CENTROCERCUS UROPHASIANUS, SAGE COCK. 



401 



Hal).— Sage plains of the "West. East to Western Kansas. South to about 35°. West 

 and north as far as suitable surface extends. Scarcely tc be found on the Missouri. 



List of specimens. 



Lieutenant Warren's Expedition. — No. 5419, fifty miles up the Yellowstone; 8921, 8923, 

 Cheyenne River. 



Later Expeditions.— 604G2, Le Bontd Creek; 60826-32, Wyoming; 61096-9, Henry's 

 Fork ; 6222:5-5, North Fork and Henry's Lake, Idaho. 



The above extensive suite of specimens illustrates this species under 

 the various conditions of age, sex, and season, from the downy young 

 to the largest cocks. The measurements given show the variation in 

 size among adult birds. Some old cocks are of great size — the birds 

 apparently growing, in some instances, after they have attained normal 

 dimensions. The lemale, as usual, is smaller than the male, averaging 

 about one-third less. There is no occasion to describe the bird minutely 

 in the present connection; its great size and various peculiar features 

 will prevent mistake respecting it. The full grown cocks average about 

 2^ feet in length ; the hens rather under 2 feet. The tail equals, or 

 rather exceeds, the wing in length, and consists of twenty very narrow 

 acuminate feathers, stilfened and graduated in length from the middle 

 pair outward. A more remarkable feature of the cock is the immen.se 

 dilatable air-sac of naked yellow skin on each side of the neck, bordered 

 by a patch of curiously stiffened, horny feathers, like fish-scales, olten 

 terminating in bristly lilaments several inches long. The feet are feath- 

 ered to the toes, as in most of our other Grouse. The most noticeable 

 color-mark is a broad black area on the under i)arts of the adult, 

 less e-\tcnsive in the lemale; it contrasts with the white of the breast. 

 The upper parts are varied with gray, black, brown, and tawny or 

 whitish. The cocks w»'igh from three to six pounds, according to age 

 and (-•oiidition ; the hens are correspondingly nnn-h lighter. 



The history of this species is generally dated from the account by 

 Lewis and Clarke, of a "Cock of the IMains" which they fouyd in the 

 Rocky ."Mountains, about the headwaters of th(> .Alis.souri, and afterward 

 more almndantly on tlie i)Iains of the Columbia. The lirst teclmiciil de- 

 scription of the .species was that of I>onai)arte, who, under the name of 

 Tctrao urvphdtdaiiUN, noticed in various periodicals, and ligured in his 

 I'd 



