H. Kobayasiii 
407 
pouch, and no distinctly differentiated pars prostatica is present, excepting 
a few glandular cells lying around the proximal part of the ductus ejaculatorius. 
The ovary lies posterior to the ventral sucker. It is smaller than the 
testes and has 4-5 lobes. The vitellaria occupy the anterior dorsal part of 
the bodv and have a dendritic outline. It is doubtful whether Laurer s canal 
has an external opening or not; the canal is a relatively broad tube which 
runs dorsally, side by side with the wall of the vesicula seminahs, and seems 
to end blindly. The uterus lies surrounded by the intestinal caeca. It forms 
several loops posterior to the ventral sucker, and some of them go exteriorly 
beyond the testes. The vagina, relatively long and slender, runs across the 
ventral sucker and ultimately unites with the ductus ejaculatorius. The egg 
measures 0-04 mm. x 0-02 mm. and has a distinct lid. The shell is brown and 
relativelv thick. In the distal part of the uterus, eggs are found containing 
embryos in an advanced stage of development. 
I have often found encysted distomes in fresh water fishes, which bear a 
close resemblance to Exorchis oviformis, differing only from the latter in the 
absence of eggs in the uterus of the former. Young specimens of Exorchis 
oviformis are often observed in the intestine of Parasilurus cisotus. No eggs 
are present in such specimens, while they have the same structure as the 
encysted distomes above mentioned. As the host of Exorchis oviformis 
usuallv feed on smaller fresh-water fishes, it is probable that this encysted 
*/ 
distome is the young stage of the above parasite. 
This encysted distome is found in various species of fishes.; especially in 
Pseudorashora yarva, various species of Lencogobio, various species of Acheilo- 
gnathus, Carassius auratus, Richardsonius hakunensis, various species of Zacco, 
and Misgrunus anguillicaudatus. 
The encysted distome lies in the muscles, under the scales or in the fins. 
The cyst is spherical with a somewhat irregular shape, the diameter being 
0* 1-0*2 mm. The wall of the cyst is hyaline and structureless. Removed from 
the cyst, the worm (PL XXVI, fig. 6) has an ovoid outline, narrowing anteriorly, 
while posteriorly it terminates roundly. In the cyst, the worm is curved on 
itself or shortened lengthwise. The skin is closely beset with fine spines, 
excepting the posterior part of the body. These spines can be detected only 
in the fresh state. The oral sucker occupies the anterior end and the ventral 
sucker is situated slightly anterior to the middle of the body-length. The 
latter is smaller than the former, the diameters being 0*05 mm. and 0*035 mm. 
respectively. The parenchyma is transparent. In the anterior dorsal part of 
the body one pair of eye-spots and one median pigment spot are present. 
The eye-spots are situated symmetrically on either side of the oral sucker, 
with the median pigment spot between them. The median spot is often 
excentric, and in some cases it is wanting entirely. 
Posterior to the oral sucker is a small pharynx measuring 0*023 mm. 
x 0*02 mm. and this is continuous posterior with the short oesophagus which 
divides into intestinal caeca; these turn outwards and backwards along the 
