49g iXoin'H A^riCKICAX BIRDS. 



IIadits. In logaril to distinctive peculiarities in habits and manners, 

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

 In its e.xternal markings and in size it apjiears to be readily distinguishable 

 from tlie T. obscurus either specifically or as a well-marked interior race. 

 'Sh: J. K. Lord refers to it in his account of tlie obscurus, where he states 

 tliat lietween the Cascades and the Eocky Mountains the Dusk}^ Grouse 

 appears to lie rejilaced by a well-marked variety, if not a distinct species. In 

 size it is a trifle 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 t\\'o varieties are pronounced to be, in every respect, similar. In regard 

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

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

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

 tops. 



Captain BlakLston thinks tliat this species is the form that inliabits the 

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

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

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

 on the slopes of the Rocky Mountains ; but, having killed only i'emales, 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 Rocky ]\Iountains 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 tliinks 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?wt'«?v<s, resembling them closely in their ground-color, as well as in their 

 markings. In the specimens in the 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. 



Ccntrnccrcus, SwAlxsox, F. B. A. II, 1831, 496. (Type, Tetrao urophasianns, 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 fossie extending very far forward, or along about two 

 thii'ds of the culmcn. Color mottled yellowish-grayish and dusky above ; beneath 

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

 birds ! 



