Bill of moderate length, but little higher at the base, flat anteriorly, the sides parallel or nearly so; nostril about a quarter of the distance from the forehead to the end of the bill; wings long and pointed, a metallic speculum formed by the outer webs of the secondary quills ; tail rather pointed, of 18 or 20 feathers ; tarsus shielded in front, hind toe with a small narrow lobe.
The species of this genus and its near allies, such as the Gad-wall and the Teals, have a habit of feeding on the bottom in shallow water, with the hinder half of their bodies sticking up vertically above the water. None of the Pochards do this.
To this cosmopolitan genus 17 species are referred by Salvadori; only two are Indian, and these two differ in characters that are often regarded as generic.
Key to the Species.
a. Sexes different; speculum purple-blue………………….. A. boscas, p. 435.
b. Sexes alike; speculum green………………….. A. poecilorhynchus, p. 436.