52 



British Dragonflies. 



of the wing, the former constituting the front margin, 

 and being bent near the centre at the cubital point. 



CUSU aic 



euia "^ 



Fig. 24. — Typical Dragonfly Wings. 



A: a., Anterior Axillary Callus; 6., Posterior Axillary Callus; f., Cubital Point; 

 d., Pterostigma ; f., Accessory Membrane (or Menibranule) ; /., Costa; f;., Sub-costa ; 

 /i., Median Nervure ; !., Sub-median Nervure ; _;'., Post-costa; k.. Principal Sector; 

 /., Nodal Sector; m.. Sub-nodal Sector; n., Median Sector; 0., Short Sector; p.. Upper 

 Sector of the Triangle; q.. Lower Sector of the Triangle; r.. Anal Angle (r'. Anal Angle 

 of Wing of Female); 5., Post-costal Space; ^, Triangle; «., Supra-triangular Space; 

 v.. Internal Triangle; k'., Basilar Space; a-., Median Space; y.. Anal Triangle (when 

 present); -., Post-trigonal Space ; arc, Arculus ; (i.e., Ante-cubital Nervures ; p.c, Post- 

 Cubital Nervures ; 11. s. a., Upper Sector of Arculus; l.s.a.. Lower Sector of Arculus 

 e.u.s.a., End of Upper Sector of Arculus; 11. n., L'ltra-nodal Sector. 



B and C: References the same, except Q., the Quadrilateral. 



