Fig. 39. Rocky Mountain White-tailed Ptarmigan in transitional plumage, 

 against snow-brindled ground. 



Photographed from life by Edward R. Warren. 



Fig. 40. Rocky Mountain White-tailed Ptarmigan on her nest. Neur-ground-picturing pattern, of the grass-type 'based, of 

 course, on full oblitera/tive shading.) [Seep. 47, Chap. VII.] 



Photograpbed from life by Evan Lewis. 



