Marshall—On the Anatomy of the Dragonfly. 763 
Pharynx. The pharynx is somewhat flattened dorso-ven- 
trally. Its cuticnlar lining is thick and varies in different 
specimens from an entirely colorless layer to one in which the 
outer part is brown; in all specimens the pharyngeal plate 
is darkly colored. This plate (fig. 10, Ph. pi.) extends trans¬ 
versely across the floor of the pharynx near its posterior boun¬ 
dary; in a longitudinal section of the pharynx it has the ap¬ 
pearance of a forwardly directed tooth (figs. 8 and 11, Ph. 
ph). Forming the ventral wall there are besides the cuticu- 
lar and hypodermal layers, a few circular muscles. Dor sally 
the cells of the hypodermis are longer than those of the op¬ 
posite surface and there is, above the hypodermis, some gland¬ 
ular tissue; this is followed by longitudinal and oblique mus¬ 
cles and above these a circular layer. In the posterior part 
of the pharynx there are small muscles arising on its dorsal 
wall and passing to the clypeus. Just posterior to the pharyn¬ 
geal plate there is a depression in the ventral wall, a little 
back of this the circular muscles increase in thickness and the 
lumen of the alimentary canal decreases in size: at this point 
might be placed the boundary between the pharynx and the 
oesophagus. The cuticular lining of the pharynx is covered 
with numerous small, blunt projections. 
The glands lying at the roof of the pharynx (fig. I'l, Gl.) 
show a fairly continuous layer just above the hypodermis. 
In a longitudinal section through the pharynx a number of 
pieces of different sizes are seen; the largest of these lie paral¬ 
lel to the roof of the pahrynx and are seldom more than two 
or three cells in thickness (fig. 12). Each gland-cell contains 
a rounded nucleus and often shows one or more vacuoles in the 
cytoplasm. 
Oesophagus. The oesophagus is narrower at its beginning 
than the pharynx; it changes but little in diameter until, at 
the beginning of the mesothorax, the sudden enlargement takes 
place which was mentioned in the general account of the ali¬ 
mentary tract. A study of transverse sections shows that in 
its most anterior part it is similar in structure to the pharynx; 
the five large folds found in the latter region change to six or 
