DRAGON-FLIES. 



cially the episterna) and the very small prothorax. The 

 abdomen is very long and slender, cylindrical, ending in a 

 pair of claspers in the male. The wings are large, densely 

 net-veined, the hinder pair being often a little larger than 

 the front pair. 



Dragon-flies either, as in Libellula and allies, lay their 

 eggs in jelly-like masses on the surface of ponds, or, as in 

 Agrion, they crawl deep in the water 

 along the stems of submerged plants, 

 and with their sword-like ovipositor 

 cut gashes into the stalk in which 

 they insert their eggs. 



The larva of the dragon-fly conceals 

 its powerful jaws, for it is very de- 

 structive to the smaller creatures 

 about it, by its enormous labium or 

 under lip. This forms a broad smooth 

 mask covering the lower part of the 

 face; it is armed at the broad spoon- 

 shaped extremity with two sharp mov- 

 able hooks, adapted for seizing and 



retaining its prey. It breathes by ad- FlG 55 ._^ S ciina larva 

 mitting water through the vent into (nymph). Natural size, 

 the intestine, which near the end is lined with folds of 

 membrane rich in tracheae, by which the air is extracted 



from the water and mixes with the 

 blood; the folds are also so arranged 

 that the water thus introduced can be 

 forced out as if from a syringe, by 

 which the insect is suddenly propelled 

 over the bottom. The entrance to the 

 intestine is protected by from three 

 FIG. 56.-Agrion. Nat. size, to five conical horny valves, which 

 open and shut at will. The larva of Agrion and its allies 

 have three external broad, leaf-like, tracheary gills situated 

 at the end (in the larva of Euphaea the gills are attached to 

 the sides) of the body. Male dragon-flies are sometimes 



