PERCHING BIRDS. 581 
and the bill is straight and strong. The tongue is long, 
flat, horny, and barbed atthe end, and can be usually darted 
out with great force, so that the bird can make holes in the 
bark of trees and draw out the larve of insects boring under 
the bark ; in this way these birds render us signal service. 
The tongue, as in all vertebrates, is supported by the hyoid 
apparatus, especially by two cartilaginous appendages to the 
hyoid bone, called ‘‘ the horns.’’ These in the woodpeckers, 
when fully developed, are curved into wide arches, each 
horn making a loop down the neck, and thence bending 
upward, sliding around the 
skull, and even down on the 
forehead. Through a peculiar 
muscular arrangement of the 
sheaths in which the horns slide, 
they can be retracted down on 
the occiput, and work as springs 
on the base of the tongue, forc- 
ing it out with great velocity. 
Lindahl has noticed in some 
European woodpeckers an asym- 
metric arrangement of the horns 
as indicated in Fig. 474. 
The second group, the Cucult, 
comprise such forms as horn- 
bills, kingfishers, toucans, and 
cuckoos. These are succeeded by 
the Cypseli, embracing the hum- Cae 
ming-birds, goatsuckers, swifts, 
nighthawk (Chordeiles Virginianus, Fig. 475), and whip- 
poorwill, which have long pointed wings, great powers 
of flight, small weak feet, and, in the humming-birds, 
long slender bills. The latter are peculiar to America, 
being chiefly confined to South and Central America, only 
one species (Zrochilus colubris Linn.) extending into the 
Eastern United States, though a dozen or more species oc- 
cur inthe Western United States, and very many in Mexico. 
The highest group of birds, those which sing, are the 
Passeres or perchers. In these birds the feet are adapted for 
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