1926] Swarth: Birds and Mammals from the Atlin Region 95

Through the courtesy of several museums and private collectors
(to whom acknowledgment is made elsewhere in this paper) a series of
168 rock ptarmigan in summer plumage was brought together, repre-
senting many parts of the mainland of North America and some Arctic
islands also. A few of these localities are represented by extensive
series of summer birds, and some such points fortunately prove to
be rightly placed to illustrate certain important features of geo-
graphical variation in the northwest. This study has not included the
ptarmigans of the Aleutian Islands, Greenland, Newfoundland, and
Anticosti.

In the portion of North America indicated, excluding the islands
mentioned, the rock ptarmigan has differentiated into three easily
recognizable branches. First, there is a gray-colored bird that extends
from Labrador westward to the coast ranges of northern British
Columbia. In the east it apparently extends northward into the
Arctic regions; it also occurs on islands north of Mackenzie, but else-
where in the west it is restricted to the southern part of the region
covered by the species Lagopus rupestris. Second, there is a ruddy-
colored form that occupies almost the entire mainland of Alaska and
extends eastward along the Arctic coast about to the one hundredth
meridian. Third, there is a dark colored form with a rather limited
range in the coastal region of southeastern Alaska (see fig. I).

The first-mentioned race, the gray-colored bird, may probably be
assumed to represent Lagopus rupestris rupestris (Gmelin), described
from ‘‘Hudson Bay.’’ It was the gray coloration of British Columbian
birds, as compared with the ruddy Alaskan specimens, that first
attracted my attention, and it seems evident that this gray race extends
practically across the continent. There are two males and one female
at hand from McLellan Strait, Labrador, and one female from the
mouth of the Nastapoka River (east coast of Hudson Bay), Ungava.
The two male birds can be matched exactly in the series of Atlin
specimens. The female from McLellan Strait is even more gray than
any of the British Columbia birds; the one from the Nastapoka River
is indistinguishable from Atlin skins.

A. half-grown juvenal from Ponds Inlet, Baffin Land, is a trifle
‘more gray than comparable Atlin specimens, but very slightly so. The
variation is no more than occurs within series from any one place.
The locality of capture of this specimen might be considered as within
the range of Lagopus r. reinhardi (see A. O. U. Committee, 1910,
p. 141), but in appearance it certainly agrees with rupestris, as repre-