Machaeramphus Western., Bijd. tol. d. Dierk., i, p. 29, pl. 12 (1848).
Type, Machaeramphus alcinus Western.
The present remarkable genus has the lores and face clothed with fine soft velvety feathers, quite unlike the scale-like feathers of Pernis. The bill is slender, much compressed, with the culmen greatly curved from the cere, which is small and thin; the gape is exceptionally large and wide; the nostril is long, narrow and horizontal and is placed immediately, in front of the lores; the wing is long, the second and third subequal or the third longest; tail rather short and square; tarsi feathered on the upper third in front, the naked portion with small scutae in front and reticulated elsewhere; toes long, the outer toe longer than the inner and the soles with enlarged knobs at the joints, middle claw dilated on the inner side. A well-developed nuchal crest.
Two species are known, one African and one found from Tenasserim through the Malay Archipelago to New Guinea.