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 Pedioccetes 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 



