SECTION III. 



THE CLASS OF AVES OR BIRDS. 



* 



SUB-SECTIOX I. 

 BIRDS CONSIDERED AS A CLASS. 



ALL of the egg-laying or oviparous vertebrates which are 

 clothed with feathers and organized for flight belong to 

 the Class of Birds one of the most interesting and one 

 of the best defined groups in the Animal Kingdom. 



The feathers of Birds do not grow from the entire sur- 

 face of the body, but are symmetrically and systematical- 

 ly arranged in rows and patches, with bare intervening 

 spaces ; they overlap one another, however, so as in most 

 cases to cover the whole body. 



The wings are furnished throughout the whole length 

 with a range of qnills, thus presenting a great surface to 

 the air. 



Birds are furnished with a bill, and their neck is so long and flexi- 

 ble that with the bill they can touch every part of the body. They 

 have only two feet, the forward locomotive members being modified 

 for wings. 



In some species the wings are not sufficiently developed to serve 

 the purpose of true flight ; yet even in these cases they greatly assist 



