Family XXXII. TETRAONINAE. GROUSE.
GENUS II. LAGOPUS. PTARMIGAN
Bill short, robust; upper mandible with its dorsal outline decurved, the ridge indistinct and rounded, the sides convex, the edges overlapping, the tip declinate, thin-edged, rounded; lower mandible with the angle of moderate length and rounded, the dorsal line convex, the sides rounded, the edges a little inclinate, the tip rounded; nasal sinuses large and covered with feathers, leaving the ridge narrow between them. Nostrils basal, roundish, concealed by the feathers. Head small, ovate; neck rather long; body bulky. Feet rather short, stout; tarsus feathered, as are the toes, which have two or three terminal scutella; hind toe extremely short, lateral toes equal. Claws slightly arched, depressed, thin-edged, rounded. Plumage full and compact, the feathers rounded. Wings short, convex, the primaries strong, narrow, tapering, the third longest, the fourth and second little shorter. Tail short, nearly even, of more than twelve broad feathers.