C CONTENTS. 



Page 



not understood— Difference in size between tiie sexes— Thysanura 

 — Diptera— Hemiptera— Homoptera, musical powers possessed by 

 the males alone— Orthoptera, musical instruments of the males, 

 much diversified in structure; pugnacity; colors— NeuVoptera sex- 

 ual differences in color— Hymenoptera, pugnacity and colors— 

 Ooleoptera, colors; furnished with great horns, apparently as an 

 ornament; battles; stridulating organs generally common to both 

 sexes 272 



CHAPTER XI. 



INSECTS, continued.— ORDER LEPIDOPTERA. 

 (Butterflies and moths.) 



Courtship of butterflies— Battles— Ticking noise — Colors common to 

 both sexes, or more brilliant in the males— Examples— Not due to 

 the direct action of the conditions of life — Colors adapted for pro- 

 tection-Colors of moths — Display— Perceptive powers of the Lep- 

 idoptera — Variability — Causes of the difference in color between 

 the males and females — Mimicry, female butterflies more bril- 

 liantly colored than th'e males- — Bright colors of caterpillars — 

 Summary and concluding remarks on the secondary sexual char- 

 acters of insects— Birds and Insects compared 304 



CHAPTER XII. 



SECONDARY SEXUAL CHARACTERS OP FISHES, AMPHIB- 

 IANS. 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— Fishes with both sexes bril- 

 liantly colored— Protective colors— The less conspicuous colors 

 of the female cannot be accounted for on the principle of protec- 

 tion—Male fishes building nests, and taking charge of the ova and 

 young. Amphibians: Differences in structure and color between 

 the sexes— Vocal organs. Reptiles: Chelonians— Crocodiles- 

 Snakes, colors in some cases protective— Lizards, battles of— Or- 

 nam.ental appendages — Strange differences in structure between 

 the sexes— Colors— Sexual differences almost as great as with 

 birds 321 



CHAPTER XIII. 



'SECONDARY SEXUAL CHARACTERS OF BIRDS. 



Sexual differences— Law of battle— Special weapons— Vocal o,rgans 

 —Instrumental music— Love-antics and dances— Decorations, per- 

 manent £ind seasonal— Double and single annual moults— Display 

 of ornaments by the males 356 



