282 TJie Descent of Man. Part IL 



IB produced by the vibration ot the lips of the spiracles, which 

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

 but this view has lately been disputed. Dr. Powell appears to 

 have proved^ that it is produced by the vibration of a mem- 

 brane, set into action by a special muscle. In the living insect, 

 whilst 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 fem.ale 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 Cii-ada septemdecim of the United States, says, ^^ 

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

 " directions. This I beliece to be the marital summons from 

 " the males. Standing in thick chestnut sprouts about as high 

 " as my head, where hundreds were around me, I observed the 

 " females coming around the drumming males." He adds, " this 

 " season (Aug. 1868) a dwarf pear-tree in my garden produced 

 " about fifty larvae of CVc. pruinosa ; and 1 several times noticed 

 " the females to alight near a male while he was uttering his 

 "clanging notes." Fritz Iilialler writes to me from S. 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 distance from each otlier : 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 female birds, they are excited or allured by the male with 

 the most attractive voice. 



I have not heard of any well-marked cases of ornamental 

 differences between the sexes of the Homoptera. Mr. Douglas 

 informs me that there are three British species, in which the 

 male is black or marked with black bands, whilst the females are 

 pale-coloured or obscure. 



Order, Orthopiera (Crickets and Grasshoppers). — The males in 

 the three saltatorial families in this Order are remarkable for 

 tlieir musical powers, namely the AchetidsB or crickets, the 

 LocustidiB for which there is no equivalent English name, and the 

 Acridiidse or grasshoppers. The stridulation produced by some 



" 'Transact. New Zealand Ih- fron-. j 'Journal of the Doings of 



fltitnte,' vol. v. 1873, p. 286. Cicada septemdecim ' by Dr. llart- 



" I am indebted to Mr. Wal»h man. 

 tor hannt; ttnt me this extract 



