significant fact, and, apart from all other considerations, lends a distinct air of probability to the theories of those who believe in the auscultatory powers of insects. It is contended by some that the possession of a sound-producing apparatus is no proof of the ability to hear. I maintain that it is strong evidence in favour of that ability, and when such apparatus is confined to one sex the hearing-powers in the opposite sex become evident. When we come to examine the male cicada and see what a large part of it is occupied by the sound-producing organs, such a highly-specialised apparatus must be of importance in the welfare of the insect in which it occurs, and can only have been produced by some very potent factor. Now, as these sounds are emitted only by the male sex, my observations show me that the female seeks the male instead of vice versa, which I think is strong evidence that the female can hear, and is attracted by the song of the male. My notes have been made on only two species, which offer greater facilities for observation than the others, and even in these it is very difficult to make accurate observations, owing to the sluggishness of their movements, the height at which they sit, and the fact that the male and female are indistinguishable on the tree unless the male happens to be singing, when the abdomen is slightly raised and the wings held at a somewhat acute angle.

I have watched solitary males when singing, and seen another cicada advance from some other part of the tree with a slow, somewhat jerky gait, stopping every now and then, and passing and repassing the calling insect until it rests alongside him. On netting such insects I have found them to be females. I have noticed that when any females are near a calling male the latter becomes very restless, walking backwards, forwards, and sideways, and giving a sharp flutter with his wings as if to try and attract the attention of the females. If the male utters his shrill cry for the purpose of attracting the female, the explanation of the different calls of the species at once can be seen, for if the female finds the male by his call, and there are a number of different species frequenting the same place, those males which acquire some peculiarly distinctive sound would be likely to attract to themselves more females of their own kind, and thereby would leave more progeny, than those males whose cry more closely resembles that of another species, for these latter would be apt to attract females of another species, with which they could not interbreed; and those females which are most apt at distinguishing the notes of their own mates from those of other species are more likely to pair and leave progeny. I have several times imprisoned male cicadas in my breeding-cage, which is 4ft. by 2ft., in twelve compartments of gauze