Monogenetic Trematodes, I — YAMAGUTI 
which the median is constricted into two por- 
tions, the paired submedian meeting in the me- 
dian line. Two pairs of eye spots present. 
Intestinal limbs simple, terminating separately 
behind testis. Testis postequatorial; vas deferens 
not looping around intestinal limb, winding be- 
hind intestinal bifurcation. Copulatory organ 
complex in structure. Prostatic reservoir present. 
Genital pore some distance postbifurcal, median 
or submedian. Ovary pretesticular, with shell 
gland complex in front. Vagina present. Vitel- 
laria co-extensive with intestine. Eggs produced 
backward into rigid filament. Gill parasites of 
marine teleosts. 
TYPE SPECIES: N. pacifcum n. sp., on Naso 
hexacanthus, N. litmatus, N. brevkostris; Ha- 
waii. 
8. Pseudodiclidophora decapteri n. g., n. sp. 
Fig. 8 
HABITAT: Gills of Decapterus pinnulatus 
(local name "opelu”); Hawaii. 
holqtype : U. S. Nat. Mus. Helm. Coll., S.Y. 
No. 8. 
DESCRIPTION ( based on 2 1 whole mounts ) : 
Body 1.5-2 .9 mm long, tapering anteriorly and 
rounded posteriorly, 0.35-0.7 mm wide imme- 
diately in front of opisthohaptor. Opisthohaptor 
extending asymmetrically along each posterior 
lateral margin of body, but separated at the 
truncate posterior end of body, consisting of 4 
pairs of asymmetrically arranged sessile clamps. 
On the right side the fourth clamp is more or 
less wider apart from the third than the second 
is from the first, and on the left side the fourth 
clamp is separated from the third by a convex 
body margin 0.17-0.5 mm long; the third clamp 
is also wider apart from the second just like the 
third on the right. Clamp skeleton of the right 
side consisting of a U-shaped median piece, a 
pair of small basal pieces, 2 pairs of lateral 
springs and a pair of accessory sclerites; median 
piece widely bifid at end of ventral prong; 
shorter dorsal prong with U-shaped apical piece, 
surmounted by accessory sclerites. One of the 
lateral sclerites is much thinner than its fellow 
of the same side, almost membranous; the inner 
lateral sclerites nearly of same thickness. One of 
the accessory sclerites distinctly longer than its 
partner. Basal pieces not projecting into lumen 
69 
of clamp valve. Skeleton of left clamp differ- 
ent from that of right clamp; dorsal prong of 
U-shaped median piece divided into dissimilar 
branches, of which the larger articulates with 
the medial projection from the outer lateral 
sclerites on one side and also with the larger 
piece of the A-shaped accessory sclerites on the 
other; two lateral sclerites of the outer side 
strongly developed, and denticulated distally on 
opposite sides, whereas one of those on the inner 
side is reduced to non-sclerotized piece, though 
its basal portion is distinctly sclerotized like that 
of its partner. Head 88-100 /x wide, with promi- 
nent rounded preoral lobe. Prohaptoral oral 
suckers paired as in Microcotyle, aseptate, 
unarmed, 22-43 X 25-53/e Pharynx rounded, 
30-43 X 25-43/e Esophagus simple, often very 
wide, 0. 3-0.7 mm long. Ceca with numerous 
short inner and longer outer branches, confluent 
at posterior end of body. 
Testes large, irregular in outline, 15-30 in 
number, occupying whole postovarian intercecal 
field. Vas deferens winding forward medial to 
left intestine in ovarial region, at the anterior 
end of which it takes the median course. No pars 
prostatica differentiated. Cirrus represented by a 
short cylindrical sclerotized structure opening at 
its tip and measuring 30-38 /x long by 15-23 n 
wide; it lies ventral to semicircle of six longi- 
tudinal cuticular rods 38-50 fj, long. This coronet 
in turn is enclosed in genital atrium provided 
with very fine circular muscle fibers. This atrium, 
45-50 X 30-47 g, opens midventrally at a dis- 
tance of 0.16-0.33 mm from head end. 
Ovary inverted U-shaped, 0.25-0.6 X 0.05- 
0.16 mm, situated in midregion of body with its 
proximal end on the right of vitelline reservoir 
and its distal end near genitointestinal duct. The 
latter duct arising from the germiduct just an- 
terior to the junction of the germiduct with the 
vitelline reservoir runs obliquely forward and 
opens into the right intestine at the level of the 
two arms of the vitelline reservoir. Uterus ven- 
tromedian, apparently opening at common geni- 
tal pore; eggs 180-220 X 60-90/q with rigid 
filament l40-200g long at each end. Vitellaria 
co-extensive with intestine and its branches; 
vitelline reservoir Y-shaped; its stem just post- 
equatorial, 0.1-0.24 mm long, largely overlap- 
ping ovary. A pair of elongate saccular seminal 
