310 
SEXUAL SELECTION : MAMMALS. 
Part II- 
until the animal is nearly mature. 45 The naked skin 
of the face differs wonderfully in colour in the various 
species. It is often brown or flesh -colour, with parts 
pei feet]\ white, and often as black as that of the 
most sooty negro. Iu the Brachyurus the scarlet tint 
is brighter than that of the most blushing Caucasian 
t amsel. It is sometimes more distinctly orange than 
m any Mongolian, and in several species it is blue, 
passing into violet or grey. In all the species known 
to Mr. Bartlett, in which the adults of both .sexes have 
strongly-coloured faces, the colours are dull or absent 
during early youth. This likewise holds good with the 
Mandrill and Rhesus, in which the face and the posterior 
parts of the body are brilliantly coloured in one seX 
alone. In these latter cases we have every reason to 
believe that the colours were acquired through sexual 
selection ; and rve are naturally led to extend the same 
view to the foregoing species, though both sexes when 
adult have their faces coloured in the same manner. 
Although, according to our taste, many kinds of 
monkeys are far from beautiful, other species are uni- 
? e ? s f' - v ^dmired ior their elegant appearance and 
nrigbt colours. The Semnopithecus nemeeus, though 
pceu nu y coloured, is described as extremely pretty! 
the orange-tinted face is surrounded by long whiskers 
o g ossy whiteness, with a line of chesnut-red over the 
eyebrows ; the fur on the back is of a delicate grey, with 
a square patch on the loins, the tail and the fore-arms 
a o a pine \\ lite ; a gorget of chesnut surmounts the 
chest; the hind thighs are black, with the legs chesnut- 
red. I will mention only two other monkeys on account 
of their beauty ; and 1 have selected these as they pre- 
sent slight sexual differences in colour, which renders it 
40 Bates, 1 The Naturalist on the Amazons,’ 1863, vol. ii. p. 310. 
