OF BIRDS. U 



itronger than the rest; the hind toe is sometimes wanting 

 This oriier contains the ostrich family, the bustards and 

 ploYers ; the cranes, herons, and storks ; and the snipes and 

 woodcocks. 



6. Palmipedes, or web-footed birds. These birds have 

 the legs and feet short, and placed behind, with their fore 

 toes united by a thick and strong membrane. The neck is 

 much longer than the legs, and their bodies are covered 

 with a dense layer of down, beneath the outer plumage, 

 which is close, and imbued with an oily fluid that repels the 

 water. The principal birds in this order are the coots and 

 grebes, the auks and penguins, the petrels, the pelican and 

 cormorant, and the swans, ducks, and geese. 



Not only does the form of the bird fit it for flying, but 

 its lungs are extended by means of air-cells extending among 

 the muscles; and its bones are hollow, and not filled with 

 marrow, but with air. Other circumstances in their internal 

 structure serve to fadilitate the flight of birds, and to make 

 them quite at ease when on the wing. 



In variety birds far exceed quadrupeds. There are many 

 thousand species, distinguished from each other by diffep* 



