BIRDS — TETEAONIDAE. 619 



Family TETRAONIDAE. The Grouse. 



As already stated, the Tetraonidae are pre-eminently characterised among gallinaceous hirds 

 hy their densely feathered tarsi, and hy the feathers of the nasal fossa or groove, which fill it 

 completely, and conceal the nostrils. The toes are usually naked, (feathered to the claws in 

 the ptarmigans,) and with pectinations of scales along the edges. The tail feathers vary from 

 sixteen to eighteen 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, beeet 

 by short fringe-like processes. 



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

 although the arrangement is probably much more artificial than natural. The species of Tetrao 

 and JBonasa inhabit wooded regions ; Lagopus belongs to the more arctic portions of the 

 continent and the snowy ridges of the Eocky mountains, while the others are found in the 

 great prairies of the west, Centrocercus being confined to the sterile plains covered with sage or 

 wormwood. 



Synopsis 9/ genera. 



A. Legs feathered to and on the basal membrane of the toes. No ruff on the side of the 

 neck, which, however, has an extensible bare space. 



Tetrao. — Tail broad, nearly even, or truncate, and rounded laterally ; two-thirds the 



wing. Nasal fossae scarcely half the culmen. 

 Centrocercus. — Tail excessively lengthened and cuneate ; longer than the wings. Nasal 



fossae two-thirds the culmen. Shafts of feathers on the lower throat very spinous. 

 Pbdiocaetes. — Tail very short, but graduated, and with the two middle feathers (perhaps 



tail coverts) lengthened beyond the rest, and two-thirds as long as the wing ; the 



next longest, half the wing. Nasal fossae not half the length of culmen. Shafts of 

 . throat feathers normal. 



B. Legs scarcely feathered to the extreme base of tarsus, the lower joint of which is bare, 

 with large transverse scutellae. 



OupmoNiA. — 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. 

 0. Legs feathered to the claws. 



Laqopus. — 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 scutellae anteriorly. 



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

 square, as long as the wings. 



