Gastrocotyline Parasites of Indian Clupeoids — Unnithan 
223 
forward parallel to the common vitelline duct, 
and opens into the unarmed uterine pore in 
front of the male genital pore. Two or three 
eggs with polar filaments were observed in most 
of the specimens, but usually were too col- 
lapsed for reliable measurements. 
The vitellaria occupy wide lateral fields ex- 
tending from the zone of intestinal bifurcation 
to the hind end of each crus; follicles are 
spherical, 20-25 \i in diameter, not confluent 
across the median line. The transverse vitelline 
ducts are broad and lie at the level of the an- 
terior quarter of the ovary ; the median vitelline 
duct is long and wide, and originates behind 
the anterior third of the ovary; it narrows as 
it passes backward, and it opens into the swollen 
vitelline ampulla in the ootype region (Fig. 25). 
The single median dorsal vaginal pore is cir- 
cular, 20 p in diameter, unarmed, but sur- 
rounded by a group of small spherical gland 
cells. It is situated a short distance behind the 
intestinal bifurcation (midway between the male 
genital pore and the transverse vitelline ducts). 
It is in this zone that asymmetry is particularly 
striking: on the side of the clamp row (usually 
at the left) there is, at least in nonextended 
worms, a marked hump on the profile before 
the indentation at the base of the neck (Fig. 
18), and a low furrow from the vulva on the 
dorsal side leads obliquely to the indentation. 
This is the anterior limit of the lateral branch- 
ing of the crus and attendant vitellaria of that 
side. On the opposite side the profile is nearly 
straight from the neck zone to the lappet, and 
the vitellaria extend farther anteriorly along 
with short external crural branches to the bi- 
furcation on that side. This notch opposite the 
vulva may facilitate a finer hold during copu- 
lation in these worms, where the torque from 
the oblique attachment must be considerable. 
The median narrow vaginal duct runs backward 
dorsal to the uterus, between the oviduct and 
the median vitelline duct, to open directly into 
the fertilization chamber. It is quite independent 
of the vitelline duct. The genito-intestinal canal 
originates from the base of the ootype, runs 
parallel to the ovijector, and opens into the in- 
testinal crus. 
Two ill-defined excretory pores, one on each 
margin, are noticeable, midway between the 
male genital pore and the pharynx. 
relationships of Engrauliscobina triaptella 
sp. nov.: 
1. In the more or less contracted state, E. 
triaptella is a triangle with the long clamp row 
as its shortest side; the inhibited haptor side of 
the worm is only slightly convex. In the gen- 
erally similar genotype, E. thris socles (Tripathi, 
1959), the body is a much narrower triangle; 
in both there is a narrow neck, about one-fifth 
of the total length. The haptoral row embraces 
more of the body in the genotype, including the 
hind region of the ovarian zone, but it is more 
restricted in E. triaptella, being barely included 
in the ovarian zone. Hence, the torque in the 
latter species is less, and the (meta-) haptoral 
wing is not so extensive, in order to balance these 
stresses, as it is in the genotype. A further con- 
sequence of the torque is visible in E. triaptella 
in the vaginal zone, marked by a hump on the 
profile on the attached side of the worm and 
an inhibition of lateral crural branches and 
vitellaria anterior to the hump and neckbase, 
the opposite side being unaffected. In fact, the 
asymmetry in this species is more marked than 
in any other gastrocotylid and approaches that 
in some Opisthogynidae and Protomicrocotyl- 
idae. 
i. The clamp flange is about 36%-48% of 
the total length in E. triaptella (the 
greater the contraction the greater the pro- 
portion, of course), while in the genotype 
it is about 50%. 
ii. The angle made by the haptoral axis with 
that of the body proper is about 45°, com- 
pared with nearly 60° in the genotype. 
iii. The body torque produces a permanent 
slight bend in the axis of the ovarian to 
the testicular zones. 
2. There are remnant clamps on the inhib- 
ited side of the haptor, only 2 in the genotype, 
but 3 in E. triaptella (hence its name). The un- 
inhibited row in mature worms bears at least 
30 nearly sessile clamps. 
i. There are up to 35 clamps in the new 
species, but 40-42 in E. thrissocles. 
ii. The secondary clamps (but not the squar- 
ish primaries) are at least twice as wide 
as long in E. triaptella. 
iii. The ventral arm of the median spring is 
