COLOUR.—Entire dorsal aspect umber brown: base of feathers on hind part of neck, white; base of those on back, irregularly banded with pale fulvous, and the scapulars with a distinct band of it. The inferior feathers of upper tail coverts banded in like manner to their extremities. Tail dusky clove brown, obscurely marked with darkened transverse narrow bands. Primaries perfectly black towards their extremities, but with the outer edge of their base, gray: inner web banded and freckled with gray, brown, and white, which in the secondaries takes the form of regular bars. _Under surface_, entirely umber brown, but rather paler than the upper. Lining of wings gray, with irregular transverse brown bars: under-side of tail the same, but paler. Thighs of a rather yellower brown. Bill and cere horn colour, mottled with pale gray: tarsi yellow. FORM.—Beak, with apex much arched, both longer and more pointed than it is in the group of the Polyborinæ. Cere naked, with few bristles; nostrils large, quite uncovered, irregularly triangular, with the angles much rounded, and situated rather above a central line between the culmen and commissure. Fourth primary longest, but third and fifth nearly equal to it; first, four inches and a half shorter than fourth, and equal to the eighth; second shorter than fifth. Extremities of wing reaching within half an inch of end of tail. Tarsi strong, feathered for nearly a third of their length beneath the joint. Scales in narrow, undivided (with the exception in some instances of one) bands, covering the front of tarsus. Toes very strong and rather long, like those of the species of _Milvago_, and much more so than in the genus _Buteo_. Hind-toe equal in length to the inner one; but not placed quite so high on the Tarsus as in _Polyborus_. Basal joints of middle toe covered with small scales, with five large ones towards the extremity. Claws very strong, thick and long, and rather more arched, and broader than in _Polyborus Brasiliensis_; their extremities obtuse, but not in so great a degree as in some species of _Milvago_. Inches. Total length from tip of bill to end of tail following curvature of body 20½ Tail 8½ Wing, from elbow-joint to extremity of longest primary 15 Bill, from tip to anterior edge of eye measured in a straight line ⁷⁄₁₀ Tarsus, from soles of feet to centre of joint 3½ Hind claw from tip to root, measured in straight line 1⅒ Claw of middle toe ⁹⁵⁄₁₀₀ _Old female._