ORGANS OF DIGESTION. 397 



other vertebrated animals. The broad depressed bills of 

 ducks, geese, swans, and many other aquatic birds, with den- 

 tated edges, and soft sensitive lips, are well adapted for ob- 

 taining worms or other small objects under water or in mud, 

 and they commonly present a well marked dental distribu- 

 tion of the alveolar nerves and blood-vessels, as well as a 

 high development of the second and third branches of the 

 trigiminal nerves. The flat spatulate jaws of the spoon-bills 

 are adapted for quick lateral motion in the waters, and for 

 extracting minute animals from the moist banks of lakes and 

 rivers. The submaxillary 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, 

 albatroses, and many predaceous aquatic birds, terminate 

 above in a sharp inverted hook, to seize firmly the smooth 

 scaly bodies of fishes. The broad bills, with cutting edges, 

 of the strutheous 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 order of birds have a similar struc- 

 ture on a smaller scale. The long tubular beak of the hum- 

 ming birds is suited for insertion into the corollse of flowers. 

 In the grosbeaks and crossbills, the sparrows and buntings, 

 and all the granivorous order, and in the larger gallinaceous 

 birds the bills form stronger and shorter cones, broader at 

 the base, to break down and remove the hard coverings of 

 grains. In the climbing frugivorous 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 and vultures, hawks and owls, and other rapa- 

 cious birds, are strong, short, compressed, arched, curved at 

 the point, dense in their texture, and with sharp cutting 

 edges, to seize, and tear, and cut the flesh of living prey. 

 So that the forms of these external parts correspond with 

 and indicate the structure of the internal organs of digestion, 

 and afford useful zoological characters for the divisions of 

 this class. The tongue, chiefly composed of a loose cellular 

 texture, is here as variable in form and adaptations as the 

 bill, or the claws, or the food, being long and filiform, like 

 that of an ant-eater, in the woodpeckers, short and muscular 



