The third group of cases include those in which the females 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 incubation.” 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 courageous 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 complete reversal not only of the parental and incubating instincts, but of the usual moral qualities of the two sexes; the females being savage, quarrelsome, and noisy, the males gentle 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.” Darwin attempts to explain these reversals of instincts on the assumption that the males have turned the tables on the females, and have themselves done the selecting; and incidentally, it may be pointed out in passing, they have had to pay the penalty by incubating the eggs. In the group of mammals, Darwin thinks that the male wins the female by conquering other males rather than by charming her through his display. The males, even when unarmed, engage in desperate conflicts with each other, and sometimes kill, but more often only wound, their fellows. The secondary sexual characters of the males have been acquired, therefore, by natural selection applied to one sex, and less frequently through the choice of the female. Since we are here more especially concerned with the latter class of phenomena, we may examine only a few cases under the first head.