pattern of this same species in summer plumage. See Figs. 40 and 41, 

 the second of which is one of the most remarkable photographs ever taken 

 of obliteratively colored birds in nature. Both photographs are of hen birds 

 on their nests. We have never been in the haunts of this ptarmigan, and 

 therefore cannot speak from personal experience as to the prevalence on 

 its breeding grounds of the strong, wiry grasses which form the brooding 

 bird's background in these pictures, as well as in others not published here. 

 But the late Mr. Evan Lewis, of Idaho Springs, Col., who took the photo- 

 graphs, wrote us confirming our foregone conclusions as to the abundance 

 and general distribution of grasses of this type in the summer home of the 

 Southern White-tailed Ptarmigan. Indeed, an examination of the photographs 

 leaves one no room for doubt upon this score. So consummate a resemblance 

 could not be merely casual. 



. The principal feature of the pattern made by grasses over ground is a more 

 or less intricate lace-work of crisscrossing, light-colored, linear forms, some 

 straight, some curled and twisted, relieving with varying intensity against 

 dark. This pattern has the important attribute of simplicity, and is worn not 

 only by many birds and some frogs, but even by certain moths, which rest on 

 the ground during the daytime.* In the case of the ptarmigan, it is achieved 

 by light-brown marginal bands, with a few small internal spots, on the dark 

 feathers of the upper parts; the predominance of light and dark being grad- 

 ually reversed as the lower breast is approached. The belly is entirely white, 

 as are the quill feathers of the wings and tail. The white of both wings and 

 tail, however, is entirely hidden by grass-marked 'coverts' when the bird is 

 brooding. In addition to the phases already described, this bird has an 

 early autumn plumage of softer and grayer colors, without white blotches, 

 which doubtless fits it to live more among the rocks, and less among the 

 grasses. The colors of ptarmigans, in fact, are almost interminably various, from 

 month to month. It seems almost as if they underwent a perpetual moult. The 

 grass-pattern plumage of the nesting season, however, must be very constant. 



* These will be considered later. 

 46 



