18 



FORM AND HABIT: THE WING. 



The young of tins bird have well-developed claws 

 on tlie tliumb and first finger, and long before tliey can 

 fly they nse them as aids in clambering abont the bushes, 

 very much as we may imagine the Archfeopteryx 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 ofiice, 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 

 from about three inches in 

 the smallest Hummingljird 

 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, 



Fig. 5.— Short, rounded win^ and largi 

 foot of Little Black Kail, a terres 

 trial bird. (Vs natural size.) 



Fig. 6.— Long, pointed wing and small foot of Tree Swallow, an aerial bird. 

 (3/6 natural size.) 



such as Eail, Quail, 'Grouse, certain Sparrows, etc., and 

 lons-wino-ed birds, like the Swallows and Albatrosses. 

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



