(2) _Warning Colours._—In this class, on the other hand, the object is not to conceal the animal, but to make it conspicuous. Certain species of gorgeously-coloured butterflies, _e.g._ are never eaten by birds, spiders, lizards, or monkeys, who eagerly feed on other butterflies. “The reason simply is that they are not fit to eat, their juices having a powerful odour and taste that is absolutely disgusting to all these animals. Now we see the reason of their showy colours and slow flight. It is good for them to be seen and recognised, for then they are never molested; but if they did not differ in form and colouring from other butterflies, or if they flew so quickly that their peculiarities could not be easily noticed, they would be captured, and though not eaten, would be maimed or killed.” Mimicry is the name given to a second and still more marvellous class of Warning Colours. They belong to defenceless creatures which so closely resemble other brightly-coloured but nauseous or dangerous animals that they are mistaken for the latter, and therefore left alone. _E.G._ “Wasps are imitated by moths, and ants by beetles; and even poisonous snakes are mimicked by harmless snakes, and dangerous hawks by defenceless cuckoos.” (3) _Typically_-coloured animals are those species which are brilliantly coloured in both sexes, “and for whose particular colours we can assign no function or use.” This group “comprises an immense number of showy birds, such as Kingfishers, Barbets, Toucans, Lories, Tits, and Starlings; among insects most of the largest and handsomest butterflies,” etc. “It is a suggestive fact that all the brightly-coloured birds mentioned above build in holes or form covered nests, so that the females do not need that protection during the breeding season which I believe to be one of the chief causes of the dull colour of female birds when their partners are gaily coloured.” (4) _Sexual Colours_, comprising those cases in which the sexes differ, and with which Darwin’s theory of Sexual Selection is directly concerned. Through no _direct_ fault of his own, Darwin leaves on his readers the impression—which has become almost a commonplace of conversation—that it is the general rule among animals for the males of each species to be more ornamented than the females. The truth is, however, that “with the exception of butterflies, the sexes are almost alike in the great majority of insects. The same is the case in mammals and reptiles; while the chief departure from the rule occurs in birds, though even here in very many cases the law of sexual likeness prevails.”