Family XXXII. TETRAONINAE. GROUSE.
GENUS I. TETRAO, Linn. GROUSE
Bill short, robust; upper mandible with the dorsal line decurved, the ridge convex, narrowed at the base, the sides convex, the edges sharp and overlapping, the tip thin-edged and rounded; lower mandible with the angle long and wide, the dorsal line convex, the sides rounded, the edges inflected, the tip rounded. Nostrils roundish, in the fore part of the large and feathered nasal depression. Head small, ovate; neck of ordinary length; body large and full. Feet stout, of moderate length; tarsus short, feathered, at the lower part sometimes bare and scutellate; toes bare, scutellate, with a marginal fringe of pectinate scales. Claws rather large, arched, compressed, obtuse. Plumage full, soft, rather blended. Wings rather short, convex, much rounded, the third and fourth quills longest. Tail rounded, of more than twelve feathers.