TREMATODE PARASITES OF INDIAN ELEPHANT             107

ventrally in front of the posterior end and is surrounded by a prominently raised
margin. Its diameter varies from 1.34 to 2.11.

The mouth is situated at the anterior extremity and is 0.34—0.57 in diameter.
It is surrounded by an oral sucker constricted in the middle. The constriction
divides the sucker into two portions: a globular oral portion measuring 0.73—
0.97×0.43 and the posterior œsophageal or bulbous portion measuring 0.7—1.1
longitudinally and 0.64 —1.36 transversely. The bulbous portion is bilobed and
each of the bulb communicates posteriorly with a pouch measuring 0.98—1.57 ×
0.7—1.27. The œsophagus starts from the base, between the two bulbs of the
oral sucker and passes posteriorly in a straight course. Its walls appear to be
glandular and it measures 0.93—1.62 in length. It bifurcates into two intestinal
cæca passing posteriorly and ending somewhat posterior to the middle of the pos-
terior sucker. Each cæcum makes an inward bend at the level of the testes.

The excretory bladder lies on the dorsal surface of the posterior sucker and
the excretory pore opens in the central line behind the posterior sucker, at a dis-
tance of 0.42—0.84 from the posterior extremity.

The testes are two large, deeply lobed cauliflower-like bodies situated slightly
posterior to the centre of the body. They measure 1—2.48 × 0.73—2.28. The
position of the testes in the body appears to be variable : being sometimes slightly
anterior, and sometimes slightly posterior. The vasa efferentia arise from the centre
of the testes and run anteriorly for a short distance where they unite with each
other centrally and from a vesicula seminalis. This latter is a thin-walled, mode-
rately dilated, but much coiled duct. It passes into a relatively thicker muscular
duct called the pars musculosa. This is not so much coiled as the vesicula semi-
nalis. Usually a few of the coils of the pars musculosa pass anterior to the
genital opening. Following the pars musculosa is a short, narrow duct called the
pars prostatica which is surrounded by a few noncellular glands. From its ventral
aspect there passes ventrally a short, muscular duct, the ductus ejaculatorius,
which unites with the terminal portion of the uterus, the metraterm, to form a
ductus hermaphroditicus. This latter is a very short canal opening into the geni-
tal atrium which communicates ventrally with the genital pore. The ductus har-
maphroditicus, the ductus ejaculatorius, metraterm and the genital atrium are
enclosed in a mass of muscle fibres.

The ovary measuring 0.42—0.87 × 0.27—0.74 is situated sometimes on the
left and sometimes on the right side of the middle line, between the testes and the
posterior sucker. Occasionally the ovary appears to be lying exactly in the centre
of the body. It may therefore be inferred from this that the normal position of
the ovary is central, but according as the worms have undergone contraction it
may be deflected either to the right or the left side like some other species of