Contents. xiii 



PAGK 



Numerous points of resemblance in body and mind between the 

 most distinct races of man — The state of man when he first 

 spread over the earth — Each race not descended from a single 

 fair — The extinction of races — The formation of races — The 

 effects of crossing — Slight influence of the direct action of the 

 conditions of life — Slight or no influence of natural selection — 

 Sexual selection ....... IGfi 



PART II. 

 SEXUAL SELECTION. 



-•o*- 



CHAPTER VIII. 



Principles of Sexual Selection. 



Secondary sexual characters — Sexual selection — Manner of actioia 

 — Excess of males — Polygamy — The male alone generally 

 modified through sexual selection — Eagerness of the male — 

 Variability of the male — Choice exerted by the female — Sexual 

 compared with natural selection — Inheritance at corresponding 

 periods of life, at corresponding seasons of the year, and as 

 limited by sex — Relations between the several forms of inheri- 

 tance — Causes why one sex and the young are not modified 

 through sexual selection — Supplement on the proportional num- 

 bers of the two sexes throughout the animal kingdom — The 

 proportion of the sexes in relation to natural selection . . 207 



CHAPTER IX. 



Secondary Sexual Characters in the Lower Classes of 

 the Animal Kingdom. 



These characters absent in the lowest classes — Brilliant colours — 

 Mollusca— Annelids— Crustacea, secondary sexual characters 

 strongly developed; dimorphism; colour; characters not ac- 

 quired before maturity — Spiders, sexual colours of; stridulation 

 by the males — Myriapoda ...... 200 



CHAPTER X. 



Secondary Sexual Characters of Insects. 



Diversified structures possessed by the males for seizing the 

 females — Differences between the sexes, of which the mean- 

 ing is not understood— Difference in size between the sexes — 

 Thysanura — Diptera — Hemiptera — Homoptera, musical powers 



