Subfamily LiBELLULINAE 
The Common Skimmers 
Dragonflies mostly of moderate or large size, generally non-metallic 
though often of brilliant coloration. Colors in many forms obscured 
by pruinosity with age. Anal loop generally well developed and foot- 
shaped, and with a distinct bisector. Triangle of hind wing retracted 





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Fics. 37. Wings of Orthemis ferruginea, labelled to illustrate Libelluline 
venation. Principal veins labelled only at the outer margin. R,, radius; R,, 
radial sector. M;, M,, Ms, and M,, Cu, and Cu,, the branches of media and cubi- 
tus respectively. St, stigma; n, nodus; an and pn, ante- and post-nodal cross 
veins; br, bridge; 0, oblique vein; r, reverse vein; My, apical sector; Ap. pl, 
apical planate; R.pl. radial planate; M.pl, median planate; ar, arculus; ac, anal 
crossing; t, triangle; t’, subtriangle; 7+3, number of cells in row subtending 
subtriangle; p, patella; b, bisector of anal loop. (From Trans. Amer. Ent. Soc.) 
to the arculus. Males with no auricle on the sides of the second abdo- 
minal segment, and the adjacent inner margin of hind wings rounded. 
KEY TO THE GENERA 
Adults 
1 Fore wing triangle four sided; anal loop open below............ 
Se ee ene aro ene Nannothemis, p. 204 
Fore wing triangle three sided; anal loop closed below and more or 
MBB TOOL SEDER «clos: adior eG ot cca ihe 5 6s he a een ee 2. 
