DUSKY GROUS. 
31 
longer and closer. All the others have the toes scabrous beneath, 
and furnished with a pectinated row of processes 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 Grous, T. scoticus, however, and the European 
Bonasias, and T. canadensis or Spotted Grous, 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 Grous. 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 gray, 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. phasianellus and T. cupido , exhibit little or 
no difference in the plumage of the two sexes; which is also the 
case in all the Bonasise 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. 
* These processes are liable to fall off', at least in preserved skins. It is owing to this 
circumstance that we committed several errors in characterizing these birds in our 
Synopsis of the Birds of the United States. 
