NO. 1571. 



DRAGON FLIES OF BURMA AND ^lAM— WILLIAMSON. 275 



VI. Three rows of postanal cells in hind wing. 



n. Anal area in front wing with maximum width of 2 cells, 



distal to the level of the triangle scarcely 2 cells 



wide, and that only for a short distance; M^ and Cui 



in front wing parallel to beyond the nodus, 2 cells 



between at level of nodus. 



0. One row of cells between Mi and Mi^ in fi'ont wing to 



the wing margin; anal area in front wing with 1 



row of cells proximal to the triangle; Cuz in front 



wing ending under the nodus.". . .Anonnogomphus 



oo. Two rows of cells between Mi and Mi,^ in front wing 



at level of distal end of stigma; anal area in front 



wing proximal to the triangle, 2 cells wide for a 



distance of 1 cell only, or only 1 cell wide; Cug 



in front wing ending ]jefore the nodus. 



Burmagoviphus 



nn. Anal aica in front wing with a maximum width of 3 



cells, proximal to level of triangle 1 cell wide; M^ 



and Cui in front wing divergent, at least 3 rows of 



cells between at level of nodus; 2 rows of cells be- 



• tween Mi and Mi^ in front wing at level of distal end 



of stigma Platygomphus 



mm. Four or more rows of postanal cells in hind wing; 2 rows 

 of cells between Mi and Mi,^ in front wing at level of 

 distal end of stigma; anal area in front wing proximal 

 to triangle, 2 (or in some American species 1) cells 

 wide, distally reaching a maximum of at least 3 cells 

 (2, fully developed, in some American species); M4 

 and Cui in front wing divergent, at least 3 cells be- 

 tween them at level of nodus Gomphusa 



II. A2 in hind wing arising near or proximal to the inner angle 

 of the subtriangle, Ai or AjOr both usually decidedly an- 

 gled, at least 4 rows of postanal cells; anal area in front 

 wing proximal to the triangle, 2 cells wide for at least the 

 length of 1 cell, followed distally l)y a maximum width 

 of not less than 3 cells. 

 m. M4 and Cui in front wing parallel to beyond the nodus, 2 

 cells between at level of nodus; arculus in front wing 

 at or proximal to second antenodal; 1 or 2 rows of cells 

 between Mi and Mi,^ in front wing at level of distal end 

 of stigma; 2 cells between Mi and M2 appearing first 

 nearer the stigma than the nodus in front wing; first 

 postanal cell in hind wing divided, not twice as wide as 

 the second; stigma with brace vein. ..Onychogomphus 

 mm. M4 and Cui in front wings divergent, 4 rows of cells be- 

 tween at level of nodus; arculus in front wing distal 

 to second antenodal; 3 rows of cells between Mi and 

 Ml,, at level of distal end of stigma in front wing; 2 

 cells between Mi and M, appearing first nearer the 

 nodus than the stigma in front wing; first postanal 

 cell in hind wing divided, twice as wide as the sec- 



a As shown by Needham's studies of some of the North American species, sub- 

 groups are definable, but more material is needed for a final disposition of the suljject. 



