CHAPTER XIII 

 BIRDS 



SUGGESTIONS. The domestic pigeon, the fowl, and the English 

 sparrow are most commonly within the reach of students. The 

 last bird has become a pest and is almost the only bird whose 

 destruction is desirable. The female is somewhat uniformly mot- 

 tled with gray and brown in fine markings. The male has a black 

 throat with the other markings of black, brown, and white, in 

 stronger contrast than the marking of the female. As the different 

 species of birds are essentially alike in structural features, the direc- 

 tions and questions may be used with any bird at hand. When 

 studying feathers, one or more should be provided for each pupil 

 in the class. The feet and bills of birds should be kept for study. 



Does the body of the bird, like the toad and turtle, have 



a head, trunk, tail, and two pairs 

 of limbs ? Do the fore and hind 

 limbs differ from each other more or 

 less than the limbs of other backboned 

 animals ? Does any other vertebrate use 

 them for \ purposes as widely different ? 



Eye. *\ Does the eyeball have parts corresponding 

 to the eyeball of a fish or frog; viz., cornea, iris, pupil? 

 Which is more movable, the upper or lower eyelid? Are 

 there any lashes ? The bird (like what other animal?) has 

 a third eyelid, or nictitating membrane. Compare its 

 thickness with that of the other lids. Is it drawn over 

 the eyeball from the inner or outer corner of the eye ? 

 Can you see in the human eye any wrinkle or growth 

 which might be regarded as remains, or vestige, of such a 

 membrane ? 



