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 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 Cuculi. 

 comprise the hoopoes, horn-bills, 

 kingfishers, toucans, and cuck- 

 oos. These are succeeded by 

 the Cypseli, embracing the hum- 

 ming-birds, goatsuckers, swifts, 



nighthawk (Chordeiles Virginia-nils, 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 colubris 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 



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