588 AGRIONID^. 



the tip ; 2nil joint of the labial palpi with more than half the breadth 

 of the labium, with the internal angle of its tip prolonged into a 

 long spine ; last joint narrow, almost cylindrical, often much shorter 

 than, but sometimes as long as, the preceding : labrum entire, con- 

 vex, rounded : abdomen of the male with 4 appendages : areolets of 

 the wings mostly quadrilateral : membranule quite obsolete. 



Rambur divides this family into the following genera : — 



a. Veinlets of the 1st costal space more or less numerous. 



b. Pterostigma very small or only visible in the female : wings 



not pediculate. 1. Caloptervx. 



bb. Veinlets of the 1st costal space always rather numerous: 

 pterostigma regular in the wings of both sexes. 



c. Epistoma without a hump. 2. Edph.ea. 

 cc. Epistoma with a hump. 3. Rhinocypha. 



bbb. Epistoma with a hump : veinlets of the 1st costal space only 

 5 or 6 in number. 4. Micromerus. 



aa. Only two veinlets in the 1st humeral or costal space. 



b. Shanks dilated, or at least in the male. 5. Platycnemis. 

 bb. Shanks dilated in neither sex. 



c. Areolets often pentagonal : pterostigma oblong-quadrate, as 



in the Libelluiides. 6. Lestes. 



cc. Almost all the areolets quadrilateral ; hind-border of the 

 wings having most often only a single row of areolets after 

 the last vein : pterostigma most often lozenge-shaped. 



d. Legs deeply fringed, 7. Argia. 

 dd. Legs with short hairs or spines. 



e. A single row of areolets on the hind-border, 



f. Size small : pterostigma small, lozenge-shaped. 8. Agrion. 

 fF, Size large : pterostigma large, or blended with a spot at the 



tip. 9. Mecistogaster. 



ee. A great number of areolets on the hind-border of the wings 

 after the 8th vein, 

 f. Pterostigma obsolete, or broader than long, 



10. MlCROSTIGMA. 



ff. Pterostigma well defined. 11. Megaloprepus. 



