PREFACE 



The present work is intended as a record of facts, in palgeontology, as the authors 

 have been able to view them ; a contribution to the great inventory of nature. No 

 attempt has been made at generalizations or theories which might attract the 

 momentary attention and admiration of the scientific community. We give this 

 premonition at the outset, to prevent disappointment in those who might be expect- 

 ant of more important I'esults than we have obtained from the great amount of 

 material at our command. We have endeavored to see and represent things 

 correctly, nothing more, though we apprehend we have not been able to avoid the 

 average amount of errors usual under such circumstances. 



The materials of our work on the Extinct Mammalian Fauna of Dakota and 

 Nebraska, etc., have been gradually and continuously accumulating the last 

 twenty-three years. Those of the Synopsis of Mammalian Remains of North 

 America, through a century and a half. The prepai'ation of our book was 

 commenced seven years ago, and, after various interruptions, was so far completed 

 as to be presented to the Academy for publication in September, 1868. 



