In the Passerine order, not the least remarkable displays are witnessed in birds that are not accounted songsters, as they do not possess the highly developed vocal organ confined to the suborder Oscines. The tyrant-birds, which represent in South America the fly-catchers of the Old World, all have displays of some kind; in a vast majority of cases these are simply joyous, excited duets between male and female, composed of impetuous and more or less confused notes and screams, accompanied with beating of wings and other gestures. In some species choruses take the place of duets, while in others entirely different forms of display have been developed. In one group--Cnipolegus--the male indulges in solitary antics, while the silent, modest-coloured female keeps in hiding. Thus, the male of Cnipolegus Hudsoni, an intensely black-plumaged species with a concealed white wing-band, takes his stand on a dead twig on the summit of a bush. At intervals he leaves his perch, displaying the intense white on the quills, and producing, as the wings are thrown open and shut alternately, the effect of successive flashes of light. Then suddenly the bird begins revolving in the air about its perch, like a moth wheeling round and close to the flame of a candle, emitting a series of sharp clicks and making a loud humming with the wings. While performing this aerial waltz the black and white on the quills mix, the wings appearing like a grey mist encircling the body. The fantastic dance over, the bird drops suddenly on to its perch again; and, until moved to another display, remains as stiff and motionless as a bird carved out of jet. The performance of the scissors-tail, another tyrant-bird, is also remarkable. This species is grey and white, with black head and tail and a crocus-yellow crest. On the wing it looks like a large swallow, but with the two outer tail-feathers a foot long. The scissors-tails always live in pairs, but at sunset several pairs assemble, the birds calling excitedly to each other; they then mount upwards, like rockets, to a great height in the anand, after wheeling about for a few moments, pro-cipitate themselves downwards with amazing violence in a wild zigzag, opening and shutting the long tail-feathers like a pair of shears, and producing loud whirring sounds, as of clocks being wound rapidly up, with a slight pause after each turn of the key. This aerial dance over, they alight in separate couples on the tree tops, each couple joining in a kind of duet of rapidly repeated, castanet-like sounds.