TJic Imago. 47 



a gradual one. It is very difficult to approach one 

 settled on the bare ground. ^Esc/iua jiincea and other 

 species sometimes have a proclivity, especiall}' on warm 

 autumn afternoons, for settling on the trunks of the 

 pine trees that fringe a certain pond in Surrey. While 

 so resting they are easih' frightened when approached 

 from the front, but if the approach is made from 

 behind the tree a stroke ma}- be made without frighten- 

 ing the insect, the handle of the net being dispensed 

 with. 



Dragonflies possess short, hair-like, inconspicuous 

 antennas, consisting of two stouter basal joints with 

 four or five more slender distal ones. 



Ql. 



Fig. 20. — Head of ^^schna cyanea. 



0., Occiput; D., Vertex; a.. Antenna; /., Frons ; ;;., Nasus ; j-., Rhinarium ; t-., Eye 

 labr., Labrum ; tcihi.. Labium. 



Fig. 20 gives in outline the arrangement of the parts 

 of the head of one of the larger Dragonflies — .^sc/ina 

 cyaiica. That part of the head in which the ocelli are 

 situated is called the vertex, which extends back as far 



