Leaving the firm dry land, we next turn our attention to the marshes--the dubious confines between land and water--and here we find the order of WADERS, or, as they have been named on account of their long stilt-like legs, GRALLATORES or stilt-walkers. These birds, as their name imports, are characterised by the height of their legs, which are naked, and thus adapted for wading to a certain depth into the water, where many species catch their prey. A remarkable example is met with in this order of the facility with which difficulties, apparently insurmountable, in the adaptation of certain species to peculiar circumstances, have been encountered and overcome. In India, the tanks and ponds of considerable depth are more or less covered with the broad leaves of water-lilies and other floating vegetation. In such places, which are far too deep to be occupied by wading birds, and yet too extensive to be left without inhabitants, we find a family provided with toes so enormously lengthened, and moreover eked out by claws of such extraordinary length, that the spread of their feet extends over a very large surface, thus enabling them to walk over the floating weeds. Another order of birds comprehends those whose feet are specially constructed for swimming, constituting a NATATORIAL TYPE; for this purpose they are placed far back upon the body, the legs are short and compressed, and the toes are united by a web. Their plumage is thick and shining, impregnated with oil, and closely packed with soft down, so as to preserve them from all contact with the water. They are the only birds the length of whose neck much surpasses that of their legs, thus enabling them, while swimming at the surface, to obtain their food at the bottom. Such are the DUCKS and SWANS, which are, moreover, further characterised by having their bill covered with a soft skin, and furnished occasionally at the sides with ridges and tooth-like points. The DIVERS, trusting to their superior powers of battling with the watery element, are met with further from the shore; while, at distances still more remote from land, daring the utmost fury of the tempestuous ocean, walking upon the waters, or riding upon the seas-- "Up and down, up and down, From the base of the wave to the billow's crown, In the midst of the flashing and feathery foam, The Stormy Petrel finds _her_ home."