CLASS AVES 



617 



and murres (Alcid^e), use their wings effectively in diving be- 

 neath the waves. 



Among the flightless birds belong a number of terrestrial 

 species, like the ostrich (Fig. 480), rhea (Fig. 481), emeu (Fig. 482), 

 and kiwi (Fig. 485). These birds all possess the remnants of 

 wings, but these are, for the most part, of no use in locomotion, 

 and in some (Fig. 485) are practically concealed beneath the 



Fig. 505. — A, lyre-bird, Menura superba. (From Evans.) B, bird of 

 paradise, Paradisca rubra. \From Brehm.) 



feathers. Their legs are, on the other hand, very well developed, 

 and quickly carry them out of danger. 



The primitive use of wings was for climbing. Archceopteryx 

 (Fig. 477) was provided with three strong claws on its fore limbs. 

 Of living birds the young of the hoactzin, a peculiar bird inhabit- 

 ing South America, should be mentioned, since it is able to climb 

 about before it can fly, by the aid of two claws on each fore 

 limb. 



Wings may also serve as organs of offense and defense, or as 

 musical instruments; for example, the " drumming " of the ruffed 

 grouse. 



Tails. — During flight the tail acts as an aerial rudder, and 

 a long-tailed bird is able to fly in short curves, or follow an 



