Gastrocotyline Parasites of Indian Clupeoids — Unnithan 
221 
genotype Engrauliscobina thrissocles (Tripathi). 
There is no demarcation of the haptoral region 
from the body proper, since the clamp row 
flanks the side of the body opposite the an- 
terior region of the testicular zone or extends 
partly into the ovarian zone providing one of 
the shorter sides of the triangle. The length of 
these typical specimens is 2.4 and 2.9 mm, and 
their maximum width (between the gonad zones 
but excluding the haptoral wing) is 0.4 and 
0.7 mm, respectively, giving a width-to-length 
ratio of 16.5% :24% — the latter being more 
typical. The worms are strongly flattened dorso- 
ventrally and highly extensible and contractile; 
in extension they are able to flex the body over 
a wide arc based on the fixed haptor, the axis 
of pivoting being in the thickest and widest 
zone; the resulting stresses would account for 
the convexity on the short side above the long 
clamp row. The shape of the whole body is like 
that of a scraper (particularly so in the geno- 
type) ; the handle of the scraper is here more 
abruptly demarcated, forming the neck which is 
about one-fifth the total length of the body axis, 
as it is in the genotype ; and here again the body 
axis is bent at a small angle between the ovarian 
and testicular zones, even in the contracted spec- 
imen (cf. my Fig. 18 and Tripathi’s [1959] 
Fig. 5 6a). 
The subterminal mouth has scattered gland 
cells only on the anterior lip. The oral pouches 
are longitudinally ovoid, 24 X 20 p, and have 
long muscle fibres extending posteriorly from 
their thick outer walls. The pharnyx is oval, 
Figs. 18-25. Engrauliscobina iriaptella sp. nov. 18, Complete worm, ventral view; 19, another complete 
worm with three clamps in the short row; 20, hind end of the haptor with the pair of incipient clamps 
of the worm with only two clamps in the short row; 21, first clamp nearest the lappet on the short row, dorsal 
view; 22, one of the middle clamps of the long row, dorsal view; 23, male genital pore with the penis head; 
24, corona of spines of the male genital pore; 23, ootype and ovarian region, ventral view. 
