11 ADVERTISEMENT. 



that admirable success, which has attended all her works. They are all of the 

 natural size with the exception of four raptorial birds, a goose and a species of 

 Rhea. As the dimensions of these latter birds are given, their proportional 

 reduction will readily be seen. I had originally intended to have added the initial 

 letter of my name to the account of the habits and ranges, and that of Mr. Gould's 

 to the description of the genera and species ; but as it may be known that he is 

 responsible for the latter, and myself for the former, this appeared to me useless ; 

 and I have, therefore, thought it better to incorporate all general remarks in my 

 own name, stating on every occasion my authority, so that wherever the personal 

 pronoun is used it refers to myself. Finally, I must remark, that after the 

 excellent dissertation, now in the course of publication, on the habits and distri- 

 bution of the birds of South America by M. Alcide D'Orbigny, in which he has 

 combined his own extended observations with those of Azara, my endeavour to 

 add anything to our information on this subject, may at first be thought super- 

 fluous. But as during the Beagle's voyage, I visited some portions of America 

 south of the range of M. D'Orbigny's travels, I shall relate in order the few facts, 

 which I have been enabled to collect together ; and these, if not new, may at least 

 tend to confirm former accounts. I have, however, thought myself obliged to omit 

 some parts, which otherwise I should have given ; and, after having read the pub- 

 lished portion of M. D'Orbigny's great work, I have corrected some errors, into 

 which I had fallen. I have not, however, altered any thing simply because it 

 differs from what that gentleman may have written ; but only where I have been 

 convinced that my means of observation were inferior to his. 



