240 



GENERAL BIOLOGY 



tions, and to take on structural peculiarities suited thereto. 

 The phylogenetic lines radiate outward, as it were, from 

 common structural type, into forms adapted to herbiv- 

 orous or car- 

 n i v o r o u s 

 aerial or aqua- 

 tic, or other 

 more special 

 modes of life. 

 Feeding and 

 locomotion 

 are the two 

 general ani- 

 mal functions 

 that require 

 the most 

 special tools 

 (fig 148). The 

 accompa ny - 

 ing marginal 

 figures will 

 serve to 

 bring to mind 

 how very di- 

 verse are two 

 such organs, 

 beak and feet, 

 in birds. Any 

 dominant 

 major divis- 

 ion of the 

 animal king- 



FIG. 148. Beak and feet of common birds, typifying their respective families. 

 a, hawk; b, grouse; c, catbird; d, woodpecker; e, sandpiper. /, duck 



