SEXUAL SELECTION 617 



female is said by Mr. T. W. Wood " to exhibit during the 

 breeding season a most pugnacious disposition; and her 

 wattles then become enlarged and more brilliantly colored. 

 So, again, the female of one of the emus {Dromoeus irrora- 

 tus) is considerably larger than the male, and she possesses 

 a slight topknot, but is otherwise indistinguishable in 

 plumage. She appears, however, "to have greater power, 

 when angry or otherwise excited, of erecting, like a turkey- 

 cock, the feathers of her neck and <breast. She is usually 

 the more courageous and pugilistic. She makes a deep, 

 hollow, guttural boom, especially at night, sounding like 

 a small gong. The male has a slenderer frame and is 

 more docile,, with no voice beyond a suppressed hiss when 

 angry, or a croak." He not only performs the whole duty 

 of incubation, but has to defend the young from their 

 mother; "for as soon as she catches sight of her progeny 

 she becomes violently agitated, and, notwithstanding the 

 resistance of the father, appears to use her utmost endeav- 

 ors to destroy them. For months afterward it is unsafe to 

 put the parents together, violent quarrels being the inevi- 

 table result, in which the female generally comes off con- 

 queror." " So that with this emu we have a complete 

 reversal not only of the parental and incubating instincts, 

 but of the usual moral qualities of the two sexes; the fe- 

 males being savage, quarrelsome and noisy, the males gen- 

 tle and good. The case is very different with the African 

 ostrich, for the male is somewhat larger than the female 

 and has finer plumes with more strongly contrasted colors ; 

 nevertheless, he undertakes the whole duty of incubation." 

 I will specify the few other cases known to me in which 



«' "The Student," April, 1810, p. 124. 



'' See the excellent account of the habits of this bird under confinement, 

 hy Mr. A. "W. Bennett, in "Land and Water," May, 1868, p. 233. 



'* Mr. Sclater, on the incubation of the Struthiones, "Proe. Zool. Soc," 

 June 9, 1863. So it is with the Bhea darwinii: Captain Musters says ("At 

 Home with the Patagonians, " 18T1, p. 128) that the male is larger, stronger, 

 and swifter than the female, and of slightly darker colors; yet he takes sole 

 charge of the eggs and of the young, just as does the male of the common 

 species of Rhea. 



