26 
d. Antenne 4-jointed, broad and flat, superior appendage 
not notched at apex. Gomphide. 
c. Labium spoon-shaped, covering most of the face, with 
subtriangular close-fitting lobes. 
if. Teeth on the opposed edges of the lateral labial lobes 
acute, very large and irregular, interlocking; two 
stout teeth with a cleft between them at the apex 
of the median lobe. Cordulegasteride. 
J. Opposed edges of the lateral labial lobes crenate or with 
} rounded teeth; at most but a single median 
tooth on median lobe. Libellulide: 
Imagos. 
aa. Front and hind wings similar, or nearly so, in outline, usu- 
ally elevated when at rest; males with two inferior 
abdominal appendages (Zygoptera). Head transversely 
elongated, eyes widely separated. Females with genital 
valves. 
bb. Not less than five antecubital cross-veins in the an- 
terior series. Calopterygide. 
b. Not more than three antecubitals, usually two. 
Agrionide. 
a. Front and hind wings dissimilar, hind wings usually much 
broader at the base, horizontal when at rest ; males with 
one inferior appendage, or none. (Anisoptera.) 
cc. Triangles of front and hind wings of similar shape; 
antecubitals of first and second series not coinci- 
dent, except the first and another thick one ; second 
series of postcubitals complete. 
dd. Abdomen with lateral carine; female with genital 
valves ; head globose, eyes meeting above along the 
middle line of the head. Aischnide. 
d. Abdomen without lateral carine. 
ff. EHyesdistinctly separated, head transversely elongated. 
gy. Median labial lobe bifid; female with genital 
valves. Petaluride, 
