g may be briefly stated as
follows. The male, when flying, seizes the prothorax of the female
with the strong appendages at the extremity of the abdomen, and the
abdomen of this latter sex is then curved upward so as to bring the
under side of the eighth segment into contact with the organs of the
second segment of the male. In the more powerful _Libellulidae_, &c.,
the act is of short duration, and it is probable that polygamy and
polyandry exist, for it possibly requires more than one almost
momentary act to fertilize all the eggs in the ovaries of a female.
But in many _Agrionidae_, and in some others, the male keeps his hold
of the prothorax of the female for a lengthened period, retaining
himself in flight in an almost perpendicular manner, and it may be
that the deposition of eggs and pairing goes on alternately. There is,
however, much yet to be learned on these points. The gravid female
usually lays her eggs in masses (but perhaps sometimes singly), and
the operation may be witnessed by any one in localities frequented by
these insects. She hovers for a considerable time over nearly the same
spot, rapidly dipping the apex of her abdomen into the water, or at
any rate touching it, and often in places where there are no
water-weeds, so that in all probability the eggs fall at once to the
bottom. But in some of the _Agrionidae_ the female has been often
noticed by trustworthy observers to creep down the stems of aquatic
plants several inches below the surface, emerging after the act of
oviposition has been effected; and in the case of _Lestes sponsa_, K.
T. E. von Siebold saw the male descend with the female. The same exact
observer noticed also in this species that the female makes slight
incisions in the stems or leaves of water plants with the double
serrated apparatus (vulva) forming a prolongation of the ninth segment
beneath, depositing an egg in each incision. He has seen two pairs
thus occupied beneath the surface on one and the same stem.

[Illustration: FIG. 1--The anterior portion of the body of _Aeschna
cynea_ freed from the nymph-cuticle.]

[Illustration: FIG. 2.--The tail being extricated.]

[Illustration: FIG. 3.--The whole body extricated.]

[Illustration: FIG. 4.--The perfect insect (the wings having acquired
their full dimensions) resting to dry itself, preparatory to the wings
being horizontally extended.]

_Larva and Ny