The Descent of Man

cheek. The appearance of Cercocebus aethiops
is grotesque, with its black face, white whiskers
and collar, chestnut head, and a large naked
white spot over each eyelid. In very many species,
the beard, whiskers, and crests of hair
round the face are of a different colour from the
rest of the head, and when different, are always
of a lighter tint (45. I observed this fact in the
Zoological Gardens; and many cases may be
seen in the coloured plates in Geoffroy St.-
Hilaire and F. Cuvier, 'Histoire Nat. des Mammiferes,'
tom. i. 1824.), being often pure white,
sometimes bright yellow, or reddish. The whole
face of the South American Brachyurus calvus
is of a "glowing scarlet hue"; but this colour
does not appear until the animal is nearly mature.
(46. Bates, 'The Naturalist on the Amazons,'
1863, vol. ii. p. 310.) The naked skin of
the face differs wonderfully in colour in the
various species. It is often brown or fleshcolour,
with parts perfectly white, and often as
black as that of the most sooty negro. In the