fall their hands to the ground, and assist themselves
forward, rather jumping than running, still keeping the body, however,
nearly erect."

Somewhat different evidence, however, is given by Dr. Winslow Lewis:

"Their only manner of walking was on their posterior or inferior
extremities, the others being raised upward to preserve their
equilibrium, as rope-dancers are assisted by long poles at fairs.
Their progression was not by placing one foot before the other, but by
simultaneously using both, as in jumping." Dr. Salomon Müller also
states that the Gibbons progress upon the ground by short series of
tottering jumps, effected only by the hind limbs, the body being held