New Monogenetic Trematodes, II — Yamaguti 
429 
dorsal opening 0.1-0.35 mm posterior to gen- 
ital pore, usually anterior to anterior end of 
vitellaria, but sometimes much posterior to this 
level. Vaginal duct inverted Y-shaped, each 
branch opening into arm of vitelline reservoir 
of its own side. 
discussion: This genus bears a superficial 
resemblance to Pterinotrema Caballero, Bravo- 
Hollis, and Grocott, 1954, but differs from it 
fundamentally in the structure of the clamps 
and the terminal genitalia, and in possessing 
a typical oral sucker and a pharynx. I prefer to 
separate it as representing a new genus, for 
which the name Pseudo pterinotrema is sug- 
gested, with the following diagnosis. 
Pseudo pterinotrema n. g. 
generic diagnosis: Pterinotrematidae. Body 
small, cylindrical. Prohaptor circular, with a 
dorsal conical papilla. Opisthohaptor with nine 
long-stalked clamps, one of which, to the ex- 
treme right in the type, bears an armed caudal 
appendage. Each clamp, except for two extreme 
right ones, with two axial sclerites fringed with 
spines on its stalk, and two terminal clamp 
valves which are also fringed with spinelets. A 
transverse row of six small, two-valved suckers 
present at base of third to seventh clamp stalks, 
extreme left one to left of base of ninth sclerite. 
At base of fourth clamp is a rod-shaped lobe 
bearing two pairs of very small larval hooklets. 
Oral sucker and pharynx present. Intestinal 
limbs with short outer branches, terminating 
separately at base of opisthohaptor. A number 
of rounded testes in a zigzag longitudinal row 
in posterior interintestinal field. Copulatory or- 
gan consisting of plug-shaped, muscular, spined 
cirrus and two accessory sclerites. Genital pore 
ventromedian, immediately behind prohaptor. 
Ovary tubular, looped, pretesticular. Vagina 
sclerotized, opening middorsally near intestinal 
bifurcation; vaginal duct inverted Y-shaped, 
each branch connected with arm of vitelline 
reservoir of its own side. Eggs elliptical, fila- 
mented at antiopercular pole. Vitellaria coex- 
tensive with intestine. Gill parasites of marine 
teleosts. 
type species: P. albulae n. sp., on Albula 
vulpes ; Hawaii. 
6. Sibitrema poonui n. g., n. sp. 
Fig. 6 
habitat: Gills of Parathunnus sibi (local 
name "poonui”); Hawaii. 
holotype : U. S. Nat. Mus. Helm. Coll., 
S. Y. No. 50. 
description (based on a single gravid speci- 
men) : Body 19-2 mm in total length, distinctly 
divided into three regions: body proper, hap- 
toral stalk, and haptoral region. Body proper 
slender, lanceolate, tapered anteriorly, with a 
pair of compact eyespots, constricted behind, 
11.7 mm long, 1.4 mm wide in posterior part 
where the ovary is situated; haptoral stalk fusi- 
form, 4.3 X 0.45 mm, containing intestine and 
vitelline gland alone, attenuated posteriorly and 
then gradually enlarged to pass into haptoral 
region which is spatulate, produced posteriorly 
into a conical terminal appendage. This appen- 
dage is 0.2 mm long, 0.2 mm wide at the base, 
and bears on the ventral surface of its apex 
two pairs of larval hooklets of different size; 
outer pair 46\i long, inner pair 21p long, both 
with a very prominent guard and a well curved 
blade. On the left border of the haptoral region 
is a single longitudinal row (about 3 mm long) 
of 48 clamps 50-90|i in transverse diameter. 
Clamp skeleton consisting of a pair of inner 
basal processes, two pairs of lateral arms, a pair 
of accessory pieces meeting in median line, and 
a stout median spring, one end of which is 
anchor-shaped, while the other end is sur- 
mounted by a Y-shaped apical piece. Mouth 
cavity wide, opening ventroterminally, with oval 
paired suckers (46 X 23[i) laterally and a 
globular, weakly muscular, median pharynx at 
its bottom; esophagus simple, 1.45 mm long, 
contracted at beginning, but soon enlarged to 
width of 0.15 mm, bifurcating immediately be- 
hind genital pore. Intestinal limbs with numer- 
ous short inner and longer outer branches; 
right limb terminating at base of terminal 
appendage, left one 0.5 mm farther in front. 
Testes rounded, 75 in total number, pre-, 
para-, and postovarian ; preovarian testes in two 
parallel submedian rows of 15 or 16 each ; para- 
ovarian testes 18 or 19, in two longitudinal rows 
immediately outside ovarian loop ; behind the 
ovary there are only several testes in the median 
field. Vas deferens median, dorsal to uterus; 
