96 University of California Publications in Zoology  [Vou. 30

sented from other regions. There are few specimens available from
intermediate points between the extremes of Labrador and British
Columbia, but two females from Clinton-Golden Lake and Cap
Mountain, Mackenzie, respectively, are unmistakably of the gray
rupestris mode of coloration. Specimens from the Arctic islands north
of Mackenzie are also to be referred to rupestris.

In my published comments upon the female rock ptarmigan from
Nine-mile Mountain, British Columbia (Swarth, 1924, p. 333, fig. A),
I described in detail the striking white tail markings seen in some
birds from that region. This proves not to be a character of any
systematic value. At the time we were shooting rock ptarmigan in the
Atlin region they were molting their tail feathers, and many birds
were flushed which, if they possessed this character, would not have
shown it in their then condition. Several were shot with tail fully
grown and with rectrices black throughout (save for the usual
restricted white markings at base and tip), and several that exhibited
white markings of irregular extent on some of the tail feathers. I
found some molted rectrices where they had been dropped on the
hillsides that were marked as in the Nine-mile Mountain bird. Among
all the specimens assembled in the present study, just one bird, an
adult female of dixoni from the White Pass, Alaska (D. R. Dickey
coll., no. 13462), has this feature developed as in the specimen I
figured. Judging from the material at hand, it would seem that this
character occurs irregularly in the female bird in the extreme south-
western part of the range of the rock ptarmigan; irregularly in that
it may or may not exist in individuals from any one place, in that it
may occur on some tail feathers and not on others, and in that it may
cover a greater or lesser area on corresponding feathers on different
birds. Curiously, there is an adult female at hand, taken near Bennett,
on the east side of the White Pass, September 11, 1924 (coll. of Allan
Brooks), mostly in the white, winter plumage, in which the central
(usually white) tail feathers are basally black, a condition I do not
find in any other specimen.

The small size of bill in the Nine-mile Mountain bird was another
feature that was commented upon in my previous paper. . The larger
series now available shows that while in the more southern birds the
bill is frequently smaller than in any of the northern specimens, it is
not a character to be relied upon. It can be described as a tendency
of the southern birds.