8i A COLONY OF BUTTERFLIES. 



sliire, it retreated all the way. It was as the falling 

 back of an army, with all its baggage and equip- 

 ments, and in perfect order. Year by year it called 

 upon its plants, its butterflies, its animals, and they 

 followed in its royal train. It had overridden all 

 obstacles, all lives and constitutions, and in its 

 retreat it shed, over the lands which again saw the 

 sun, floods of water, the source of fresh life and 

 civilizations. 



But it was careful of its own plants and animals ; 

 they were to go back with the ice, nor be seduced 

 by the lakes and streams its retreat unveiled, and 

 so become companions to the mammoth. And it 

 succeeded, for the most part, until it reached the 

 White Mountains. Though, year by year, the indi- 

 vidual butterflies perished, they planted their suc- 

 cessors ; the longer-lived reindeers laid their bones 

 by the way, and in the Connecticut Valley itself, 

 but fresh herds still were ready to follow the north- 

 ward march of the great glacier. 



Out of the valley of the White Mountains, the 

 main ice-mass gradually retreated ; and here it lost 

 some of its followers. At that time the White 

 Mountains must have presented an appearance not 

 unlike the Alps of to-day — an aspect which, owing to 

 their inferior elevation, they have since lost under 

 a climate growing in warmth. The local glaciers, 

 which then filled the mountain-gullies, attracted 

 some of the wayward, flitting Oencis butterflies by 

 a display of the food-plants which they had har- 

 boured and detained from the main glacier. 



Year after year the great glacier retreated farther 



