536 CLASS AVES. 



to the touch, the debris of insects, the small white and crys- 

 talline stones, and the slimy sediment which the viscera 

 usually contained, led to the presumption that the nvitriment 

 of these birds consisted in fish-spawn, in small worms, and 

 aquatic insects, with which they sometimes swallowed small 

 stones or mud. This conjecture becomes extremely probable 

 on a consideration of the habits of the bird. Its bill, whose 

 form appears so singular, has, in fact, some advantages for 

 searching in the sand, where its extremity, almost membranous, 

 causes a perception in the animal of the qualities of the matter 

 which it touches, and enables it to seize the small animals, 

 which it recognizes by their softness. The horizontal flatness of 

 the mandibles, advantageous for side movements, wovild prove 

 an obstacle in this case, if the bird should raise up, perpendicu- 

 larly, the broad surface of the bill covered with sand ; but 

 this action is performed with facility by means of its sharp edge, 

 and the bird always draws out its bill on the right or left, with- 

 out being obliged to change place. Its progress, in fact, may be 

 traced on the sand by the series of semicircles which it leaves 

 after it. As the bottom, which it is continually sounding, 

 has but little tenacity, its bill, whose consistence may be 

 compared to that of the beak of the whale, is more fit for its 

 intention than if it were osseous. Flexibility and suppleness 

 are usefully substituted for strength, which in this case is less 

 necessary, as the avoset can run upon a soft and slimy bottom, 

 covered by five or six inches of water, by means of its long 

 legs. Nature, who would appear on a superficial view to 

 have treated this bird so ill, has again supplied it with 

 another means of facilitating its search for subsistence over a 

 larger space, by supplying it with webbed feet, by the aid of 

 which it can swim when it traverses deeper places, or seize 

 the spawn as it floats along the surface of the water. If the 

 bill of the avoset is useless for defence, the same is the case 

 with many other birds that have this organ more naturally 



