Xxli THE STORY OF THE BIRDS. 
animal, as shown by their teeth. Subsequent loss of teeth neces- 
sitated gizzard in grain eaters. Flesh eaters now do not need it. 
Various feeding habits noted. Peculiarities of Apteryz, snipe, 
and woodcock’s beak, rail form’s feet, penguin’s wings, geese 
form’s bill fringes, pelican’s sac, heron’s spear, and birds of prey’s 
talons, terribly hooked upper mandible, ete. 
For Study.—Note elevated rear toe out of the way in the 
scratching fowls and (in the market) the soft sensitive beaks of 
snipes and plovers. Note that birds with strongly decurved 
beaks are usually ground or water feeders. 
CuapTeR XXIII.—A bird’s implements are related to its habits; 
instance the bill of the Apferyx. Hxamples of habit preceding struc- 
ture and of structure inducing habit. Parrots, cuckoos, and wood- 
peckers as illustrations. Habits noted as compensating for defec- 
tive structure. Interesting and striking variation between swifts 
and humming birds. Various feeding habits. Habit away ahead 
of structure in the water ousels. 
for Study.—Note with a glass the outspread outer rear toe of 
woodpecker on atree trunk. Observe that a nuthatch head down- 
ward stretches a leg far back up the tree asa squirrel. Observe 
nutcrackerlike bill of parrot, and crushing and cutting form of 
cardinal’s bill—an extreme example of the seed-eating finch forms. 
CHapTteR XXIV.—Roosting with the breast on the perch or 
support is usual with most birds. Waders stand and hawk forms 
never squat. Some midocean haunters may sleep on the wing. 
Some aquatic birds sleep floating. Picarian birds sleep in holes 
often. Woodpeckers and swifts roost in an upright position, usu- 
ally in cavities. All birds using a perch strain the toe tendons in 
squatting till automatic clasping is effected. There are different 
methods of accomplishing this in different birds. 
Some parrots hang (head down) by one foot, some by both, and 
others hang by the beak. 
For Study.—Place the finger in the grasp of any freshly slain 
bird and bend the leg up to the body. Note the automatic clasp 
as the bird appears to squat. In such birds as sleep with head 
under the wing note if the right wing is used, since this is the 
position in the shell before hatching. 
Cuaprer XXV.—Toe arrangement and peculiarities very help- 
ful in diagnosing, but do not always indicate kinship. Various 
