310 Proceedings of the Royal Physical Society, 
face of its ovigerons sac. The ova (fig. 6) are enclosed in 
the sac, and are arranged in a racemose manner, enveloped 
in a very delicate membrane. 
The internal ovaries (figs. 2, 3, & 3', h) are situated pos- 
teriorly to the peduncle. They constitute an oval, flattened, 
pulpy mass, dividing the cavity of the parasite into two 
compartments ; they are attached by the centre of their pos- 
terior margin to the left wall of the ovario-branchial orifice ; 
and also, as previously mentioned, by the septum which 
runs along the left side of the sac, they are connected to the 
corium (fig. 2 g). In the many specimens examined, I have 
always found a small tubercle (figs. 2 & 3 o), with a minute 
and apparently horny speck on its summit, placed on both 
surfaces (figs. 3 & 3', o) of the body of the ovaries lying op- 
posite to one another, a little to the left of the centre of its 
posterior margin. On removing the little speck of horny 
matter, a depression is seen in the centre of the tubercle, 
apparently communicating -with the substance of the ovaries. 
May not these structures be the orifices of the oviducts, 
closed by a temporary secretion of horny matter till the brood 
of ova in the ovigerous sac has attained its full develop- 
ment ? This view of the nature of these tubercles has sug- 
gested itself to me from the difiSculty of accounting for the 
passage of the ova into the ovigerous sac. The fact that the 
ova found on the external surface of the ovaries are always 
more fully developed than those further removed from the 
surface suggests another view of the subject, — viz., that they 
are developed in successive layers, and thus constitute the 
ovigerous lamellse. 
Situated immediately posterior to the peduncle, is a well- 
defined cavity, lined by a special membrane, and containing 
two oval-shaped bodies (h) placed side by side. These pel- 
lucid sacs (figs. 7 and 8) contain in their cavities peculiarly 
shaped bodies (c), and are provided with convoluted ducts 
(a). The ducts appear to pass towards the right side of the 
parasite (figs. 3 and 3', h) along the anterior margin of the 
ovaries, where they unite and become lost. From the close 
relation of their ducts to the ovaries, it has all along appeared 
to me that these vesicles probably play an important part 
