212 
GENUS NEONEURA (oDONATA) 
usually relatively weakly chitinized and some variation or post- 
•mortem distortion must lie looked for. The superior appendages 
of the male are involved, the inferiors sinpile. A real comprehen- 
sion of the form of the superior can come only after prolonged 
study in many views with a binocular microscope. Throughout 
the genus the parts may be honiologized in all the species. The 
external face of the superior is divided more or less distinctly 
into two parts, the lower part usually the smaller and simpler, 
consisting generally of a more or less horizontal plate, the outer 
angle of which (alone seen in profile view) is commonly better 
developed than the inner angle, which is ordinarily acute, black- 
tipped and resting against the inferior appendage. The upper 
branch of the superior consists of a more or less expanded plate, 
with a generally interno-dorso-posteriorly directed surface. The 
dorsal edge of this plate varies in different species from a practi- 
cally smooth, continuous condition to a more or less indentate or 
armed condition, with prominent or large, but usually blunt, 
posteriorly directed tubercles. The dorsal view of the appendage 
shows the various forms of this edge; for example, joana has it 
developed near the base in a broad blunt triangle; in aaroni 
there is near its mid-length a small distinct beak-shaped prom- 
inence. The dorso-posterior angle of the upper part of the su- 
perior appendage is also more or less variable in the different 
species; usually it is a rather uniformly rounded and incon- 
spicuous end, as in aaroni for example, but in joana it is produced 
posteriorly in a long triangular projection overhanging the in- 
ferior appendage. But the greatest modifications of the superior 
appendage are concerned with the inner surface of the upper 
part, below the dorsal edge discussed above. This surface is 
often irregularly triangular in form, the apex occupying more or 
less of the cleft dividing the appendage into the superior and 
inferior parts, as may be seen in the profile view of sylvatica 
(figure 37) for example. A number of modifications of this part 
occur, the most peculiar of which possilily is in fulvicoUis, where 
the surface cannot be detected in dorsal or lateral views, but where 
a posterior view shows it as a long, narrow, ventrally directed, 
thorn-like body (figure 70, which compare with figure 39). In 
myrthea also this part is strikingly different from the more usual, 
roughly triangular form, being long and finger-shaped (see figure 
