Marshall — On the Anatomy of the Dragonfly. 
755 
ON THE ANATOMY OF THE DRAGONFLY. LIBELLULA 
QUADRIMACULATA, LINNE. 
Wm. S. Marshall. 
From time to time the Odonata have been the subject of 
special morphological, anatomical and embryological papers ; 
some of these have dealt with the insect during its nymphal 
life, others have been restricted to the imago. Among the 
earlier entomologists there have been several, Dufour (8), 
Burmeister (4), Bamdohr (20), Bathke (21) whose work has 
been of a general nature-—later the work has been more along 
the line of investigating some special problem or working on a 
single organ. 
The following paper does not include all the organs; or parts 
of the body of LiBdlula quadrimaculata; some of these have 
been investigated both anatomically and histologically and the 
results, while not giving as much of interest as anticipated, 
are presented as the result of the work, however incomplete. 
Head. 
The vertex (fig. 1, Vt.), frontal vesicle, is, as seen anterior¬ 
ly (2mm x 1. 5mm), very prominent; it appears as a small 
conical cap placed on the head between the antennae. Viewed 
from above the vertex is seen to be a little broader than long, 
it has an oval base, each end of which is drawn out to a 
blunt point; at each of these ends is situated a lateral ocellus. 
The curve of the base, anterior, passes to the median ocellus ; 
posteriorly the margin runs nearly parallel to the compound 
eyes. The anterior surface of the vertex is slightly concave. 
