xiv Contents. 



PACK 



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 

 g onerally common to both sexes .... 274 



CHAPTER XL 



Insects, continued. — Order Lepidopter.v. 



(butterflies and moths.) 



Cjurtship of butterflies — Battles — Ticking noise — Colours common 

 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 — Perceptive 

 powers of the Lepidoptera — Variability — Causes of the difference 

 in colour between the males and females — Mimicry, female 

 butterflies more brilliantly coloured than the males — Bright 

 colours of caterpillars — Summary and concluding remarks on 

 the secondary sexual characters of insects — Birds and insects 

 compared ........ 307 



CHAPTER XII. 



Secondary Sexual Characters op Fishes, Amphibians, and 



Reptiles. 



Fishes: Courtship and battles of the males — Larger size of the 

 females — Males, bright colours and ornamental appendages; 

 other strange characters — Colours and appendages acquired by 

 the males during the breeding-season alone — Fishes with both 

 sexes brilliantly coloured — Protective colours — The less con- 

 spicuous colours of the female cannot be accounted for on the 

 principle of protection — Male fishes building nests, and taking 

 charge of the ova and young. Amphibians: Differences in 

 structure and colour between the sexes — Vocal organs. Rep- 

 tiles: Chelonians — Crocodiles — Snakes, colours in some cases 

 protective — Lizards, battles of — Ornamental appendages — 

 Strange differences in structure between the sexes — Colours — 

 Sexual differences almost as great as with birds . . 330 



CHAPTER XIII. 



Secondary Sexual Characters of Birds. 



Sexual differences — Law of battle — Special weapons — Vocal 

 organs — Instrumental music — Love-antics and dances — Deco- 

 rations, permanent and seasonal — Double and single annual 

 moults — Display of ornaments bj the males . . 358 



