Bill rather shorter than the head, nearly straight, moderately stout, compressed. Upper mandible with its dorsal outline straight to the middle, then curved and declinate, the ridge convex, the sides rapidly sloping, the edges sharp and direct, the tip rather obtuse but sharp-edged. Nasal groove rather long and narrow; nostrils in its fore part, longitudinal, submedial, large, linear-oblong, broader anteriorly, pervious. Lower mandible with the angle long and pointed, the outline of its crura decurved anteriorly, that of the ridge slightly concave and ascending, the sides erect and nearly flat.
Head of moderate size. Neck of ordinary length. Body compact. Feet rather long, stoutish; tibia bare below for three-fourths of an inch, covered behind with narrow scutella; tarsus compressed, anteriorly covered with numerous curved scutella, laterally with small oblong scales, posteriorly with small scutella. Toes slender, of moderate length, covered above with numerous scutella; first extremely small, second much shorter than fourth, third two-twelfths of an inch longer than the latter; anterior toes connected by reticulated webs, the outer and inner slightly marginate; claws small, slightly arched, compressed, thin-edged, that of the middle toe with an expanded inner margin.
Plumage close, soft, and blended. Wings very long and pointed; primaries tapering to a rounded point; first longest, second a twelfth of an inch shorter, the rest rapidly diminishing; secondaries broad, incurvate, and obliquely rounded, the inner straight and more elongated. Tail of moderate length, even, of twelve broad, rounded feathers.
Bill and feet, as well as the margin of eyelids, and the inside of the mouth, of a rich deep carmine; claws brownish-black. Iris bluish-black. The head and a portion of the upper part of the neck all round, blackish lead-grey, darker on the upper part of the head and along the posterior margin, which descends lower in front, or to the extent of about two inches and a half from the base of the lower mandible; two narrow white bands bordering the upper and lower eyelids. Lower neck all round, the whole lower surface, the rump and tail, pure white; but the fore part of the neck and the breast, down to the legs, of a beautiful light rosy tint. The back and wings are greyish-blue, with a very slight tinge of purple, excepting a large terminal portion of the secondaries, and the tips of the primaries, which are white. The first primary is black, with a tinge of grey on the inner web at the base; the second and third similar, with the grey more extended; on the fourth it extends over two-thirds; the fifth is black only for an inch and a half; and on the sixth the black is reduced to two spots near the end; the other parts and the remaining primaries of the same general colour as the back.
Length to end of tail 17 inches, to end of wings 20, to end of claws 17; extent of wings 40 3/4; wing from flexure 12 10/12; tail 5 2/12; bill along the ridge 1 11/12, along the edge of lower mandible 2 1/4; tarsus 2; hind toe and claw 4/12; middle toe and claw 1 9/12; outer toe and claw 1 1/2; inner toe and claw 1 3/12.
The female is precisely similar to the male, but considerably smaller.
In winter the head is white, the feathers on its upper part and on the nape more or less brownish-grey in their concealed part, that colour appearing in slight patches here and there, and especially along the posterior margin of the part that is coloured in summer, as well as on a small space before the eye. The rosy tint of the breast disappears after the breeding season. In other respects the plumage is as in summer.
Young fully fledged. Plate CCCXIV. Fig. 2.
Bill, feet, inside of mouth, and edges of eyelids, olivaceous brown. The upper parts are brownish-grey, the feathers edged with paler; the hind part of the back light bluish-grey; upper tail-coverts nearly white; tail pale greyish-blue, with a broad band of brownish-black at the end, the extreme tips narrowly edged with white, the outer margin of the lateral feathers of the same colour. The first four primaries are destitute of white at the tip. A smaller patch before the eye, two slight bands on the eyelids, and the throat, greyish-white; the lower part of the neck brownish-grey, the rest of the lower parts greyish-white, the sides darker, the axillars ash-grey, the lower surface of the wing dusky-grey.
In an adult male, the tongue is 1 1/4 inch long, slender, tapering, emarginate at the base, with minute papillæ, the tip horny along the back. The œsophagus is 6 1/2 inches long, 5 twelfths in diameter until it enters the thorax, then dilates to 1 inch and 5 twelfths; its walls are extremely thin, its inner coat longitudinally plaited. Proventriculus very short, the belt of oblong glandules being only 7 twelfths in breadth. Stomach rather small, oblong, 1 1/2 inch long, 10 twelfths broad; its lateral muscles rather thick, the tendons large; the inner coat thick, horny, and thrown into very prominent longitudinal rugæ, its upper margin abrupt, and manifestly not continuous with the inner coat of the proventriculus, as some have supposed the epithelium to be in all birds. In the stomach remains of fishes. Intestines 1 foot 9 1/2 inches long, its general diameter 1/4 inch. Rectum 1 1/2 inch; cœca extremely small, 2 1/2 twelfths long, 1/2 twelfth in diameter.