JXDIA X DliA a ON FLIES. 



613 



(). Thf Ist and 2u(l series of the antenod.il norvnres corresponding. 



The outoiMuost aiitenodal nervuro often incomplete. 

 7. No ear shaped process to the sides of the '2nd abdominal seg- 

 ment. 

 S. No marked projection on the hind border of the eyes. 

 9. No tuft of hairs at the distal (uid of the fore fomorte. 

 Kis, moi'e for the sake of convenience in classification than for any natural 

 philogenetic sequence, has divided the Libellulin:o up into 10 groups and 

 a still hiter classification has split up the subfamily into S tribes, which 

 latter arrangement it will be convenient to follow here. 



Of the 34 Indian genera, 2 fall into Tribe 1 ; 8 into Tribe 2 ; 1 each hito 

 Tribes 3 and 4 ; 9 into Tribe o : 3 into Tribe 7 ; and 10 into Tribe 8, whilst 

 Tribe 6 has no Indian representatives. 



Key to the Genera of the Libellulin.?c. 



1. Arc between antenodal nervures 2-3, less often between 1-1?. 



Tribe], — Trigone nearly equilateral and poorly dove- 

 loped in the transverse diameter of the fore- 

 wing. 



Discoidal field commencing with but one row 



of cells. 

 Costal side of trigone in fore-wing bent. 

 7a absent or rudimentarj'. 

 Loop poorly developed or absent. 



i. Arc between antenodal nervures 1-2. 

 Antenodal nervures numbering 7-9. 

 Trigone in hind-wing entire . . . . Tetrathemis. 



ii. Arc between antenodal nervures 2-3. 

 Antenodal nervures numbering 14-16. 

 Trigone in hind-win"' traversed. . .. Hi/fceothemis. 



Tribe 2. — Trigone well-developed in the transverse dia- 

 meter of the wing ; its costal side in the fore- 

 wing not bent (except in very occasional spe- 

 cimens of Amphitheniis) and considerably 

 shorter than the proximal or distal sides. 

 Discoidal field with at least 2 rows of cells. 

 Antenodal nervures never less than 10 (ex- 

 cept in occasional specimens of Li/notJie- 

 wn".s). 

 Sectors of arc fused for a short distance in 

 the fore-wing (except in LiJtellula) and to 

 a longer extent in the hind. 

 Loop generally well-developed, often reach- 

 ing well beyond the external angle of 

 trigone. 

 The lateral border of 8th abdominal seg- 

 ment of female more or less dilated (ex- 

 cept in Am2)hithemis and variably in 

 Libellula). 

 A. Lobe of prothorax small, not fringed with long 

 hairs, 

 i. Not more than 2 rows of cells in discoidal field. 

 More than 1 cubital nervure in hind-wing. 

 (>ften supplementary nervures to bridge. 



