PREFACE. 
XI 
A few words may be added on some additional features which I have thought it desirable to 
introduce into the Work. It was impossible, in the first instance, to number the pages, on account 
of the irregular order in which, from various causes, it was necessary that the subfamilies should be 
issued ; but in the Table of Contents I have shown how the numbers of the pages should run with the 
several articles, and this paging will be found greatly to facilitate the consultation of t . 
During the five years of its progress much additional matter has been carefully collected, which » 
added in the Appendices, where many new species, and other information published or met wit i 
subsequently to the publication of the several articles to which they refer, will be found recorded, for 
the purpose of completing, as nearly as possible up to the present time, the summary of our knowledge 
of the species belonging to each genus. Lastly, to facilitate the finding of the names of those 
which have been figured in various standard ornithological works of large extent, I have ta iv 
series of Lists of the Names employed in this Work, with references to each plate of those works 
consecutive order, which I trust may prove useful in naming collections fiorn those gieat stores 
published figures, by enabling the student at a glance to obtain the infoimation he desires with vc a 
to any particular figure. 
G. R. GRAY. 
Hampstead, August 20. 1849. 
POSTSCRIPT BY THE ILLUSTRATOR. 
It is perhaps scarcely necessary to state that the Illustrations of this Book have no claim to be con- 
sidered as works of art. My constant object has been to represent, as closely as possible, those 
characteristic variations of form which are relied on by ornithologists as the distinctive marks of generic 
separation. 
When I accepted the office of Secretary to the Zoological Society, and found myself no longer a 
to devote to the completion of this series of plates the time which the work demanded, I was fortunate 
enough to obtain the assistance of Mr. Wolf of Coblentz ; and I have the pleasure of believing, that, as 
I thus secured the best available talent in Europe as a substitute for my own pencil, my nen s wi 
have no cause to regret that the latter part of the Work has been intrusted to anotl 
D. W. MITCHELL. 
Montague Street, Aug. 29. 1849. 
