vi PREFACE 







The present volume treats only the primary evolution of the molar 

 and premolar teeth of mammals, and is thus more restricted in scope 

 than the admirable ' Dental Anatomy ' of Tomes which covers the teeth 

 of the vertebrates generally. 



The writer is especially indebted to his assistant Mr. W. K. Gregory 

 for invaluable assistance not only in bringing together and rearranging 

 the essays and figures, but for many original suggestions, and for the 

 critical resmnt of the opposing views which is set forth in the last 

 chapter. 



HENRY F AIRFIELD OSBORN. 



COLUMBIA UNIVERSITY AND 



A M KRICAN MUSEUM OF NATURAL HISTORY, 



September, 1907. 



