368         Amphistomatous Parasites of Indian Food-Fishes

The anteriorly directed, cup-shaped oral sucker of 0.76—0.88 × 0.76—
0.98 in size opens to the outside through a small vestibule. Posteriorly it bears
two small laterally directed pouches, measuring 0.16—0.5×0.16—0.24 in
size, which open dorsally into it. The posterior sucker is a large, circular struc-
ture of 6.2 to 7.5 in diameter, and is studded on its inner surface with a large
number of prominent papillae. It is situated at the posterior end of the conical
body forming its base. The oesophagus is a narrow tube, 1.3—1.4 long,
and has an oval oesophageal bulb, 0.52—0.84 × 0.26—0.4 in size, at its
posterior end. The oesophagus and its bulb are both surrounded by numerous
deeply staining cells. The caeca follow a typical course and end blindly at
the base of the conical body. Their blind ends are slightly swollen. (Plate
XXIX, fig. 2.)

The testes are deeply lobed structures situated at about the middle of the
body length, one on either side between the caeca and the body wall. The
left testis, measuring 1. 54—1.84 × 0.76—1.02 in size, is situated a little in
front of the right testis of 1.8—1.9 × 0.88—1.08 in size. From each testis is
given off a vas efference which runs transversely towards the median line where
the two meet to form a common swollen sac. The latter continues anteriorly
into a coiled vas deferens which swells up to form the vesicula seminalis on
entering the cirrus sac. The cirrus sac is a well-developed, bulb-shaped
structure of 0.34—0.46 × 0.24—0.28 in size. It encloses the vesicula seminalis,
a small tubular pars prostatica surrounded by prostate gland cells and an
elongated, tumbler-shaped ductus ejaculatorius. The male and female pores
lie close together in a shallow depression of the ventral body surface, surround-
ed by a huge but feebly muscular genital sucker, 1.0 to 1.4 in diameter. The
genital pore is slightly sinistral, lying in level with the oesophageal bulb.

The ovary is a small, ovoid body of 0.46—-0.64× 0.38—0.52 in size,
situated close to the blind end of the left caecum at the circular base of the body.
The elongated sac-shaped shell gland complex lies immediately behind the
ovary and measures 0.5—0.6 × 0.24—0.36 in size. The oviduct gives off a
narrow fairly long and conspicuous Laurer's canal just before entering the shell
gland complex. The vitellaria consist of numerous small follicles of irregular
shape and varying sizes, arranged in the form of an U. They begin from the
hinder end of testes and extend laterally to the caeca and in the space at the
base between the blind intestinal ends. The yolk reservoir lies in the centre
of the base. The uterus consists of a single, long, transversely coiled ascending
tube containing a large number of eggs, 0.114—0.152 × 0.053—0.072 in
size. The uterine coils are confined to the intercaecal space. The excretory
system is H-shaped. The lymphatic system consists of three pairs of longi-
tudinal canals. The details of the two systems could not be studied.

The new genus, Nicollodiscus, is named in honour of Dr. W. Nicoll the
well-known English parasitologist. It is assigned to the family Cladorchidae on