=The ostriches, cassowaries, etc. (Ratitæ).=--The ostriches, familiar to all from pictures and to some from live individuals in zoological gardens and menageries, or stuffed specimens in museums, together with a few other similar large species, are distinguished from all other birds by having the breast-bone flat instead of keeled. There are about a score of species of ostriches and ostrich-like birds all confined to the southern hemisphere. In them the wings are so reduced that flight is impossible, but the legs are long and strong, and they can run as swiftly as a galloping horse. They are said to have a stride of over twenty feet. They use their legs also as weapons, kicking viciously when angered. The true ostriches (_Struthio camelus_) (fig. 135) live in Africa. They are the largest living birds, reaching a height of nearly seven feet and weighing as much as two hundred pounds. They are hunted for their feathers, and are now kept in captivity and bred in South Africa and California for the same purpose. About five million dollars' worth of ostrich-feathers are used each year. The eggs, which are from five to six inches long and nearly five inches thick, are laid in shallow hollows scooped out in the sand of the desert. The male undertakes most of the incubation, although when the sun is hot no brooding is necessary. The young (fig. 136) hatch in from seven to eight weeks, and can run about immediately. [Illustration: FIG. 135.--Ostriches on ostrich farm at Pasadena, California. (Photograph from life.)] The rheas, found in South America, and the cassowaries of Australia are the only other living ostrich-like birds. Their feathers are of much less value than those of the true ostrich. [Illustration: FIG. 136.--Young ostriches just from egg; on ostrich farm at Pasadena, California. (Photograph from life.)] =The loons, grebes, auks, etc. (Pygopodes).=--The loons, grebes, and auks are aquatic birds, living in both ocean and fresh waters. Their feet are webbed or lobed, and their legs set so far back that walking is very difficult and awkward. But all the birds of this order are excellent swimmers and divers. They are distinctively the diving birds. They have short wings and almost no tail. The dab-chick or pied-billed grebe (_Podilymbus podiceps_) is common in ponds over all the country. Its eggs are laid in a floating nest of pond vegetation and are often covered with decaying plants. The horned grebe (_Colymbus auritus_) is common west of the Mississippi in lakes and ponds. The loon or great northern diver (_Gavia imber_), found all over the United States in winter, is the largest of this group, reaching a length (from bill to tip of tail) of three feet. It is black above with many small white spots, and with a patch of white streaks on each side of the neck and on the throat; it is white on breast and belly. The female is duller, being brownish instead of black.