490 PALMIPEDES. 



the toucli of its tongue. It thrusts its bill into the 

 niud just as a fisherman casts his net into the sea, 

 and brings up whatever it contains ; from this 

 mouthful of stuff it selects, by the tongue alone, 

 what is good for food, and everything else is re- 

 jected. The gizzard of the Anatidac is muscular, 

 and lined with a tough skin, so as to be able to 

 grind down the substances on which they feed. The 

 framework of the body of the Natatorial Birds is 

 differently constructed from that of the Terrestrial 

 Orders. In the aquatic tribes, the breast-bone and 

 ribs extend along the entire length of the thorax 

 and abdomen, and thus that part of them which is 

 in the water does not move in the act of breathing, 

 but remains perfectly steady. They are ribbed 

 much in the same way as the hull of a ship, and 

 any change of form which they undergo while swim- 

 ming takes place in that part of their body which 

 is raised above the water. Moreover, in their shape 

 these birds are fashioned in strict conformity with 

 the kind of life to which they are appointed. If their 

 principal occupation requires them to remain nearly 

 stationary, floating and dabbling in the water, their 

 body is shaped somewhat like a punt ; if they are 

 to fly rapidly through the air, their form is narrowed 

 posteriorly, as in the Terns, or Sea Swallows ; and 

 if destined to dive and shoot along wholly immersed 

 in the water, they taper towards the forepart, as 

 is exemplified in the Divers. 



The nests of the Anatidiie are generally placed 

 upon the ground, amidst coarse herbage, by the 

 bank of a lake or river ; they are principally com- 

 posed of grass and other vegetation, and lined more 

 or less carefully with down and feathers. 



To this family belong the Flamingoes, the Spur- 

 winged Gireese, the Geese proper, the Swans, the 

 River- Ducks, the Sea- Ducks, the Spine-tailed 

 Ducks, and the Mergansers. 



