424 



THE DESCENT OF MAN. 



note. The head-crest and neck-appendage are rudimentary 

 in the female.* 



The vocal organs of various web-footed and wading birds 

 are extraordinarily complex, and differ to a certain extent 

 in the two sexes. In some cases the trachea is convoluted. 



Fig. 40. The Umbrella-bird or Cephalopterus ornatus, male (from Brehui). 



like a French horn, and is deeply embedded in the sternum. 

 In the wild swan {Cygnus fertis) it is more deeply 

 embedded in the adult male than in the adult female or 



* Bates. " The Naturalist on the Amazons," 1863, vol. ii, p. 284; 

 Wallace, in " Proc. Zool. Soc," 1850, p. 206. A new species, with 

 a still larger neck appendage (O. penduUger), has lately been dis- 

 covered, see '' Ibis," vol. i, p. 457. 



