KELLlCOTT. 85 



as 9+10, narrow at base, inferior edge widened at 

 basal third, width nearly uniform from thence to near 

 the apex; longitudinal carina present, denticulated on 

 posterior third ; apex rounded and furnished with a 

 spine which points obliquely downward. 



SIXTH SUB-FAMILY. 

 CORDULIN^©. 



The members of this sub-family are medium sized 

 to large species, and unlike those of the preceding, are 

 seldom seen except in the vicinity of water. 



All I have seen ovipositing fly leisurely near the 

 bank and strike the water from time to time with the 

 tips of their abdomens to wash off the eggs. Some of 

 the forms fly quite early in spring but none of them are 

 on the wing late in the fall. 



The following will aid the student in separating 

 our genera : 



1. Hypertriagonal space free, sectors of the arculus free at origin. ..2 

 Hypertriagonal space traversed, sectors of the arculus more or 

 less united at origin 4 



2. Hind wings with dark markings at least at base 3 



Hind wings without dark markings, colors metallic. 



Somatochlora. 



3. Hind wings, dark only at base with triangles iree...Tetragonuria 

 Hind wings, dark at base, middle and apex, triangles traversed. 



Epicordulia. 



4. Large species, expanse over 90 millimeters, tenth segment of the 



abdomen black in both sexes Macromia. 



Smaller species, expanse 70-75 millimeters, tenth segment light. 



Didymops. 



MACROMIA, Rambur. 



The members of this genus are easily rocognisable 

 on the wing by the transverse yellow band of the ab- 

 domen. They are large species and fly from middle to 

 late summer. Both males and females, in apparently 



