NATURAL SELECTION; SEXUAL SELECTION 



73 



absence in the female in numer- 

 ous insect species), or special 

 sense organs "(the much more 

 expanded antennae of male cecro- 

 pia, promethea, polyphemus, and 

 other bombycine moths, as com- 

 pared with those of the female), 

 or special structures for the care 

 of the young (milk glands of 

 female mammals, brood pouches 

 of female marsupials, pits on the 

 back of the male of the frog Pipa 

 (Fig. 43), for carrying the eggs, 

 etc.), or recognition marks (the 

 eye spots, collars, wing bands, 

 tail blotches, and such other con- 

 spicuous color spots and mark- 

 ings possessed by the males and 

 wanting in the females of various 

 bird species), or, finally, char- 

 acters connected with special 

 habits of one sex differing from 

 those of the other (the pollen 

 baskets and wax plates of the 



worker female honey bees, the winglessness of certain female 

 parasitic insects, the males being nonparasitic and winged, etc.). 



The special characters may be 

 apparently for the purpose of attract- 

 ing or exciting the other sex, as the 

 brilliant colors, markings, and other 

 ornamentation of many male birds, 

 some mammals, and some reptiles 

 and very many fishes, and the cries 

 and songs, special odors, and curious 

 antics or dancing of the males of 

 various animals (mammals, birds, 

 spiders, insects, etc.). In many of 

 these cases the special secondary 

 sexual characters appear only during 

 -A male fro g Pipa ih breedmg seas on; in others they 



americana, carrying eggs in pits 



on its back. (After Darwin.) are persistent. 



FIG. 42. Fore leg of male water beetle, 

 Dyticus, showing special suckerlike 

 expansion of the leg. (After Miall.) 



