24 
Trematodes of North Queensland 
is situated a trifle in front of the middle of the body. In young speci¬ 
mens, however, it lies behind the middle. 
The well-marked prepharynx is of rather imusual structure. It 
consists of two parts, an anterior muscular ring attached to the oral 
sucker and a thin-walled posterior part. The fibres of the muscular 
part, which are apparently mostly longitudinal, are attached to the 
outer side of the external limiting membrane of the sucker. At the 
other end they are attached to the cuticle lining the prepharyngeal 
cavity. This muscular structure is bounded by an extremely dehcate 
limiting membrane. The posterior part of the prepharynx conforms to 
the usual type. Its total length is 0-07 mm. The pharynx is extremely 
well developed and measures 0-27 x 0-29 mm. The wide oesophagus is 
about a third of the length of the pharynx. The diverticula are 
uniformly wide and extend to near the posterior end of the 
body. 
The excretory vesicle is a simple narrow tube which reaches the 
level of the ovary. 
The genitalia conform to the type of the Allocreadiidae. The 
median genital aperture is situated over the intestinal bifurcation and the 
short plump cirrus-pouch extends back to the anterior border of the 
ventral sucker. The walls of the pouch are very thin and poorly supplied 
with muscle fibres. Inside the pouch there is a large highly convoluted 
vesicula seminalis and a simple straight ductus. A moderate number 
of prostatic cells are present within the pouch but there is no distinctly 
diSerentiated pars prostatica. The testes lie in the posterior third of 
the body directly behind and contiguous with each other. The post- 
testicular space is a little less than one-sixth of the body length. The 
testes are transverse, roughly oval, bodies, their greatest diameter being 
about one-quarter of the maximum breadth of the body. 
Immediately in front of the anterior testis and contiguous with it 
lies the ovary which is transversely oval in outhne and has a greatest 
diameter of about three-quarters that of the testes. It is displaced 
somewhat to the right side. On its anterior border and still further to 
the right lies a globular receptaculum seminis. A short Laurer’s canal 
is present. The yolk glands are fairly voluminous but are somewhat 
obscured by the pigment spots. They are mainly lateral and extend 
from the pharynx to the posterior end of the body where they fill up 
the post-testicular space. They overlap the intestinal diverticula and 
are found in considerable numbers on the inner side of the latter. The 
uterus is of restricted extent and the ova are not numerous. They 
