S72 THE DESCENT OF MAN 



female birds, thej are excited or allured by the male with 

 the most attractive voice. 



I bave not beard of any well-marked cases of orna- 

 mental differences between tbe sexes of tbe Homoptera. 

 Mr. Douglas informs me that there are three British species 

 in which the male is black or marked with black bands, 

 while the females are pale- colored or obscure. 



Order, Orthoptera (Crickets and Grasshoppers).— The 

 males in the three saltatorial families in this Order are 

 remarkable for their musical powers, namely, the Achetidas, 

 or crickets, the Locustidee, for which there is no equivalent 

 English name, and the Acridiidse, or grasshoppers. The 

 stridulation produced by some of the Locustidai is so loud 

 that it can be heard during the night at the distance of a 

 mile;"' and that made by certain species is not unmusical 

 even to the human ear, so that the Indians on the Amazons 

 keep them in wicker cages. All observers agree that the 

 sounds serve either to call or excite the mute females. 

 "With respect to the migratory locusts of Eussia, Korte 

 has given'" an interesting case of selection by the female of 

 a male. The males of this species (Pachytylus migratorius) 

 while coupled with the female stridulate from anger or 

 jealousy if approached by other males. The house- cricket 

 when surprised at night uses its voice to warn its fellows."" 

 In North America the Katydid {Platyphyllum concavum, 

 one of the Locustidee) is described'" as mounting on the 

 upper branches of a tree, and in the evening beginning ' ' his 

 noisy babble, while rival notes issue from the neighboring 

 trees, and the groves resound with the call of Katy- did- she- 

 did the livelong night." Mr. Bates, in speaking of the 

 European field- cricket (one of the Achetidse), says, "The 

 male has been observed to place himself in the evening 



" Guilding, "Trans. Linn. Soc," vol. xv. p. 154. 



^^ I state this on the authority of Eoppen, "Ueber die Heuschreeken in 

 Siidrussland," 1866, p. 32, for I have in vain endeavored to procure Korte'a 

 work. 



" Gilbert White, "Nat. Hist, of Selborne, " vol. ii., 1825, p. 262. 



8» Harris, "Insects of New England," 1842, p. 128. 



