PERCHING BIRDS. 



551 



and the bill is straight and strong. The tongue is long, 

 flat, horny, and barbed at the 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 larvae of insects boring under 

 the bark ; in tnis 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 Guculij 

 comprise such forms as horn- 

 bills, kingfishers, toucans, and 

 cuckoos. These ai-e succeeded by 

 the Cypseli, embracing the hum- 

 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 {Trochilus coluhris Linn.) extending into the 

 Eastern United States, though a dozen or more species oc- 

 cur in the 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 



Fig. 475. — Nighthawk. — Prom 

 Tenney's Zoology. 



