54 British Dragon flics. 



When everything is still around, the wings of the 

 larger species may be heard beating at several yards 

 distance. So skilful is a Dragonfl)- in the use of its 

 wings that it is often impossible to see how it turns 

 in its flight, and it has been stated that it is even 

 able to fl}' backward, an operation which the author 

 has not been able to verif}'. 



Ten segments, of which the basal one near the thorax 

 is reckoned the first, form the abdomen (Figs. 22 and 23). 

 Their shapes and relative sizes will be best seen from 

 the illustrations of the various species, and it will be 

 found that the variation is by no means limited. On 

 the ventral surface of the second segment of the 

 male are some accessor}' reproductive organs, from a 

 receptacle in which the eggs are immediately fertilised. 

 The sexual organs proper of male, and ovipositor (when 

 present) of female, are found on the ventral side of the 

 ninth segment. Attached to the tip of the abdomen of 

 the male are two superior appendages, and one inferior 

 in the Anisoptcridcs (two inferior ones in the Zygop- 

 tcridcs). The inferior appendages belong to the anal, or 

 eleventh segment, the superiors to the tenth. In the 

 female there are two superior appendages onl)-, both 

 attached to the tenth segment. These appendages, 

 which in the male vary greatl}-, are important for 

 classificator}' purposes. 



Breathing is carried on by ten pairs of spiracles, one 

 pair on the meso-thorax, another on the meta-thorax, 

 and the remaining eight pairs on the abdomen. As 

 the insect breathes its abdomen rh\-thmicalh- expands 

 and contracts lateralh", not longitudinalh-, that is, it 

 does not alter in length, but in breadth. 



