410 



ZOOLOGY. 



Division II. Carinatcc. Birds with the keeled breast bone, 

 the wings, and the other organs of flight usually well devel- 

 oped. Barbs of the feathers have barbules. All the modern 

 flying birds are embraced in this subclass. 



The further subdivisions of the Carinatse, as given in the 

 recent classifications, based upon internal structure, are entirely 

 unsuited for beginners. An older arrangement of the prin- 

 cipal orders, based upon habits and certain superficial features, 

 is presented below for the convenience of the student. It 

 should be remembered however that the classification is not 

 the best possible, inasmuch as forms in reality not very closely 

 related in structure are, according to it, placed together because 

 of similar habits. 



FIG. 211. 



FIG. 211. Green Heron (Ardea virescens). Photographed by Dr. R. W. Shufeldt. 



Questions on the figure. To what order of birds does the heron be- 

 long? What are its nearest relatives? What can you say of the habits 

 of the order? 



