SEXUAL SELEGTION- 371 



pleasing to the ears of some men." The Oicadidse usually 

 sing during the day, while the Fulgoridse appear to be 

 night-songsters. The sound, according to Landois," is pro- 

 duced by the vibration of the lips of the spiracles, which 

 are set into motion by a current of air emitted from the 

 tracheae; but this view has lately been disputed. Dr. Powell 

 appears to have proved" that it is produced by the vibration 

 of a membrane, set into action by^a special muscle. In the 

 living insect, while stridulating, this membrane can be seen 

 to vibrate; and in the dead insect the proper sound is heard, 

 if the muscle, when a little dried and hardened, is pulled 

 with the point of a pin. In the female the whole complex 

 musical apparatus is present, but is much less developed 

 than in the male, and is never used for producing sound. 



With respect to the object of the music, Dr. Hartman, 

 in speaking of the Cicada septemdecim of the United States, 

 says," "the drums are now (June 6 and 7, 1851) heard in 

 all directions. This I believe to be the marital summons 

 from the males. Standing in thick chestnut sprouts about 

 as high as my head, wbere hundreds were around me, I ob- 

 served the females coming around the drumming males." 

 He adds: "This season (August, 1868) a dwarf pear-tree 

 in my garden produced about fifty larvae of Gic. pruinosa; 

 and I several times noticed the females to alight near a male 

 while he was uttering his 'clanging notes.' Fritz Miiller 

 writes to me from South Brazil that he has often listened 

 to a musical contest between two or three males of a species 

 with a particularly loud voice, seated at a considerable dis- 

 tance from each other: as soon as one had finished his song, 

 another immediately began, and then another. As there is 

 so much rivalry between the males, it is probable that the 

 females not only find them by their sounds, but that, like 



^ These particulars are taken from Westwood's "Modern Class, of Insects, " 

 vol. iL, 1840, p. 422. See also, on the Fulgoridse, Kirby and Spence, "Intro- 

 duet.," vol. ii. p. 401. 



M "Zeitschrift fur wissenschaft Zoolog.," B. xvii;, 1867, s. 152-158. 



» "Transact. New Zealand Institute," voL v., 1873, p. 286. 



'' I am indebted to Mr. Walsh for having sent me this extract from a 

 "Journal of the Doings of Cicada septemdecim," by Dr. Hartman. 



