4 PREFACE TO THE REVISED EDITION. 



In this revised edition I have not changed the general 

 plan of the work as already explained in the preface 

 of the previous edition, but have only made such modi- 

 fications and additions as seemed necessary to bring it 

 up to the present condition of science. Among these 

 additions, certainly not the least important are the beau- 

 tiful restorations of vertebrate skeletons and photo- 

 graphs of natural objects for which I am indebted to 

 Professors Marsh, Dean, Williston, and Scott. I wish 

 hereby to thank these gentlemen for their hearty cooper- 

 ation. Acknowledgment is due also to the American 

 Museum of Natural History, New York, N. Y., for the 

 photograph of the Great Barrier Reef, shown on page 97. 



JOSEPH LE CONTE. 

 BERKELEY, CALIFORNIA, January, 1898. 



