272 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxin. 



e. Median labial lobe divided. Stigma of uniform width, the distance 



■ between C and R^ a cell or two beyond stigma less than the distance 



between Ri and M^ at the same level; in front and hind wings at least 



4 cross veins between M^_-f and M4^. 



/. Subtriangles of front and hind wings similar in shape. Eyes touching 



dorsally or but little separated. 



g. Median space without cross veins; triangle of hind wing more elongate 



than triangle of front wing subfamily cordulegasterin^ 



gg. Median space with cross veins; triangle of front wing at least as elon- 

 gate as triangle of hind wing subfamily CHLOROGOMPHiNiE 



/(. Triangle of hind wing strongly narrowed in the direction of the 



long axis of the wing Chlorogomphus 



hh. Triangle of hind wing about equilateral Orogomphus 



ff. Subtriangles of front and hind wings dissimilar; triangle of front wing 

 not as elongate as triangle of hind wing. Eyes widely separated. 



SUBFAMILY PETALURiN^E (uot regional) 



ee. Median labial lobe entire. Eyes widely separated. Stigma wider at 



middle than at either end, the distance between C and Ri a cell or two 



beyond stigma about equaling the distance between Ri and Mj at the 



same level; triangle of front wing less elongate than triangle of hind 



wing SUBFAMILY GOMPHINjE 



/. Subtriangle of front wing crossed (except in Gomphidia javanica) ; super- 

 triangular cross veins present; distance from forking of Mi_2 and M3 to 

 subnodus equal in front and hind wings, in front wing equal to one- 

 fourth the distance from wing base to subnodus; cross veins between 

 Mi_3 and M^ numerous, at least 4 in hind wing; M3 in hind wing slightly 

 waved; Rg and M4 with accessory sectors; stigma long, equaling one- 

 third the distance from nodus to distal end of stigma. 

 g. Lateral margins of abdominal segment 8 dilated. Triangle of front 



wing short, the inner and superior sides about equal Ictinus 



gg. Lateral margins of abdominal segment 8 not dilated. Triangle of 

 front wing longer, the outer and superior sides about equal. 



Gomphidia 

 ff. Subtriangle of front wing and all supertriangles without cross veins; dis- 

 tance from forking of Mi_2 and M3 to subnodus equal to about one- 

 third the distance from wing base to subnodus in front wing; R^ and 

 M4 without .distinct accessory sectors; stigma shorter, in length less 

 than one-third the distance from nodus to distal end of stigma. 

 g. Triangle of hind wing crossed; at least 3 rows of cells between M4 and 

 Cui at level of penultimate antenodal in front wing. 

 h. Triangle of front wing crossed; arculus in front and hind wings at 

 level of second antenodal; anal area of front wing with 2 rows of 

 cells proximal to the triangle, followed distally by more than 2 

 rows; M4 and Cu^ in front wing divergent, about 15 cells between 

 at wing margin; in hind wing 2 cross veins between M,_3 and M^; 

 trigonal supplement distinctly present; distance from forking of 

 Mi_2 and M3 to subnodus about equal in both wings. 

 i. Cubital space with 2 or 3 cross veins in addition to the one forming 

 the subtriangle; Mj^ in front wing arising nearer nodus than 

 stigma; basal antenodal of second series present in four wings; 

 sectors strongly curved, the angle of R^ with the hind margin 



obtuse Sieholdivs 



a. Cubital space with 1 cross vein in addition to the one forming the 

 subtriangle; Mi^ in front wing arising nearer stigma than nodus; 



