The bill is the most important organ of the four we are discussing. It has the offices of the hand. There is an almost limitless variation in its shape, admirably adapted in each instance to its food requirements. The fish-eating duck grasps its prey with a saw bill. The pelican catches its fish by diving from the air, often from distances of forty feet, and catches its fish in a bill an inch and a half in width. As it throws its head out in diving, it widens the rim of its bill and catches the prey in its curious pouch. The flamingo catches, with its food, mud and sand, which it expels through a curious straining apparatus. The woodcock has the power of curving up the upper portion of its bill, giving it the grasping power of a finger, which greatly aids it in probing for worms. The woodpecker uses its bill as a chisel. In southern Arizona the Californian woodpeckers have used the poles of the Western Union Telegraph Company in which to store acorns, and in some instances have bored large holes entirely through the poles. In those woodpeckers which feed on bark we find the tongue brush-like to swab up the sap. Where woodpeckers chisel the tongue is horny. In prying off cones from trees the cross-bill finds its apparently malformed tongue most helpful. In humming birds there is a marked variation in the bill, enabling them to feed on different sorts of flowers. The hurabird of New Zealand has the most curious bill known. The male has one sort which he uses in excavating, after which the female can insert her bill and secure the food which the male has thus obtained. After a study of the various forms of bird structure and habits has been made, it still remains a problem whether their structure is the result of natural selection, or natural selection is the result of their structure. WILSON'S THRUSH. (_Turdus fuscescens._) This very interesting bird is found in all parts of eastern North America. Breeds in the states bordering on the Great Lakes and as far north as Manitoba. It winters in Central America. It is generally partial to low, swampy woodlands. He is much more shy than his pretty cousin, the wood thrush; he lives nearer the ground and is not so likely to leave the cover of his haunts. In localities where he is equally common with the wood thrush he is less frequently observed. The nest of this thrush is made of strips of bark, rootlets and leaf stems, wrapped with leaves and lined with fine rootlets. The nest is always on or near the ground. Mr. Chapman says of him: "He has a double personality, or he may repeat the notes of some less vocally developed ancestor, for on occasions he gives utterance to an entirely uncharacteristic series of _cacking_ notes, and even mounts high in the tree to sing a hesitating medley of the same unmusical _cacks_, broken, whistled calls and attempted trills.