14 CONTENTS 



OHAPTEE XI 



INSECTS, conUntied — order lepidoptbra (bdtterplibs and moths) 



Courtship of butterflies — feattles — Ticking noise — Colors common to both, 

 sexes, or more brjDiant in the males — Examples — Not due to the direct 

 action of the conditions of life — Colors adapted for protection — Colors 

 of moths — Display — Perceptive powers of the Lepidoptera — ^Tariability 

 — Causes of the difference in color between the males and females — 

 Mimicry, female butterflies more brilliantly colored than the males 

 — Bright colors of caterpillars — Summary and concluding remarks 

 on the secondary sexual characters of insects — ^Birds and insects 

 compared ........... 401 



CHAPTER XII 



SBCONDAET SEXUAL CHARACTERS OF PISHES, AMPHIBIANS, AND REPTILES 



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

 — Males, bright colors and ornamental appendages; other strange 

 characters — Colors and appendages acquired by the males during the 

 breeding season alone — Pishes with both sexes briUiautly colored — 

 Protective colors — The less conspicuous colors 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 : Differ- 

 ences in structure and color between the sexes — Yocal organs. Rep- 

 tiles : Chelonians — Crocodiles — Snakes, colors in some cases protec- 

 tive — Lizards, battles of — Ornamental appendages — Strange differences 

 in structure between the sexes — Colors — Sexual differences almost as 

 great as with birds 431 



CHAPTER Xin 



SECONDARY SEXUAL CHARACTERS OP BIRDS 



Sexual differences — Law of battle — Special weapons — Vocal organs — 

 Instrumental music — Love-antics and dances — Decoratioiis, perma- 

 nent and seasonal — Double and single annual moults — Display of 

 ornaments by the males 466 



CHAPTER XIT 

 BIRDS — continued 

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

 Mental qualities and taste for the beautiful — Preference or antipathy 

 shown by the female for particular males — Variability of birds — 

 Variations sometimes abrupt — Laws of variation — Formation of ocelli 

 —Gradations of character — Case of Peacock, Argus pheasant, and 

 Urosticta . . . , 622 



