Page:The birds of America, volume 7.djvu/209

Rh Larcs eburnecs, Bonap. Syn., p. 360.

Laros eburneds, Ivory Gull, Swains, and Rich. F. Bor. Amer.

Ivory Gull, Nutt. Man., vol. ii. p. 301.

Ivory Gull, Lams eburneus, Aud. Orn. Biog - ., vol. iii. p. 571. Adult, 19, 41.

Accidental on the coast of the United States. Common in winter in Labrador and Newfoundland. Breeds in high latitudes. Adult Male.

Bill shorter than the head, robust, nearly straight, compressed. Upper mandible with the dorsal line nearly straight at the base, arched and decli- nate towards the end, the ridge convex, the sides slightly so, the edges sharp, a little inflected, somewhat arched, the tip rather obtuse. Nasal groove rather long and narrow; nostrils in its fore part, lateral, longitudinal, linear, wider anteriorly, pervious. Lower mandible with a prominence at the end of the angle, which is long and narrow, the dorsal line slightly concave and ascending, the sides flattened, the edges sharp and inflected. Head rather large. Neck of moderate length, strong. Body rather full. Feet of moderate length, stout; tibia bare below; tarsus somewhat com- pressed, covered before with numerous scutella, on the sides and behind with series of small angular scales; the hind toe very small and elevated, the fore toes of moderate length, the fourth much longer than the second, the third longest, the hind one with a single scutellum and three transverse series of scales, the rest scutellate above and connected by reticulate membranes having a concave margin, the lateral toes margined externally with a narrow membrane. Claws stout, rather large, arched, compressed, rather obtuse, that of middle toe with an enlarged inner edge.

The plumage in general is close, full, elastic, soft and blended, on the back rather compact. Wings very long, rather broad, acute, the first quill longest, the other primaries rapidly graduated; secondaries broad and rounded, the inner tapering but rounded. Tail of moderate length, even, of twelve rather broad rounded feathers.

Bill bright yellow, greenish-dusky at the base. Iris brown, edges of eye- lids vermilion. Feet and claws black. The whole of the plumage is pure white.

Length to end of tail 19 inches, to end of wings 20^; extent of wings 41; wing from flexure 13^; tail 6i; bill along the back 1 T 5 2, along the edge of lower mandible 2; tarsus 1 T 7 ^; middle toe 1 T 2 2, its claw f|. Weight 20 oz. Young of the second year, killed in September.

After the second moult, the bill is pale yellow at the end, dusky at the base for two-thirds of its length; the edges of the eyelids vermilion, the iris brown, the feet black. The plumage is white; the forehead and sides of the