This subfamily is separated from all the preceding subfamilies by the structure of the hind toe, which is rather larger and stronger and is broadly lobed, whereas the species of the other subfamilies have only a narrow lobe or no lobe at all. Blanford did not divide the diving ducks of this group from the swimming ducks, retaining all of them in the Anatinae but the two groups seem to be well defined not only structurally but also in habits.
The Nyrocinae contain a large number of genera of ducks all of which are expert divers, many feeding on deep-water plants etc. but which have proportionately shorter, smaller wings than the non-diving ducks and, though they fly with great speed, have a quicker wing-motion. They swim at a great pace, the powerful legs and feet, set rather far back, being more adapted for swim¬ming than walking.
Three genera are represented in India, the subfamily being cosmopolitan.
Key to Genera.
A. Primaries with their bases more or less white.
a. Lamellae long and prominent………… Netta, p. 447
b. Lamellae short, set well apart and not very prominent………… Nyroca, p. 450.
B. Primaries without any white at their bases………… Glaucionetta, p. 460.