152 THE OLDEST BUTTERFLY 



themselves, flecked with minute brown and yellow- 

 green lichens, that it is almost impossible to dis- 

 cover one in its resting-jDlace unless one has seen 

 it alight. The resemblance is of a very marked 

 character, and is unquestionably a great means of 

 protection. 



With regard to the Brenthis, we have here again 

 a case of protective resemblance, though to a less 

 extent ; for in the brilliant red and ashy checkered 

 surface of the under wings, seen when the insect 

 is at complete rest, we have contrasted colors fre- 

 quently to be met with in the subalpine region in 

 the latter part of the season when frosts have 

 begun their work. But whether these protective 

 resemblances are very necessary in a district where 

 so few birds are found — hawks and snow-birds 

 being almost the only persistent inhabitants — may 

 perhaps be doubted, and the markings which we 

 find on these insects may be only their ancestral 

 inheritance, useful on the arctic barrens where 

 birds are more various and plentiful. The Bren- 

 this indeed seems really doomed to destruction. 

 In the scanty numbers that one may find upon the 

 mountain slopes, one sees the sign of their early 

 departure ; for, in the many years that I have 

 searched for them with special pains, I have never 



