CONTENTS. Xl 



Pa«e 

 CHAPTER XIV. 



BIRDS.— Continued. 



Choice exerted by the female— Length of courtship— Unpaired birds 

 — Mental qualities and taste for the beautiful— Preference or an- 

 tipathy shown by the female for particular males — Variability of 

 birds — Variations sometimes abrupt— Laws of variation— Forma- 

 tion of ocelli— Gradations of character— Case of Peacock, Argus 

 pheasant and Urosticte ' 399 



CHAPTER XV. 



BIRDS.— Continued. 



Discussion as to why the males alone of some species, and both 

 sexes of others are brightly colored— On sexually-limited inherit- 

 ance, as applied to various structures and to brightly-colored 

 plumage — Nidiflcation in relation to color — Loss of nuptual plum- 

 age during the winter 438 



CHAPTER XVI. 



BIRDS.— Concluded. 



The immature plumage In relation to the character of the plum- 

 age in both sexes when adult— Six classes of cases — Sexual differ- 

 ences between the males of closely-allied or representative spe- 

 cies—The female assuming the characters of the male — Plumage 

 of the young in relation to the summer and winter plumage of 

 the adults — On the increase of beauty in the birds of the world- 

 Protective coloring— Conspicuously-colored birds— Novelty appre- 

 ciated—Summary of the four chapters on birds 458 



CHAPTER XVII. 



SECONDARY SEXUAL CHARACTERS OF MAMMALS. 



The law of battle— Special weapons,' confined to the males— Cause 

 of absence of weapons in the female — Weapons common to both 

 sexes, yet primarily acquired by the male — Other uses of such 

 weapons— Tneir high importance — Greater size of the male — 

 Means of defense— On the preference shown by either sex in the 

 pairing of quadrupeds 49S 



CHAPTER XVIII. 



SECONDARY SEXUAL CHARACTERS OF MAMMALS— Con- 

 tinued. 



Voice— Remarkable sexual peculiarities in seals— Odor— Develop- 

 ment of the hair — Color of the hair and skin — Anomalous case of 

 the female being more ornamented than the male— Color and or- 



