A decurved crest of narrow feathers; a bare space on each side of the neck capable of being inflated; tail short, much graduated, of sixteen feathers, all of which are more or less concave, excepting the two middle ones along the inner edge, obliquely and abruptly terminated, the two middle projecting an inch beyond the next. Upper parts variegated with light yellowish-red, brownish-black, and white, the latter in terminal triangular, or guttiform spots on the scapulars and wing-coverts; quills greyish-brown, primaries with white spots on the outer web, secondaries tipped and barred with white; tail white, at the base variegated, the two middle feathers like the back; loral space, and a band behind the eye yellowish-white, a dusky streak under the eye; throat reddish-white, with dusky spots; fore parts and sides of neck barred with dusky and reddish-white; on the breast the dusky spots become first curved, and then arrow-shaped; and so continue narrowing on the hind part of the breast and part of the sides, of which the upper portion is barred; abdomen, lower tail-coverts, and axillars, white; tarsal feathers light brownish-grey, faintly barred with whitish. Female smaller, but similar to the male, with the tints duller. _Male_, 17-1/2, 23. Missouri, Lat. 41°, to Slave Lake, Lat. 61°. Rocky Mountains. Abundant on the Saskatchewan Plains. Accidental in the northern parts of Illinois. Resident. Tetrao Phasianellus, Bonap. Amer. Orn. v. iii. p. 37. Tetrao Phasianellus, Bonap. Syn. p. 127. Tetrao (Centrocercus) Phasianellus, Sharp-tailed Grouse, Swains. & Rich. F. Bor. Amer. v. ii. p. 361. Sharp-tailed Grouse. Nutt. Man. v. i. p. 669. Sharp-tailed Grouse, Tetrao Phasianellus, Aud. Orn. Biog. v. iv. p. 569. 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. 301. 1. Lagopus albus, Gmel. Willow Ptarmigan.--Willow-Grouse. Plate CXCI. Male, Female, and Young.