58 SEXUAL SELECTION : BIEDS. Part IL 



deep hollow tones. With his neck-feathers erect, his 

 wings lowered and buzzing on the ground, and his long 

 pointed tail spread out like a fan, he displays a variety 

 of grotesque attitudes. The oesophagus of the female 

 is not in any way remarkable,^^ 



It seems now well made out that the great throat- 

 pouch of the European male bustard (Otis tarda), and 

 of at least four other species, does not serve, as was 

 formerly supposed, to hold water, but is connected with 

 the utterance during the breeding-season of a peculiar 

 sound resemblinor "ock." The bird whilst utterincy this 

 sound throws himself into the most extraordinarv atti- 

 tudes. It is a singular fact that with the males of the 

 same species the sack is not developed in all the indi- 

 viduals.*^ A crow-like bird inhabitino: South America 

 (CejjJialopterus ornatus, fig. 40) is called the umbrella- 

 bird, from its immense top-knot, formed of bare white 

 quills surmounted by dark-blue plumes, which it can 

 elevate into a great dome no less than five inches in 

 diameter, covering the whole head. This bird has on 

 its neck a long, thin, cylindrical, fleshy appendage, which 

 is thickly clothed with scale-like blue feathers. It pro- 

 bably serves in part as an ornament, but likewise as a 

 resounding apparatus, for Mr. Bates found that it is 

 connected " with an unusual development of the trachea 

 " and vocal organs." It is dilated when the bird utters 

 its singularly deep, loud, and long-sustained fluty note. 



'^'^ Eichardson, ' Faiina Bor. Americana : Birds,' 1831, p. 359. Au- 

 dubon, ibid. vol. iv. p. 507. 



''3 The following papers have been lately written on this subject : — 

 Prof. A. Newton, in the 'Ibis,' 1862, p. 107; Dr. Cullen, ibid. 1865, 

 p. 145 ; Mr. Flower, in ' Proc. Zool. Soc' 1865, p. 747 ; and Dr. Murie, 

 in 'Proc. Zool. Soc' 1868, p. 471. In this latter paper an excellent 

 figure is given of the male Australian Bustard in full display with the 

 sack distended. 



