STUDIES OX THE ECTOPARASITIC TBEMATODES OF JAPAX. 251 



a capacious ovoidul receptacuhim seminis at about two-thirds of its whole 

 course, and finally opening into the yolk-ressrvoir. Testes numerous, 

 globular, present not only in the median region posterior to the ovaiy, 

 but extending on both sides a little way into the lateral regions of the 

 body. Vas deferens formed as usual, proceeding at first forwards on the 

 left side of the ovary ; forming, also as usual, a large loop at the 

 front end of the ovary, and after describing numei'ous, complicated 

 convolutions it enters the penis, inside which it expands and forms 

 a sort of vesicula seviinalis, and finally opens into the cavity of the 

 penis at a short distance from its apex. 



The body of this species is so transparent that even in alcoholic 

 specimens the internal organs, even the smallest vasa efferentia, can be 

 seen through, and their relations ascertained without staining and 

 mounting. 



Habitat — Fin of Thynmis sibi (Jap. Shibi). 



Locality — Osatsube (Hokkaido); collected by Mr. Nozaw^a in 

 whose honour it is named. 



Date — Not recorded. 



6. Tristomwn bipamsiticum, n. sp. 

 (PI. XXV, figs. 4-8.) 

 Body elongated-oval, about 6 mm. long by 3 mm. broad, w4th 

 a sudden diminution of breadth in the aliteiior part a little behind 

 the anterior suckers ; with the antex'ior border slightly convex ; with 

 a notch at the posterior end of the body ; lateral margins entire, with 

 a series (of about sixty-two) of chitinous corpuscles like those of Trist. 

 siimatum, one of which is represented in fig. 5, PL XXV; the series 

 beginning a little behind the anterior suckers at the point where 

 the body undergoes a sudden increase of breadth, and terminating a 

 little before reaching the posterior sucker. Anterior suchers nearly 



