BY S. J. JOHNSTON. 327 



even thickness ; the intestinal limbs joining the base of the 

 oesophagus, reach right up to the posterior end of the body. 

 As a rule, they curve round the ventral sucker, passing quite 

 lateral to it ; but sometimes one of the limbs passes dorsal 

 rather than lateral to it. 



The nervous systeiii and ejxretory systtm closely resemble 

 what is described by Looss for D. cygnoides in "Dist. unserer 

 Fische u. Frosche"; but I have not attempted to count the 

 number of fiame-cells. The excretory vesicle runs as a single 

 tube in the middle line, near the dorsal surface, and between 

 the lines of testes, as far forward as the level of the middle 

 of the ovary, where it divides into two branches that diverge, 

 and extend anteriorly up to the oral sucker. The flame-cells 

 have a form very similar to that described and figured by 

 Looss (48). 



Genital Organs. — The testes, more or less rounded bodies, 

 with deep grooves or indentations on the surface (Fig. 64), 

 are nine in number, five on one side and four on the other, 

 joined together in two series, in the characteristic way, by a 

 tube passing from one to the next in front. The vasa deferen- 

 tia unite near the anterior edge of the ventral sucker, to form 

 a very short common tube, 0-048 mm. long, before opening 

 into the base of the vesicula seminalisj in G. cygnoides they 

 unite much further back (just in front of the yolk-glands), 

 and have a considerable course as a single tube before enter- 

 ing the vesicula seminalis (Looss 48). The vesicula seminalis 

 (Fig. 65) is a shortly coiled tube, very wide posteriorly, when 

 filled with sperms, suddenly narrowing to the ejaculatory 

 duct, whch runs straight to the genital atrium, a narrow 

 space opening on the ventral surface (Fig. 65). There is no 

 cirrus-sac, but the vesicula seminalis is surrounded by a layer 

 of slightly modified parenchyma-cells ; the prostate is repre- 

 sented by a very few cells lying near the junction of the 

 ejaculatory duct and the vesicula seminalis. The ovary lies 

 in front of the line of five testes, generally on the left side : 

 but, as in the other species of this genus, the sexual amphi- 



29 



