viii CONTENTS 



PAGE 



CHAPTER IV. 



TRITUEERCULY IN ITS APPLICATION TO THE MOLAR TEETH OF THE 

 UNGULATES OR HOOFED MAMMALS. COMPLETION OF THE 

 NOMENCLATURE. 



1. Disadvantages of previous systems of nomenclature of the molar cusps, 66 



2. Methods of analysis of molar elements. Nomenclature of the molars 



of Ungulates, - 66 



3. Application of the theory of trituberculy to the Perissodactyla, p. 72. 



The horse molar, p. 72. The rhinoceros molar, p. 72. 



CHAPTER V. 

 TRITUBERCULY : A REVIEW DEDICATED TO THE LATE PROFESSOR COPE, 74 



Polybuny, p. 74. Comparison of nomenclatures, p. 76. Tritubercular 

 homologies, p. 77. The early stages of sexituberculy, p. 80. Lower 

 molars, p. 80. The nomenclature of the molar cusps and crests, p. 82. 

 The evolution of the Ungulate molar, p. 83. 



CHAPTER VI. 

 CHRONOLOGICAL OR GEOLOGICAL SUCCESSION OF MOLAR TYPES. 



1. Reptilian Ancestors of Mammals in the Trias, - 



2. The Triassic Mammals, 94 



3. Mammals of the Jurassic, 94 



4. Upper Cretaceous Mammals, 95 



5. Basal Eocene Mammals, 98 



6. Lower Eocene Mammals, 98 



Resume of Geological Succession of Types, 99 



CHAPTER VII. 



THE ORIGINAL OR PRIMITIVE STRUCTURE OF THE MOLAR TEETH IN 



THE DIFFERENT ORDERS OF MAMMALS, 100 



The major classification of the Mammalia, p. 100. Protodonta, p. 101. 

 Allotheria or Multituberculata, p. 101. Monotremata, p. 105. Mar- 

 supialia, p. 108. Molar teeth of Multituberculates, Marsupials (?), and 

 Placentals in the Upper Cretaceous, p. 115. Insectivora, p. 117. 

 Cheiroptera, p. 129. Carnivora, p. 131. Evolution of carnasial teeth in 

 Creodonta and Fissipedia, p. 135. Convergence of upper carnassials in 

 Creodonta and Fissipedia, p. 1 38. Fissipedia, p. 1 42. Rodentia, p. 1 44, and 



