300 ON SOME TREMATODK PARASITKS OF AUSTRALIAN FROGS, 



between the ovary arid the anterior edge of the cotylophore, 

 whilst laterally they do not quite reach the sides of the body 

 (Figs.l and 24). The single vas deferens springs from the middle 

 of the anterior surface of tlie testes, and runs forwards and 

 dorsally so that it passes the ovai-y on its dorsal side, and pursues 

 a pretty straight course to the level of the genital opening, when 

 it bends towards the ventral surface and terminates at the end of 

 the penis. For about a third of its course, near the ovaiy, it is a 

 pretty wide tube, and is filled with sperms, so that this part may 

 be looked upon as a vesicula seminalis; towards the end of its 

 course, its walls become thickened to forin the ejaculatory duct. 

 Two laterally placed, small groups of gland-cells, lying near the 

 beginning of the duct, represent the prostate. The end of the 

 penis is armed by a crown of eight curved chitinous spines. The 

 male duct opens into a distinct genital chamber, which opens on 

 the ventral surface in the mesial plane, about halfway between 

 the ovary and the anterior end. 



The ovary is a large oval body, obliquely placed, generally on 

 the right side, with its narrower end anterior and ventral. This 

 end is alone the germinal area, and here the ova are veiy small, 

 while they gradually increase in size to the other end, where the 

 large, ripe ova are foundiFigs. 1 and 22). The oviduct coming off 

 from this end, runs at first ventrally, and soon widens to form 

 the ootype, which is surrounded by the cells of the shell-gland; 

 the main unpaired duct of the yolk-glands and the genito-intestinal 

 canal open into the oviduct, close together, just in front of the 

 ootype(Fig.2). From the ootype, the oviduct runs forwards to 

 a point in front of the ovary, when it bends sharply backwards 

 and runs in a straight course close to the ventral surface, almost 

 to the level of the cotylophore, where it opens into the wide 

 uterus. The uterus is a wide, elongated sac, extending back to 

 the extreme posterior end of the body, in its posterior part, when 

 it is distended with eggs, occupying almost the whole width of 

 the body. Tt runs forwaid in a dorsal position(Figs.24, 25), along 

 the middle line of the body, in a straight coui'se to near its 

 termination, when it runs ventrally and opens; into the genital 

 chamber, ventral U> the male opening. 



