MERGUS ALBELLUS, _Linn._ Syst. Nat. vol. i. p. 209.—_Lath._ Ind. Ornith. vol. ii. p. 831.—_Ch. Bonaparte_, Synopsis of Birds of United States, p. 398. SMEW or WHITE NUN, MERGUS ALBELLUS, _Wils._ Amer. Ornith. vol. viii. p. 126, pl. 71, fig. 4. Male. The SMEW, or WHITE NUN, _Nuttall_, Manual, vol. ii. p. 467. Adult Male Plate CCCXLVII. Fig. 1. Bill rather shorter than the head, straight, rather slender, a little higher than broad at the base, tapering, somewhat cylindrical toward the end. Upper mandible with the dorsal outline sloping gently and slightly concave to the middle, then straight, at the tip declined, the ridge rather broad and flat at the base, then convex, the sides sloping at the base, convex toward the end, the edges serrate beneath, with about forty slightly reversed, compressed, tapering, tooth-like lamellæ, the unguis elliptical, much curved. Nasal groove oblong, sub-basal, filled by a soft membrane; nostrils oblong, submedial, direct, pervious. Lower mandible with the angle very narrow and extended to the obovate, very convex unguis, the sides rounded, with a long groove, the edges with about sixty perpendicular sharp lamellæ. Head of moderate size, oblong, compressed. Neck of moderate length. Body full and depressed. Feet placed far behind, extremely short; tibia bare for a quarter of an inch; tarsus extremely short, much compressed, anteriorly covered with a series of very small scutella, and another row on the lower half externally, the sides reticulate. Hind toe very small, with an inferior free membrane; anterior toes double the length of the tarsus; the second shorter than the fourth, which is nearly as long as the third; all connected by reticulated webs, of which the outer is deeply emarginate. Claws short, considerably curved, compressed, acute, that of the middle toe with a thin inner edge. Plumage full, soft, and blended; feathers of the head and upper part of the hind neck very slender, and elongated along the median line into a narrow decurved crest; those of the shoulders obovate and abrupt, of the rest of the upper parts ovate, of the lower elliptical. Wings very short, narrow, curved, and pointed; primaries narrow, tapering, the first scarcely longer than the second, the rest rapidly graduated; secondaries short, narrow, rounded, the inner tapering to an obtuse point. Tail short, graduated, of sixteen rather narrow, tapering feathers.