Near the lower end of Bird Valley, as a sort of climax for the Goose Aviary when seen from the north, rises a lofty, web-like structure, in the form of a huge, gothic arch. It is 55 feet in height, 75 feet wide, and 152 feet long. The whole structure consists of a series of steel-pipe arches and purlins, the former eight feet apart, over which wire-netting has been tightly stretched. The wire-netting seems peculiarly open. It is of the kind known as chain-netting, which offers the least possible obstruction to the eye. This cage is so large that a very respectable block of houses, three stories high and of ample dimensions, could stand within it without touching the wire. It completely encloses three forest trees of very considerable size, two hickories and an oak; and it contains a pool of water a hundred feet long, and shrubbery in abundance. [Illustration: CEREOPSIS GEESE.] The idea of a very large cage for herons and egrets, is not new, for there are in existence several other flying cages, somewhat smaller than this. The first was erected in the Rotterdam Zoological Garden by its Director, the late Dr. A. Von Bemmelin, whose experiment proved very successful. Others are at London and in Paris Jardin d’Acclimatation. The Flying Cage is the summer home of a mixed flock of such large and showy water birds as are most inclined to fly about within it, and afford students and the public an opportunity to study their movements and attitudes. Save for such allowances as must be made for accidents and epidemics, this enclosure will contain the following noteworthy species, along with others of less importance: The American Flamingo, (_Phoenicopterns ruber_), is, in appearance, a connecting link between the herons and ducks, resembling the former in the great length of its legs, and the latter in the duck-like bill and webbed feet. When the plumage of this species is perfect, it is of a beautiful scarlet color throughout, excepting the primaries, which are black. In captivity, the color fades somewhat. This bird is found in the Bahama Islands and Cuba, but in Florida, where once it was fairly numerous, it no longer exists. Fortunately, this remarkable bird takes kindly to captivity, and the Zoological Park is never without a good-sized flock. Their strange form, showy colors and droll attitudes render them unusually interesting to visitors. [Illustration: WHITE-FACED GLOSSY IBIS.] [Illustration: ROSEATE SPOONBILL.] With the birds of the above species are shown a few specimens of the European Flamingo, (_P. roseus_), which is almost white. The only parts which show the characteristic scarlet of this genus, are the wing coverts, which are pale red, or pink.