STATES OF INSECTS. (Jmago.) 295 
scribed above; and, according to their size, is ended in 
five, ten, or fifteen minutes: in some butterflies half an 
hour, in some even an hour. A few species, such as 
Macroglossa Ginothere, require several hours, or even a 
day, for this operation; and, from the distance to which 
they creep before it has taken place, a considerable de- 
gree of motion seems requisite for causing the necessary 
impulse of the expanding fluids?. In a few genera, how- 
ever, as the gnat, the gnat-like Tipulariz, and the Ephe- 
meree, this process is so rapid and instantaneous, that the 
wings are scarcely disengaged from the wing-cases before 
they are fully expanded and fit for flying. These genera 
quit the pupa at the surface of the water, from which, 
after resting upon it for a few moments, they take flight: 
but this would evidently be impracticable, and immersion 
in the fluid, and consequent death, would result, were not 
the general rule in their case deviated from. 
Some species of the last of these genera, Ephemera, 
are distinguished by another peculiarity, unparalleled, as 
far as is known, in the rest of the insect world. After be- 
ing released from the puparium, and making use of their 
expanded wings for flight, often to a considerable di- 
stance, they have yet to undergo another metamorphosis. 
They fix themselves by their claws in a vertical position 
upon some object, and withdraw every part of the bedy, 
even the legs and wings, from a thin pellicle which has 
inclosed them, as a glove does the fingers; and so exactly 
do the exuvize, which remain attached to the spot where 
the Ephemera disrobed itself, retain their former figure, 
that I have more than once at first sight mistaken them 
for the perfect insect. You can conceive without diffi- 
a Brahm. Zusek: ii. 423. 
