224 PHILIP p. CALVERT. 



Hind ]ol)e of the prothorax with its middle portion produced upwards and 

 backwards and narrower than the other lobes, its hind margin 

 usually entire; triangle not densely reticulated. 

 Sectors of the arculus in the front wings not arising by a common stalk ; 

 nodal sector distinctly waved in its middle: front wings with supra- 

 triangulars, 11 or more antecubitals, 8 or more postcubitals. 

 % with no ventral hooks on 1 ; 9 with third tibiae at least a little longer 



than third femora 30. L.ibellula. 



% with a pair of ventral hooks on 1 ; f with third tibife as long as third 



femora 31. Platlifiiiis. 



Sectors of the arculus in front wings arising by a common stalk. 



Anterior side of triangle of front wings not broken to form a trapezium ; 

 last antenodal on front wings not continued to the median vein ; 

 lower sector of the triangle in hitid wings arising from the hind 

 angle, the upper from the outer side of the triangle. 



32. Micratliyria. 



Anterior side of triangle of front wings broken to form a trapezium, the 



outer broken piece shorter than the inner; no supratriangulars; 



hind wings with no internal triangle 33. jVaiiiiOtiieiliis. 



Hind lobe of the prothorax erect, wider than the other lobes, its hind margin 

 usually bilobed. 

 Both sectors of the triangle in the hind wings arising from its hind angle; 

 nodal sector not waved in its middle. 

 Abdomen at least fairly slender, compressed at base; if depressed it is so 

 in a special widening of the anteapical segments; hamute of % 

 bifid. 

 Pterostigma at least four times as long as wide : vertex truncated at tip : 

 front wings with 7-10 antecubitals, the last one variable; hind 

 wings with at least two dark brown basal patches, one in front of 

 the other, and separated by a clear yellow space, the front one 

 reaching forwards to the submedian vein ; 3-7 black with a mid- 

 dorsal, maculate, yellow band 34. C'elitliemis. 



Pterostigma at most twice as long as wide; vertex rounded at tip; front 

 wings with 6-8 antecubitals, the last one usually continued to the 

 median vein; hind wings with a small basal black patch reaching 

 forwards to the submedian vein : frons and nasus white; abdomen 



not widened at base and before apex 3.5 Ijeucorliiiiia. 



Pterostigma variable; vertex truncated at tip; front wings with 7-10 

 antecubitals, the last one rarely continued to the median vein ; ab- 

 domen aud hind wings without the characteristic patterns of color- 

 ing described for Celithemis iin(\ Leucorhinia 36. Diplax. 



Abdomen at least fairly stout, depressed, tapering to apex ; hamule of ^ 

 not bifid ; front wings with last antecuhital not continued to the 

 median vein ; 4 with an additional transverse carina. 



.37. Perillieiuis. 

 Lower sector of the triangle in the hind wings aiising from its hind angle, 

 the upper from its outer side; sectors of the arculus in the front 

 wings arising by a common stalk; hamule of % bifid. 



