Vlll CONTENTS OF VOL. I. 



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 acquired 

 before maturity — Spiders, sexual colours of ; stridulation by the 

 males — Myriapoda Page 321-340 



CHAPTER X. 



Secondary Sexual Characters of Insecst. 



Diversified structures possessed by the males for seizing the females 

 — Differences between the sexes, of which the meaning is not 

 understood — Difference in size between the sexes — Thysanura 

 — Diptera — Hemiptera' — Homoptera, musical powers possessed 

 by the males alone — Orthoptera, musical instruments of the 

 males, much diversified in structure ; pugnacity ; colours — 

 Neuroptera, sexual differences in colour — Hymenoptera, pug- 

 nacity and colours — Coleoptera, colours ; furnished with great 

 horns, apparently as an ornament ; battles ; stridulating organs 

 generally common to both sexes 341-385 



CHAPTER XI. 



Insects, continued. — Order Lefidoptera. 



Courtship of butterflies — Battles — Ticking noise — Colours com- 

 mon to both sexes, or more brilliant in the males — Examples — 

 Not due to the direct action of the conditions of life — Colours 

 adapted for protection — Colours of moths — Display — Per- 

 ceptive powers of the Lepidoptera ■ — Variability — Causes of the 

 difference in colour between the males and females — Mimickry, 

 female butterflies more brilliantly coloured than the males — 

 Bright colours of caterpillars — Summary and concluding re- 

 marks on the secondary sexual characters of insects — Birds 

 and insects compared 386-423 



