130 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



There is a thick- walled, narrow duct which runs along the 

 convex margin of the worm (that is, the latter coils so that this 

 margin is always the convex one). This duct is apparently con- 

 tinuous throughout. It is very much coiled and twisted — much 

 more so than is represented in the figure, but it lies, on the 

 whole, on the convex side of the worm. Looking at it closely 

 we see that its anterior part is structurally different from the 

 posterior part, and the transition from one part to the other 

 occurs in the region of the shell-gland. The actual disposition 

 of the parts in this region is represented in fig. 2, PI. II. The 

 calibre of the duct in question suddenly diminishes and it is 

 joined by a short fine duct coming from a receptaculum seminis, 

 and almost at the same place another fine duct leaves it. 

 The latter is the oviduct, and this is surrounded, at its origin, 

 by a shell-gland entirely similar to the homologous organ in 

 other Trematodes. The oviduct, convoluted at this region, 

 then enlarges in calibre and passes into the first segment of 

 the uterus. The anterior part of the fine duct we have men- 

 tioned is the ovary : the posterior part is the vitelline gland. 



The male organs are greatly reduced. There is a very 

 fine efferent duct opening close to the female genital orifice 

 on the tip of the genital papilla. This enlarges to form a 

 feebly-convoluted duct, similar to the structure called the 

 vesicula seminalis in most Trematodes, but which Odhner calls 

 the unpaired vas deferens. The distal part of this is the 

 greatest in calibre. From it two very fine short ducts proceed, 

 and these rapidly enlarge to form thick, richly- convoluted 

 ducts — the paired vasa deferentia of Odhner. Then they 

 are continued into short, narrow, feebly-coiled ducts, called the 

 testes by Odhner. There are no traces of prostate gland or 

 intromittent organ. 



In PL I, the various genital ducts have been 

 " straightened- out." Their convolutions are really far more 

 complex than is represented in the figure. 



