220 Gastrothylax hubalis 
The reproductive system is fairly complex and situated almost entirely 
at the posterior end, in what may be termed the genital area, i.e. between 
the base of the atrium and the posterior sucker. In all the other 
species, except G. mancupatus, the reproductive organs are placed more 
laterally. 
The male system consists of a pair of large round testes,—which do 
not extend close to the body-wall of the parasite, nor into the atrial 
cavity—two vasa efferentia, and a single long vas deferens opening along 
with the vagina at the genital aperture. The vas deferens and vagina 
run along the dorsal fork of the atrium (Fig. 6, Vd., Vg.). The two 
vasa efferentia come one from each testis and unite to form the vas 
deferens. 
Fig. 5. Fig. 6. 
Fig. 5. Diagrammatic longitudinal section of G. bubalis. 21. mouth. A.P.G. genital 
and atrial apertures. Ph. pharynx. Vg. vagina. Vd. vas deferens. At. atrium. 
L.G. gut-limb. TJt. uterus. T. testes. A.P.G. aperture of Laurer’s canal. A.P.E. 
aperture of excretory vesicle. P.S. posterior sucker. 
Fig. 6. Cross section through middle region of G. hubalis. At. atrium. L.G. right and 
left gut limbs. Vg. vagina. Vd. vas deferens. 21.B. muscle bundles. Y.F. yolk 
follicles. 
The female system consists of ovary, shell gland, oviduct, uterus and 
vagina. In this species the shell gland and ovary are very close together, 
the latter is about the same size as the shell gland, and the duct from 
the shell gland almost immediately joins that of the ovary (Fig. 7). 
