Monogenetic Trematodes, I — Yamaguti 
voir; after crossing the distal end of the uterus 
dorsally it comes to lie on the dorsal side of the 
cirrus pouch where it enters the cirrus pouch 
and turning back on itself leads into the mus- 
cular ejaculatory duct. Ejaculatory duct joining 
narrow prostatic duct at base of cirrus; latter 
short conical, projecting into genital atrium, cov- 
ered all over with very small recurved spines; 
from the base of the cirrus arises a claviform 
muscular gonotyl which is about 100 X 40ft in 
the type and directed obliquely backward. Cirrus 
pouch subcylindrical, curved, 0.22-0.4 X 0.08- 
0.15 mm, situated almost longitudinally behind 
pharynx, provided with circular and oblique 
muscle fibers. Prostatic reservoir ovoid, 75-140 
X 60-l40ft, posterior to cirrus pouch; prostatic 
duct a little swollen and enclosed in a prominent 
muscle bulb of oblique fibers at posterior end of 
cirrus pouch, then running straight forward 
within cirrus pouch and finally uniting with 
ejaculatory duct. Genital atrium cylindrical, en- 
closing cirrus pouch, receiving uterus at level of 
cirrus, opening ventrally beneath left prohaptor. 
Ovary subglobular, 0.12—0.24 X 0.08-0.21 
mm, situated nearly in median line at posterior 
end of anterior third of body. Ootype and shell 
gland well developed between cirrus pouch and 
convoluted vas deferens. Uterus opening into 
genital atrium distal to cirrus; eggs one at a time, 
pentagonal, about 0.1 mm in diameter, with 
filament at one pole. Vagina lined with thick 
corrugated cuticle, opening dorsally near left 
margin of body at level of pharynx; vaginal duct 
with fusiform swelling distally, united with 
vitelline reservoir near its distal end; no recep- 
taculum seminis vaginae. Vitellaria co-extensive 
with intestine; vitelline reservoir on left side of 
ovary, more or less curved toward ovary, 0.1- 
0.23 X0.06-0.12 mm. 
DISCUSSION: This new genus is characterized 
by the opisthohaptor being unarmed, although 
in general antomy it resembles Nitzschia Baer, 
1826. It is separated from all the known sub- 
families of Capsalidae as representing a new 
subfamily on account of this unarmed opis- 
thohaptor. 
Pseudonitzschiinae n. subf. 
SUBFAMILY DIAGNOSIS: Capsalidae. Opistho- 
haptor disc-shaped, unarmed, with indented 
61 
muscular margin and delicate marginal mem- 
brane, without septa, loculi, or papillae. Prohap- 
tors saucer-shaped, paired. One pair of eye spots. 
Pharynx without constriction. Intestinal limbs 
with side branches, not united posteriorly. Testes 
numerous, confined to anterior postovarian inter- 
intestinal field. Vas deferens convoluted anterior 
to vitelline reservoir. Cirrus pouch muscular, 
postpharyngeal, enclosing ejaculatory duct and 
prostatic duct; cirrus short, armed. A muscular 
gonotyl present in genital atrium. Common 
genital pore opening ventrally beneath left pro- 
haptor. Ovary entire, pretesticular. Ootype well 
developed. Uterus opening into genital atrium 
distal to male pore. Vagina opening dorsally 
close to left margin of body at level of pharynx. 
No receptaculum seminis vaginae. Vitellaria 
co-extensive with intestinal limbs and their 
branches. Vitelline reservoir immediately sinis- 
tral to ovary. Gill parasites of marine teleosts. 
Pseudonitzschia n. g. 
GENERIC DIAGNOSIS: Capsalidae, Pseudonitz- 
schiinae: With characters of subfamily. 
TYPE SPECIES: P. uku n. sp., on gills of Aprion 
vires cens; Hawaii. 
4. Diploheterocotyla dasyatis n. g., n. sp. 
Fig. 4 
HABITAT: Gill of Dasyatis sp. (? D. hawaiien- 
sis)\ Hawaii. 
HOLOTYPE: U. S. Nat. Mus. Helm. Coll., S.Y. 
No. 4. 
DESCRIPTION ( based on 7 whole mounts ) : 
Body elliptical in outline; 0.9-1. 2 X 0.3-0.53 
mm, covered with smooth cuticle. Opisthohaptor 
circular, 2.12-3.15/x in diameter, divided into a 
round central loculus 65-1 15/x across and eight 
muscular marginal loculi, provided with a mar- 
ginal membrane up to 30-3 5 /x wide and a pair 
of anchors measuring 27-33/x long lineally from 
tip of ventral root to height of curve of blade 
and 35-53g lineally from tip of dorsal root to 
height of curve of blade; dorsal root inserted 
deeply into the septum between posterior sub- 
median and posterolateral loculi. Marginal hook- 
lets hardly recognizable at each interlocular mar- 
ginal notch. Oral sucker subterminal, 65-100 X 
100-155/q surmounted on its anterodorsal bor- 
der by a transversely elongated pillow-like lobe. 
