Birds of America
By John James Audubon, F. R. SS. L. & E.
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.