COURTSHIP AMONG BIRDS 131 



conspicuously thickened and peculiarly curved, while 

 the vane or web of the inner side of the feather is of great 

 width and structurally differs from the vanes of the other 

 feathers, whereby the vane becomes more resistant to 

 the rush of air caused by the wings during the descent. 



But in the case of these Snipe it is to be noted this 

 curious form of musical instrument is found in both sexes, 

 and there is little difference in the quality of the sounds 

 produced, but the bleating of the male is said to be the 

 more resonant. 



The Common Snipe is the best performer among several 

 different species, and it is to be noted presents, to a 

 casual examination, no remarkable or peculiar feature 

 whatever — the structural differences just described are 

 only to be discovered by very patient scrutiny. But in 

 the Pin-tailed Snipe (Gallinago stenura) the number of 

 the feathers has been greatly increased, while at the 

 same time their webs have been so reduced that the out- 

 spread tail seems to consist of little more than spines. 

 With such a transformation one expects to find a quite 

 exceptional performance, far surpassing that of the 

 Common Snipe. Yet so far as observation and experiment 

 go they effect absolutely nothing ! Here again we have 

 a case where modification of structure has passed the 

 bounds of need and passed so far as to make the whole 

 tail useless as a sound-producing organ ! 



A contrast and a parallel are afforded by some of the 

 gallinaceous birds of South America. The Black Penelope 

 {Penelopina nigra) of Guatemala, while on the wing, 

 will, during its " love-flights," pitch suddenly earthwards 

 with outstretched wings, and at such times a crashing, 

 rushing sound is produced, which has been likened to 

 the sound of a falling tree. Yet there is nothing in the 



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