So far the displays which have been described have been such as are confined to the use of more or less resplendent plumage. There are, however, many species which contrive to secure most startling results, not so much by the parade of coats of many colours as by grotesque changes of shape produced by wind-bags of various kinds. The Pouter-pigeon affords a case in point. This bird possesses the power of inflating the gullet to an enormous size, so as to produce a strangely distorted form, at any rate, to our eyes. The “Pouter,” it is hardly necessary to mention, is an artificial product of the “fancier,” who has taken advantage of the natural tendency, seen in the Wild Pigeon, to inflate the neck during moments of excitement. By the selection from each generation of the finest performers in his stock, the Pouter of to-day has been developed. But there are many birds which, while not even remotely related, have developed the same strange device. The most striking illustration of this kind is furnished by the Great Bustard, a bird once common on the fen-lands of Great Britain, but now, unhappily, exterminated within these islands. The means of inflation in this case is afforded by a large thin-walled sac of a very remarkable character. Opening by a small slit just under the tongue, it is continued down the front of the neck immediately under the skin, which in this region is thickened by an accumulation of fat and blood-vessels. Between the arms of the furcula, or merry-thought, its cavity is constricted, to expand again immediately to form a pear-shaped termination. How it is filled is something of a mystery. But once inflated, the bird draws its neck downwards and backwards, so that the head is brought to rest between the shoulders and is there almost buried, partly by pressure on this curious air-cushion and partly by the erection of a number of bristle-like feathers, which in calmer moments project backwards on each side of the head. At the same time the tail is drawn forwards to lie upon the back, thus exposing a billowy mass of white feathers forming the under tail-coverts. The tips of the wing-feathers are used to hold the tail in position. Meanwhile the scapulars are set on end, and the long inner secondary quills are similarly erected. The feathered contortionist, having completed his preparations, now approaches his partner with a mincing gait, then halts before her and solemnly utters a series of low grunts like “oak, oak, oak.” Having thereby declared his passion, and commonly without gaining any answering response, he returns to his normal shape again!