hin the general cavity of the body. These false
gills also act as a rudder to aid the insect in swimming.

It is interesting to watch the Dragon flies through their
transformations, as they can easily be kept in aquaria. Little, almost
nothing, is known regarding their habits, and any one who can spend the
necessary time and patience in rearing them, so as to trace up the
different stages from the larva to the adult fly, and describe and
figure them accurately, will do good service to science.

[Illustration: 130. Pupa of Cordulia.]

Mr. Uhler states that at present we know but little of the young stages
of our species, but the larva and pupa of the Libellulas may be always
known from the AEschnas by the shorter, deeper and more robust form, and
generally by their thick clothing of hair. Figure 130 represents the
pupa of Cordulia lateralis, and figure 131 that of a Dragon fly referred
doubtfully to the genus Didymops. For descriptions and figures of other
forms the reader may turn to Mr. Louis Cabot's essay "On the Immature
State of the Odonata," published by the Museum of Comparative Zoology at
Cambridge.

[Illustration: 131. Pupa of Didymops?]

The pupa scarcely differs from the larva, except in having larger
wing-pads (Fig. 132). It is still active, and as much of a gourmand as
ever. When the insect is about to assume the pupa state, it moults its
skin. The body having outgrown the larva skin, by a strong muscular
effort a rent opens along the back of the thorax, and the insect having
fastened its claws into some object at the bottom of the pool, the pupa
gradually works its way out of the larva-skin. It is now considerably
larger than before. Immediately after this tedious operation, its body
is soft, but the crust soon hardens. This change, with most species,
probably occurs early in summer.

[Illustration: 132. Pupa of AEschna.]

When about to change into the adult fly, the pupa climbs up some plant
near the surface of the water. Again its back yawns wide open, and from
the rent our Dragon fly slowly emerges. For an hour or more, it remains
torpid and listless, with its flabby, soft wings remaining motionless.
The fluids leave the surface, the crust hardens and dries, rich and
varied tints appear, and our Dragon fly rises into its new world of
light and sunshine a gorgeous, but repulsive being. Tennyson thus
describes these changes in "The Two Voices":--

To-day I saw the Dragon fly
Come from the wel