﻿EXTERNAL ANATOMY. 



19 



passes into one that is insessorial. The parrots and the 

 woodpeckers unquestionably follow each other ; the one 

 being typical, the other subtypical, of the scansorial tribe. 

 We should much have wished, in this place, to have 

 shown how beautifully the primary orders of birds re- 

 present the primary orders of insects ; but as our theory 

 on the annulose animals has not yet been laid before 

 the scientific world, and would require to be accompa- 

 nied with ample details, in support of the novel views 

 it contains, we must reserve this comparison for a sub- 

 sequent volume. 



CHAP. II. 



ON THE EXTERNAL ANATOMY OF BIRDS IN REFERENCE TO THEIR 



HABITS AND ECONOMY. ON THE PARTS OF A BIRD. 



CRESTS, EYES, EARS, TONGUE, MOUTH, BILL. 



(23.) Before we enter into further details on Sys- 

 tematic Ornithology, let us for a while contemplate the 

 different modifications of form which belong to birds 

 in general ; and trace how far these variations effect cor- 

 responding ones in their food, habits, and economy. It 

 might be thought, at first, that this inquiry should have 

 preceded the exposition of the primary orders contained 

 in the last chapter ; but, as we shall frequently have 

 to mention the names of those types and divisions which 

 have been just explained, it is clear that our present 

 disquisition would have lost half its interest, had not the 

 reader been first put in possession of the meaning of 

 those terms which it is absolutely necessary for us here 

 to use. The student will therefore do well to peruse 

 the last chapter with attention, before he enters upon 

 this. 



(24.) Comparative anatomy regards two distinct por- 

 tions of the structure of an animal, — its inward and its 

 c 2 • 



