100 University of California Publications in Zoology [Vou. 30

region. The Port Snettisham bird differs but slightly from skins from
Seward Peninsula and rather more so from young birds from the
Arctic coast of Alaska. It is somewhat darker colored. It can be
matched very closely by a young bird from Kodiak Island.

A pair of adults from Mount Dewey, on the Alaska side of the
White Pass, are of especial interest. These are from the D. R. Dickey
collection: no. 13462, female, July 26, 1923; 18463, male, August 7,
1923. The male bird is exactly like others from Baranof and Chichagof
islands. The female is distinguished from other rock ptarmigan by
dark tone and extremely rufescent coloration. It differs far more
from Atlin females, and indeed from a female from Bennett, on the
opposite side of White Pass, than from those from northern Alaska.
Whether or not this specimen represents the mode of female dixoni,
in its typical form, on Baranof and Chichagof islands remains to be
seen. So far as I know there are no such specimens extant in any
collection at this time.

The present study takes into account certain phases of geographical
variation in the North American rock ptarmigan, and suffices to make
clear some certain points, but there still remains far more work to be
done before any satisfactory understanding can be reached of the
manner of variation over the whole of the range of this species, or
several species, as the case may be.

It may be pointed out that I have not touched upon the relations
of the New World Lagopus rupestris and the Old World Lagopus
mutus, which are admittedly close; the two forms may well be con-
specific, as has been claimed (see Hartert, 1921, p. 1871). It is con-
ceivable that the ptarmigan of northeastern Siberia is the same as the
Alaskan subspecies here designated Lagopus rupestris kelloggae. The
latter certainly attains its extreme of differentiation from rupestris
on the Alaskan coast most nearly approaching Siberia.

I have not attempted to take into consideration such variation as
oceurs among the several forms described from the Aleutian Islands.
There, too, a comprehensive study should help toward an understand-
ing of the relationships of Old World and New World forms. The
few specimens that I have examined from the Alaska peninsula exhibit,
it seems to me, intergradation from kelloggae toward nelsoni, of the
easternmost Aleutian Islands, but there is not at hand material to
demonstrate this satisfactorily.