414 NORTH AMERICAN BIRDS. 



Family TETRAONIDJE. — The Grouse. 



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

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

 the nasal fossa or groove, which iill it completely, and conceal the nostrils. 

 Tlie 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, beset by short fringe-like processes, while 

 many genera have an inflatable air-sac on the side of the neck. 



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

 American 2'etraonidw, although the arrangement is more artificial than 

 natural. The species of Tetrao and Bonasa inliabit wooded regions ; 

 Lago'pus belongs to the more arctic portions of the continent and the snowy 

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

 the West, Centrocercus being confined to the sterile plains covered with sage 

 or wormwood. 



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

 not profess to constitute a natural arrangement. 



Genera. 



A. Leo-s feathered to and on the basal membrane of the 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 the wing. Nasal fossae scarcely half the culmen. 



Centrocercus. Tail excessively lengthened and cuneate ; longer than the 



wino-s. Nasal IbssiB two thirds the culmen. Shafts of feathers on the 



lower throat very spinous 



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



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



as long as tlie w'mg ; the next longest half the vising. Nasal fossae not half 



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



B. Legs feathered to the lower end of tarsus. 



Ciipidonia. 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 scutellae anteriorly. 



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



very broad, square, as long as the wings. 



