THE CAMEL10N FLY. 3J5 



Has two large tracheae. 



important purpose deserves our particular notice. 

 The last ring or termination of their bodies is 

 open, and serves as a conductor or air. From 

 this ring proceed a number of hairs, which, when 

 examined by the microscope, are found to be 

 real feathers with regular vanes. In particular 

 situations the larvae bend the last ring in such a 

 manner as to reach the surface of the water or 

 mud in which they are placed. The feathers 

 prevent the water from entering the tube or or- 

 gan of respiration ; and, when the animal raises 

 the termination of its body to its surface, in order 

 to receive air, it erects and spreads the feathers, 

 and by these means exposes the end of the tube 

 to the atmosphere* When it wishes to descend, 

 it contracts the filaments into the form of a ball, 

 and the bubble of air contained within it serves 

 to keep the body in a vertical position. 



These insects have two large vessels or tracheae, 

 on each side occupying almost one half of the 

 body. Both of these terminate in the open tube, 

 or last ring. Though these larvae are furnished 

 with powers of respiration, and actually respire 

 air, yet some of them are able to live more than 

 twenty four hours without respiration. 



In the middle part of this creature's mouth is 

 placed a hard, pointed, horny substance, im- 

 movable, and somewhat resembling the upper 

 mendible in the beak of a bird. On each side 

 pf this there is a small and very singular kind of 

 process. These have lately been discovered to, 



