Vi CONTENTS. 



PART II. 



SEXUAL SELECTION" 



CHAPTER VIII. 



Paob. 

 principles of Sexual Selection 234 



CHAPTER IX. 



Secondary Sexual Characters in the Lower Classes of the Ani- 

 mal Kingdom 294 



CHAPTER X. 

 Secondary Sexual Characters of Insects 311 



CHAPTER XL 

 Insects, continued Order Lepidoptera. Butterflies and Moths. 348 



CHAPTER XII. 



Secondary Sexual Characters of Fishes, Amphibians, and 



Reptiles 375 



CHAPTER XIII. 

 Secondary Sexual Characters of Birds 407 



CHAPTER XIV. 

 BSx^ia continued 459 



CHAPTER XV. 

 'BUx^?, continued 505 



CHAPTER XVI. 

 Birds concluded , . . . 528 



CHAPTER XVII. 

 ^condar^ Sexual Characters of Mammals , . . . , , 57Q 



