necessity for concealment does not exist, and sexual selection has had no check in developing the brightest and most conspicuous colours. If such a bird was not able to defend itself from all foes, its loud cries would attract them, its bright colours direct them, to its own destruction. The white cockatoo of Australia is a similar instance. It is equally conspicuous amongst the dark-green foliage by its pure white colour, and equally its loud screams proclaim from afar its resting-place, whilst its powerful beak protects it from all enemies excepting man. In the smaller species of parrots the beak is not sufficiently strong to protect them from their enemies, and most of them are coloured green, which makes them very difficult to distinguish amongst the leaves. I have been looking for several minutes at a tree, in which were scores of small green parrots, making an incessant noise, without being able to distinguish one; and I recollect once in Australia firing at what I thought was a solitary "green leek" parrot amongst a bunch of leaves, and to my astonishment five "green leeks" fell to the ground, the whole bunch of apparent leaves having been composed of them. The bills of even the smallest parrots must, however, be very useful to them to guard the entrances to their nests in the holes of trees, in which they breed. I believe that the principal use of the long sharp bill of the toucan is also that of a weapon with which to defend itself against its enemies, especially when nesting in the hole of a tree. Any predatory animal must face this formidable beak if seeking to force an entrance to the nest; and I know by experience that the toucan can use it with great quickness and effect. I kept a young one of the largest Nicaraguan species (Ramphastus tocard) for some time, until it one day came within reach of and was killed by my monkey. It was a most comical looking bird when hopping about, and though evidently partial to fruit, was eager after cockroaches and other insects; its long bill being useful in picking them out of crevices and corners. It used its bill so dexterously that it was impossible to put one's hand near it without being struck, and the blow would always draw blood. That in the tropics birds should have some special development for the protection of their breeding-places is not to be wondered at when we reflect upon the great number of predatory mammals, monkeys, raccoons, opossums, etc., that are constantly searching about for nests and devouring the eggs and young ones. I have already mentioned the great danger they run from the attacks of the immense armies of foraging ants, and the importance of having some means of picking off the scouts, that they may not return and scent the trail for the advance of the main body, whose numbers would overcome all resistance.