HOW TO KNOW THE BUTTERFLIES 



is an Arctic species, but is found also on the 

 higher parts (above 5,000 feet) of the White 

 Mountains and among the Rocky Mountains of 

 Colorado. 



These two widely separated colonies of this 

 butterfly are believed to be the remnants of an 

 arctic fauna, which was forced southward during 

 the Ice age. At the close of this period, as the 

 arctic animals followed the retreating ice north- 

 ward, the tops of these mountains became colo- 

 nized by the cold-loving forms. Here they 

 found a congenial resting-place ; while the main 

 body of their congeners, which occupied the in- 

 tervening region, was driven northward by the 

 increasing heat of the lower land. And here 

 they remain clinging to these islands of cold pro- 

 jecting above the fatal sea of warmth filling the 

 valleys below. 



The Gemmed Brown 



Neonymplia gemma (Ne-o-nym'pha gem'ma) 



Plate XXXI, Fig. 6, 9 



The upper surface of the wings is a moderately dark mouse 

 brown, with two darker shades beyond cell R + M of the hind 

 wings and with indistinct blackish spots near the outer mar- 

 gin of the hind wings. The lower surface is gray brown ; 

 the fore wings are crossed by three fine transverse threads; on 



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