Gibbons, which are very common in this part of China, are a small species of tailless ape, thoroughly arboreal in their habits. They make the woods sound with unearthly cries at night, and are unsurpassed in agility and so swift in movement as to be able to catch flying birds with their paws.

The gibbons are an Indo-Malayan group of monkeylike anthropoids with small, long-nosed faces, and arms so long that when the gibbon stands erect the fingers touch the ground. By means of these long arms they swing themselves through the tree tops with astonishing speed, and are adept at climbing and leaping about the mountain slopes that are their favorite resorts. All the gibbons are noted for their far-carrying voices, and often a band will utter weird howls in chorus answered by another band, so that the forest is filled with indescribable noises. The largest is the jet black, Sumatran "siamang," three feet tall.