iv PUBLISHER'S PREFACE TO FIFTH REVISED EDITION. 



3. The full collation in the text (not in an appendix, as in former editions) 

 of the nomenclature of species in the Key, with the nomenclature and numera- 

 tion of the American Ornithologists' Union Check-List. 



4. The full synonymies and bibliographical references in the case of very 

 many species — a new feature of the Key, and invaluable to students of all 

 degi'ees of advancement. To the preparation of this important feature Dr. Coues 

 brought his rare gifts as a bibliographer and nomenclator. 



5. The previous very extensive series of illustrations has been largely in- 

 creased by the addition of over two hundred new figures of species hitherto 

 seldom figured, from life studies by Louis Agassiz Fuertes executed with a 

 delicacy, beauty, and accuracy never before equalled. 



6. The introductory (i. e. general) descriptions of ordinal, family, and other 

 groups are much amplified over those in preceding editions of the Key, being of 

 a broad scope which make plain the comparative relationships of North Ameri- 

 can families, genera, and species of birds, with extralimital forms (Old World 

 and neotropical). This broad treatment makes the Key more than the purely 

 faunal work its title would imply. 



7. An appendix containing the additions to the American Ornithologists' 

 Union-Check List of North American Birds and the changes in nomenclature 

 not noted elsewhere which have been made since Dr. Coues' death. 



DANA ESTES AND COMPANY. 

 Boston, October, 1903. 



