OF SOUNDS. 473 



At the close of this description of the several organs whereby insects 

 produce peculiar sounds, we still have to speak of the sound and the 

 mechanism that produces it in a Lepidopterous insect, the well-known 

 death's head moth (Acherontia atropos, O.), which it emits upon being 

 touched or disturbed. Reaumur and Rossi were both acquainted with 

 the plaintive cry of this moth, and expressed their opinion that it pro- 

 ceeded from the friction of the tongue against the palpi. More recently, 

 the experiments which Passerini has made to ascertain the organ which 

 produces this sound have proved that it must lie somewhere in the 

 head. He found a cavity in the head which has connexion with the 

 false canal of the tongue (or rather, it should be said, with the central 

 canal formed by the application of the two halves of the proboscis 

 together), and about the entrance to which muscles lie which rise and 

 sink alternately, and by these motions drive the air out of it and re- 

 udmit it. I do not, however, distinctly see how the mere streaming in 

 and out of air could produce so loud a noise, if at the entrance there 

 be not some body made to vibrate by its passage. Such must therefore 

 be shown to exist, to explain fully the mechanism whereby the death's 

 head moth produces its plaintive cry. I have not yet possessed a living 

 individual of this otherwise not uncommon moth, I can therefore say 

 nothing from my own experience ; according to Duponchel *, whom 

 we have to thank for the communication of Passerini's observations, 

 there is a delicate membrane stretched between the eyes and the base of 

 the proboscis, which certainly might be the cause of the sound if we 

 adopt that the above cavity immediately adjoins it, and that it is made 

 to vibrate by the air passing to and fro. Duponchel found this mem- 

 brane also in Sphinx Convolvuli, which, however, produces no such 

 sound ; but then the internal cavity may be wanting whereby the faculty 

 of causing the membrane to vibrate, as in the death's head, is lost, and 

 it is consequently dumb. Passerini purposes making his observations 

 public, which will then doubtlessly spread more light over this inter- 

 esting subject. Thus much, however is certain, that the death's head 

 moth makes a peculiar plaintive cry, which is produced by a particular 

 organ seated in the head. 



* See Annales des Sciences Naturcllcs, torn. xiii. p. 332 (Mar. 1828), and Heusingci 

 Zethshrift fur die Org. PJiys. vol. ii. part iv. p. 442. 



