often most beautifully tinted in charming patterns. As bearing upon this theory of Sexual Selection, it can be observed that birds pay the closest attention to the songs of each other. A bullfinch, for instance, had been taught to pipe a German waltz, and in doing so was a most excellent performer. He was placed in a room where there were kept some eighteen canaries and linnets, and immediately commenced producing his melodies. The birds all ranged themselves on the sides of their cages nearest the performer, listening to his singing with the greatest interest. Undoubtedly this singing is most often a matter of courtship; the female finch selects that one out of a hundred males whose notes charm her the most; the female canary always chooses the best singer. The soft cooing of pigeons and of turtledoves is a matter of courtship. In the breeding season there is the most intense rivalry between the males in singing; a bird will sometimes sing until he drops down almost dead. That female birds exercise choice in mating was believed by Audubon. He describes how a woodpecker hen was followed by six gay suitors who continued to perform strange antics until a marked preference was shown for one of them. A study of the Australian bower-birds illustrates both the courting antics of the males and the exercise of choice by the females. These birds build bowers which are sometimes quite large. That of one species is raised on a thick platform of sticks and is nearly four feet in length and eighteen inches in height. These bowers are built on the ground, and are for the sole purpose of courtship, since the nests are formed in the trees. They are highly decorated with leaves, berries, feathers, shells, and kindred objects. Both sexes assist in the erection of the bower, although the male bird is the principal worker. The bower-constructing instinct is so strong that it is practiced even in confinement. A naturalist in describing the habits of some satin bower-birds kept in an aviary says that at times the male will chase the female all over the aviary, then go to the bower, pick up a gay feather or a large leaf, utter a curious kind of note, set all his feathers erect, run round the bower, and become so excited that his eyes appear to start from his head. He continues opening first one wing and then the other, uttering a low, whistling note, and, like the domestic cock, seems to be picking up something from the ground, until at last the female goes gently toward him and the wooing is completed.