44 THE ENTOMOLOGIST. 



lends a distinct air of probability (to put it no stronger) to the 

 theories of those who believe in the auscultory powers of insects. 

 Mr. A.rkle quite rightly argues that the possession of a sound- 

 producing apparatus is no proof of the ability to hear. Yet I 

 maintain that it is strong prima facie evidence in favour of that 

 ability; and when such apparatus is confined to one sex the 

 evidence becomes so strong as to fully justify the assumption of 

 hearing powers, at all events in the opposite sex. Moreover, 

 when we come to examine the male cicada and see what a large 

 portion of its economy is occupied by the sound-producing organs, 

 the mind of any man who has read with ordinary intelligence the 

 works of such authors as Darwin, Huxley, or Wallace, must revolt 

 from any theory which would explain away this mechanism as 

 being merely adventitious, or else supplied by the kindness of 

 Nature for the delectation of the Kafirs in the wilds of Africa, 

 and to prevent their being annoyed by the monotony of pleasanter 

 sounds. Such a highly specialised apparatus must be of immense 

 importance in the welfare of the insect in which it occurs, and 

 can only have been produced by some very potent factor, which, 

 as I will show hereafter, I believe to have been natural selection 

 acting on the basis of the reproductive instinct, a most powerful 

 combination. We have already seen that sounds are emitted 

 only by the male sex, and therefore if it can be shown that the 

 female seeks the male, instead of vice versa, I think it will be 

 admitted that we have very strong circumstantial evidence, 

 amounting practically to proof, that the female can hear and is 

 attracted by the song of the male. Now, although I am aware 

 that by doing so I lay myself open to *' the suspicion that science 

 may end and enthusiasm begin," I must state that such observa- 

 tions as I have made have undoubtedly pointed to the fact 

 that the female does seek the male. My notes have been made 

 on only two species, which offer greater facilities for observation 

 than the others. For it is not always easy to make accurate 

 observations on these insects owing to the difficulty of detecting 

 them, the sluggishness of their movements, the height at which 

 they usually sit, and especially to the fact that the male and female 

 are indistinguishable on the tree, unless the former happens to 

 be singing, when the abdomen is slightly raised and the wings 

 held at a somewhat acute angle. I have frequently watched 

 solitary males when singing, and seen another cicada advance 

 from some other part of the bough or trunk with its slow some- 

 what jerky gait, stopping every few seconds, and even passing and 

 repassing the calling insect, until at last it comes to a rest along- 

 side of him. On netting such insects I have invariably found 

 them to be females, and on one occasion I took three which had 

 gathered round a single male. I have noticed that when there 

 are any impassive females in the near vicinity of calling males 

 these latter after a time become restless, walking backwards, for- 

 wards, and sideways, singing all the time, and occasionally giving 



