404 
Bicjenetic Trematodes in Japan 
This species resembles in external form Didymozoon lampridis , but I am 
uncertain as to its identity on account of the lack of literature. 
(24) Lepodora sp. (PL XXVI, fig. 3). 
\ his species infests the intestine of Oncorhynchus masou. The body is 
elongated and compressed dorso-ventrally. The broadest part of the body 
lies slightly posterior to the ventral sucker and anteriorly tapers rapidly, 
while posteriorly it narrows gradually. Dorso-ventrally the thickest part lies 
at the level slightly posterior to the ventral sucker. The size is 5-6 mm. in 
length and 1mm. in the widest breadth and 0*8 mm. in thickness dorso- 
ventrally. 
The oral sucker is situated at the anterior end of the body, and the ventral 
sucker at the anterior fourth of the body-length. The diameters of the oral 
and the ventral suckers are (h28—0*35 mm. and 0*42—0 - 6 mm. respectively. 
Both suckers are round in outline. The cuticle is armed with large scale-like 
spines which are present all over the body. 
The oral sucker is succeeded by the prepharynx, the length of which is 
0-55 mm. The pharynx is large and well developed, its length being 0-28 mm. 
The oesophagus is very short and it rapidly bifurcates into the intestinal 
caeca. The intestinal caeca are broad and straight and end near the posterior 
end of the body. 
The unpaired part of the excretory vesicle is long and straight. It runs 
along the ventral body wall and is divided into two short arms at the level 
of the anterior testis. 
The two testes are large and elliptical, and lie between the intestinal caeca, 
one behind the other, at the middle and the posterior third of the body-length 
respectively, so closely along the intestine as to press the latter somewhat 
outward. The length of the anterior testis is 07 mm. and the posterior one 1 mm. 
They lie separated from each other by a short interval. A large and curved 
cirrus-pouch is present. It extends posteriorly beyond the ventral sucker. 
The genital opening lies directly anterior to the ventral sucker. The space of 
the posterior half of the cirrus-pouch is filled with the broad and convoluted 
seminal vesicle. There is a relatively short pars prostatica lying in the middle 
part of the pouch. The ductus ejaculatorius has an epithelial wall and opens 
into the genital sinus. 
The ovary lies directly anterior to the anterior testis. It is spherical in 
shape, its size being 0*3 mm. There is no receptaculum seminis. Laurer's 
canal opens dorsally. The vitellaria lie along the lateral body margins in the 
posterior part of the body, partly overlapping the intestinal caeca dorsally 
and ventrally. The uterus is relatively short, forming several transverse loops 
between the ovary and the ventral sucker. The vagina is not well marked. 
At the posterior margin of the ventral sucker the uterus is continuous with a 
somewhat muscular canal, which has an epithelial wall. This canal, or rudi¬ 
mentary vagina, runs anteriorly along the dorsal border of the cirrus-pouch, 
