CLASSIFICATION 313 



marked transformation with a resting stage before the 

 final mouh. 



Order 13. EPHEMEROPTERA 



The Ma}^ies are delicate insects with short feelers, 

 vestigial jaws, and net-veined wings, the forewings markedly 

 longer and larger than the hindwings. There are long 

 jointed cercopods and the genital ducts have no chitinous 

 lining. The young are aquatic nymphs with the essential 

 features of the Thysanura, the abdominal limbs modified 

 into tracheal gills (Fig. 52, A). There is an aerial sub- 

 imaginal stage before the final moult. 



Order 14. ODONATA 



The Dragon-flies are strong insects with short feelers,, 

 large eyes, and powerful biting jaws. They have four net- 

 veined wings of glassy texture and an elongate abdomen 

 with rigid, unjointed tail processes, ovipositor in the female, 

 and genital armature on the second segment in the male. 

 The immature insects are aquatic larvae with varying 

 adaptations for breathing dissolved air. 



Sub-order i. ANISOPTERA 



This group includes the large, robust dragon-flies 

 in which the hindwing is markedly broader than the 

 forewing at the base. The larvae breathe by means of 

 tracheal gills on the walls of the hind- gut, and their 

 three tail-processes are rigid. 



Sub-order ii. ZYGOPTERA 



This group includes the slender damsel-flies whose 

 forewings and hindwings are alike narrow at the base. 

 The larvae breathe by means of their three elongate 

 tail-processes which are flexible and often flattened. 



