_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.