146 



THE WONDERS OF GEOLOGY. 



Lect. II. 



they are widely different, for its talons are constructed to 

 lacerate and tear its prey {fig. 4). The feet of aquatic 

 birds are formed like a paddle or oar, to enable them to 



Lign. 23. — Different forms of feet in birds. 



Fig. 1. Foot of the Heron; Fig. 2. of the Ostrich ; Fig. 3. of the Parrot ; 

 Fig. 4. of the Eagle; Fig. 5. of the Pelican. 



make their way through the water {fig* 5); those of birds 

 that frequent marshes have a great expansion, like a tripod, 

 that they may move over the unstable surface of the morass 

 {fig. 1) ; while in species destined to inhabit sandy deserts, 

 as the Ostrich {fig. 2), the feet present a corresponding 

 modification of structure. 



We perceive, therefore, that every vertebrated animal 

 has a solid and durable skeleton, or osseous support, formed 

 upon one general plan, but modified in almost endless 

 variety, in the relative magnitude, situation, and aspect of 

 the different parts, so as to adapt itself to the various habits 



