Monogenetic Trematodes, I — YAMAGUTI 
and paired nerve trunks conspicuous, former 
dorsal to anterior end of esophagus. Esophagus 
simple, without diverticles; intestinal limbs sim- 
ple at the beginning as well as at the posterior 
portion intruding into the opisthohaptor, giv- 
ing off numerous short inner and longer outer 
branches in swollen region of body proper. 
Testes rounded, 10-20 in number, arranged 
irregularly in postovarian interintestinal field, 
but not beyond level of posterior end of vitel- 
laria. Vas deferens slightly winding on the right 
of median line, provided with a dense coat of 
prostatic cells along greater distal portion. No 
pars prostatica differentiated. Ductus ejacula- 
torius wider than distal end of vas deferens, 
provided with circular muscle fibers. Cirrus com- 
plex, consisting of a more or less pointed pyri- 
form bulbus cirri of lamellar muscles enclosed 
in a horseshoe-shaped pad of lamellar muscles, 
and an inverted cone, on the anterior base of 
which is set a midventrally interrupted crown of 
long, apically outcurved spines projecting into 
the genital atrium. The pointed conical apex of 
the bulbus cirri fits into the midventral groove 
of the above-mentioned cone and projects a little 
into the base of the genital atrium, whereas the 
apex of the inverted cone is attached to the mid- 
dorsal side of the bulbus cirri. The ejaculatory 
duct leads into the bulbus cirri ventral to this 
point of attachment. Genital atrium forming a 
powerful ring (69-84/a in outside diameter) of 
circular muscle fibers basally, but thin-walled 
distally, provided with circular and longitudinal 
muscles; the latter fibers extend backward over 
the atrial ring and continue to the outer surface 
of the horseshoe-shaped muscle pad, thus simu- 
lating the cirrus pouch. Common genital pore 
ventral to posterior part of esophagus, 0.28-0.35 
mm from head end. 
Ovary shaped like an interrogation mark, 0.5- 
0.7 X 0.35-0.4 mm, originating at posterior end 
of middle third of body to right of median line; 
its swollen distal portion with three constric- 
tions in the type and occupying whole breadth 
of interintestinal field; germiduct arising from 
backwardly directed distal end of ovary, giving 
off genito-intestinal canal just before joining 
vitelline duct; ootype immediately anterior to 
anteriormost testes medial to left intestinal limb. 
93 
Genito-intestinal duct crossing proximal portion 
of ovary and emptying into right intestinal limb. 
Uterus midventral, very wide, may be distended 
with numerous eggs, thus occupying greater part 
of preovarian interintestinal field, opening into 
genital atrium across anterior rim of atrial ring 
mentioned above. Uterine eggs elongate oval, 
130-152 X 65-72/a; anterior filament rather 
rigid, 35-70/a long; posterior filament extremely 
long and slender, forming close coils at posterior 
end of egg. Vagina funnel-shaped, 58/a by 30/a 
in the type, provided with circular and longi- 
tudinal muscle fibers, opening dorsally just on 
the right of median line shortly behind intestinal 
bifurcation; vaginal duct arising from posterior 
end of vagina, provided with heavily sclerotized 
walls down to end of its fusiform swelling, then 
reduced to a narrow duct, but soon becoming 
enlarged to a small ampulla 23-39/* long by 
18-26/a wide. The comparatively wide duct aris- 
ing from the posterior end of this ampulla soon 
(70/a behind the ampulla in the type) divides 
into inverted V-shaped duct distended with yolk 
cells. Each limb of this duct empties into the 
lateral arm of the Y-shaped vitelline reservoir of 
its own side, so that the vagina is directly con- 
nected with the vitelline reservoir. Vitellaria 
co-extensive with intestine and its branches in 
fusiformly enlarged portion of body proper, leav- 
ing simple anterior and posterior portions of in- 
testine free. Vitelline reservoir Y-shaped, largely 
overlapping ovary. 
DISCUSSION: This genus bears a certain re- 
semblance to Pyragraphorus Sproston, 1946 and 
Allopyragraphorus Yamaguti, 1963, in general 
anatomy, but differs fundamentally from either 
of them in the structure of the clamp skeleton, 
especially in the paired basal pieces articulating 
with the median piece. Moreover, the structure 
of the cirrus is entirely different from that of 
any of the known members of the Monogenea. 
In view of these characteristics there is no doubt 
that the present genus, apparently of microcoty- 
loid type, represents a distinct family. 
Allomicrocotyla n. g. 
GENERIC DIAGNOSIS: Microcotyloidea, Allo- 
microcotylidae: Body proper fusiform; opis- 
thohaptor semicircular, asymmetrical, strongly 
constricted off from body proper, fringed with 
