NEUKOPTERA. 



421 



begin to eat it. I have remarked that they do not spare those 

 of their own kind, but that they eat each other up when they can, 

 and I have also seen them devouring very small fish which I put 

 by them. It is very difficult for other insects to avoid their blows, 

 because, walking along generally in the water very gently, and, 

 as it were, with measured steps, almost in the same way a cat does 

 on the look-out for birds, they suddenly dart forward their mask 

 and seize their prey instantaneously." * Fig. 393 represents, to 

 the left, the larva of the dragon-fly, with the instrument of attack 

 which we have called a " mask," and which it is making use of 



Fig. 393. Larva of the Libellula and the perfect insect emerging. 



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, whose sides 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 lateral gills, which in the 



* Charles de Geer, " Memoires pour servir k 1'Histoire des Insectes," tome ii. 

 2 e partie, p. 674. 



