This remarkable genus has been placed by ornithologists generally near Pernis, which it resembles in its densely feathered lores. At the same time the peculiar very compressed bill and wide gape and the long unequal toes and claws show the present to be a very aberrant and specialized form. It comprises two species—one inhabiting South Africa and Madagascar, the other a Malay bird found also in Southern Tenasserim.
The bill is small and excessively compressed anteriorly, so that the sharply curved culmen forms a narrow keel; cere very thin and inconspicuous, the feathering of the lores extending almost to the elongate narrow quasi-longitudinal nostril. Gape very broad. A nuchal crest present. Feathers of lores dense but not scalelike, without bristles in the Indian species. Wings long, the 3rd quill longest; tail moderate, square, lower tail-coverts long. Tarsus only feathered at the base in front, naked portion reticulated; toes very long, unequal, outer much longer than inner, but the inner claw much larger than the outer and nearly equal to the hind claw, middle claw slightly dilated on the inner side.