Bill broader at base than high, of equal width or wider at tip, with numerous lamellae. Tongue large and fleshy, denticulated laterally to correspond with lamellae. Anterior toes fully webbed to end of digits (Anseranas excepted). Hind toe always present. Primaries eleven. Fifth secondary wanting. After-shaft rudimentary or wanting. Oil-gland tufted. Monogamous. In moulting most, if not all, shed all their quill-feathers at once, and are consequently for a time unable to fly. Rough nest. Numerous eggs. Swans and Geese have no lobe on the hind toe. In Ducks the hind toe is narrowly lobed, while the Diving Ducks and Mergansers have a broad lobe.
(i.) Hind toe not lobed (286-297). Subfamily CYGNINAE. Lengthened neck, but short legs. Bill high at base, and of equal breadth throughout. Lores bare (except in Coscoroba.) Of very large size. Feed on seeds, roots of water-plants, and also on grass. Sexes alike, no seasonal change. Principally Arctic.