Four New Diclidophorid Gill Parasites-— Unnithan 
83 
oral pouches "saccular”; ovary C -shaped, testes 
postovarian; vitellaria large; receptaculum sem- 
inis and seminal vesicle present. Parasitic on the 
gills of marine fishes. 
GENOTYPE: Urocotyle pristipoma n. sp. 
Urocotyle pristipoma n. sp. 
Figs. 6-12 
Body spindle-shaped, connected by a short 
narrow isthmus with a haptor (Fig. 6). Total 
length 2.83 mm and maximum width 0.429 mm 
across the middle of the body proper. 
Mouth subterminal, slitlike, transversely elon- 
gate and situated immediately in front of the 
anterior border of the oral pouches. Oral pouches 
(Fig. 7) almost spherical or vesicular, 52 X 42 /x, 
with a narrow oval aperture which is plugged 
with a dark substance; wall of the pouch thick, 
muscular, and fibrous. (It is interesting to note 
that the oral pouches of this species are slightly 
more advanced than are those of Microcotylidae 
and Gastrocotylidae, showing a remote resem- 
blance to a sucker-like structure embedded in 
the body muscle, and are devoid of the long and 
wavy muscle bundles which are usually found 
attached to the oral pouches of many species of 
Microcotylidae and Gastrocotylidae. ) Pharynx 
median, oval, thin-walled, more or less the same 
size as the oral pouches, 52 X 40 /x. Oesophagus 
short, narrow, and without branches, bifurcating 
into the two crura at the level of the male genital 
pore, 0.185 mm from the anterior end; crura 
fairly wide, with irregular lateral pouchlike 
bulgmgs. In front of the narrow isthmus be- 
tween the body and haptor the two crura become 
confluent across the median line, and the result- 
ing single median unbranched crus extends 
through the isthmus as a tapering tube into the 
haptor about two-thirds its total length (Fig. 6). 
Haptor one-fourth the total length, with four 
pairs of symmetrical clamps and a median pos- 
terior tail-like lappet. Lappet cylindrical, 147 X 
42 /x, and armed with double pair of anchors, 
of which the anterior pair is prominently hooked 
and measures 12 u in length, while the posterior 
pair is shorter (8 /x long) and only slightly 
curved. Clamps with stout cylindrical muscular 
peduncles; damp capsule thick and fleshy with 
broad fleshy lips. Each damp with a broad, well- 
developed, cuticularized sclerite at the base, the 
lateral ends of which arch upwards as a flap on 
each side, the adjacent posterior margins being 
connected dorsally by a thin, narrow, cuticu- 
larized bridge, the entire structure thus forming 
an uneven ring. This structure represents the 
median spring. From the inner surface of this 
broad ventral platelike sclerite a long and nar- 
row peglike, heavily cuticularized spine projects 
into the damp capsule. The rest of the damp 
armature resembles more or less that of Cbori- 
cotyle except that here it appears to be more 
advanced in structure. It consists of a pair of 
oblique sclerites, one long and narrow, the other 
short and broad; the inner end of the shorter is 
articulated with the inner end of the longer, 
which in turn is attached to a small concavity 
on the anterior margin of the median ring 
sclerite. There is a second pair of unequal scle- 
rites with slightly curved inner ends along the 
margin of the damp capsule. Behind this is a 
third pair consisting of one long and narrow 
component, another broad and short component. 
Both of these articulate with the lateral sides 
of the median spring. The wall of the damp 
capsule has numerous cuticularized ridgelike 
thickenings. 
Testes oval or spherical, 6-3—105 /x wide, nine 
in number, and distributed in a longitudinal, 
alternating intercrural row between the ovary 
and the intestinal confluence. Seminal vesicle 
irregularly oval, 60 X 48 /x, situated dose to the 
anteriormost testis and with small vasa efferentia 
directed towards the testes. Yas deferens long 
and narrow, arises from the anterior margin of 
the seminal vesicle and extends forward ven- 
trally to the left half of the ovary. Beyond this 
level it extends as a wavy duct parallel to the 
vaginal duct on its right side, and opens out 
through the male pore by way of the unarmed 
conical muscular penis. Male genital pore sit- 
uated at the angle of intestinal bifurcation and 
0.185 mm from the anterior end. It is a small 
ventral aperture with an irregular rim, armed 
with a circlet of 10 sickle-shaped short hooks 
(Fig. 11), which converge to the center of the 
pore. 
Ovary median, C-shaped, situated in front of 
