CONTENTS. 



GENERAL. 



CHAPTER XXVII. 

 Comparative Physiology, ..■•■731 



CHAPTER XXVIII. 

 Distribution, . ■ • • 



753 



CHAPTER XXIX. 



Etiology, ..•-•■■ 7oS 



APPENDIX ON BOOKS, . . . • • 773 



INDEX, ....■■■ 779 



