USE OF THE KEYS. 33 
     
    
   
   
    
     the most highly developed ones, Thrushes, Bluebirds, etc. Two main 
     
     divisions are given: first, Water Birds; second, Land Birds. In no 
     
    
   
   
    
     (Bluebird, slightly reduced). 
     
    
   
   
    
     FIG. 2.—Topography of a bird. 
     
    
   
   
    
       
     
    
   
   
    
     case will it be difficult to decide in which of these groups a bird be- 
     
    

    
     longs. Now glance over the illustrations and select the one which 
     
    

    
     you think most» nearly resembles the bird you are identifying. At 
     
     4 l