Space between the bill and eye, and around the latter, bare. Plumage soft, thin, and blended. Feathers of the upper and hind part of the head very long, linear, with loose barbs; of the sides of the neck loose and inclined obliquely backwards, of its lower part much elongated, narrow, and tapering to a point; of the middle of the back extremely long, linear, acuminate, their tips projecting about five inches beyond the tail. Wings long, and very broad; primaries broad, tapering, and rounded, the first, second and third almost equal, the latter being only a twelfth of an inch longer; secondaries broad and rounded; some of the inner only half an inch shorter than the longest primary, when the wing is closed. Tail very short, small, even, of twelve rather weak feathers.
Bill ultramarine blue at the base, gradually shaded into black towards the point; the bare space between it and the eye, as well as the edges of the eyelids, ultramarine. Iris pale yellow. Legs, tarsi, toes, and claws, black. Head and neck of a rich deep purple, inclining to vinaceous; the lower part of the neck and all the other parts deep greyish-blue, the edges of the feathers lighter.
Length to end of tail 24 1/2 inches, to end of wings 25, to end of elongated dorsal feathers 26 1/2, to end of claws 30 3/4; wing from flexure 11 1/2; tail 4 2/12; extent of wings 42; bill along the ridge 3 4/12 along the edge of lower mandible 4; bare part of tibia 2 2/12; tarsus 3 5/12; first toe 11/12, its claw 2/12; middle toe 2 1/4, its claw 7/12. Weight 1 lb.
The female is similar to the male, but smaller. Weight 11 oz.
The young are at first sparely covered with yellowish-white down. When a fortnight old, the bill is yellow, with the tips greenish-black; the feet greenish-yellow, the claws dusky, with the tips greyish-yellow. The general colour of the plumage is pure white, but the down which tips the feathers of the head is brownish-white; two of the alular feathers are tinged with dull bluish-grey, and the outer seven or eight primaries are broadly margined on both sides to the length of about an inch and a half with the same colour of a deeper tint, the extreme tip white.
When fully fledged, the bare parts at the base of the bill, and the basal half of the upper mandible, are light greenish-blue, the rest black; the lower mandible yellow, with a patch of black, an inch and a quarter in length on each side at the end. Legs, tarsi, and toes greenish-blue, the sides yellowish; claws dusky. The feathers of the head are slightly elongated; those of the back are also elongated, but much broader and shorter than in the adult. The feathers on the upper part of the head are of a faint bluish-grey; and the alular feathers and eight outer primaries are tinged with the same colour. At this period, the length to the end of the tail is 22 inches, to end of claws 28 1/2; bill along the ridge 2 7/8; wing from flexure 11; tail 4 2/12.
In November, when the moult is advanced. The bill is black, dull blue at the base. The feet are nearly black, as are the claws. The occipital feathers are now two inches and a half in length, and some of the dorsal feathers extend as far as the tips of the wings; those of the lower part of the neck have also a length of about three inches. The general colour of the plumage is white; the upper part of the head, the hind neck, back, anterior edge of the wing, and outer primaries at the end, of a faint bluish-grey tint; some of the elongated feathers of the back darker.
Length to end of tail 22 inches; to end of claws 29 1/2; bill 3; wing from flexure 11 1/4.
A year old. Bill nearly as in the adult; feet bluish-black, the plumage is white, with the upper parts pale greyish-blue as in November, but the whole interspersed with numerous feathers of a deep greyish-blue, similar to that of the adult; the primaries and tail being still white.
Length to end of tail 23 1/4; extent of wings 32 1/2; bill 3 1/8. Weight 9 oz.