PREFACE TO FOURTH EDITION. 



XV 



to the Summary while in the latter heavy faced page numbers 

 refer back to the main text. 



Index. The Index has been prepar^d by the chairman and 

 has been checked to a great extent by Dr. Palmer whose wide 

 experience with indexes renders his aid particularly valuable. 



The typography of the present edition follows that of the third 

 with the exception that the dropping of the binomial species 

 headings has made it possible to abandon the two sizes of type 

 so that the entire text is printed in eight point. 



To all who have so generously aided in the preparation of the 

 work the chairman, on behalf of the Committee, extends grateful 

 thanks while he would express his deep appreciation of the cheer- 

 ful cooperation of his fellow members of the Committee at all 

 times, which has made his work a pleasure rather than a task. 



'Wither Stone, Chairman. 



Jonathan Dwight.* 



Joseph Grinnell. 



Waldron DeWitt Miller.* 



Harry C. Oberholser. 



T. S. Palmer. 



James Lee Peters. 



Charles W. Richmond. 



Alexander Wetmore. 

 .John T. Zimmer. 



Deceased. 



Committee. 



