STUDIES OX THE ECTOPARASITIC TREMATODES OF JAPAN. 915 



swollen, giving rise to an elevated patch on the ventral side of the 

 body. Genito-intcstinal canal arising from the oviduct a little nearer its 

 origin than the opening of the unpaired yolk-duct, proceeds forwards 

 and a little towards the right, and finally opens into the intestine. 

 Testes small, comparât ivel}^ few in number, together forming a 

 triangular patch behind the ovary, Ijctween the two trunks of the 

 intestine ; not extending into the stalk-like portion. 



Habitat — Gill of Telroiloii sp. s]). (Jap. Koo-omé-fugu and Kôyosé- 

 fugn). 



Locahtij — Phigi. 



.Z)((^t'— August 1S89. 



Although this species presents conspicuous diiferences from the 

 two foregoing species, there m no douljt that it is to be included in 

 the same genus, both from the form of the penis and its hooks and the 

 form of the sucker and its chitinous framework, as well as from s(3me 

 other less significant points of similarity. As to the chitinous 

 frame-work of the suckers, it is to be remembered that, as already 

 mentioned in the anatomical part, that of the first pair presents 

 such a change in the relative position <)f the component pieces as 

 to have to be regarded as having undergone a rotation of 180° on its 

 own axis, the piece directed forwards in the other suckers being 

 turned backwards in this. In fact this species represents an aberrant 

 member of the s^enus. 



Y. IIexacotyle, Blainville. 



This genus was founded in 1828 by Blainville, and contains at present onl}^ 

 a single species, wliich was first met with by De la RocheO on the gill of Sco)iiber 



1). De la Roche — Sur deux animaux vivants sur los branchies des poissons. Xouv. Bull, 

 d. sciences d. 1. soc. Philom., 1811., No. 11., 270-273. I cito this on the authority of Dujardin, 

 Diesing, and Braun. 



