354 TRANSFORMATIONS OF INSECTS. 
beautiful and most delicate membrane, which it has to escape 
from before it takes to flight. When thus enclosed it is called 
the pseud-imago, in contradistinction to the imago or the perfect 
insect. 
The engraving represents the metamorphoses of the May fly. 
In the water, amongst the weeds, there are larve and a large 
nymph, on a leaf at the side one is escaping from its covering, and 
the perfect insects are flying over the lake. 
The European Lphemertde have been carefully studied by 
LARVA AND PUPA OF AN Zphemera. 
Pictet, and the kinds which can properly be united together, on 
account of their having numerous transverse nervures on_ their 
wings, and their abdomens being terminated by three bristle- 
shaped hairs, are called Ephemera. The commonest are the May 
flies, which appear in early summer in such enormous quantities. 
The adults have a short life, which only lasts a few hours; they 
never take any nourishment; and their beautiful wings, which 
are exquisitely made, and delicately marked with brown spots, 
appear almost to be wasted, so short is their time of flight. Their 
larve and nymphs, like those of the species which are allied to 
them, are long and cylindrical, and have projecting jaws and 
