Page:Natural History, Birds.djvu/45

32 feet, the large ears and eyes, as also the sort of disk that surrounds the face, and the saw-like edge of the first wing-quill, observable in some species, the downiness of the plumage, its sombre but varied hues, and their exquisitely mottled and pencilled arrangement, all form so many characters, which evidently point to the Nightjars as the connecting link between the Accipitrine and the Passerine Orders,

The Caprimulgidæ have the beak exceedingly small, but the gape enormous; its sides are for the most part furnished with long and stiff bristles, which point forwards, and the interior of the mouth is moistened with a glutinous secretion. All these provisions aid the capture of large insects in flight, which form the principal prey of these birds. The wings are long, and formed for powerful flight; the feet are very small, plumed to the toes, which are connected at the base by a membrane; even the hind toe, which is directed inwards, is thus joined to the inner toe. The claw of the middle toe, in most of the genera, is dilated on one side, and its edge is cut into regularly formed teeth, like those of a comb.

The voices of the Nightjars, like those of the Owls, are often harsh and uncouth; but their utterance frequently possesses a vibratory or quivering character that is peculiar. "With a single exception, they are nocturnal in their activity. Their eggs are laid on the ground, with but a slight mat of loose materials in place of a nest. The species are widely spread; and some of those which inhabit tropical countries have remarkable appendages to some of their feathers.