THE DRAGON-FLY. 309 
T. Fig.26, side view of false-gill, showing but one leaf), 
Lestes and Calopteryx, the respiratory leaves, called the 
tracheary, or false-gills, are not enclosed within the body, 
but form three broad leaves, permeated by tracheæ, or 
air-vessels. They are not true gills, however, as the 
blood is not aerated in them. They only absorb air to 
supply the tracheæ, which aerate the blood only within 
the general cavity of the body. These false-gills also act 
as a rudder to aid the insect in swimming. 
It is easy to watch the Dragon-flies through their trans- 
formations, 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. 
Mr. Uhler states that at present we know but little of 
the young stages of our species, but Fig. 3. 
“the larva and pupa of the Libellulide $ 
may be always known from the Æsch- 
nidæ by the shorter, deeper, and more ` 
robust form, and generally by their 
thick clothing of hair.” 
The pupa scarcely differs from the 
larva, except in having larger wing- 
pads (Fig. 3). 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 
ving outgrown the larva skin, by a 
strong muscular effort a rent opens Pupa of Æschna. — 
along the back of the thorax, and the insect, having 
fastened its claws into some object at the bottom of the 
