100 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
Again, one must remember that we are dealing with a 
protandrous hermaphrodite animal in the functional 
male phase. 
The ova seen in the ovary are all obviously immature, 
and I do not give dimensions. Some are represented in 
figs. 6 and 7, Pl. IT, and it will be seen that they are of 
the usual type. They are contained chiefly in the anterior 
part of the ovary. 
The Vagina. 
There is only one vagina in this species, and 
it lies on the left. The external vaginal aperture 
is a slit, elongated in the longitudinal direction, and is 
situated in nearly the same plane as the common genital 
aperture. This leads into a narrow tube, which can be 
traced backwards with little difficulty in cleared prepara- 
tions (itis well shown in Mr. Scott’s figure*) and in serial 
sections. The whole organ is small, and it is represented 
both in Pl. I and in text-fig. 4, which shows part 
of a horizontal section passing through the vagina. 
The wall of the organ consists of outer and imner limiting 
oe 
membranes composed of the homogeneous “‘ chitinous ”’ 
material, which enters into the composition of the walls of 
almost all genital ducts in Trematoda and Cestoda alike. 
But the posterior part of the vagina expands considerably, 
and here one would expect to find a large, thin-walled 
vesicle acting as a receptaculum for the semen received 
during copulation. Instead of this we find that the 
calibre of the tube does not increase at all, and that the 
dilatation is caused by a relatively enormous development 
of muscular tissue round the proximal part of the vagina, 
but certainly forming an integral portion of its wall. 
There are two series of fibres (fig. 4), a strongly developed 
* Scott, loc. cit. 
