PTARMIGANS. 187 
as far south as Newfoundland on the eastern coast. 
It has been traced as far north as man has yet pene- 
trated, in Alaska, and the probability is that its range 
extends far within the Arctic Circle. It bears such a 
close resemblance to the ZL. mutus of Europe, that it 
would be exceedingly difficult to tell them apart in win- 
ter, there being no specific difference between them; but 
in summer and autumn the latter is the more grayish of 
of the two. The rock ptarmigan is smaller than the 
willow grouse, and has a more slender and elongated 
bill. An adult male attains a length of about fourteen 
and a half inches, and a weight of two pounds, but 
the female seldom weighs more than a pound and a half. 
The summer plumage is blackish, striped with narrow 
transverse bars of yellowish-brown, tipped with white; 
the chin is whitish, spotted with black; the wings, ex- 
cept the middle coverts and tertials, are white; and the 
middle of the abdomen and the outer web of the external 
tail feathers are of the same hue. Tke Alaskan species 
differs from this in being of a more chestnut hue, mot- 
tled with black, and having little or no white edging. A 
black stripe runs through and behind the eye of the male 
at all seasons, but it is absent in the female. The plum- 
age in winter is pure white, except the fourteen tail 
feathers, which are black, tipped with white. In this 
season the female differs but little in color from the male, 
but in summer her legs and wings, except the upper 
coverts, are white. The tail, excluding the four middle. 
feathers, is black, tipped with white, the remainder of 
the plumage being ochreous, tipped in parts with white. 
All are marked with broad, transverse bars of black, 
especially the back, but the buff bars beneath are wider 
than the black. This species, like the willow grouse, is 
partially migratory. It retires into the thickets of the 
interior late in the autumn, and remains there until the 
following spring, when it moves north again until it 
