40 



GENERAL PRINCIPLES OF ZOOLOGY 



females, since these are less numerous and have heavier bodies than the 

 males. So there arises a sexual dimorphism. If the mimicing species 

 have a wide distribution, different bad flavored species may be mimicked 

 in different parts of the range. The females of Papilio merops mimic, 

 in different regions, Danais chrysippus, Amanris eclieria and A. mavias, 

 while the males have the same appearance throughout the whole habitat. 



FIG. 14. a, Mygnimia aviculus, a wasp imitated by a beetle, b, Coloborhombus'fascia- 

 tipennis (after Wallace). Three-fourths natural size. 



Sexual Selection is a special phase of natural selection, chiefly 

 observed in birds and hoofed animals. For the fulfilment of his sexual 

 instincts the male seeks to drive his competitors from the field, either in 

 battle or by impressing the female by his charms. With strong wings and 

 with spurs the cock maintains possession of his flock, the stag by means 

 of his antlers, the bull with his horns. The male birds of paradise win the 

 favor of the females by means of beautiful coloring; most singing-birds, 

 by means of song; many species of fowl, by peculiar love-dances. Since 

 all these characters belong chiefly to the male, and since only exception- 

 ally are they inherited by the female (and even then are less pronounced), 





