96 University of California Publications in Zoology [Vol. 30 



sented from other re^ons. 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 reetrices 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 reetrices 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. 



