AYTLOBATES 149 
FAMILY 4. HYLOBATID/E. 
GENUS I. HYLOBATES. GIBBONS. 
2—2 1—1 2—2 3—3 
I. o-33 C. 7s P. ays M. 3g =3?. 
HYLOBATES Illig., Prodr. Syst. Mamm. et Avium, 1811, p. 67. Type 
Homo lar Linnzus. 
Satyrus Oken, Lehrb. Naturg., 3ter Theil, Zool., 2te Abth., 1816, 
pp. XI, 1225-1227, (nec Meigen 1803 Diptera). 
Laratus Gray, Lond. Med. Repos., XV, 1821, p. 297. 
Cheiron Burnett, Quart. Journ. Scien. Lit. and Art, XXVI, 1828, 
p. 307. 
Brachiopithecus Sénéchal, Dict. Pitt. Hist. Nat., VIII, Pt. II, 
1839, p. 428. (Part.). 
Head small, round; body slender; arms very long, the forearm 
exceeding the arm in length; thumb and great toe widely separated 
from the next digits; great toe well developed, and nearly half as long 
as the foot; callosities present ; cheek pouches and tail absent ; skull has 
large orbits; supraorbital ridges prominent; canines large; cusps of 
molars not forming transverse ridges; last lower molar without pos- 
terior talon; vermiform appendage present; sternum consisting of a 
manubrium and a single bone only; ribs usually seven, but sometimes 
eight pairs. . 
Of all the Anthropoids the Gibbons are farthest removed from 
man. They are well named Hylobates or Tree-walkers, for their lives 
are passed upon trees, through whose branches they move with 
the ease and swiftness of a bird, but are practically helpless on the 
ground, over whose surface they progress awkwardly and with no 
little difficulty, balancing themselves by holding the long arms above 
the head and hastening forwards as rapidly as possible in order to 
maintain an equilibrium. But let one of the long slim hands touch a 
bough of some low tree and how marvellous the change; the struggling 
animal of earth becomes endowed with flying powers, and in many a 
graceful sweep and an amazing accuracy of aim, it passes with in- 
credible speed through the forest, holding its course from bough to 
