18 FORM AND HABIT: THE WING. 



tabus). The young of this bird have well-developed claws 

 on the thumb and first finger, and long before they can 

 fly they use them as aids in clambering about the bushes, 

 very much as we may imagine the Archreopteryx did. 

 In the adult these claws are wanting. 



Some eminently aquatic birds, as Grebes and Pen- 

 guins, when on land, may use their wings as fore legs in 

 scrambling awkwardly along ; while some flightless birds, 

 for example, the Ostrich, spread their wings when run- 

 ning. 



But let us consider the wing in its true office, that of 

 an organ of flight, showing its range of variation, and 



finally its degradation into 

 a flightless organ. Among 

 flying birds the spread 

 wings measure in extent 

 Fio. 6,-Short, rounded win? and large from about three inches in 



foot of Little Black Rail, a terres- fl, crnnllfxit TTnrnrmnrrhirrl 

 trial bird. ('/ 5 natural size.) 



to twelve or fourteen feet 



in the Wandering Albatross. The relation between 

 shape of wing and style of flight is so close that if you 

 show an ornithologist a bird's wing he can generally 

 tell you the character of its owner's flight. The ex- 

 tremes are shown by the short-winged ground birds, 



Fio. 6. Long, pointed wing and small foot of Tree Swallow, an agrial bird. 

 ( 9 /6 natural size.) 



such as Rail, Quail, Grouse, certain Sparrows, etc., and 

 long-winged birds, like the Swallows and Albatrosses. 

 There is here a close and, for the ground-inhabiting 



