66 
PACIFIC SCIENCE, VoE XIX, January 1965 
15/* long; anterior medial hooklets abnormally 
large; dorsal anchor stout, 47-53/* from tip of 
ventral root to height of curve of blade, its dorsal 
root shorter than ventral root, turned medially 
to form a dorsal swelling, at the inner end of 
which the anchor articulates with its fellow of 
the other side by means of a median bar; this bar 
looks like an approximately quadrangular shield, 
but its convex anterior border, 12.5-15/* lineally 
from end to end, is thickened in form of an in- 
verted V or an arc. The muscle fibers coming 
from the ventral median body wall are mainly 
attached to the dorsal root, whereas the ventral 
roots of the two stout anchors are connected 
with each other by a broad muscle band. Ventral 
anchor very small, simple, only 10-15/* long, 
wider apart one from the other than stout dorsal 
anchors, with its root articulated with a simple 
oblique bar about 15/* long. Head trapezoidal, 
with a compact group of head glands antero- 
laterally. Two pairs of eye spots dorsal to mouth. 
Pharynx globular, 45-65 X 57-75/*. Esophagus 
wide, up to 40-5 0/x long, with a group of gland 
cells on each side; the ducts of these gland cells 
are directed toward the posterior end of the 
pharynx. Ceca comparatively wide, united pos- 
terior to testis at a variable distance in different 
individuals, sometimes far posteriorly, each with 
a number of undivided diverticula laterally; pos- 
terior common cecum also with diverticula on 
each side, terminating blindly some distance an- 
terior to opisthohaptor. 
Testis round to oval, 32-85 X 25-60/x, me- 
dian, toward middle of anterior half of body. Vas 
deferens passing along right margin of ovary, 
leading to small seminal vesicle which lies at the 
base of the copulatory apparatus. Cirrus tubular, 
slender, about 5 0/x long, enclosed in a cylindrical 
sheath for its proximal portion, but free in the 
distal portion and twisted at the junction of the 
two portions just at the level of the distal end 
of the sheath which is armed with a circle of very 
fine spiniform structures. Genital atrium me- 
dian, just postbifurcal; into this atrium projects 
a small, muscular, acetabular disc 22-30/x in 
diameter from the anterolateral side; the postero- 
medial border of the disc sometimes showing in 
the postbifurcal median genital pore. 
Ovary 50-100 X 50-78/x, turned back on it- 
self between testis and transverse vitelline duct, 
with its distal end turned forward. Neither 
seminal receptacle nor vagina. Eggs oval, with- 
out polar filament, about 90 X 70/x in life, one 
at a time. Vitellaria forming numerous trans- 
versely elongated lobes intercalated between 
cecal diverticula and connected medially with 
paired longitudinal vitelline ducts commencing 
at level of intestinal bifurcation or genital pore; 
some of the posterior lobes of the two sides are 
confluent, although the level of the anterior limit 
of this union varies individually. 
DISCUSSION: This genus resembles Diplecta- 
notrema Johnston and Tiegs, 1922 on the one 
hand, and Empleurosoma Johnston and Tiegs, 
1922, on the other; the differences are shown in 
the following table: 
Diplectano- 
Empleuro- 
Pseudem- 
trema 
soma 
pleurosoma 
Intestinal 
united 
united 
ceca 
separate 
posteriorly 
posteriorly 
Vagina 
Receptacu- 
present 
absent 
absent 
lum seminis 
present 
? 
absent 
Vitellaria 
separate 
separate 
confluent 
posteriorly 
P seudempleurosoma n. g. 
GENERIC DIAGNOSIS: Dactylogyridae, Ancyro- 
cephalinae: Body more or less uniform in width; 
opisthohaptor truncate, shallowly constricted 
from body proper, with 14 marginal hooklets, of 
which the anterior medial pair is unusually large, 
2 pairs of dissimilar anchors, an unpaired me- 
dian shieldlike bar for larger anchors, and paired 
rod-shaped bars for smaller, widely separated 
anchors. Two pairs of eye spots present. Esopha- 
gus short, with gland cells on each side; ceca with 
numerous lateral diverticula, confluent posteri- 
orly and terminating a short distance anterior to 
opisthohaptor. Testis about middle of anterior 
half of body; seminal vesicle near base of copu- 
latory apparatus. Cirrus tubular, slender, enclosed 
in sheath proximally but free distally. Genital 
pore median, postbifurcal. A small, muscular, 
acetabular disc projecting into genital atrium. 
Ovary immediately pretesticular, turned back on 
itself. Neither seminal receptacle nor vagina. 
Eggs without polar filament, produced one at a 
time. Vitellaria divided into numerous, trans- 
versely elongated lobes, co-extensive with ceca 
