VI 
PREFACE. 
of Birds, known and described up to his time, as nearly 
five hundred ; he supposed that about a third more might 
exist yet undiscovered. In the last edition of the ^ Systema 
Naturse^ Linnseus gives the characters of nearly nine hun- 
dred and fifty species. At the present time between six 
and seven thousand species of Birds are known in collec- 
tions, and the number is every year gradually increasing, 
as the unvisited parts of South America, Africa, Asia, and 
the Eastern Isles are being searched. 
In Mr. G. R. Gray^s ^Catalogue of the Genera and Sub- 
genera of Birds contained in the British Museum,^ pub- 
lished in 1855, there are upwards of 2400 Genera and 
Sub-genera recorded. Those who have not seen the noble 
and well-arranged gallery of which this Work is a slight 
conspectus, may form some idea of its richness by seeing 
how few of the genera are marked as being desiderata to the 
collection at the time of the publication of the Catalogue. 
London, November 1st, 1855. 
