Page:The birds of America, volume 7.djvu/151

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THE ARCTIC TERN.
111


extremely short, slender, roundish, covered anteriorly with small scutella, laterally and behind with reticular scales; toes very small, slender, the first extremely small, the third longest, the fourth nearly as long, the second much shorter, all scutellate above, the anterior connected by reticulated webs having a concave margin; claws arched, compressed, acute, that of hind toe smallest, of middle toe by much the largest, and having the inner edge thin and dilated.

Plumage soft, close, blended, very short on the fore part of the head; the feathers in general broad and rounded. Wings very long, narrow and pointed; primary quills tapering, slightly curved inwards, the first longest, the rest rapidly graduated; secondary short, broad, incurved, rounded, the inner more tapering. Tail long, very deeply forked, of twelve feathers, of which the outer are tapering, the middle short and rounded.

Bill, mouth, and feet vermilion tinged with carmine. Iris brown. The upper part of the head and elongated occipital feathers greenish-black; the sides of the head and chin white; the upper parts pale greyish-blue, the rump lighter, the tail white, excepting the outer webs of the two lateral feathers which are dusky-grey; primaries dusky towards the ends, the two outer with their outer webs blackish, all with the greater part of the inner web white; secondaries tipped with white. Neck, breast and sides pale greyish-blue, like the upper parts, but lighter; abdomen, under tail-coverts, and lower surfaces of wings and tail white.

Length to end of tail 15^ inches, to end of wings 13^, to end of claws 9f; extent of wings 32; wing from flexure 10^; tail to end of shortest feathers 3^, to end of longest 7^; bill along the ridge H, along the edge of

lower mandible lyf ; tarsus T 8 ? ; middle toe , its claw ff . Weight 2f oz.