BACKBONELESS ANIMALS WHICH BREATHE IN AIR 441 



to time at the surface for the purpose of taking in air, but the 

 details have not yet been made out. 



life' ,^ 



'^'^Z- 559' — The Drone-Fly \Eristalis tenax) and its larva, the Rat-tailed Maggot 



The larvae of a great many Two-winged Insects {Dipta-a) live 

 in water, and in many cases come to the surface to breathe air. 

 It is then usual to find a breathing- tube at or near one end of the 



