pore. Each testis communicates by means
of an efferent duct with a common collecting duct of its side of the
body, which opens on to the exterior by means of a protrusible penis,
and to which is sometimes appended a seminal vesicle. The efferent
ducts are ciliated, and there is a patch of cilia at the point where
they communicate with the cavity of each testis. The ovaries are more
extensive in some forms (e.g. _Ozobranchus_) than in others, where
they are small rounded bodies. The two ducts continuous with the
gonads open by a common vagina on to the exterior behind the male
pores. This "vagina" is sometimes of exaggerated size. Thus, in
_Philaemon pungens_ (Lambert) it has the form of a large sac, into
which open by a single orifice the conjoined oviducts. From this
vagina arises a narrow duct leading to the exterior. In _Ozobranchus_
the structures in question are still more complicated. The two long
ovarian sacs communicate with each other by a transverse bridge before
uniting to form the terminal canal. Into each ovarian sac behind the
transverse junction opens a slender tube, which is greatly coiled,
and, in its turn, opens into a spherical "spermathecal sac." From this
an equally slender tube proceeds, which joins its fellow of the
opposite side, and the two form a thick, walled tube, which opens on
to the exterior within the bursa copulatrix through which the penis
protrudes. These two last-mentioned types show features which can be,
as it seems, matched in the Eudrilidae.

The gonads develop (O. Burger) in coelomic spaces close to nephridial
funnels, which have, however, no relation to the gonad ducts. The
ovaries are solid bodies, of which the outer layer becomes separated
from the plug of cells lying within; thus a cavity is formed which is
clearly coelom. This cavity and its walls becomes prolonged to form
the oviducts. A stage exactly comparable to the stage in the leeches,
where the ovary is surrounded by a closed sac, has been observed in
_Eudrilus_. In this Annelid later the sac in question joins its
fellow, passing beneath the nerve cord exactly as in the leech, and
also grows out to reach the exterior. The sole difference is therefore
that in _Eudrilus_ the ovarian sac gives rise to a tube which
bifurcates, one branch meeting a corresponding branch of the other
ovary of the pair, while the second branch reaches the exterior. In
th