PREFACE 



FIVE years ago I published a short essay on the Classification 

 of Birds. Since then, in addition to original research, I 

 have had an opportunity of studying various collections of 

 facts bearing upon the question, of which the most im- 

 portant are Fiirbringer's " Morphologic und Systematik der 

 Vogel," Lydekker's " Catalogue of the Fossil Birds in the 

 British Museum," and Gadow's " Thier-Eeichs." 



The result has been that I have discovered many blunders 

 in my original essay, which require correction, and have 

 modified my views in various ways, so that it no longer 

 expresses my present opinions. 



I trust that my readers will regard this supplementary 

 essay as a step in the right direction, and will assist me to 

 the utmost of their power in the arduous task of eliminating 

 the errors, both of facts and of deduction from facts, which 

 still obscure our attempts to discover the natural Classifica- 

 tion of Birds. 



LONDON, 1895. 



