Contents. xv 



CHAPTER XIV. 



BiKDS — erniiiwued,, 



vkai 

 Choice exerted by the female — Length of courtship — Unpaired 

 birds — Mental qualities and taste for the beautiful — Preference 

 or antipathy shewn by tlie female fur particular males — Vari- 

 ability of birds — Variations sometimes abrupt — Laws of varia- 

 tion — Formation of ocelli — Gradations of character — Case of 

 Peiicotk Argus pheasant, and Urostiote . . " . 404 



CHAPTER XV. 



B iBDS — continued. 



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

 sexes of others are briglitly coloured — On sexually-limited 

 inheritance, as applied to various structures and to briglitly- 

 ooloured plumage — Nidifloation in relation to colour — Loss of 

 nuptial plnir,agB during the winter .... 441 



CHAPTER XVI. 



Birds — concluded. 



The immature plumage in relation to Ihe chaiactei- of the plumage 

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

 ences betwesn the males of closely-allied or representative 

 species — The female assuming the characters of the male — 

 Plumage of the young in ri-latiou to thp summer and winter 

 plumage of the adults — On the increase of beauty in the birds 

 of the world — Protective colouring — Conspicuously-coloured 

 birds — ^Novelty appreciated — Summary of the four chapters on 

 birds i63 



CHAPTER XVII. 



Secondaht Sbxdal Chaeacters of Mammals. 



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

 of absence of weapons in the female — Weapons common to b./th 

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

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

 Means of defence — On the preference shewn by either sex in the 

 pairing of quadrupeds ...... 501) 



CHAPTER XVIIL 



Secondabt Sexual Chakactees of Mammals — eoatinued. 



Voice — Remarkable sexual peculiarities in seals— Od"ur — D-vclop- 

 m^nt of the hair — Colour of the hair and skin— Anomalous 



