338          Gasterostomatous Parasites of Indian Food-Fishes

median line at about three-fifths of body length from the anterior end. It is
followed by a small oesophagus which opens into the bulb-shaped intestine,
0.16—0.24 × 0.12 — 0.15 in size.

The testes are in tandem. The posterior testis of 0.1—0.12 × 0.08—
0—12 in size lies in the median line in front of the hinder fifth of the body length.
The anterior testis measures 0.1 — 0.12 in diameter and lies close in front of the
posterior one. The small, narrow, club-shaped cirrus sac of 0.4—0.26 ×
0.06 — 0.08 in size lies along the right body wall, extending forward upto the
middle of the hinder testis. It encloses a small vesicula seminalis, 0.08—0.12
× 0.04—0.06, an elongated, narrow pars prostatica, 0.14—0.22 × 0.04—
0—06, surrounded by prostate glands, and a minute ductus ejaculatorius. The
small genital tongue is hook-shaped. The genital sinus opens a little in front
of the hinder end on the ventral surface of the body.

The small, ovoid ovary 0.08—0.12 in diameter, lies immediately in front
of the anterior testis. The shell gland complex lies in the space between the
ovary, anterior testis and the left body wall. A small Laurer's canal is
present. The vitellaria consisting of small, pear-shaped follicles and arranged
longitudinally in pairs on either side of body extend from the level of the
posterior margin of ovary to the level of the pharynx. The uterus contains
a fairly large number of eggs and extends from the anterior two-fifths of
the body length to the genital tongue. The eggs measure 0.023 × 0.012 in
size.

The excretory bladder is a small, elongated, saccular tube extending from
the level of pharynx to the excretory pore which is situated near the genital
opening.

In having a cylindrical body and the testes arranged in tandem P. arabiana
resembles the species with which the preceding species has been compar-
ed. However, it differs from all of them in the position of its pharynx, intes-
tine, gonads and of the vitellaria, and in the extent of uterus and the
characteristic shape of the rhynchus, besides differences in measurements.

The author is deeply grateful to the Director and the Pathologist of the
Imperial Veterinary Research Institute, Mukteswar-Kumaun and to Dr. H. R.
Mehra of the Allahabad University for their much kind help and encourage-
ment.

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