58 
SEXUAL SELECTION : BIRDS. 
Part It 
deep liollow tones. With his neck-feathers erect, hi3 
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. 42 
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 w» s 
formerly supposed, to hold water, hut is connected with 
the utterance during the breeding-season of a peeuha r 
sound resembling “oek.” The bird whilst uttering tin 9 
sound throws himself into the most extraordinary atti- 
tudes. It is a singular fact that with the males of tb e 
same species the sack is not developed in all the indi- 
viduals. 43 A crow-like bird inhabiting South A meric 0, 
( Oephahpterus 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 ca® j 
elevate into a great dome no less than five inches i® / 
diameter, covering the whole head. This bird has 0® 
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 9 
resounding apparatus, for Mr. Bates found that it 19 
connected “ with an unusual development of the tracin' 9 ■ 
“ and vocal organs.” It is dilated when the bird utter 3 
its singularly deep, loud, and long-sustained fluty not®* 
/ 
42 Richardson, ‘Fauna Bor. Americana: Birds,’ 1831, p. 359. A' r 
dubon, ibid. yol. iv. p. 507. 
43 The following papers have been lately written on this subject 
Prof. A. Newton, in the ‘Ibis,’ 1S62, p. 107; Dr. Cullen, ibid. I8*p' 
p. 145 ; Mr. Flower, in ‘ Proc. Zool. Soc.’ 1865, p. 747 ; and Dr. Mu ric j 
in ‘Proc. Zool. Soc.’ 1868, p. 471. In tbis latter paper an exoell eI) 
figure is given of the male Australian Bustard in full display with tk e 
sack distended. 
\ v_ln . j mm: i im \ ns 
