THE ENGLISH SPARROW AND ITS ALLIES 807 



powerful fliers and swimmers, which are found in the 

 lakes of the Northern Hemisphere. They are quick 

 divers, and can swim under water for a considerable 

 distance. 



The order of Cursores includes the African ostrich, the 

 American ostriches or rheas, the cassowaries of the East 

 Indies, and certain wingless birds of New Zealand (Ap- 



FKJ. 292. Common tern (Sterna hirundo}. 



teryx *) . These are regarded as the most lowly developed 

 of the birds ; the vanes of their feathers are not united, 

 but separate to form a sort of hair-like covering to the 

 body. The African ostrich is the largest living bird. It 

 wanders in families or flocks in the deserts of Africa, and 

 feeds on grass, grain, and small animals. It also swallows 

 undigestible matters, such as stones, which probably aid 



i Fig. 293. 



