422 THE INSECT WORLD. 



instrument of attack which we have called a " mask," and which it is 

 making use of for seizing a small insect; on the right, the adult 

 dragon-fly coming out of the nymph. 



The respiration of these larvae is very singular. Their abdomen 

 is terminated by appendages, which they open to allow the water to 

 penetrate into the digestive tube, the sides of which are furnished with 

 gills communicating with the tracheae. The water, deprived of oxygen, 

 is then thrown out, and the larva advances thus in the water by the 

 recoil. It has no tufts of external lateral gills, which in the case of 



Fig- 395 — LibcHula depressa, the Common Dragon-Fly. 



the Ephemerce do the duty of fins. The pupa already presents stumps 

 of wings. To effect its metamorphosis it drags itself out of the 

 water, where it has lived for nearly a year, climbs slowly to some 

 neighbouring plant, and hangs itself there. Very soon the sun dries 

 and hardens its skin, which all of a sudden becomes crisp, and cracks. 

 The dragon-fly then sets free its head and its thorax, and its legs ; its 

 wings, still soft and wanting in vigour, gain strength by coming in 

 contact with the air, and, after a few hours, they have attained their 

 full development. Immediately the insect abandons, like a worn-out 

 suit, the dull slimy skin which had covered it so long, and which still 

 preserves its shape (Fig. 394), and dashes ofl" in quest of prey. 



The LibellulcB are common all over the world. Their type is the 

 Libellula depressa (Fig. 395), very common in Europe. The male is 



