New Monogenetic Trematodes, II — Yamagutx 
bulbus cirri weakly muscular, 70p in diameter, 
situated just ventral to intestinal bifurcation. 
Cirrus consisting of several sharp-pointed spines 
which are 35jx long and bundled together im- 
mediately in front of atrial crown of 12 spines; 
these spines are 51-5 6p in length including base 
which forms a ring of 12 backwardly directed 
prongs; the shaft of each spine is straight, but 
the apex is curved inward and bifid at the tip. 
This crown of spines is enclosed in a very thick- 
walled atrial bulb of radial muscle fibers, which 
in turn is enclosed in a membranous genital 
atrium. Genital pore midventral, at anterior 
end of genital atrium, 1.45 mm from head end. 
Ovary tubular, bent back on itself on right 
side of median line, 3.15 mm long as a whole, 
swollen (0.3 mm wide) at postequatorial proxi- 
mal end in form of a recurved mass and at distal 
end in form of a club, from the posterior end of 
which the germiduct arises. Genito-intestinal 
canal arising from near middle of germiduct, 
running obliquely forward across proximal por- 
tion of ovary ventrally to empty into right intes- 
tinal limb. Vitelline follicles small, coextensive 
with intestinal branches, commencing a little 
behind vaginae; vitelline reservoir Y-shaped, to 
left of distal end of ovary, connected with 
germiduct by a narrow descending median stem 
0.15 mm long. Uterus sraight, midventral, con- 
taining a few eggs; eggs fusiform, 0.23-0.25 
X 0.07-0.09 mm, with filament 40-6 Op long 
at each pole. Vaginae symmetrical, about 0.5 
mm long, divided into a series of several (8- 
14) areolae, situated laterally about halfway 
between genital pore and anterior end of vitel- 
laria. 
discussion: This genus closely resembles 
Allop seudaxine Yamaguti, 1943, in internal 
anatomy, but differs markedly in general body 
shape and, what is more important, in the 
structure of the clamp. On the basis of the latter 
difference I prefer to propose the new subfamily 
Sibitrematinae for its reception, with the follow- 
ing diagnosis. 
Sibitrematinae n. subf. 
subfamily diagnosis: Axinidae. Body 
divided into three distinct regions. Opisthohap- 
tor asymmetrical, without prehaptoral larval 
431 
anchors. Clamp skeleton consisting of two pairs 
of lateral sclerites, one pair of basal inner 
sclerites, an arcuate median spring, and a pair 
of accessory sclerites. A terminal lappet bearing 
larval hooklets present. Testes numerous, pre-, 
para-, and postovarian. Ovary inverted U- 
shaped. Vaginae double, symmetrical. 
Sibitrema n. g. 
generic diagnosis: Axinidae, Sibitremati- 
nae. Body long, divided into three distinct 
regions: body proper, haptoral stalk, and opis- 
thohaptor with a row of numerous clamps uni- 
laterally and a terminal lappet bearing two pairs 
of anchors. Paired oral suckers poorly devel- 
oped. Esophagus bifurcating near genital pore. 
Intestinal limbs with numerous side branches, 
terminating blindly near base of terminal lappet. 
Testes numerous, pre-, para-, and postovarian. 
Genital atrium membranous, immediately pre- 
bifurcal, enclosing atrial bulb of radial muscle 
fibers at bottom, latter in turn provided inside 
with a crown of spines, beyond which the 
bundled cirrus spines project forward. Ovary 
tubular, bent back on itself in middle third of 
body. Genito-intestinal canal crossing proximal 
portion of ovary. Eggs with filament at each 
pole. Vitellaria coextensive with intestinal 
branches; vitelline reservoir Y-shaped, in ovar- 
ian region. Vaginae divided into a series of 
several areolae, situated about halfway between 
genital pore and anterior end of vitellaria. Gill 
parasites of marine teleosts. 
type species: S. poonui n. sp., on Parathun - 
nus sibi; Hawaii. 
7. Cypselurobranchitrema spilonotopteri 
n. g., n. sp. 
Fig. 7 
habitat: Gills of Cypselurus spilonotop- 
terus ; Hawaii. 
holotype; U. S. Nat. Mus. Helm. Coll., 
S. Y. No. 51. 
description (based on four whole mounts) : 
Body 7-10 mm in total length, enlarged later- 
ally up to 2. 3-3. 5 mm wide in midregion; 
anterior third abruptly tapered toward head end 
which is 0. 2-0.4 mm wide at the level of the 
oral suckers; posterior third occupied by large 
