PREFACE. 



N preparing this volume I have done my best ; but I do not 

 presume that it is without fault or errors, and it is probable 

 that in the next twenty years or so, many new forms will be 

 discovered, and will enable other authors to make a better classifi- 

 cation of these Birds : but nevertheless, I think that this work, like 

 those of my predecessors, from Linne, Vieillot, Gmelin, Lesson, 

 Jardine, &c., to Gould, Mulsant, Bourcier, Elliot, Salvin, 

 Berlepsch, Lawrence, Ridgway, Reichenbach, Heine, and others, 

 will help greatly to attain that end. Each author must be satisfied 

 in adding a stone to the edifice until its perfect completion. 



I am more convinced than ever that these beautiful birds stand 

 quite alone by themselves. They can be considered as the hand- 

 somest and most perfect, and are fully entitled to be classified 

 separately under the name of TROC H I LI, as I have proposed for 

 them in my Catalogus Avium, London, 1876. 



In this volume, I have distributed all the species known into 

 eighteen families, believing that in doing so, it will facilitate their 

 study. 



