76 



S. YOSUIDA : 



in a space behind ventral sucker. Uterus in the median space between 

 testes and posterior body-end. Yolk-glands in lateral areas along the 

 margin, extending from about the level of testes posteriorly for a length 

 equal to \ — ^ the body-length (see fig. 4). 



The two testes (h in figs. 3, 4, 5, 6, 7. and 8) lie side by side behind 

 ovar}-, but usually the one on the same side as the ovary situated somewhat, 

 but not entirely, behind the other ; subequal in shape and size ; nearly 

 spherical when still small, but commonly somewhat laterally compressed in 

 full)' mature state. In adult specimens, the length in anteroposterior 

 direction may vary from 140// to 260/z. Each testis sends forth, from a 

 point of its anteromesial part, a vas deferens, which, after running a short 

 distance obliquely forwards and inwards, joins with its fellow of the other 

 side and forms the unpaired vas deferens. This, after taking again a short 

 forward course, joins the posterior end of the cirrus pouch. The cirrus 

 pouch is represented by a bent fusiform body of a compact appearance 

 (figs. 7 and 8, cb); its broader postero-dorsal parts lie over, and to one side 

 of, the ventral sucker ; ventrally it descends nearly vertically right in front 

 of the same, finally to terminate at the male genital pore. In the postero- 

 dorsal parts of the body the lumen is dilated into a seminal vesicle (s), 

 which in mature specimens is filled with spermatozoa. Antero-ventrally, 

 the vesicle is continued as a narrow canal, which at first is somewhat 

 tortuous but soon takes a straight downward course to the genital pore. 

 The wall of the duct exhibits a cellular structure, possibly of glandular 

 nature ; close upon the lumen there exists a layer of muscular fibres which 

 are best developed along the narrow and straight canalar passage (fig. 7, c) 

 leading down to the external opening. 



The single ovary lies on one side, cither right or left, of the median 

 line and in front of, and somewhat more dorsally than, one of the testes. 

 Both in shape and size it is approximately the same as a testis in adult 

 specimens, though in the young it is much smaller than the latter (fig. 3). 

 In some adult specimens the ovary was seen to overlap with its posterior 

 parts the anterior parts of the testis on the dorsal side (fig. 6). The short 



