STUDIES ON THE DIGENETIC TREMATODKS. 47] 
several irregular convolutions dorsal to the ventral sucker 
and thence proceeds to the genital aperture. This backward 
prolongation of the uterus forms a ready means of distinguish- 
ing the species with the naked eye from F.fellis. The ova 
are somewhat larger than those of the latter species, measuring 
about 048 by °024 mm. 
For the genus Fellodistomum, which Stafford has 
somewhat scantily characterised, the following definition may 
be offered : 
Small to middle-sized forms with thick fleshy body, sub- 
cylindrical, tapering more or less towards each end. Cuticle 
thick and rough, but without spines. Oral sucker sub- 
terminal, simple. Ventral sucker about the middle of the 
body, larger than oral sucker, globular, Pharynx small, 
pre-pharynx short, cesophagus very short or absent. Diver- 
ticula, simple wide sacs terminating a little behind the testes. 
Excretory vesicle Y-shaped, the bifurcation taking place 
behind the ventral sucker and the limbs stretching far into 
the neck. Genital aperture situated on a prominent papilla 
to the left of the middle line immediately in front of the 
ventral sucker. Small genital sinus. Testes symmetrical, 
a moderate distance behind the ventral sucker. Cirrus- 
pouch compact, bulbous. Vesicula seminalis small, bipartite. 
Pars prostatica well marked ; ductus ejaculatorius short, wide, 
with walls thrown into irregular folds (in the retracted 
state). Ovary multilobate, situated just in front of the 
right testis. Receptaculum seminis absent; Laurer’s canal 
present. Yolk-glands lateral, of very limited extent. Initial 
part of uterus functions as receptaculum seminis uterinum. 
Uterus restricted in extent, either confined between the 
testes and the genital aperture, or with a loop passing back- 
wards between testes to the posterior end of the body. Ova 
small, thick-shelled, measuring ‘04-05 mm. by ‘02-025 mm. 
Type.—Fellodistomum fellis (Olsson, 1868) = ? F. 
incisum (R.) Stafford. Including also F.agnotum n, sp. 
Both Stafford and Odhner have noted a close resemblance 
between this genus and the genus Steringophorus Odhn., 
VOL. 95, PART 5.—NEW SERIES. 35 
