GENUS I.--POLYBORUS, Vieill. CARACARA.
Bill large, high, rather long, much compressed; cere large, covered with
hair-like feathers; upper outline convex and declinate to the edge of the cere,
then decurved; edge of upper mandible slightly arched and nearly even, tip of
lower compressed and rounded. Nostrils elliptical, oblique, in the anterior
part of the cere near the ridge. Eyelids and space anterior to the eye denuded,
as is the skin over the crop. Feet rather long; tarsi anteriorly scutellate,
sharp-edged and scaly behind; toes rather long broadly scutellate, the first
much shorter than the second; claws long, little curved, that of the middle toe
being only slightly arched. Wings long rounded, the third and fourth quills
longest, the first five having the inner web cut out. Tail rather long rounded.