CHAPTER II 



THE ANATOMY OF BIRDS 



BY FREDERIC A. LUCAS 



HERE are, broadly speaking, two sets of characters to be found in the 

 skeleton of any animal. There are, first, those which bear a direct 

 relation to its position in the class of vertebrates, bear witness to its 

 origin and relationship, and are shared to a greater or less extent 

 by every member of the group to which it belongs. These are termed structural 

 or morphological characters. 



There is also another set of characters which are connected with the animal's 

 habits or mode of living and are believed to have been acquired during the de- 

 velopment of the species, and are called secondary or teleological. It is owing to 



FIG. 6. Wing bones of a Bat. 



FIG. 7. Wing bones of a pterodactyl. 



the fact that the skeleton is influenced by these two great factors that it is possible 

 to tell from the skeleton, or even from parts of it, not only what position the animal 

 holds in the scale of life, but what were its habits as well. So the modifications 

 of a bird's skeleton are primarily morphological, those due to the fact that it is a 

 bird, but these are associated with others rendered necessary by the adaptation 



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