. 98 STRUCTURE OF BIRDS. 



Those that live in trees, and spend their time on 

 land, have the toes separate ; as the sparrow, the 

 linnet, and the canary; whilst the goose, the duck, 

 the swan, and other waterfowl have their toes 

 connected by a membrane or web, and are hence 

 called web-footed. This web enables them to 

 swim readily and quickly, as it offers a wide sur- 

 face to T he water, and serves as a broad oar. 



The feathers of birds are of very curious con- 

 struction, and have a series of webs or beards, one 

 lying over the other so as effectually to keep out 

 moisture, and forming a complete dress. To assist 

 in keeping the body dry, birds are also provided 

 with a gland or little bag, seated near the tail, from 

 which they procure a supply of oil to smear over 

 their feathers, and thus allow the water to run off 

 without penetrating. 



Questions. 



What is particular in the structure of birds 1 



In what way are their feathers arranged*? 



In what part is a bird provided with powerful muscles 1 



What are the uses of these ? 



What is peculiar about the lungs of birds 1 



Do they differ in this respect from the mammalia'? 



Do some birds swallow their food whole 1 



Does it then pass at once into the stomach or gizzard ? 



What is the name of the pouch into which it is received ? 



What difference is there in the toes of land and water birds T 



How are birds protected from wet 1 



