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; œsophagus with an enormous crop;
stomach a very powerful gizzard, having the lateral muscles extremely
developed, the epithelium dense, with two concave grinding surfaces;
the intestine long and wide; cœca excessively elongated,
cylindrical, with internal longitudinal ridges. Nest on the ground,
rudely constructed. Eggs numerous, spotted. Young covered with
stiffish down.
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.
* Tarsus partially bare.