NORTH AMERICAN ODONATA. 223 



Subfamily 6. COEDULIN^E. 



I. Legion Macromia Selys. — Supra-triangular space crossed ; triangle of the front 



wings regular, with the anterior side unbroken ; membrannle large ; 



sectors of the arculus more or less united at their origins. 

 Basilar space free; inner side of triangle of hind wings farther from the base 



than the arculus; two posttriangular rows (rarely one) on the front 



wings. 

 Eyes touching for hardly more than a point ; occiput quite prominent on the 



dorsal surface of the head and considerably larger than the vertex ; 



distance from nodus to pterostigma on costal border of front wings more 



than half as long as from base to nodus; all triangles free. 



22. nidyinops. 

 Eyes touching for a short dsitance ; occiput inconspicuous and much smaller 



than the vertex ; triangles crossed or free 23. Iflacroniia. 



II. Legion Cordulia Selys. — Supratriangular space free; sectors of the arculus 



almost always separate at their origins. 

 Triangle of the front wings regular, anterior side unbroken ; membranule 

 moderate or large. 



Wings with dark spots at base, apex and frequently at nodus; triangle of 

 hind wings crossed ; abdomen slightly depressed, longer than hind 

 wings ; one cross-vein immediately beneatTi the pterostigma. 9 • Vulvar 

 lamina almost as long as 9, deeply bilobed 24. Epicordulia. 



Hind wings with some black at base; triangle of hind wings free; abdo- 

 men depressed, as long as, or a little shorter than hind wings; one cross- 

 vein immediately beneath the pterostigma. J ■ Vulvar lamina at least 

 as long as 9, deeply bilobed 25. TetragoneurJa. 



Wings with small dark spots at base and along front margin; triangle of 

 hind wings crossed or free; abdomen usually longer than hind wings; 

 two cross-veins immediately beneath the pterostigma. J. Vulvar 

 lamina not more than half as long as 9, divided into two divaricate, 

 triangular plates 26. Neurocordulia. 



Wings without dark spots ; triangle of hind wings crossed or free ; colors 

 metallic 27. Soinatochlora. 



Subfamily 7. LIBELLULIN^. 



I. Lower angle of triangle of front wings placed as far beyond the level of the 



outer angle of the triangle of the hind wings, as the latter triangle is 

 long; eyes connected for a space at most not much greater than the 

 thickness of the vertex; no antenodal concavity on front margin of 

 wings. 



Ab. seg. 3 and 4 with two additional transverse carinse, 5 with one ; nodal 

 sector waved 28. Paulala. 



Ab. seg. 3 and 4 with one additional transverse carina, 5 with none; sectors 

 of the arculus arising from a common stalk; triangle of front win^s 

 crossed, nodal sector not waved or broken 29. Traiuea. 



II. Lower angle of triangle of front wings placed on a level with the outer 



angle of the triangle of the hind wings, or only a little beyond it ; 

 tarsal nails toothed ; otherwise as in (I). 



TEANS. AM. ENT. SOC. XX. AUGUST, 1893. 



