APART from the familiar instances of male colour-decoration afforded by birds, we find that even some of the minute water-fleas inhabiting freshwater lakes and the sea, and known as Crustacea Entomostraca, put on a courting dress at the breeding season; that is to say, the males become brilliantly coloured with patches of red and blue. And among the highest mammals we find that the same colours are, in some cases, displayed by the males as a fascination to the females. This is the case with the males of some of the baboons, though not with those of the highest man-like apes, who, like the primitive "savage" man, have no decoration, no pretty seductive ways appealing to either the eye or the ear, but rely on their strength and ferocity to overawe and paralyze the female. In the male "mandrill" baboon the skin of the sides of the great snout is of a deep blue colour, whilst the nose and a tract behind it is wax-like and bright red. Not only that, but the buttocks are brilliantly coloured, a central red area passing at the sides through rich purple to pale blue. The animal, which is often to be seen in menageries, is evidently proud of this finely-coloured region of his body, and turns it to a visitor and remains quietly posed, so that it may be well seen and duly admired. The hind-quarters of other monkeys, both male and female, show a brilliant red colouring during the mating season, and the skin and hair of the face is variously coloured, so as to produce a decorative pattern (eyebrows, moustache, beard, nose, all strongly contrasted in colour) in the smaller monkeys, usually more strikingly in the males than in the females. A brilliant emerald-green patch of colour is shown in the hinder part of the body of the male in one species sometimes to be seen at Regent's Park.