224 [ Marclt. 



into my power to thoroughly inform myself on this subject, two species 

 of Setina being widely distributed there. I have been able to assure 

 myself that, as I had supposed, the Setince produce, by means of the 

 organ that I have characterized, sounds very easy to perceive ; and one 

 of our colleagues, M. Constant, who on his part has verified it, even 

 indicated to me the means of causing these sounds at will. In order 

 to do that, it suffices to press the insect softly between the thumb and 

 finger (in the way that one would do in order to suflTocate it in the net), 

 and to place it to the ear. One hears then distinctly a sort of crepi- 

 tation, consisting of repeated strokes, which imitate slightly the ticking 

 of a watch, or the pulsations of Anobium, rather than they resemble the 

 stridulations of grasshoppers or crickets, with which the analogy would, 

 however, appear most striking at first sight. There can be no doubt 

 that, when the creatures produce these sounds in liberty, and during 

 their flight, they make them heard yet more distinctly ; since they are 

 not then stunned by the pressure : and that the vibration of the drums 

 makes itself then heard with all its sonorousness, especially in the 

 silence of night. 



The male alone appears able to emit this sound, or, if you like, 

 this song; not that the female is deprived of the organ in 

 question, biit in this sex the tympaniform vesicle is much smaller, 

 depressed, aud reduced, so to speak, to a rudimentary condition. I 

 dare not, however, affirm that it is totally deprived of the faculty of 

 producing sounds, perhaps, perceptible to the delicate organs of 

 these insects. 



However, what is the use of these songs in our Setina ? Is it a 

 call for the union of the sexes ? This is the first supposition which 

 presents itself to the mind, aud would appear perfectly justified if it 

 were the female that possessed it, because she has, as we know, the 

 wings so much reduced in proportion to her enormous abdomen, that 

 she is almost deprived of the faculty of flight. But we have just seen 

 that it is, on the contrary, the male that is provided with the means of 

 call, though with it the means of locomotion are complete. Besides, 

 this supposition would not be capable of being applied to the other 

 Lcpidopteron furnished with these drums — Chelonia pudica, the female 

 of which has the wings as much developed as the male. We must, 

 then, seek another explanation ; and I avow that, for my part, I am 

 not able to imagine anything plausible. 



TiCt us now examine by what means the sound is produced ; this 

 is still a question not altogether plain to my eyes, and I much fear 

 that it will remain as long disputed as that which operates a propos of 



