When walking on the ground the Hoolock rests on its hind feet alone, with the sole flat on the ground and the great-toe widely separated from the other digits. "They walk erect," writes Dr. Borrough, "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 elbows, 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." VI. THE HAINAN GIBBON. HYLOBATES HAINANUS. _? Hylobates pileatus_, Swinhoe, P. Z. S., 1870, p. 224 (nec Gray). _Hylobates hainanus_, Thomas, Ann. & Mag. Nat. Hist. (6), ix., p. 145 (1892). CHARACTERS.--Very closely related to _H. hoolock_, but differs by the entire absence of the white superciliary streak, the animal being jet black all over. DISTRIBUTION.--The island of Hainan. HABITS.--This species has not been seen alive in its native haunts by any European naturalist. Consul Swinhoe made many efforts to obtain a living specimen in the island of Hainan, but was unsuccessful. "I never ceased," he says, "to enquire after it. Every one knew that such an animal did exist, and many had seen it; but they all spoke of the great difficulty of keeping it alive. At Taipingsze (Central Hainan) the wonderful stories that were told about it showed that the Yuen was not often seen there. The magistrate of that district assured me, {165}with a serious face, that it had the power of drawing into its body its long arm-bones, and that when it drew in one arm, it pushed out the other to such an extraordinary length, that he believed the two bones united in the body; and he said that the bones of the arm were used for chop-sticks." Mr. Swinhoe, however, published, in 1870, some curious extracts from the Chinese gazetteer of the Kiung-shan district of Hainan, which with little doubt relate to this interesting animal, of which skins have, since he wrote, been received at the British Museum, while a young individual lived for some months in 1893 in the Zoological Gardens of London, where it attracted much attention. The gazetteer says as follows: "Yuen: male black, female white; like a Macaque but larger, with the two fore-arms exceedingly long. Climbs to tree-tops and runs among them backwards and forwards with great agility. If it falls to the ground, it remains there like a log. Its delight is in scaling trees, as it cannot walk on the ground. Those desiring to rear it in confinement should keep it among trees; for the exhalations of the earth affect it with diarrhoea, causing death; a sure remedy for this, however, may be found in a draught made of the syrup of fried Foo-tsze (seeds of _Abrus precatorius_, Linn.)." The gazetteer then continues: "Hainan has also the Rock Yuen. It is small, about the bigness of one's fist. If