m beneath, instead of the
formidable array of jaws and accessory organs commonly observed in most
carnivorous larvae, we see nothing but a broad, smooth mask covering the
lower part of the face; as if from sheer modesty our young Dragon fly
was endeavoring to conceal a gape. But wait a moment. Some unwary insect
comes within striking distance. The battery of jaws is unmasked, and
opens upon the victim. This mask (Fig. 127) is peculiar to the young,
or larva and pupa of the Dragon fly. It is the labium, or under lip
greatly enlarged, and armed at the broad spoon-shaped extremity (Fig.
127, _x_) with two sharp hooks, adapted for seizing and retaining its
prey. At rest, the terminal half is so bent up as to conceal the face,
and thus the creature crawls about, to all appearance, the most innocent
and lamb-like of insects.

[Illustration: 128. Abdominal valves; _a_, side view.]

Not only does the immature Dragon fly walk over the bottom of the pool
or stream it inhabits, but it can also leap for a considerable distance,
and by a most curious contrivance. By a syringe-like apparatus lodged in
the end of the body, it discharges a stream of water for a distance of
two or three inches behind it, thus propelling the insect forwards. This
apparatus combines the functions of locomotion and respiration. There
are, as usual, two breathing pores (stigmata) on each side of the
thorax. But the process of breathing seems to be mostly carried on in
the tail. The tracheae are here collected in a large mass, sending their
branches into folds of membrane lining the end of the alimentary canal,
and which act like a piston to force out the water. The entrance to the
canal is protected by three to five triangular horny valves (Fig. 128,
9, 10, 128 _a_, side view), which open and shut at will. When open, the
water flows in, bathing the internal gill-like organs, which extract the
air from the water, which is then suddenly expelled by a strong muscular
effort.

[Illustration: 129. Agrion; _b_, False Gill of Larva.]

In the smaller forms, such as Agrion (A. saucium, Fig. 129; Fig. 129
_b_, side view of false gill, showing but one leaf), the respiratory
leaves, called the tracheary, or false-gills, are not enclosed within
the body, but form three broad leaves, permeated by tracheae, or
air-vessels. They are not true gills, however, as the blood is not
aerated in them. They only absorb air to supply the tracheae, which
aerate the blood only wit