Hydrophasianus Wagler, Isis, 1832. Col. 279.
Type by orig. desig., Parra chinensis auct. = P. chirurgus Scopoli.
In this genus the bill is more slender than in Metopidius and there is no lappet; the hind claw is shorter; the first and fourth primaries are attenuated, the first into a barbless shaft terminating in a spatulate web and the fourth prolonged into an attenuated point; the wing is furnished with a strong sharp spur at the bend. Sexes alike, both assuming a nuptial dress which is attained by a moult and not by a change in the colour of the plumage as was supposed.
The female is rather larger than the male, A single species.