338 



COMPARATIVE ZOOLOGY. 



Fig. 324. — White-thi-oiited Sparrow (Zonotrichia 

 alWcollU). Uuited States. 



merous and varied in tlie whole class. It comprehends all 

 those tribes which live habitually among trees, excepting 



the Rapacious and 

 Climbing Birds, and 

 whose toes — three 

 in front, and one be- 

 hind — are eminently 

 fitted for perching 

 only. The legs are 

 slender, and seldom 

 used for locomo- 

 tion. 



They are divisible- 

 iiito two sections : 

 a. Clamatores, with 

 nothing in common 

 but a harsh voice. In 

 most, the tarsus is 

 enveloped in a row 

 of plates, which meet 

 behind in a groove, 

 and the bill broad, 

 and bent down ab- 

 ruptly at the tip. 

 Tlie typical repre- 

 sentatives are the 

 Tyrant Fly-catchers. 

 h. Oscines, or Song- 

 sters, all of whom 

 have a vocal appa- 

 ratus, thougli not 

 all sing. The an- 

 terior face of the 

 tarsus is one continuous plate, or divided transversely 

 into large scales ; and the plates on the sides meet be- 



PiG. 325.— Redstart {Setojiliaga rnticUla), 

 States. 



Uuited 



Fio. 326.— White-eyed Viieo (Vireo Noveboraoenaii). 

 United Stntes. 



