Family XXXII. TETRAONINAE. GROUSE.
Bill short, stout, with the upper mandible convex, thin edged, without notches, its tip thin edged, obtuse, the lower mandible with the dorsal line slightly convex, the edges thin, the tip rounded. Head small, oblong; neck of moderate length; body very bulky. Feet short, stout; tarsus partially or entirely feathered; hind toe small, third long, lateral nearly equal, all scutellate, anterior webbed at the base. Claws moderate or long, arched, rather depressed, blunt. Plumage full and soft; feathers with the plumule much developed. Wings rather short, convex, rounded. Tail various, of more than twelve feathers. A bare coloured space on each side of the neck, usually concealed by the feathers; but in some species capable of being distended so as to protrude. A bare red membrane over the eye, more developed in the males. Tongue triangular, pointed; oesophagus with an enormous crop; stomach a very powerful gizzard, having the lateral muscles extremely developed, the epithelium dense, with two concave grinding surfaces; the intenstine long and wide; coeca excessively elongated, cylindrical, with internal longitudinal ridges. Nest on the ground, rudely constructed. Eggs numerous, spotted. Young covered with stiffish down.