INTRODUCTION 5 



The data here presented are intricately bound up with broader questions, notably 

 that of the origin of the Mammalia and that of the evolution of the mammalian denti- 

 tion, but these highly theoretical and controversial topics are not here treated, save 

 incidentally. The presentation of the actual data is conceived to be of more immediate 

 importance than the attempted correlation of these facts with current speculations, 

 although such a correlation is also an eventual necessity and will be undertaken at 

 another time. 



