202 Evolution and Adaptation 



of the brighter-colored individuals of either sex ; both sexes 

 transmitting their characters to their young at a rather 

 earlier age than usual. Whether this is the true explanation 

 I will not pretend to say ; but the case is too remarkable to 

 be passed over without notice." 



The third group of cases include those in which the fe- 

 males are more brightly colored, or more ornamented, than 

 the males. These cases are rare, and the differences between 

 the sexes are never so great as when the male is the more 

 highly colored. Wallace thinks that since in these cases the 

 male incubates the eggs his less conspicuous colors have 

 been acquired through natural selection. In the genus 

 Turnix the female is larger than the male, and lacks the 

 black on the throat and neck, and the plumage as a whole is 

 lighter than that of the male. The natives assert that the 

 females after laying their eggs associate in flocks, and leave 

 the males to do the incubating; and from other evidence 

 Darwin thinks that this is true. 



In three species of painted snipe the females " are not only 

 larger but much more richly colored than the males," and the 

 trachea is more convoluted in some species. " There is also 

 reason to believe that the male undertakes the duty of incu- 

 bation." In the dotterel plover the female is larger and 

 somewhat more strongly colored. The males take at least 

 a share in the incubation. In the common cassowary the 

 female is larger and the skin of the head more brightly 

 colored than in the male. The female is pugnacious during 

 the breeding season and the male sits on the eggs. The 

 female emu is large and has a crest. She is more coura- 

 geous and pugilistic and makes a deep, hollow, guttural boom. 

 The male is more docile and can only hiss or croak. He 

 not only incubates the eggs, but defends the young against 

 their own mother. " So that with this emu we have a com- 

 plete reversal not only of the parental and incubating instincts, 

 but of the usual moral qualities of the two sexes ; the females 



