GEN. CHAR. Bill smooth, with no lateral groove, depressed, or broader
than high. Feathers of the head and neck all normal, i.e. no crest,
nor lengthened plumes of any kind. Tail lengthened (i.e. nearly equal
to wing), rounded, the feathers broad to the end; consisting of from
sixteen to twenty feathers. Toes naked.
Subgenera.
=Canace.= Tail of sixteen feathers; no air-sac on side of the neck.
Size small. (Type, _T. canadensis_, L.)
=Dendragapus.= Tail of twenty feathers; an inflatable air-sac on side
of the neck. Size large. (Type, _T. obscurus_, Say.)
The American species of Wood Grouse appear, on comparison, to be
generically distinct from _Tetrao_, of the Old World, (type, _Tetrao
urogallus_,) and, moreover, are themselves comprised under two definable
subgenera. _Canace_ proper has a near relative in _Falcipennis_, Elliot,
(type, _Tetrao falcipennis_, Hartlaub,) of Siberia, which differs merely
in the attenuation of the primaries, and seems to us not separable
from _Canace_. There is no European genus nearly related to our birds.
_T. urogallus_ differs very essentially in high, compressed, and
light-colored bill, elongated and stiffened feathers of the whole head
and neck, metallic colors, etc. _T._ (_Lyrurus_) _tetrix_ approaches
nearer in the bill, but also has metallic colors and a very peculiarly
formed tail. Thus it seems absolutely necessary to adopt the name
_Canace_, of Reichenbach, as a generic term by which to designate the
American Wood Grouse.