THE LIDELLULA. 



357 



the intestine and admits a quantity of water. Tliis, of course 

 contains air mechanically suspended, which is taken up the 

 tracheae just mentioned. Curiously enough, these insects, which 

 walk very slowly, manage to get out of the way of enemies by 

 expelling the water in their intestine with considerable violence, 

 and this projects them to some distance. 



When about to undergo its transformation the nymph leaves 

 the water and crawls upon plants by the side. Then the skin 

 dries, splits, and sets the perfect insect free. The larvae live 



NYMPH OF THE LibcUula AND THE PERFECT INSECT EMERGING. 



about a year before acquiring their full growth, and the nymph is 

 very active, and has the rudiments of wings. 



The AiscJinitcB have a rounded and robust body, and three 

 articulations to their lip. Some have enormous eyes, set close 

 together, so that they nearly touch each other in the middle 

 hne, and others have their eyes set wide apart. 



The engraving shows the metamorphosis of jEschna inacu- 

 latissima. On the right one of them is flying; immediately below, 

 in the water, a nymph may be seen projecting her long under 

 lip with its pincers ; by its side is a larva in a quiet condition. 



