INTRODUCTION. 



When I undertook to prepare the fifth volume of the Catalogue of 

 Birds, at the request of Dr. Giinther, I hoped to be able, bj' 

 devoting to it a year's work, to render it as nearly perfect as the 

 present state of our ornithological knowledge would permit. After 

 two years' close application I am obliged to admit that many 

 difficult points have had to be somewhat hurriedly settled for want 

 of time to work them oiit, or to be left undetermined for want of 

 material upon which to base an opinion. I must also ask for in- 

 dulgence for the errors and omissions which are sure to be found 

 in the voluminous synonymy required to make an index, not only 

 to the nomenclature, but also to the general literature of each 

 species treated of in the volume. I hope, however, that the results 

 of my work are at least worth the labour I have bestowed upon it, 

 and that I have not only removed many difficulties from the study 

 of a group of birds which have hitherto been in a greater confusion 

 tlian nitmy others, but also smoothed the way towards the solution 

 of some problems which puzzle all ornithological students. 



It is only fair to those who cannot but think that my treatment 

 of genera in this volume is more or less heterodox, that I should 

 attempt some defence or explanation in these introductory re- 

 marks. If I am accused of disturbing the existinor genera of 



