306 ON SOME TREMATODK PARASITES OF AUSTRALIAN FROGS, 



a.nterior sui'faces. The two vasa deferentia soon join to form 

 a wide thin-walled tube, the vesicula seininalis, which after a 

 course of two or three turns, transversely placed, enters a 

 muscular sac, which may perhaps be called the cirrus-sac, 

 though not entirely in agreement with that sac in other trema- 

 todes, for towards its outer end, the female duct also enters it 

 from the ventral side. Several coils of the vesicula seminalis 

 occupy the posterior part of this sac, and in front gradually 

 narrow down to the much thicker-walled ejaculatory duct. 

 Tiic vagina enters the sac near its distal end, occupying a 

 position ventral to the male duct. The rest of the cavity of 

 the rather wide sac is filled up by parenchyma-cells and some 

 prostate-cells. 



The ovary is an oval body, also laterally placed, lying some 

 distance behind the testis, just behind the level where the 

 intestinal limbs end. The oviduct is given off from the dorsal 

 side, and after a short course, enters the mass of shell-glands 

 (Fig. 42), lying over the ovary, just under the doi'sal surface 

 of the body. Just in front of the shell gland, the Laurers 

 canal takes its origin, and runs forward for a distance of 

 0-15 mm., to open on the dorsal surface near the middle line. 

 From the shell-glands, the uterus runs down to the posterior 

 end of the body and back in several wide coils ; behind the 

 testis, several coils occupy a rather dorsal position, but in 

 front of that body, they arc more ventrally placed ; near the 

 cirru.s-sac, the lumen becomes considerably narrowed, and the 

 walls thicker to form the vagina. The first part of the 

 uterus, near the shell-gland, is filled with spermatozoa, and 

 may be looked upon as the receptaculum seminis uterinum. 

 The yolk-gland is composed of large (0186 x 0123 mm.) 

 oval follicles, which run in a single or double row from a 

 position behind the diverticula of the oral sucker, to a level 

 just behind the ovary ; in this part of their course, they are 

 laterally placed, lying for tlie most part between the intes- 

 tinal liinbs and the lateral body-wall. Behind the intestinal 

 limbs, on each side, they turn sharply inwards and stretch 



