PREFACE 



In endeavoring to lay before my students truths embodied 

 in the evolution of tooth form, I have been hampered as others 

 undoubtedly have been by the relative inaccessibility of the 

 essential literature. One cannot refer the undergraduate 

 student to all sources of information with which one would 

 like him to become acquainted. They are too scattered and 

 too numerous to permit a student whose time is very limited 

 and who is as yet only upon the threshold of the subject to 

 glean those essential data which he ought to possess. From the 

 profusion of material in the Anatomical Museum of Western 

 Reserve University I have gathered typical examples of the 

 various mammalian dentitions and have briefly presented these, 

 allowing them for the most part to tell their own tale ; for in 

 the compass of so small a volume it is unavoidable that the 

 writer's thoughts outstrip his pen and his conclusions lie often 

 beyond the matter presented. 



It has not been possible nor do I think it necessary to draw 

 the attention of the reader to all theories and conceptions re- 

 garding the evolution of teeth. The views of Schwalbe and 

 Bolk, for example, find no place within these pages. This is 

 not because the writer has underestimated or brushed lightly 

 aside the work of certain investigators. The volume has for 

 its aim the presentation of essentially American views regard- 

 ing the evolution of tooth forms, views which so far have not 

 been made the basis of an introductory handbook. It is extra- 

 ordinary that the Tritubercular Theory of Cope and Osborn 

 in its more recent garb should find so small a place in the 

 various treatises upon comparative anatomy of teeth. Noav 

 that facts in embryology hitherto regarded as incompatible 



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