GOMPHUS 81 
isolated from 3 by a broad yellow stripe; 3, 4 and 5 wider, entire. Legs blackish, 
greenish at base. Wings hyaline; stigma black. Abdomen with the usual line 
of middorsal yellow triangles narrowing apically and disappearing on segment 9; 
on 2 a rather broad trilobed band covers the dorsum, separated by black lines 
from the yellow of the sides. Appendages yellow. 
10. Gompuus Leach 
The Common Club-tails 
These are clear-winged dragonflies of moderate or large size with 
greenish bodies broadly striped with black or brown (the darker color 
sometimes prevailing over the green). The triangles are free from cross 
veins. There is no anal loop. There is a well developed brace vein 
behind the stigma. The inferior abdominal appendage of the male is 
broadly furcate. The side margins of the sub-terminal abdominal 
segments are often broadly dilated, forming the club shaped abdomen 
to which the generic name alludes, (Gomphus, a club). 
Dassen 
Fig. 30. Color pattern of front of thorax in Gomphus. Left to right: 
scudderi, plagiatus, amnicola, brevis, and villosipes. 

This is the largest genus in our fauna. It is distributed around the 
northern hemisphere but the eastern United States is the center of its 
abundance. It is not reported from below the Mexican border. 
The task of determining species in this genus is somewhat difficult. 
The ultimate criteria are found in the accessory genitalia in both sexes. 
The figures of these parts should therefore be carefully compared with 
the specimens collected before names are applied. 
ARTIFICIAL KEY TO THE SPECIES 
Adults 
1 Face cross lined with black or brown (faintly so in brimleyt, 
COUUMATIS SANG ODOUR) <i) 3%. 56 3h sete. ee te ee 2. 
Face not cross lined with black or brown................... 15. 
Zen Lipise. paler externally... 2.0% Uehara brimleyi, p. 106 
Wibiaé not:paler externall yi. ia. cc. 2 eee) scl eae eee Oe 3. 
