DUSKY GROUSE. 
193 
become still longer and closer. All the others have 
the toes scabrous beneath, and furnished with a pecti- 
nated row of processes on each side.* This roughness 
of the sole of the feet enables them to tread firmly on 
the slippery surface of the ground or frozen snow, or to 
grasp the branches of trees covered with ice. Their 
nails are manifestly so formed as to suit them for 
scratching away the snow covering the vegetables which 
compose their food. The wings of the grouse are 
short and rounded ; the first primary is shorter than 
the third and fourth, which are longest. The tail is 
usually composed of eighteen feathers, generally broad 
and rounded. The red grouse, T. scoticus , however, 
and the European Bonasice , and T. canadensis , or 
spotted grouse, have but sixteen ; while our two new 
North American species have twenty, one of them 
having these feathers very narrow and pointed, the 
narrowness being also observed in the sharp-tailed 
grouse. They have the head small, the neck short, 
and the body massive and very fleshy. * 
The females of the larger species differ greatly from 
the males, which are glossy black, or blackish, while 
the former are mottled with graj^, blackish, and rufous : 
such are all the typical Tetraones of Europe, and the 
cock of the plains, the dusky, and the spotted grouse 
of America. The smaller species, in which both sexes 
are mottled, such as T. phasaniellus and T. cupido , 
exhibit little or no difference in the plumage of the 
,two sexes ; which is also the case in all the Bonasice 
and Lagopodes. The young in their first feathers are 
in all respects like the female, and the males do not 
acquire their full plumage until after the second moult. 
All moult twice a-year, and most of the Lagopodes 
change their colours with the seasons in a remarkable 
manner. 
The genus Tetrao is now composed of thirteen 
species, — three Lagopodes , two Bonasice , and eight 
typical Tetraones. This enumeration does not include 
* These processes are liable to fall off, at least in preserved skins. 
VOL, IV. F 7 
