BRANCH CHORDATA; CLASS AYES: THE BIRDS 363 



fectly opposable to the middle front one. This is the 

 perciiing foot. Note the so-called zygodactyl foot of the 

 woodpecker, with two toes projecting in front and partly 

 yoked together, and two similarly yoked projecting 

 behind. Note the webbed swimming foot of the aquatic 

 birds; note the different degrees of webbing, from the 

 totipalmate, where all four toes are completely webbed, 

 palmate, where the three front toes only are bound 



CK 



FIG. 143. Russet-backed thrush, Turdus ttstulatus. (Photograph from 

 life by Eliz. and Jos. Grinnell.) 



together but the web runs out to the claws, to the semi- 

 baluiate, where the web runs out only about half way. 

 Note the lobate foot of the coots and phalaropes. Note 

 the long slender wading legs of the sandpipers, snipe 

 and other shore birds ; the short heavy strong leg of the 

 divers; the small weak leg of the swifts and humming 

 birds, almost always on the wing; the stout heavily nailed 

 foot of the scratchers, as the hens, grouse, and turkeys; 

 and the strong grasping talons, with their sharp long 



