The Banteng bull (_Bos sondaicus_) of the Malayan archipelago is almost black, with white legs and buttocks; the cow is of a bright dun, as are the young males until about the age of three years, when they rapidly change colour. The emasculated bull reverts to the colour of the female. The female Kemas goat is paler, and the female _Capra ægagrus_ is said to be more uniformly tinted than their respective males. Deer rarely present any sexual differences in colour. Judge Caton, however, informs me that with the males of the Wapiti deer (_Cervus Canadensis_) the neck, belly, and legs are much darker than the same parts in the female; but during the winter the darker tints gradually fade away and disappear. I may here mention that Judge Caton has in his park three races of the Virginian deer, which differ slightly in colour, but the differences are almost exclusively confined to the blue winter or breeding coat; so that this case may be compared with those given in a previous chapter of closely-allied or representative species of birds which differ from each other only in their nuptial plumage.[358] The females of _Cervus paludosus_ of S. America, as well as the young of both sexes, do not possess the black stripes on the nose, and the blackish-brown line on the breast which characterise the adult males.[359] Lastly, the mature male of the beautifully coloured and spotted Axis deer is considerably darker, as I am informed by Mr. Blyth, than the female; and this hue the castrated male never acquires.
The last Order which we have to consider--for I am not aware that sexual differences in colour occur in the other mammalian groups--is that of the Primates. The male of the _Lemur macaco_ is coal-black, whilst the female is reddish-yellow, but highly variable in colour.[360] Of the Quadrumana of the New World, the females and young of _Mycetes caraya_ are greyish-yellow and alike; in the second year the young male becomes reddish-brown, in the third year black, excepting the stomach, which, however, becomes quite black in the fourth or fifth year. There is also a strongly-marked difference in colour between the sexes in _Mycetes seniculus_ and _Cebus capucinus_; the young of the former and I believe of the latter species resembling the females. With _Pithecia leucocephala_ the young likewise resemble the females, which are brownish-black above and light rusty-red beneath, the adult males being black. The ruff of hair round the face of _Ateles marginatus_ is tinted yellow in the male and white in the female. Turning to the Old World, the males of _Hylobates hoolock_ are always black, with the exception of a white band over the brows; the females vary from whity-brown to a dark tint mixed with black, but are never wholly black.[361] In the beautiful _Cercopithecus diana_ the head of the adult male is of an intense black, whilst that of the female is dark grey; in the former the fur between the thighs is of an elegant fawn-colour, in the latter it is paler. In the equally beautiful and curious moustache monkey (_Cercopithecus cephus_) the only difference between the sexes is that the tail of the male is chesnut and that of the female grey; but Mr. Bartlett informs me that all the hues become more strongly pronounced in the male when adult, whilst in the female they remain as they were during youth. According to the coloured figures given by Solomon Müller, the male of _Semnopithecus chrysomelas_ is nearly black, the female being pale brown. In the _Cercopithecus cynosurus_ and _griseo-viridis_ one part of the body which is confined to the male sex is of the most brilliant blue or green, and contrasts strikingly with the naked skin on the hinder part of the body, which is vivid red.