Architecturally, the Ostrich House is the counterpart of the Small-Mammal House, the two being identical in size and form, and connected by a handsome pavilion. Each building is 170 feet long, and 54 feet wide. The Ostrich House contains 13 cages, each 10×12 feet, by 8 feet in height. A flood of warm light pours through a glass roof into these cages, and makes them as light as the yards without. It is no wonder that birds thrive in this building. Movable partitions were provided, so that a few of the cages might be subdivided whenever necessary. This provision has proven of much practical value. Each interior cage connects with a spacious outside yard, in which the big birds spend the warm months. The yards are enclosed by wire fences, and to the eye of the visitor they are open from three directions. The members of the Subclass _Ratitae_,—once called the Cursores, or the “running birds,”—are the present-day giants of the avian world. We have reason to be glad that all these splendid birds did not disappear from the earth before ornithology took form as a science. Undoubtedly, they mark the end of the line of birds of their kind, for the far-reaching destructiveness of civilized man has already put a period to the natural evolution of animal life. To-day, the preservers of wild life are engaged in a hand-to-hand struggle with the annihilators, over the preservation of a remnant for those who come after us. The African Ostriches are now very prominently in the public eye, not because of their relationship to the Dinornis and Aepyornis of the past, but by reason of the value of their plumes in enhancing the attractiveness of woman. And surely, no plume-bearing bird ever enlisted in a better cause, or on a more satisfactory basis; for to-day the plume crop is being grown and plucked and marketed with almost as much certainty as the annual crop of wool. In the United States, the most important plume-producing ostrich farms are situated in southern California and Arizona, where the industry is quite successful. So valuable are the adult birds that it is possible to purchase specimens imported from Africa for less money than would be necessary to procure them in the United States. [Illustration: NORTH AFRICAN OSTRICH: MALE.] A full-grown male African Ostrich stands 8 feet in height, and weighs about 300 pounds. Its value on arrival in New York, before acclimatization and moulting into perfect plumage, is from $200 to $250. The female lays about 90 eggs in a year, each of which is equal to about 20 hen’s eggs. The time of incubation is about 40 days. In captivity only about 60 per cent of the eggs hatch, and of those not more than one-half live to attain full maturity. The plumage of immature birds and adult females is gray, but that of the adult male is black on the body, and white on the wings and tail.