AS A HOME FOR BUTTERFLIES 87 



What the higher levels of the White Mountains 

 would be as a home for butterflies, if a thousand 

 or two more feet were added to their elevation 

 and snow crowned the higher summits, it might 

 be hard to say, but it would certainly be still very 

 different from the fauna of the Swiss or the Col- 

 orado alps. Many of the generic forms which 

 are common to them scarcely occur in eastern 

 America; so that the difference between the three 

 alpine faunas we have mentioned accentuates the 

 distinction which exists between eastern America 

 and Europe, and the agreement found between 

 western America and Europe. 



