H. Kobayashi 
409 
posterior end of the body. Both arms run along the inner side of the intestinal 
caeca. Anteriorly they almost reach the posterior lateral border of the oral 
sucker. 
Both the testes lie at the same level between the postero-lateral border of 
the ventral sucker and the intestinal caeca. They have a round or ellipsoidal 
shape, being 0-3-0-4 mm. in diameter. There is a well-developed cirrus-pouch, 
which is situated between the anterior part of the two intestinal caeca and 
the anterior border of the ventral sucker and slightly to the left of the median 
plane. It is somewhat round, the diameter being 0*5 mm. In the cirrus-pouch 
is the vesicula seminalis and the pars prostatica, the latter being divided into 
two parts by a constriction; the proximal part is narrower and curved, while 
the distal part is broader and short. The pars prostatica is long and wide and 
follows a circular course. In the genital sinus and near the opening of the pars 
prostatica is an invagination, which seems to perform the function of penis. 
There is no distinctly differentiated ductus ejaculatorius in the distal part of 
the pars prostatica, for the latter opens directly into the genital sinus. Around 
the pars prostatica are numerous prostate glands which fill up the entire space 
of the cirrus-pouch. The ducts of the glands terminate as long cilium-like 
processes on the wall of the pars prostatica. The processes lie closely together, 
their length being 0*02-0-06 mm. 
The ovary lies on the posterior median side of the right testis, near the 
posterior margin of the ventral sucker, and a little to the right of the median 
plane. It has a somewhat lobate form, being broader transversely. It is 
smaller than the testis, the transverse diameter being 0*2 mm. The oviduct 
arises from the median border of the ovary. The vitellaria lie exterior to the 
intestinal caeca extending along the side of the ventral sucker. Each vitel- 
larium consists of 5-6 ascini, each of which has a special yolk duct which 
unites with the rest to form a main duct. The main yolk duct runs mesially 
and unites with its partner from the opposite side in the median plane near 
the posterior margin of the ventral sucker, and forms a common duct which 
soon widens into a yolk reservoir and then opens into the oviduct. Laurer’s 
canal is present, and takes a winding course in its proximal part, but hnallv 
it runs straight and opens to the dorsal surface. The receptaculum seminis 
is totally wanting. The loops of the uterus lie side by side with the posterior 
and left-hand border of the ventral sucker. At the side of the cirrus-pouch it 
is continuous with the vagina. The female genital opening lies close to that 
of the cirrus-pouch, in the genital sinus. The proximal part of the uterus 
widens slightly. The spermatozoa fill up this portion. 
The genital sinus lies slightly to the left of the median plane, towards the 
ventral and anterior margin of the cirrus-pouch. It is nothing more than a 
depression of the body surface, provided with double circular folds. 
The size of the egg is 0*045 mm. x 0*025 mm. The shell is relatively thick 
and the lid is conspicuous. The eggs in the distal part of the uterus contain 
embryos at a quite advanced stage of development. 
