On the wing the stilt sandpiper resembles the lesser yellow-legs closely. Its smaller size is scarcely appreciable, even in a flock of yellow-legs, the members of which will usually be at slightly varying distances from the observer. Adults have appreciably darker (barred) lower parts, and young birds, particularly, are greyer above than yellow-legs at the same season in this latitude. The somewhat shorter legs do not project so far beyond the tail, but the proportionately longer bill (with slight apparent drop at its tip) is the stilt sandpiper's best field mark. Its bill is proportionately longer even than that of the greater yellow-legs, with which this species is unlikely to be confused, varying as it does away from the lesser yellow-legs in an opposite direction, both as regards size and in other subtle characters. The head and neck of a yellow-legs are more "shapely," differing in this respect somewhat as a black duck differs from sea ducks. On the ground the stilt sandpiper stands lower than a yellow-legs, having decidedly shorter legs, and correspondingly higher than our other shore birds of the same size. The color of its legs, dull olive green, is usually diagnostic. The legs are sometimes yellowish, and very rarely yellow, only one such having come under the writer's personal notice, a young bird in southward migration. The name "greenleg" is often used for it by Long Island baymen, who also suspect it of being a cross between yellow-legs and dowitcher. At sufficiently close range the margination of the feathers of the upper parts is quite unlike the spotting of the yellow-legs' plumage. The broad white stripe over the eye is conspicuous in any plumage and the whitish tail shows in flight, as different from the whitish triangle on the rump and back of the dowitcher or the white rump of the yellow-legs. Most of these field marks, however, are too subtle for easy recognition, unless seen under favorable circumstances. Prof. William Rowan has sent me the following notes: