170
A New Parasite, Waretrema piscicola
thirty minutes, though in sea water they remain alive for nearly two hours.
The body is fairly muscular and fusiform. In permanent mounts it measures
2.24 to 5.36 * in length and 0.48 to 0.94 in maximum breadth, which occurs
at about the middle of the body length. It has feebly developed cutaneous
gland cells all over the body and the cuticle is studded with very minute,
backwardly directed spines in the pre-acetabular region. The suckers are
spherical and muscular. The oral sucker, measuring 0.15 to 0.3 in diameter,
is markedly subterminal and has a crown of six prominent, conical papillae,
arranged radially on the dorsal side of the anterior half of the sucker. The
papillae have minute spines like those of the body wall. In some specimens
the ventral margin of the oral sucker appears to be cleft. The acetabulum,
0. 24 to 0. 4 in diameter, is situated at the end of the first third or quarter
of the body length. The size ratio between the oral sucker and the acetabu-
lum is as 2 : 3 or 3 : 4. The prepharynx is fairly long, 0.1—0.3, and tubular,
and is followed by the pharynx which measures 0.1 to 0.2 in diameter. The
oesophagus is fairly long, 0.3 to 1.5, and bifurcates posteriorly into two,
moderately long, saccular caeca of 0.54 to 1.2 by 0.14 to 0.24 size. The
caeca terminate blindly usually a little in front of the testis, but in contracted
specimens they may extend posteriorly up to the middle of the testis.
The single ovoid, median testis measures 0.32 to 0.68 by 0.2 to 0.38
in size. Its position varies from in front of the last quarter to the posterior
seventh of the body length, depending on the state of contraction of the
parasite. The vesicula seminalis is divided into two elongated, bulb-shaped
parts—vesicula seminalis interna and vesicula seminalis externa. The latter
measures 0.16 to 0.4 by 0.1 to 0.16 in size and extends posteriorly up to the
level of the intestinal bifurcation. A well-developed, elongated cirrus
sac like structure—hermaphroditic sac—of nearly uniform breadth, except
for a little constriction at the level of the anterior end of the vesicula seminalis
interna, encloses the vesicula seminalis interna of 0.16 to 0.4 by 0.1 to 0.16
size which narrows anteriorly to form a small, 0.15 to 0.24 by 0.01—0.015,
tubular coiled pars prostatica and a well-developed metraterm and ductus
hermaphroditicus. A large number of prostate gland cells lie all round the
ductus hermaphroditicus and open into the pars prostatica. The latter opens
into the metraterm through a small ductus ejaculatorius, 0.03 to 0.07 long,
to form the ductus hermaphroditicus, which is equal to the metraterm in
length. The metraterm measures 0.25 to 0.5 by 0.04 to 0.08 in size. The
hermaphroditic sac, 0.54 to 0.9 by 0.16 to 0.18 in size, lies to the right of
the acetabulum and extends posteriorly a little beyond it. The genital pore
is situated usually in the median line close in front of the acetabulum.
The ovary is a small, spherical or oval structure of 0.08 to 0.14 by 0.12
to 0.18 size, situated a little to the right of the median line close in
front of the testis. Only rarely it may come to lie in level with the anterior
margin of the testis. The shape and size of the receptaculum seminis depend
on the amount of its contents. Its size varies from 0. 4 to 0. 46 by 0. 1 to
* All measurements are in mm.