68 



CLASS-BOOK OF ZOOLOGY. 



5th Order. — Long-legged Birds. 



Fig. 19. 



The African Ostrich. — (Struthio Camelus.) 

 6 th Order. — Swimming Birds. 



Fig. 20. 



The Canvass-back. — (Onas Vallisneria.) 



questions on sect. xm. 



§250. What are birds? 



§251. By what is the flying of birds facilitated? 

 §252. How is the formation of the bird's embryo effected? 

 § 253. In what time does the metamorphosis of an inanimate egg to 

 an animate being take place ? 

 § 254. What is the use of birds to man ? 



§255. Why are birds the greatest ornament in the Animal Kingdom? 

 §256. Into what Orders are birds divided? 



