Four New Diclidophorid Gill Parasites™ Unnithan 
85 
lateral notches (Fig. 15). Total length 3. 7=3. 9 
mm; maximum width across the ovarian zone, 
0=9 mm. 
Mouth subterminal, circular, bordered by a 
'sphincter' of thin muscle fibers; oral pouches 
thin- walled, elliptical or oval, 16 X 12 /x- 20' X 
16 /x, situated behind the mouth and parallel to 
the median line; pharynx median, oval, 36 X 28 
jut, and with a row of gland cells on each dorso- 
lateral side. Pharynx and oral pouches have long 
muscle fibers extending to the level of the male 
genital pore. Oesophagus wide, without lateral 
branches and bifurcating into the crura at the 
level of the vagina 0.609' mm from the anterior 
end of the body; crura wide and saclike with 
irregular margin. At the junction of the body 
and the haptor the two crura become confluent 
and continue into the haptor as a single median 
crus which considerably expands in the base of 
the haptor. From the sides of this median crus 
are given off short stumpy branches to the bases 
of each peduncle. The intercrural field is reduced 
in front of and behind the ovarian zone owing 
to the highly expanded condition of the crura 
(Fig. 13). 
Haptor forms slightly less than half the total 
length, with four pairs of pedunculate clamps; 
peduncles of varying length, each with a thick 
bundle of axial muscle fibers extending from the 
base of the damp to the middle of the haptor; 
damps triangular with rounded corners, 189 X 
189 /x-210 X 210 /x, with fleshy capsule and 
thick lips but no riblike striae in the wall of the 
capsule. Clamp structure (Fig. 14) more or less 
as in Urocotyle pristipoma ; but the lidlike me- 
dian spring forms a broader cuticularized con- 
tinuous ring at the base of the damp, the 
spinous process is longer and narrower, paired 
sclerites on either side are long and narrow, and 
the damp capsule contains two fleshy suckerlike 
pads, one at the base and another in the distal 
dorsal region of the damp. Terminal lappet and 
anchors absent. 
Testes five to six, spherical, 42 /x in diameter, 
and confined to a small intercrural space behind 
the ovary, not entering the haptor. Vas deferens 
long and narrow, arises from the anterior mar- 
gin of the testes, runs forward along the median 
line and, crossing over to the left side of the 
vagina, opens into the base of the penis; penis 
muscular, conical, unarmed; male genital pore 
median ventral armed with a ring of 10 conical 
convergent cuticularized spines (Fig. 15) and 
situated midway between the mouth and in- 
testinal bifurcation. Seminal vesicle and penis 
bulb absent. 
Ovary U-shaped, 273 X 210 /x, and situated in 
the median intercrural field in front of the testes; 
proximal limb narrower and shorter with small 
ova, distal limb with large ova (Fig. 1.6) ; ovi- 
duct arises from the distal end of the ovary and 
curving downward runs obliquely beneath the 
ovary to open into the ootype dose to the me- 
dian vitelline duct; uterus long and narrow, 
arises from the anterior margin of the ootype 
and runs forward along the median ventral 
plane, where it can be traced up to the level of 
intestinal bifurcation. 
Vitellaria coextensive with the crura from the 
zone of intestinal bifurcation to the terminal end 
of the median crus in the haptor; follicles spher- 
ical or polygonal, 2 1 /x wide; transverse vitelline 
ducts arise from each side in the middle of the 
body proper and unite to form a long, wide, 
median vitelline duct, with large follicles in the 
anterior two-thirds (Fig. 16). The narrow pos- 
terior end of this duct opens into the ootype. 
Ootype small, oval, surrounded by two or 
three rows of small Mehlis’ gland cells and 
situated at the terminal end of the median vitel- 
line duct on the left posterior margin of the 
ovary. 
Vagina, median dorsal (Fig. 13), unarmed, 
and in the form of a transverse slitlike aperture, 
situated at the level of the intestinal bifurcation; 
vaginal duct wide and thick-walled in the an- 
terior half, while narrow and thin-walled in the 
posterior half. At the level of the transverse 
vitelline ducts the vaginal canal curves to the 
right side and opens into the anterior corner of 
the receptaculum seminis; receptaculum seminis 
median triangular, 126 X 126 /x, placed close to 
the anterior margin of the ovarian zone. From 
the left corner of the receptaculum seminis the 
vaginal duct continues around the distal limb of 
the ovary and opens into the ootype close to the 
oviduct. Genito-intestinal canal arises from the 
posterior margin of the receptaculum seminis, 
runs obliquely backward and opens into the 
right crus. 
