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The Descent of Man

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as a resounding apparatus; for Mr. Bates found<br />

that it is connected "with an unusual development<br />

<strong>of</strong> the trachea and vocal organs." It is dilated<br />

when the bird utters its singularly deep,<br />

loud and long sustained fluty note. <strong>The</strong> headcrest<br />

and neck-appendage are rudimentary in<br />

the female. (44. Bates, '<strong>The</strong> Naturalist on the<br />

Amazons,' 1863, vol. ii. p. 284; Wallace, in 'Proceedings,<br />

Zoological Society,' 1850, p. 206. A<br />

new species, with a still larger neck-appendage<br />

(C. penduliger), has lately been discovered, see<br />

'Ibis,' vol. i. p. 457.)<br />

<strong>The</strong> vocal organs <strong>of</strong> various web-footed and<br />

wading birds are extraordinarily complex, and<br />

differ to a certain extent in the two sexes. In<br />

some cases the trachea is convoluted, like a<br />

French horn, and is deeply embedded in the<br />

sternum. In the wild swan (Cygnus ferus) it is<br />

more deeply embedded in the adult male than<br />

in the adult female or young male. In the male<br />

Merganser the enlarged portion <strong>of</strong> the trachea

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