428 NORTH AMERICAN BIRDS. 



Habits. In regard to distinctive peculiarities in habits and manners, 

 of this form of Grouse, if it possesses any, our information is quite limited. 

 In its external markings and in size it appears to be readily distinguishable 

 from the T. ohscurus either specifically or as a well-marked interior race. 

 Mr. J. K. Lord refers to it in his account of the ohscurus, where he states 

 that between the Cascades and the Eocky Mountains the Dusky Grouse 

 appears to be replaced by a well-marked variety, if not a distinct species. In 

 size it is a tritie smaller, but the great mark of distinction is the entire 

 absence of the white band at the end of the tail. In their habits, in their 

 periods of arrival and departure, or rather of appearance and disappearance, 

 the two varieties are pronounced to be, in every respect, similar. In regard 

 to their unexplained disappearance and reappearance, Mr. Lord is of the 

 opinion that these birds do not migrate, but only retire into the thickest 

 trees, and, living on the buds, pass the winter thus sheltered in the tree- 

 tops. 



Captain Blakiston thinks that this species is the form that inhabits the 

 interior of British North America, and refers the figure of the male in 

 Eichardson's Fauna to the Hchardsoni, — the Black -tailed and smaller species. 

 In his wanderings he met with these birds only in or near the pine woods 

 on the slopes of the Eocky Mountains ; but, having killed only females, he 

 could not feel certain of the species. These Grouse range towards the 

 Pacific as far as the Cascade Mountains of Oregon and British Columbia, 

 and along the Eocky Mountains from the head-waters of the Platte to the 

 Liard Eiver, a tributary of the Mackenzie. When the ranges of the two 

 species are fully defined, he thinks the T. richardsoni will be found the 

 more northern bird. 



The eggs of Tetrao richardsoni are very similar, except in size, to those of 

 the o&scwrws, resembling them closely in their ground-color, as well as in their 

 markings. In the specimens inthe cabinet of the Boston Natural History 

 Society the spots are smaller, a little less distinct, and less numerous. 

 The eggs are 1.75 inches in length, and from 1.35 to 1.36 inches in breadth. 



Genus CENTROCERCUS, Swainson. 



Centrocereus, Swainson, F. B. A. II, 1831, 496. (Type, Tetrao urophasianus, Bon.) 



Gen. Char. Tail excessively lengthened (longer than the wings), cuneate, the feathers 

 all lanceolate and attenuate. Lower throat and sides of the neck with stiffened, apparently 

 abraded, spinous feathers. Nasal fossae extending very far forward, or along about two 

 thirds of the culmen. Color mottled yellowish-grayish and dusky above ; beneath 

 whitish with black abdominal patch. Stomach not muscular, but soft, as in the Raptorial 

 birds ! 



