Dragon-flies and Damsel-flies 
89 
lengthwise one at each end of the body, are used by some. Specimens 
intended for exchange should not be pinned up, but “papered,” i.e., put 
with folded wings into an enclosing little triangular paper envelope made 
by folding an oblong paper sheet once diagonally and then folding over 
slightly the two margins. 
Fig. 121.—Diagram of venation of wing of dragon-fly. <2, antecubitals; b, postcubitals; 
N, nodus; P, pterostigma; A, arculus; /, triangle. (After Banks.) 
TABLES FOR CLASSIFICATION. 
Key to Suborders (Imagoes). 
Front and hind wings nearly similar in outline, and held vertically over the back 
when at rest; head wide and with eyes projecting and constricted at base. 
(Damsel-flies.) Suborder Zygoptera. 
Front and hind wings dissimilar, hind wings usually being much wider at base, and 
both pairs held horizontally outstretched when at rest; eyes not projecting 
and constricted at base.(Dragon-flies.) Suborder Anisoptera. 
Key to Suborders (Nymphs). 
Posterior tip of abdomen bearing three, usually long, leaf-like tracheal gills. 
(Damsel-flies.) Suborder Zygoptera. 
Posterior tip of abdomen with five, converging, short, spine-like appendages. 
(Dragon-flies.) Suborder Anisoptera. 
SUBORDER ZYGOPTERA. 
Key to Families (Imagoes). 
Wings with not less than five antecubital cross-veins (Fig. 121). 
Family Calopterygid^e. 
Wings with not more than three, usually two, antecubitals (Fig. 121). 
Family Agrionidze. 
Key to Families (Nymphs). 
Basal segment of the antennae extremely elongate.Family Calopterygid^e. 
Basal segment of the antennae short, subrotund.Family Agrionid^e. 
The family Calopterygidse includes but two genera, Calopteryx, in which 
the basilar space of the wings is open and the wings themselves are rather 
broad near the tip, and Hetaerina, in which the basilar space is net-veined 
and the wings narrow. 
Calopteryx maculata (Fig. 122), the most familiar representative in the 
Eastern States of the first genus, has velvety black spoon-shaped wings, 
