238 VERTEBRATES: BIRDS. 



is twenty-nine inches long, and the wing over eleven 

 inches ; the upper parts mottled with black, brown, and 

 brownish yellow ; the under parts black and white. 



The Genus Pedioccztes has the central tail-feathers 

 lengthened. 



The Sharp-tailed Grouse, P. phasianellus , Baird, of the 

 plains of Wisconsin and westward, is eighteen inches 

 long, and the wing eight and a half inches, and distin- 

 guished by the tail, which has eighteen feathers, the cen- 

 tral pair elongated beyond the rest an inch or more. 



The Genus Cupidonia has the tail short, the bare space 

 of the neck concealed by a tuft of lanceolate feathers. 



The Pinnated Grouse, or Prairie Chicken, C, cupido, 

 Baird, of the Western prairies, is sixteen and a half inches 

 long, and the wing nearly nine inches ; the colors whitish 

 brown and brownish yellow, the feathers with transverse 

 bars of brown. A tuft of long, pointed feathers on each 

 side of the neck covers a naked, orange-colored air-sack, 

 which is capable of great inflation. These air-sacks en- 

 able the males to produce the peculiar booming sounds 

 which are always heard during the pairing season. When 

 the air-receptacles are inflated, the bird lowers his head 

 to the ground, and, opening its bill, utters a succession 

 of sounds, going from loud to low till the air of the sacks 

 is exhausted ; then immediately erecting itself, and inflat- 

 ing the sacks, it proceeds as before. These sounds may 

 be heard a mile or more. In autumn and winter, they 

 associate in flocks of hundreds. They are easily tamed. 

 Audubon caught sixty in the early autumn, and, having- 

 clipped the tips of their wings, put them in a garden and 

 orchard of four acres ; within a week they were not 

 frightened at his approach, and before winter was over 

 they would eat from the hand. 



The Genus Bonasa has eighteen tail-feathers, the lower 

 half of the tarsi naked, the naked space upon the neck 



