58 
SEXUAL SELECTION : BTEDS. 
Paet 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 ot the female 
is not in any way remarkable,^^ 
It seems now Aveli 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 resemblinfy ‘^ock.” The bird whilst utterino; this 
sound throws himself into the most extraordinary 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 inhabiting South America 
{Cephahioterus 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, ‘Fauna Bor. Americana: Birds/ 1831, p. 359. Au- 
dubon, ibid. vol. iv. p. 507. 
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. 
