4 
PREFACE. 
tinguished from one another, and in species which resemble each 
other so much as to render identification difficult, the character- 
istic points of difference are put in italics. 
In conclusion, I wish to express my sincere thanks to my 
ornithological friends in general, for their kind assistance, and 
especially to Mr. George N. Lawrence, of New York, for much 
valuable information. 
C. B. CORY. 
