248 THE LIFE OF AN INSECT. 



means are found in the endowment of them with 

 the power of swimming. Surely our readers must 

 often have seen the wriggling movements of cer- 

 tain little blackish objects, which are to be found 

 in every stagnant puddle in the summer. Many 

 of these are the pupae of various species of gnats ; 

 and when we watch them come darting upwards 

 by a succession of flaps with their tail, until they 

 reach the surface, where they remain for a short 

 time, we see the means by which, although they 

 live immersed in water, they are enabled to breathe 

 the air. For if we scrutinized them a little nar- 

 rowly, we might detect on each side of their 

 largest extremity or head, a pair of minute tubes 



Pupa of the Ephemera, showing its gill-like Organs. 



which open into the air at the surface of the water. 

 It may sink beneath the water for a time without 

 inconvenience, and it is soon found plunging 



