310 SEXUAL SELECTION : MAMMALS. Part U. 



until the animal is nearly mature.^^ The naked skin 

 of the face differs wonderfully in colour in the various 

 species. It is often brown or flesh-colour, with parts 

 perfectly white, and often as black as that of the 

 most sooty negro. In the Brachyurus the scarlet tint 

 is brighter than that of the most blushing Caucasian 

 damsel. It is sometimes more distinctly orange than 

 in any Mongolian, and in several species it is blue, 

 passing into violet or grey. In all the species knoun 

 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 Khesus, 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 w^e are naturallv 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- 

 versally admired for their elegant appearance and 

 bright colours. The Semnopithecus nemseus, though 

 peculiarly coloured, is described as extremely pretty ; 

 the orange-tinted face is surrounded by long whiskers 

 of glossy 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 

 all of a pure white ; a goiget 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 I have selected these as they pre- 

 sent slight sexual differences in colour, which renders it 



'^^ Biites, ' The Naturalist on the Amazons,' 18615, voL ii. p. 310. 



