THE DRAGON FLY S MASK. 



109 



128. Abdominal valves ; a, side view. 



This mask (Fig. 127) is peculiar to the young, or larva and pupa 

 of the Dragon fly. It is the labium, or under lip greatly 

 enlarged, and armed at the broad spoon-shaped extremity (Fig. 

 127, x} with two sharp hooks, adapted for seizing and retaining 

 its prey. At rest, the terminal half is so bent up as to conceal 

 the face, and thus the crea 

 ture crawls about, to all |\ 7 

 appearance, the most inno 

 cent and lamb-like of in 

 sects. 



Not only does the imma 

 ture Dragon fly walk over 

 the bottom of the pool or 

 stream it inhabits, but it 

 can also leap for a consid 

 erable distance, and by a most curious contrivance. By a 

 syringe-like apparatus lodged in the end of the body, it dis 

 charges a stream of water for a distance of two or three inches 

 behind it, thus propelling the insect forwards. This apparatus 

 b combines the functions of 



locomotion and respiration. 

 There are, as usual, two breath 

 ing pores (stigmata) on each 

 side of the thorax. But the 

 process of breathing seems to 

 be mostly carried on in the tail. 

 The trachea? are here collected 

 in a large mass, sending their 

 branches into folds of mem 

 brane lining the end of the ali 

 mentary canal, and which act 

 like a piston to force out the 

 water. The entrance to the 

 canal is protected by three to 

 five triangular horny valves 

 (Fig. 128,9, 10,- 128 a, side 

 I2 ( j. Agrion; 6, False Gill of Larva, view), which open and shut at 

 will. When open, the water flows in, bathing the internal gill- 

 like organs, which extract the air from the water, which is then 

 suddenly expelled by a strong muscular effort. 

 In the smaller forms, such as Agrion (A. saucium, Fig. 129 ; 

 10 



