Packaud] ESTSECTS of THE POND AND STREAM. 153 



Fig. 110. 



jects for the microscope, their bodies then are so transpar- 

 ent. Now iu the young of the larger dragon flies, such as 

 Diplax, Cordulia (Fig. 120), iEschna (Fig. 121), and Ma- 

 croinia (Fig. 122), the 

 breathing process is carried 

 on within the body. The 

 terminal portion of the di- 

 gestive tract is provided 

 with ridges of mucous mem- 

 brane. Into these folds or 

 ridges numerous tracheal 

 twigs penetrate (Fig. 123, 

 x). The water is admitted 

 through the conical valves 

 at the end of the body ; 

 there it is deprived of its 

 air, which is absorbed by 

 the trachea and ejected in 



a gentle stream, or, if the Agnon an.l Kespimtovy Leaf of Larva. 



creature is startled, it is driven out as if by a force pump 

 Fig. 120. or syringe, sending the insect forward 



several times its own length. 



Returning again to the Ma}^ flies, 

 Walsh has described a mode of respi- 

 ration unique in that group, but which 

 reminds us of the internal lung-like 

 apparatus of the larval dragon fl)^ 

 This curious form is otherwise an ex- 

 ception to all insects, in that its three 

 thoracic rings above are, instead of 

 Coidiiiia lateralis. being separate, consolidated into one 

 plate which extends back half-way over the abdomen. Fig. 

 124, III, shows the position of the tracheal lungs in the end 

 of the abdomen. AVe need further observations to show 

 how the animal takes in and expels the water. 



25 



