46 THE BRITISH WOODLICE.
The openings are very difficult to identify, and Lereboullet
(39, p. 113) was unable to find them. It is obvious that the
openings must be underneath the plates that form the egg pouch,
and as a change of skin is required to set these free, it would
appear that at ordinary seasons the ducts from the ovaries are
closed. The writers have
been able to determine
from external examin-
ation of specimens which
had moulted and were
about to lay eggs, that
the oviducts at such time
open to the inside of the
base of each walking leg
on the fifth segment. In
similar specimens the
oviducts were also follow-
ed to the opening from
within. The brood pouch has
already been described.
The male organs con-
sist of six testes arranged
in two pairs, each of which
is provided with a reservoir
(see fig. 21). The efferent
ducts from the two reser-
voirs unite at the base of
the thorax to form a com-
mon duct (or "penis").
Development.—The
eggs, in the common
species of woodlice, at
least, are laid at the
beginning of summer, and are retained in the brood pouch,
where they undergo their development. The process has been
recently traced with great care by Professor Louis Rouse (58)
in Porcellio scaber and the description which follows is based
upon his researches.
As. practically speaking, the larval stages are passed within
the egg, and there is no free embryo differing in form from the