The second order includes the climbing birds, such as the woodpeckers. The birds of this order can readily be recognized, since two of the toes of each foot point backward, to give support in climbing. The next order, that of the perching birds, includes all our common song-birds, such as the robin, bluebird, and blackbird, as well as a few larger birds, like the crow. The scratching birds form another order, including our domestic fowls and many wild game-birds. The next order comprises the ostrich and a few other large birds, which have such small wings that they are unable to fly, but with very large and powerful legs, so that they are excellent runners. Although this order includes the largest bird at present living, there were formerly running birds very much larger than any which now exist; for, in Madagascar and New Zealand, the bones, and even the eggs, of gigantic birds have been found. One of these eggs was over a foot in length, and contained more than ten quarts or as much as six ostrich eggs or one hundred and fifty hen's eggs. A nearly complete skeleton of one of these birds has been found, and this must have belonged to a bird fifteen feet high, or taller than the largest elephant! The next order includes the wading birds such as the snipe, plover, woodcock, heron, and rail. Another order is that of the gulls, ducks, geese, pelicans, penguins, and other swimming birds. Besides these living birds, fossil birds have been found in the rocks. Some of these are very different from any species now living, and very much like reptiles, so that it is not easy to decide whether they are to be called birds or reptiles.