THE UAKARI MONKEYS. yas 
jaw, is not borne out by their internal anatomy. The caudate 
lobe of the liver is very large. This character distinguishes 
the whole of the Cedzd@ from the Old World families. 
The Uakaris are arboreal Monkeys, very gentle and timid. 
The distribution of the various species is singularly restricted, 
each being confined to a small and particular district. 
I. THE BLACK-HEADED UAKARI. BRACHYURUS MELANO- 
CEPHALUS. 
Szmia melanocephala (Cacajao), Humboldt, Obs. Zool., p. 317, 
pl. xxix. (1811). 
Fithecta melanocephala, Geoffr., Ann. Mus., xix., p. 117 
(1812); Schl., Mus. Pays Bas, vii., p. 227 (1876). 
Brachyurus ouakary, Spix, Sim. et Vespert. Bras., p. 12, pl. 
Vill. (1823). 
Ouakarta spixiu, Gray, P. Z. 8., 1849, p. 10, cum fig. 
Ouakaria melanocephala, Gray, Cat. Monkeys Brit. Mus., p. 62 
(1870). 
Brachyurus melanocephalus, W. A. Forbes, P. Z. S., 1880, p. 
645, pl. Ixii. 
Characters.— Head and nude face-black ; back, sides, thighs, 
upper surface of tail, and outer and inner sides of legs more or 
less chestnut-brown ; shoulders, arms, hands, feet, and rest of 
tail, black. Ears large, naked, and similar in form to those 
in Man. 
Distribution Confined, so far as at present known, to the 
forests traversed by the Rio Casiquiare, Rio Negro, and Rio 
Branco. This is the most northern form of the three species 
of the genus, and apparently the most widespread also 
(see map, p. 180). This is doubtless the ‘“ black-faced, grey- 
haired ” species, neither white nor red, which Mr. Bates was 
