Family XL. MERGINIE. MERGANSERS.
Bill rather long, straight, rather slender but strong, tapering, higher than broad at the base, nearly cylindrical toward the end; upper mandible with the dorsal outline sloping gently to the middle, then straight, along the unguis suddenly decurved; the ridge broad and flattened at the base, then convex, the sides sloping, toward the end convex, the edges serrate internally with oblique dentiform lamellae, the unguis oblong, much curved, abruptly rounded at the end; nasal groove elongated, covered by the soft skin of the bill; lower mandible with the angle very narrow and extended to the unguis, which is obovate, the sides nearly erect, with a long narrow groove, the edges internally serrate, the unguis convex, thick-edged. Head rather large, compressed, oblong; neck of moderate length; body full, depressed, rather elongated. Feet placed far behind, stout; tibia bare for a short space; tarsus very short, compressed, anteriorly covered with small scutella, and another series on the lower half externally. Hind toe very small, with an inferior free membrane; anterior toes half as long again as the tarsus, second shorter than the fourth, which is almost as long as the third, all scutellate, and connected by anteriorly concave webs. Claws rather small, moderately arched, compressed, acute. Plumage moderately full, dense, soft, glossy, blended beneath. Wings of moderate breadth, convex, acute;, inner secondaries elongated and tapering. Tail short, much rounded, of more than twelve feathers. Upper mandible with an internal series of small papillae or laminae on each side, besides those on the margin. Tongue long, fleshy, emarginate and papillate at the base, tapering, with a double row of slender reversed papillae, along the upper surface, and two lateral series of filaments on each side, the tip lacerated; oesophagus very wide, of nearly uniform diameter; stomach a strong gizzard of moderate or small size, with the lateral muscles thick; the epithelium dense and longitudinally rugous; intestine long, rather narrow; coeca rather long; cloaca globular. Trachea with one or two extensive dilatations, besides the enormously developed tympanum at the bifurcation; no inferior laryngeal muscles. Nest on the ground, or in hollow trees. Eggs numerous.