PART II. SYSTEMATIC 
The two suborders of Odonata have already been distinguished on 
page 11. We now proceed with their further analysis. 
1. SUBORDER ANISOPTERA 
Dragonflies 
Insects of rather robust stature. Eyes convergent or touching on 
the top of the compact head. Wings held horizontally in repose: Hind 
wings broader at base than are the fore wings. Triangle and supra- 
triangle and membranule present. Males with a single median inferior 
appendage at end of abdomen. Females with or without an ovipositor. 
KEY TO THE FAMILIES 
Adults 
1 Triangles about equally distant from the arculus in fore and hind 
wing and similarly shaped... .o.-..0560.-68 Aeschnidae, p. 53 
Triangles nearer the arculus in the hind than in the fore wing 
shd‘of difierent shape: os '.., .Libellulidae, p. 161 
Nymphs* 
1 Labium flat, or nearly so, without raptorial setae (except in 
Gordulegaster, fig 15)... 2.25. 02 se eee Aeschnidae, p. 53 
Labium mask shaped or spoon shaped; when closed covering the 
face up to the base of the antennae; armed within with raptorial 
RETA IEe Pir saree ee, Bd AR ae Libellulidae, p. 161 
* Some additional data on the nymphs of the eastern species will be found 
in Garman’s (’27) paper on the dragonflies of Connecticut, which came to hand 
after our tables for nymphs had been set. That paper is cited under each of 
the species that Garman treated. 
There are seven principal groups of North American dragonflies, 
whose most available diagnostic characters are set forth comparatively 
in the following table: 
51 
