Sound-production in the Lmncllicorn Beetles. 721 



One of the few Dynastid genera whose voice has 

 actually been heard and recorded is Philcurus, several 

 South-American species of which are stated by Lacordaire* 

 to produce a noise by rubbing the abdomen against the 

 elytra. Curiously enough, the instruments used have not 

 yet been satisfactorily determined, although according to 

 Lacordaire there is a longitudinal band inside the elytra 

 near the outer margin. Other investigators have failed to 

 confirm this, and in spite of a careful search I have been 

 unable to find any specially-developed ridges either on the 

 elytra or in any other part of the body. 1 have been 

 driven to conclude that the sound is produced by the fric- 

 tion of the two dorsal segments preceding the propygidium 

 against a horny plate in the wing. This plate bisects the 

 angle forming the apex of the folded wing, and on its lower 

 side is studded with short, strong and erect spines. The 

 greater part of the upper surface of the two segments men- 

 tioned is also covered with very minute spinose processes, 

 but these become much more crowded and form a micro- 

 scopic rasp which corresponds in position to the extremity 

 of the wing, so that the movement described by Lacordaire 

 would no doubt produce a shrill scraping or hissing noise. 

 This structure is quite different from any so far described 

 in this paper, but, as will presently be seen, living beetles 

 belonging to other families of Lamellicorns have recently 

 been proved to produce sounds by means almost identical 

 but much more specialized and clearly defined. 



The larvae of the beetles belonging to the family Apho- 

 diidaj possess an apparatus in the mouth closely resembling 

 that of the Sacred Beetles and their allies, but no vocal 

 powers have been recorded in any adult insect of this 

 family, the members of which, although small, are ex- 

 tremely common everywhere : nor do they seem to exist 

 in the allied group of the Hybosoridse, of which the 

 immature forms are as yet entirely unknown. Of the 

 Copridse themselves (to which gi'oup the Sacred Beetles 

 belong), only a very few of the mature insects are known 

 as stridulators. I have shown that Scarabxus has been 

 wrongly included amongst these, but many observers have 

 testified to the squeak emitted by species of Copris, one 

 of which inhabits our own country. There has been some 

 contradiction, however, as to the means by which it is done 

 in this genus. 



* Annales des Sciences Naturelles, vol. xx, p. 2'"7. 



