The black-cock is a still larger bird; the male with a wonderful metallic, steel-blue plumage, and lyrate tail.
Its horns are of the lyrate form, and its colour a bright rufous.
The lowest leaves are not entire, but lyrate and pinnatified below to the mid-rib, with a terminal lobe.
It is strongly characterized by the lyrate shape of the horns and certain anatomical features.
lyrate: lyre-shaped: cut into several transverse segments, and gradually enlarging towards the extremity.
The impalla is about the same size as the Grant's gazelle, but has horns of a lyrate shape.