allowed to drink water, it grows in size. This is also called Black Yuen, and is now likewise difficult to obtain." Those who had an opportunity of observing the specimen that lived in the Zoological Gardens, will recall its extraordinary acrobatic feats, which were performed with marvellous precision and certainty, either with one or with both hands, and yet with the most careless air. It offered a striking contrast to an Orang-utan, which occupied the adjoining cage. This more {166}robust Ape exhibited in its arms equally perfect powers of climbing; but it moved with the greatest circumspection, deliberation, and composure, exhibiting none of the volatile activity so characteristic of the Gibbons; but moving only one pair of its limbs at a time, and only when the other pair had firm hold of some support. VII. THE SIAMANG GIBBON. HYLOBATES SYNDACTYLUS. _Pithecus syndactylus_, Desmar., Mamm., p. 531 (1820). _Hylobates syndactylus_, F. Cuv., Hist. Nat. Mammif., pl. iv. (1821); Is. Geoffr., Cat. Méth. Primates, p. 9 (1851); Bennett, Wanderings in N. S. Wales, ii., p. 151 (1834); Martin, Mammif. An., p. 420 (1841); Flower, Nat. Hist. Rev., 1863, p. 279 (cum fig.); Giebel, Z. Ges. Nat., p. 186 (1866); Schl., Mus. Pays-Bas, vii., p. 22 (1876); Anderson, Zool. Res. Exped. Yun-nan, p. 10 (1878; with full synonymy). _Simia syndactylus_, Raffl., Tr. Linn. Soc., xiii., p. 241 (1822). _Siamanga syndactyla_, Gray, Cat. Monkeys Brit. Mus., p. 9 (1870), id., _op. cit._, p. 9 (1870); H. O. Forbes, Nat. Wand. East. Arch., p. 129 (1885). (_Plate XXXVIII._) CHARACTERS.--This is the largest species of the genus, measuring more than three feet; it is stouter than _H. hoolock_, and its hair is entirely glossy black, having no white hairs anywhere; the face is black, as is also the distensible skin of the large bare patch on the throat, which overlies its great laryngeal pouch. The second and middle toes are united by a web as far as the last joint. The hair on the arms and fore-arms converges towards the elbow. The skulls in most of the species of this genus closely resemble each other; that of the Siamang is distinguished by its larger size, and in having the supra-orbital ridges more developed, while the occipital region is more truncated, and there is at the symphysis of the lower jaw a true, though slight, chin. PLATE XXXVIII. [Illustration: THE SIAMANG GIBBON.]