6 PREFACE. 



browu and dull white. As the bird before us has slaty brown axillars banded with 

 dull white, it must be the Hudsonian Curlew, Numenius hudsonicus. The 'axillary 

 plumes are often a very important aid in determining a species, and the beginner 

 should learn where to look for them and to recognize them at a glance. (See cut, 

 page 10.) 



All measurements of birds are given in inches and fractions of an inch. The 

 following diagrams will illustrate how a bird should be measured, and the chart (page 

 10) will be useful to the young student of ornithology who may not be familiar with 

 the technical terms used in describing birds. Such terms as primaries and axillars 

 should be learned at once. It is customary to indicate the sexes by the signs of 

 Mars and Venus; the male, of course, being given that of Mars, $, and the female, 

 Venus, 9. 



In preparing the Key, a large number of birds were examined and measured. In 

 this connection, my thanks are due to Dr. J. A. Allen, of the American Museum of 

 Natural History ; and to Mr. Robert Ridgway, of the Smithsonian Institute, for the 

 loan of many specimens for examination ; and especially to Mr. William Brewster, 

 for free access to his magnificent collection in Cambridge. 



The illustrations are the work of Mr. Edward Knobel. 



CHARLES B. CORY. 

 BOSTON, MASS., June 20, 1897. 



