326 THE LIFE OF AN INSECT. 



very soft and pliable, and therefore can be easily 

 withdrawn from the cases in which they were con- 

 tained. But in the Ephemera, the wings, after it 

 has left the pupa-case, are fully developed and 

 expanded, and seem to have acquired all their con- 

 sistence, and to have become hard and inflexible. 

 Moreover, its wings are so thin, that we can 

 scarcely believe that they are in reality double ; 

 that is, that they are covered by an outside sheath ; 

 and it seems incomprehensible how, if such is the 

 fact, the wings can be withdrawn from this case 

 or sheath, when the only opening that can be dis- 

 covered for that purpose, is a very minute hole 

 near the spot where the wings take origin from 

 the body of the insect. Let us now see how all 

 these difficulties are overcome, and how the insect 

 withdraws itself from this, as we might almost call 

 it, second pupa-case. 



The Ephemeras, when they leave the water, 

 rise high into the air, and wing their way per- 

 haps far from the place of their birth. They 

 may often be found wheeling over green fields, 

 or wandering among the forest shades, far from 

 the bubbling stream in whose waters so large a 

 portion of their existence was spent; but more 



