'•il'2 ON SOME TRKMATODE PAKASITKS OF AUSTRALIAN KKOGS, 



The posterior third of the cirrus-sac is occupied by the vesi- 

 cula seminalis, which is constricted in the middle, affording, 

 in its form, a very close resemblance to the swimming bladder 

 of cyprinoid fishes (Fig. 4), a resemblance mentioned by Looss 

 for the vesicula seminalis of Glossidhnn (50). Anterior to 

 this, is a well-developed pars pi'ostatica and a strong pro- 

 trusible penis, traversed by a very muscular-walled ejacula- 

 tory duct. The ovary is a large, rounded or somewhat oval 

 body, a little smaller than the testes, 0-197 mm. in diameter, 

 laterally placed on the right side just in front of the middle 

 Oi the body, some distance behind the ventral sucker. The 

 oviduct leaves the ovary on its inner posterior aspect, and 

 runs transversely close behind the ovary for a distance of 

 about U15 mm., when it opens by a comparatively wide open- 

 ing into a sac-like structure, which I must call the fertiliza- 

 tion-space, though, in fixed and stained whole-mounts, one 

 would naturally call it tlie receptaculum seminis. A study of 

 the living worms shows that the ova are fertilized in this 

 space, just near its wide opening into the oviduct. The sac 

 itself is of comparatively considerable proportions, measuring 

 0-121 xOlOl mm. If this sac does not represent the recep- 

 taculum seminis, then no such structure is present in the 

 species of this genus. Laurer's canal, which opens into the 

 oviduct just beyond the fertilization-space, is especially strong- 

 ly developed. It is a thick-walled, elongated tube, lying in 

 the dorsal region of the body, and pursuing a tortuous, con- 

 voluted course backwards, as far as the level of the anterior 

 testis, where it opens on the posterior surface (Figs. 5, 44). 

 Just beyond its junction with Laurer's canal, the oviduct 

 expands to form the ootype, which is surrounded by the cells 

 of the shell-gland, a not very strongly developed structure. 

 Into the ootype, opens the short duct from the somewhat con- 

 spicuoiis yolk-reservoir. Leaving the ootype, the female duct 

 soon turns forward as the uterus, and, after crossing the body 

 in several narrow, transverse coils, which lie in tlie region in 

 front of the ovary, it runs forward to the genital oj)ening. 



