Adult Male.
Bill rather shorter than the head, nearly straight, rather slender, com- pressed. Upper mandible with its dorsal line straight to the middle, then curved and declinate, the ridge convex, the sides slightly convex, the edges sharp and inflected, the tip rather obtuse. Nasal groove rather long and narrow; nostrils in its fore part, longitudinal, sub-medial, linear, pervious. Lower mandible with a slight prominence at the end of the angle, which is long and narrow, the dorsal line then straight or slightly concave, the ridge convex, the sides nearly flat.
Head of moderate size. Neck short. Body rather slender. Wings very long. Feet of moderate length, rather strong; tibia bare below for a short space, covered behind with narrow scutella; tarsus compressed, anteriorly covered with numerous scutella and three inferior series of transverse scales, laterally with rounded scales, posteriorly with oblique scutella. Toes slender, scutellate above; first extremely small, second much shorter than fourth, third longest, anterior toes connected by reticulated webs, the outer and inner slightly marginate; claws small, compressed, obtuse, that of middle toe with an expanded inner edge.
Plumage close, soft, blended. Wings very long and pointed; primaries tapering and rounded, first longest, second almost equal, the rest rapidly graduated; secondaries obliquely pointed, the rounded extremity extending beyond the tip of the shaft, which is exterior to it, the inner feathers more elongated. Tail of moderate length, forked, of twelve feathers.
Bill black at the base for more than half its length, the rest pure yellow. Edges of eyelids vermilion, as is the inside of the mouth. Feet black. Head and upper part of neck all round blackish-grey, that colour terminated below by a ring of pure black encircling the neck. Lower neck all round, the whole lower surface, the upper tail-coverts and the tail, pure white. The back and wings are bluish-grey, excepting a large terminal portion of the secondaries, and the tips of the primaries, which are white, the primaries themselves being black, with their shafts brownish-black. The first quill of the specimen figured had no white on the tip, but some individuals differ in this respect.
Length to end of tail 13 inches, to end of wings 14|; extent of wings 33; wing from flexure lOf; tail 5; bill along the ridge 1, along the edges H; tarsus lfV; middle toe 1, its claw T 2 ? . Weight 7 oz.
The Female is rather less than the male, but in other respects similar.
