226
A
REDESCRIPTION
OF
PARAMPHISTOMUM
[Vol. XXV, Part III,
The excretory system (Fig. 4) is typical of the amphistomes. The main
excretory ducts begin on either side of the oesophagus near its origin. These ducts
run posteriorly medial to the intestinal caeca to open into the elongated excretory
bladder which opens on the dorsal side of the body through the excretory pore.
Each main duct gives a median transverse duct slightly behind the intestinal bifurca-
tion. These transverse ducts unite in the middle, giving the system a typical
H-shaped appearance. The transverse ducts give out anteriorly two pairs of
branches to the oesophagus. Besides these, the main ducts give off branches to the
intestinal caeca, reproductive organs and other parts of the body, forming a net-
work, like that described by Thapar and Sinha [1945] in the genus Olveria.
The lymphatic system (Fig. 5) consists of only one pair of lateral longitudinal
vessels, running medial to the intestinal caeca. Anteriorly each longitudinal vessel
divides into three branches that surround the oral sucker. Posteriorly the main
ducts cross the intestinal caeca and run on the sides to reach the acetabulum which
is richly supplied on all sides by a large number of branches. The main ducts
during their course give branches to the various organs of the body forming plexuses
bound them.
The testes are two in number, more or less spherical with slightly lobed margins
and lie in the middle of the body. The anterior testes is generally smaller than the
posterior. It measures 0.772-1.104 x 0.945-1.545 mm. in size. The posterior
testis, lying just behind the anterior, measures 0.975-1.316 mm. X 1.085-1.6 mm.
The vasa defferentia arising from the anterior margins of the two testes unite a
little in front of the anterior testis to form the vas deferens. The vas deferens,
after a short course, forms a muscular vesicula seminalis, which makes a few coils
and leads into an elongated cirrus to open to the outside through the genital atrium
situated near the intestinal bifurcation.
The ovary is oval and is situated behind the testes in front of the acetabulum.
The oviduct arises from the antero-lateral margin of the ovary. After a short
course it meets the Laurer's canal and the common vitelline duct to form the
oötype, which is surrounded by Mehlis' gland cells. The uterus emerges from the
posterior end of the oötype, and after making a few coils behind the ovary it runs
forward anteriorly to open at the female genital pore in the genital atrium. The
eggs are oval and operculated and measure 0.1085-0.1209 mm. long and 0.0684-
0.0744 mm. broad (Fig. 6).
The vitellaria consist of well-developed small follicular structures lying on the
lateral sides of the body extending from the caecal bifurcation to the acetabulum.
The Laurer's canal opens anterior to the excretory pore, as described by Dawes.
Fukui described its opening behind the excretory pore, but Dawes explains this
departure to variability of character; in none of our specimens, however, the
opening was posterior to the excretory pore.
A comparative table of characters showing variations pre-previous descriptions
is given in Appendix I.
Host. Bos bubalis
Location. Rumen
Locality. Lucknow