SEXUAL SELECTION 489 



fhat by blowing on these feathers, or by fastening them to 

 a long, thin stick and waving them rapidly through the air, 

 he could reproduce the drumming noise made by the living 

 bird. Both sexes are furnished with these feathers, but 

 they are generally larger in the male than in the female, 

 and emit a deeper note. In some species, as in S. frenata 

 (Fig. 42), four feathers, and in S. javensis (Fig. 43), no less 

 than eight on each side of the tail are greatly modified. 

 Different tones are emitted by the feathers of the different 

 epecies when waved through the air; and the Scohpax 

 Wilsonii of the United States makes a switching noise 

 while descending rapidly to the earth." 



In the male of the Ghamcepetes unicolor (a large gallina- 

 ceous bird of America) the first primary wing-feather ia 

 arched toward the tip and is 

 much more attenuated than 



in the female. In an allied f,o. «.-o.ter t^u-feather of sooiopa^ 

 bird, the Penelope nigra, frenata. 



Mr. Salvin observed a male 

 which, while it flew downward 



"with outstretched wings, Pio. 48.-Outer tan-feather of scotomas 



gave forth a kind of crashing javensis. 



rushing noise," like the falling of a tree." The male alone 

 of one of the Indian bustards {Sypheotides auritus) baa its 

 primary wing- feathers greatly acuminated; and the male of 

 an allied species is known to make a humming noise while 

 courting the female. " In a widely different group of birds, 

 namely Humming-birds, the males alone of certain kinds 

 have either the shafts of their primary wing-feathers 

 broadly dilated, or the webs abruptly excised toward the 

 extremity. The male, for instance, oi- Selasphortts platy- 



" See Mr. Meves' interesting paper in "Proc. ZooL Soo.," 1858, p. 199. 

 For the habits of the snipe, Macgillivray, "Hist. British Birds," vol. iv. p. 

 871. For the AEaerican snipe, Capt. Blakiston, "Ibis," vol. v., 1863, p. 131. 



" Mr. Salvin, in "Proe. Zool. Soc," IBS'?, p. 160. I am much indebted to 

 this distinguished ornithologist for sketches of the feathers of the Chamsepetes, 

 and for other information. 



M Jerdon, "Birds of India," vol. iiL pp. 618, 62? 



