LESSON 49.] NUTRITION IN BIRDS. 173 



Turtle (Fig. 278) well illustrates this fact. We here see the gastric 

 cells of the mucous membrane of large size, and the capillaries me- 

 andering on their surface in a tortuous direction. 



LESSOJST XLIX. 



NUTEITION IN BIRDS. 



757. In this class the alimentary apparatus is adapted for the 

 higher forms of animal and vegetable matter, which they obtain in 

 the air, in the waters, or on the earth. The jaws have their margins 

 covered with horny plates, like the Chelonian reptiles, which vary in 

 their forms according to the kind of food they are destined to 

 feed on. 



758. The broad, depressed bills of Ducks, Geese, Swans, and 

 many other aquatic birds, with dentated edges and soft, sensitive lips, 

 are well adapted for obtaining worms, and other small objects under 

 water or in mud. The flat, spatulate jaws of the Spoonbills are 

 adapted for quick, lateral motion in the water, and for extracting mi- 

 nute animals from the moist banks of lakes and rivers. 



759. The sub-maxillary pouch of the Pelican serves as a net for 

 seizing fishes ; the straight, sharp bills of Cranes and Storks dart 

 with precision through the water upon their moving prey, and the 

 long, compressed bills of Cormorants, Gulls, Albatrosses, and other 

 predaceous aquatic birds, terminate above in a sharp inverted hook, to 

 seiEe firmly the smooth, scaly bodies of fishes. The broad bills, with 

 cutting edges, of the Struthious (pertaining to the Ostrich, two- 

 toed) birds, are adapted to prune the leaves and shoots of plants, 

 and the long, narrow bills of Woodpeckers to be inserted into small 

 crevices to seize minute insects, and most of the insectivorous birds 

 have a similar structure on a smaller scale. 



760. The long, tubular beak of the Humming-bird is suited for 

 insertion into the corollas of flowers. In the Grosbeaks and Cross- 

 bills, the Sparrows and Buntings, and all the granivorous (feeders 

 on grain) order, and in the common poultry, the bills form stronger 

 and shorter cones, broader at the base, to break down and remove 

 the hard coverings of grain. In the climbing Cockatoos, Parrots, 

 and Maccaws, the broad and powerful bills serve as prehensile organs, 

 and to break the hard, shelly coverings of seeds. The bills of Eagles, 



