414 NORTH AMERICAN BIRDS. 



Family TETRAONIDiE. — The Grouse. 



As already stated, the Tetraonidce are pre-eminently characterized amoncr 

 gallinaceous birds by their densely feathered tarsi, and by the feathers of 

 the nasal fossa or groove, wliich fill it completely, and conceal the nostrils 

 The toes are usually naked (feathered to the claws in the Ttarmiaans) and 

 with pectinations of scales along the edges. The tail-feathers vary from 

 sixteen to eigliteen and even twenty in number; the tail is rounded, acute 

 or forked. The orbital region is generally somewhat bare, with a naked 

 stripe above the upper eyelid, beset by short fringe-like processes, while 

 many genera have an inHatal)le air-sac on the side of tlie neck. 



The following synoptical table will give a general view of the North 

 American Tdraonidw, although the arrangement is more artificial than 

 natural. The species of Tetrao and Bonasa inhabit wooded re-ions- 

 Lagopus belongs to the more arctic portions of the continent and the snowy 

 ridges of the llocky Mountains ; the others are found in the great prairies of 

 the West, Centrocercus being confined to the sterile plains covered with sac^e 

 or wormwood. ° 



The following synopsis is intended to aid in defining the genera, but does 

 not proless to constitute a natural arrangement. 



Genera. 



A. Leg.s feathered to and on the basal membrane of tlie toes, which are bare. 

 No ruff on the side of the neck, which, however, has an extensible bare space. ' 

 Canace. Tail broad, nearly even, or truncate, and rounded laterally, two 

 thirds tlie wing. Nasal fossae scarcely half the cuhnen. 

 Centrocercus. Tail excessively lengthened and cuneate; longer than the 

 wmgs. Nasal fossaj two thirds the culmen. Shafts of feathers on the 

 lower throat very spinous- 



PedloBcetes. Tail very short, but graduated, and with the two middle 

 featiiers (perhaps tail-coverts) lengthened beyond the rest, and two thirds 

 as long as the wing ; the next longest half the wing. Nasal fossa not half 

 the length of cuhnen. Shafts of throat-feathers normal. 

 B. Legs feathered to the lower end of tarsus. 



Cupidonia. Tail very short, truncate, but laterally graduated; half the 

 wings. Sides of neck with long, pointed, or lanceolate, stiff feathers. Nasal 

 fossae scarcely one third the culmen. 

 C Legs feathered to the claws. 



Lagopus. Tail about two thirds the wing, truncate; of sixteen to eighteen 

 feathers. Most species becoming white in winter ; none of the other genera 

 exhibiting this peculiarity. 

 D. Lower half of tarsi bare, with two rows of scutelte anteriorly. 



Bonasa. Sides of neck with a ruff of broad, truncate, soft feathers. Tail 

 very broad, square, as long as the wings. 



