Fig. 8. Rocky Mountain White-tailed 

 Ptarmigan in winter plumage, on snow, and 

 favorably lighted for ineonspicuousness. 

 Rotundity as dimly apparent as is possible 

 without counter-shading. 



Photographed from life by Edward R. Warren. 



Fig. 9. Rocky Mountain White-tailed Ptarmigan, in winter plu 

 mage, off snow. Their rotundity, revealed by their lack of counter 

 shading, is marked. But they may still pass for lumps of snow. 

 Photographed from life by E. R. Warren. 



Fig. 10. Rocky Mountain White-tailed Ptarmigan in winter plumage, on snow but 

 itavorably lighted for ineonspicuousness. 



Photographed from life by E. R. Warren. 



