I. RAPACIOUS BIRDS (_Accipitres_) Have the upper mandible hooked, and an
angular projection on each side near the point, as the _eagles_, _hawks_,
and _owls_.
II. PIES (_Picæ_) Have their bills sharp at the edge, somewhat compressed
at the sides, and convex on the top, as the _crows_.
III. PASSERINE BIRDS (_Passeres_) Have the bill conical and pointed, and
the nostrils oval, open, and naked, as the _sparrow_ and _linnet_.
IV. GALLINACEOUS BIRDS (_Gallinæ_) Have the upper mandible arched, and
covering the lower one at the edge, and the nostrils arched over with a
cartilaginous membrane, as the _common poultry_.