ORNITHOLOGY AND OOLOGY. 
INTRODUCTION. 
S I have generally adopted, in the present volume, the 
system of classification, and the nomenclature, &c., 
presented by Professor Baird in his report on the Birds of 
North America, I will state here, that I have given, so far 
as possible, his own remarks in the explanations of the 
characteristics of the different orders, families, genera, &c., 
because they are expressed in the most concise and com- 
prehensive language possible. I have also given the same 
descriptions of the species as those contained in the above- 
mentioned report, because, being made from a much greater 
number of specimens than I could possibly have access 
to, they are certainly better than I could present from 
my own observations. The descriptions of the character- 
istics of the Raptores, the Gralle, and the <Alcide, are by 
John Cassin, of Philadelphia; those of the Longipennes 
Totipalmes and Colymbide were written by Mr. George N. 
Lawrence, of New York; those of the other birds were 
prepared by Professor Spencer F. Baird, of the Smithsonian 
Institute. 
In order that the descriptions of the birds in the follow- 
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