IV BIRDS OF EASTERN NORTH AMERICA. 



not stiff and pointed, and Section 2, tail feathers stiff and pointed. Our duclj has 

 stiff, pointed tail feathers, and therefore belongs in Section 2. Section 2 contains two 

 species ; one having whole front of head and cheeks black, the other, with sides of 

 head more or less white. As our duck has a patch of white on the side of the head, 

 it must, therefore, be the Ruddy Duck, JErismatura jamaicensis. 



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

 diagrams on page 8 will illustrate how a bird should be measured, and the chart (pages 

 viii and ix) 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 very large number of birds were examined and measured. 

 In addition to the large collection of North American birds contained in tlie Field 

 Columbian Museum, by courtesy of my friends. Dr. ,J. A. Allen and Prof. Robert 

 Ridgway, the collections of the Smithsonian Institution and the American Museum 

 of Natural History were always open to me, as well as the splendid private collection 

 of Mr. William Brewster, at Cambridge, Mass. 



A few species which occur in Greenland, liut which have not been observed else- 

 where in North America, and rare exotic stragglers have been excluded from the Key, 

 but are given in their proper place in the body of the work. 



The larger portion of the illustrations are original and are the work of Mr. Edward 

 Knobel, of Boston. Numerous cuts are also included by arrangement with Messrs. 

 Little, Brown & Co., of Boston, which are taken from Baird, Brewer & Ridgway's 

 North American Birds. A few others were obtained from Messrs. Estes & Lauriat, 

 used in Dr. Elliott Cones' Ivey to North Amekican Birds. 



C. B. CORY. 



