276 f^'^J-' 



'Ageronia in Doubleday's " Genera of Diurnal Lepidoptera"). There 

 is reference in Hagen's " Bibliotlieca " to a stridulating Noctua of 

 the genus Orthosia, and the authority given is Haldeman (Sillimann's 

 Journal, ser. 2, vol. v, p. 435) ; but the name "Or^/tosia" is a misprint 

 ior " Lithosia.'' Haldeman says that " Lithosia «^m^a^ff, or an allied 

 species, produces an audible stridulation by vibrating the pleura 

 beneath the wings, this part being marked in recent specimens by 

 parallel lines, apparently indicating the positions of the muscles." 



Stridulation in the genus Halias appears also characteristic of 

 the male ("Scottish Naturalist," i, pp. 213 — 215). " On the evening 

 of 28th May, when mothing in the oak-wood surrounding my house," 

 says Dr. F. Buchanan White, " I noticed what I thought was a beetle, 

 flying round a small oalc, and giving vent all the time to a sharp, 

 quick sound, very similar to that produced by the Lougicorn beetle 

 Astinomus when held between the fingers. Though I failed to catch 

 this individual, I was more successful with another which was 

 behaving in the same manner. When in the net the sound ceased, 

 and I saw to my astonishment that the insect was a moth. It 

 then occurred to me that Hylopliila prasinana was said to produce 

 a sound." 



" The following morning I ti'ied some experiments with my 

 captive, moving his wings and making him fly, but was not able to 

 elicit any sound from him. I conclude, therefore, that the noise is 

 not produced by the mere mechanical action of the wings, but is 

 dependent on the will of the animal. I then killed the creature, 

 which was a male, and dissected him. On removing the patagia and 

 hairs from the thorax, several small projecting horny plates, both 

 frontal and lateral, were apparent, but I could not discover that the 

 wings produced any sound in connection Avith them." 



" I then directed my attention to the structures between the 

 thorax and hind-body, and from them I believe the sound proceeds. 

 On examining the under-side of the animal, a large semi-lunar 

 opening, immediately behind the metasternum, will be perceived. 

 On dissection, this opening will be found to communicate with a large 

 membranous plate, not flat, but folded at its posterior and inferior 

 edge, and elevated and depressed in other parts, and somewhat semi- 

 lunar in outline. To this plate numerous strong muscles are attached, 

 and by action of these muscles on the plate I think the insect pro- 

 duces the noise in question. This sound-producing structure (if 

 such indeed be its function) is analogous to the ' drum ' of the male 

 Cicatla, and occupies a similar position* The same evening I again 



