Male with the bill black in its basal half, orange-yellow towards the end; the scapulars much elongated and tapering, the tail very long, acuminate, of fourteen feathers; a large oblong greyish-white patch on each side of the head from the bill to behind the ear; the upper part of the head and nape black, that colour being narrowed in front by the encroachment of the white patches; neck all round, and anterior half of the breast, dark chocolate; back and wing-coverts brownish-black; scapulars broadly margined with light reddish-brown; quills chocolate, secondaries externally margined with lighter, primaries internally; middle four feathers of the tail brownish-black, the outer two of these margined with white, all the rest white, but the inner with a longitudinal patch of dusky on the outer webs. Male in winter with the head, neck, fore part of back, and scapulars, white; space about the eye pale greyish-red, and a large oblong patch of chocolate-brown on the side of the neck; upper parts including the middle four tail-feathers, brownish-black, but the secondary quills tinged with reddish-brown, and having paler margins; anterior half of breast chocolate-brown, the rest of lower parts and the four lateral tail-feathers white. Female considerably smaller, with the scapulars not elongated, and the tail short and rounded; bill dusky green; head dark greyish-brown, with a patch of greyish-white surrounding the eye, but not extending to the bill; a large patch of the same colour on the side of the neck, the hind part of which is dusky brown, the fore part greyish-brown, the feathers broadly margined with whitish; the upper parts dark greyish-brown, the two lateral tail-feathers edged with white; lower parts white, the feathers under the wings slightly tinged with grey. _Male_, 23, 29-1/2. _Female_, 15-3/4, 26. Breeds from Labrador northward to the Arctic Seas. Abundant during winter along the coasts of the Atlantic Districts to the mouth of the Mississippi. Never in the interior. Long-tailed Duck, Anas glacialis, Wils. Amer. Orn. v. viii. p. 93. Fuligula glacialis, Bonap. Syn. p. 395. Long-tailed Duck, Harelda glacialis, Swains. & Rich. F. Bor. Amer. v. ii. p. 460. Long-tailed Duck, Nutt. Man. v. ii. p. 453. Long tailed Duck, Fuligula glacialis, Aud. Orn. Biog. v. iv. p. 103. FAMILY XL. MERGINÆ. MERGANSERS.