Bill about the same length as the head, rather slender, compressed, nearly straight, tapering to a narrow point. Upper mandible with the dorsal line slightly arched, the ridge rather broad and convex at the base, narrow towards the end, the sides sloping, convex towards the end, the edges sharp and inflected, the tip very slender. Nasal groove rather long, and with a faint groove and ridge extending obliquely to the edge of the mandible; nostrils sub-basal, linear, direct, pervious. Lower mandible with the angle very narrow, extending beyond the middle, the dorsal line straight, the sides ascending and convex, the edges sharp and inflected, the tip very acute. Head of moderate size, oblong; neck of moderate length; body very slender. Feet very small; tibia bare for a considerable space; tarsus very short, slender, compressed, covered anteriorly with twenty-two small scutella, laterally and behind with reticular scales; toes very small, slender, the first extremely small, the third longest, the fourth considerably shorter, the second shorter than the fourth in the same proportion; the anterior toes connected by reticulated webs, which are deeply concave at their margin. Claws arched, compressed, that of the hind toe smallest, of the middle by much the largest, and having the inner edge thin and dilated. Plumage soft, close, blended, very short on the fore part of the head; the feathers, in general, broad and rounded; wings very long, narrow, and pointed; primary quills tapering to a rounded point, slightly curved inwards, the first longest, the rest rapidly graduated; secondary quills short, broad incurved, obliquely rounded, the inner more tapering. Tail long, very deeply forked, of twelve feathers, of which the outer are tapering, the middle short and rounded.