CONTENTS. IX 



Generic and specific summary — Continued. Page. 

 Revision of species — Continued. 



The Monoclonius-Triceratops phylum — Continued. 



Triceratops sulcatus 170 



T. elatus 170 



T. calicornis 171 



T. (Sterrholophus) flabellatus 171 



T. obtusus 1 171 



Relationship of species \ ' 171 



The Ceratops-Torosaurus phylum 172 



Ceratops montanus 172 



C. (Monoclonius) canadensis 172 



C. (Monoclonius) belli 173 



C. (Monoclonius) recurvicornis 173 



Torosaurus latus 174 



T. gladius 174 



Geology and physiography of the principal Ceratopsia localities 174 



Judith River localities of Montana 174 



Correlation 174 



Dog Creek 175 



Birch Creek 176 



Cow Creek 176 



Judith River (Belly River) of Canada 177 



Laramie localities 179 



Black Buttes, Wyoming 179 



Converse County, Wyoming 179 



Hell Creek, Montana 182 



Denver, Colo., localities 182 



Relationship of Black Buttes, Converse County, and Denver bedf 183 



Geological sequence of Ceratopsia 184 



Collecting ceratopsian material 185 



Probable appearance, habits, and environment of the Ceratopsia, and causes of extinction 187 



Evolutionary summary 187 



Probable appearance .• 188 



Judith River types. 188 



Laramie types 189 



Probable habits 193 



Environment 194 



Causes of extinction 195 



Bibliography 196 



Plates 199 



Index 295 



