CONTENTS xvii 



CHAPTER XXI 



SUBPHYLUM VERTEBRATA: Class VII. Mammalia . . . 632 



1 . The Rabbit . ' -633 



2. A Brief Classification of Living Mammals . . . 641 



3. A Review of the Principal Orders and Families of Living 



Mammals . . * 645 



4. General Remarks on the Mammalia .... 676 



a, Integumentary Structures, 676 ; b, The Teeth of Mam- 

 mals, 678 ; c, The Development of Mammals, 680 ; 

 d, Hibernation, 682 ; e, Migration, 683 ; f, Domesti- 

 cated Mammals, 684 ; g, Fossil Mammals, 685 ; h, The 

 Economic Importance of Mammals, 688. 



CHAPTER XXII 



THE ANCESTORS AND INTERRELATIONS OF THE VERTEBRATES 691 



1. The Relations between Vertebrates and Invertebrates . 691 



2. The Phylogenesis of Vertebrates 693 



3. The Fossil Remains of Vertebrates 696 



a, Succession of Life in General, 696; b, The Evolu- 

 tion of the Horse, 698. 



