Adult Male. Plate CCCLXXXI. Fig. 1.
Bill about the length of the head, much higher than broad at the base, somewhat conical, compressed, rounded at the tip. Upper mandible with the dorsal line sloping, the ridge broad and flattened at the base, narrowed towards the unguis, which is roundish and very convex, the edges beset with compressed, hard teeth-like lamellæ, their outline ascending and slightly arched; lower mandible ascending, nearly straight, the angle long and of moderate length, the dorsal line beyond it convex, the sides erect, and beset with lamellæ; similar to those of the upper, but more numerous, the unguis obovate and very convex. Nasal groove oblong, parallel to the ridge, filled by the soft membrane of the bill; nostrils medial, lateral, longitudinal, narrow-elliptical, open, pervious.
Head of moderate size, oblong, compressed. Neck rather long and slender. Body full, slightly depressed. Feet rather short, strong, placed about the centre of the body; legs bare a little above the joint; tarsus rather short, strong, a little compressed, covered all round with hexagonal, reticulated scales, which are smaller behind; hind toe very small, with a narrow membrane; third toe longest, fourth considerably shorter, but longer than the second; all the toes reticulated above at the base, but with narrow transverse scutella towards the end; the three anterior connected by a reticulated membrane, the outer having a thick margin, the inner with the margin extended into a two-lobed web. Claws small, arched, rather compressed, obtuse, that of the middle toe bent obliquely outwards, and depressed, with a curved edge.
Plumage close, full, compact above, blended beneath, as well as on the head and neck, on the latter of which it is disposed in longitudinal bands, separated by narrow grooves; the feathers of the lateral parts small and narrow, of the back ovato-oblong, and abruptly rounded, of the lower parts curved and oblong. Wings rather long, broad; primaries strong, incurved, broad, towards the end tapering, the second longest, but only a quarter of an inch longer than the first, which scarcely exceeds the third; the first and second sinuate on the inner web, the second and third on the outer. Secondaries long, very broad, rounded, the inner curved outwards. Tail very short, rounded, of sixteen broad rounded feathers.
Bill carmine-red, the unguis of both mandibles white, their edges black. Iris light brown. Feet dull lake, claws brownish-black. The general colour of the plumage is pure white; the fore part of the head tinged with yellowish-red; the primaries brownish-grey, towards the end blackish-brown, their shafts white unless toward the end.
Length to end of tail 31 3/4 inches, to end of claws 33 1/2, to end of wings 31 3/4, to carpus 14; extent of wings 62; wing from flexure 19 1/2; tail 6 1/4; bill along the ridge 2 5/8, along the edge of lower mandible 3 1/4; bare part of tibia 3/4; tarsus 3 5/8; hind toe 1/2, its claw 4 1/2/12; middle toe 3, its claw 4/12. Weight 6 3/4 lb.
Young Female, in first winter. Plate CCCLXXXI. Fig. 2.
The colours of the young bird, in its first plumage, are unknown; but in its second plumage, in autumn and winter, it presents the appearance exhibited in the plate. The bill is pale flesh-colour, its edges black, and the unguis bluish-white; the feet flesh-colour, the claws dusky. The head and upper part of the neck are white, tinged above with grey, the lower part of the neck all round, the fore part of the back, the scapulars, the fore part of the breast, and the sides, blackish-grey; paler beneath. The hind part of the back and the upper tail-coverts, are ash-grey; as are the wing-coverts; but the secondary coverts are greyish-black in the middle; and all the quills are of that colour, the secondaries margined with greyish-white; the tail-feathers dusky-grey, broadly margined with greyish-white. The dark colour of the fore part of the breast gradually fades into greyish-white, which is the colour of the other inferior parts, excepting the axillar feathers, and some of the lower wing-coverts, which are white.
Length of an individual in this plumage, kept four years, to end of tail 26 inches, to end of claws 25; extent of wings 55; bill along the ridge 2 1/4, from frontal angle 2 1/2; tarsus 2 7 1/2/12; hind toe 6/12, its claw 4 1/2/12; middle toe 2 1/4, its claw 4/12. Weight 2 lb. 13 oz. The bird very poor.
In an adult male preserved in spirits, the roof of the mouth is moderately concave, with five series of strong conical papillæ directed backwards. The posterior aperture of the nares is linear, margined with two series of extremely slender papillæ. The marginal lamellæ of the upper mandible are 25, of the lower about 45. The tongue is 2 inches 5 twelfths long, nearly cylindrical, with strong pointed papillæ at the base, and on each side a series of flattened, sharp lamellæ, directed backwards, together with very numerous bristle-like filaments. It is fleshy, has a soft prominent pad at the base above, and towards the end has a median groove, the point rounded thin, and horny. The œsophagus; which is 17 inches long, has a diameter of 9 twelfths at the upper part, and at the lower part of the neck is dilated to 1 inch. The proventricular glands are cylindrical, simple, and arranged in a belt nearly 1 inch in breadth. The other parts were removed.