PREFACE. Vll 



will be found, it is hoped, fully intelligible to the ordinary 

 reader. 



Special students of paleontology and geology will miss the 

 expected descriptions of fossils and the means for identifying 

 them and for recognizing the horizons they indicate. To 

 such readers the author has to say that this book is offered 

 only as an introduction to the grand field of study open before 

 them, with the hope that it may be useful in guiding and 

 suggesting methods of investigation, and in encouraging that 

 deep research which will be found necessary to interpret the 

 full story of the history of organisms, of which only a glimpse 

 is here attempted. 



H. S. W. 



NEW HAVEN, October 5, 1895. 



