ARCTIC MOTHS AND BIRCHES. 1 77 



light, there fluttered, half skipping and half-flying, over 

 the lichened bowlders a butterfly I had never before 

 seen, the high arctic bluet, {Polyommatus franklinii), 

 heretofore only known to occur in the arctic world, and 

 discovered by the naturalist of Franklin's voyage. I 

 also netted an Argynnis, not hitherto discovered so far 

 south ; it was likewise a polar form. 



The moths were all arctic species, and when at rest 

 so harmonized in color with the lichens and other vege- 

 .tation in which they nestled as to entirely deceive me. 

 And yet what was the use of practising, even uncon- 

 sciously to themselves, this deception ? The answer was 

 not far off — ^there was a shore-lark, or some such bird, 

 flitting about and running over the rocks, busily search- 

 ing for just such moths as these, and the only hope of 

 safety for the insects from their sharp eyes was in their 

 resemblance to the lichens. 



The only tree seen here was the dwarf birch, Betula 

 nana; those who have seen this Lilliputian tree on the 

 summit of Mt. Washington will well remember its 

 humble stature and little round leaves. No tree per- 

 haps ever underwent greater modification by climate 

 than did the ancestor of this species, and we cannot well 

 doubt but that all these dwarf arctic trees and shrubs, so 

 closely allied to their congeners in the north temperate 

 zone, only escaped utter extinction by adapting them- 

 slvees to the extremes of their arctic surroundings. It 

 will be remembered that the oak, gum, and tulip tree, 

 the sassafras and maple, the cypress and sequoia, once 

 flourished in what is now Greenland in growths as luxu- 

 riant as the forests of the Gulf States. When the ice- 

 period was ushered in, and climate and other circum- 



