42 KEY AND DESCRIPTION 



For convenience of reference the pictures of bird parts are 

 repeated in the Key. The map on p. 41 shows the portion of 

 the United States covered by the birds in this book. 



KEY TO THE FAMILIES OF BIRDS 



* Swimming birds : legs rather short ; three front toes either with full 



webbing,! or with such membranes along their sides ^ as to take the 

 place of webbing. (All birds with the front toes webbed to about 

 the nails will be found in this group, excepting one very long-legged 

 bird with the tarsus 12 inches or more long. All the illustrations in 

 this book, from p. 279 to p. 348, are of swimmers.) 



Key to the Families of Swimming Birds, p. 48. 



* Wading birds : legs in most cases much elongated ; tibia always ex- 



serted, and in most cases more or less naked below (see p. 248); tail 

 relatively short ; few have the tail extending beyond the tip of the 

 wings when closed ; toes frequently with more or less webbing at 

 base,^ sometimes narrowly lobed along the sides. (Some species of 

 these birds live habitually in dry localities, but their forms are very 

 characteristic, and only a few ground birds, such as the meadow 

 lark or quail, could possibly be placed in this group. All the illus- 

 trations from p. 227 to p. 275 are of waders.) 



Key to the Families of Wading Birds, p. 46. 



* Birds fitted neither for swimming nor for wading. (A.) 



A. With only 2 toes In front, and in most species 2 behind ;* eyes on 

 the side of the head, as is usual with birds. (Q.) 



A. Eyes in a facial disk, and thus directed forward instead of side- 

 wise ; ^ outer toe can be used either before or behind — 



— Nail of middle toe smooth on the inner side 



XXVII. Horned Owls, etc. 



— Nail of middle toe saw-like on the inner side « 



XXVIII. Barn Owl. 



A. With 3 toes permanently in front and 1 toe (rarely absent) be- 

 hind ; ' eyes directed sideways. (The vultures, p. 212, are excep- 

 tions, as the outer toe can be used behind as with the owls : these 

 are large birds, with the head and neck nearly bare of feathers.") (B.) 



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