466 WILLIAM NICOLL. 
being about -2 mm. and greatest breadth ‘1 mm. It lies 
between the two testes and bifurcates at their anterior border, 
The limbs pass round the sides of the ventral sucker and take 
up a position immediately ventral to the intestinal diverticula. 
They run forward as far as the level of the pharynx, and their 
ends occupy a position about midway between the pharynx and 
the margins of the body. The whole vesicle, both stem and 
limbs, is lmed by a well-marked epithelium, the individual 
cells of which in many cases stand out prominently and can 
be easily observed (figs. 13, 14, Ex.). At other places they 
are flattened and not so distinct, so that here, again, we are 
evidently dealing with cells which are able to change their 
shape in some degree. ‘lhe nuclei of these cells are oval and 
measure about ‘Ol by ‘(008 mm. ‘The vesicle communicates 
with the exterior by a short narrow muscular tube, around 
which are numerous nucleated cells. The excretory aperture 
is at the posterior end of the body. 
Genital System.—The genital aperture is situated on a 
large papilla, which is seen prominently on external in- 
spection. It hes immediately in front of the ventral sucker, 
and displaced well to the left of the middle line. At first 
sight the genital sinus appears to be of great size, but this is 
due to a wide expansion of the ductus ejaculatorius, In 
reality the genital sinus is comparatively small. 
Male Organs.—The testes are two oval bodies sym- 
metrically placed about midway between the ventral sucker 
and the posterior end of the body. Their long axes are 
oblique, the posterior end being nearer the middle line; they 
are separated by the breadth of the excretory vesicle. They 
are distinctly ventral in position, lying under the ends of the 
intestinal diverticula. Their average dimensions are ‘45 by 
‘19 mm., and the thickness equals the breadth. The vas 
deferens arises from a little nodule about the middle of their 
inner surface. 
The vasa deferentia unite in a small bipartite vesicula 
seminalis, both parts of which are enciosed within the cirrus- 
pouch. Jacoby failed to note this bipartite condition, but 
