STUDIES OX THE ECTOPAEASITIC TEEMATODES OE JAP AX. 235 



respectively from the anterior and posterior portions; proceeding towards 

 the median line, and uniting with its fellow of the opposite side 

 at the front end of the ovary a little to the left of the median 

 line. UnpaireJ, yolk-duct very short, proceeding from the point of 

 union of the paired yolk-ducts straight to the oviduct. Vaginal 

 opening a short distance behind the common genital opening, 

 nearly on the same longitudinal line ; vaginal canal long, mak- 

 ing numerous convolutions and opening into the yolk-duct at 

 the point of union of the paired ducts of the two sides. Testes 

 large, two in number, paired, irregularly ellipsoidal, situated just 

 behind the ovary. A single short vas efferens arising from each 

 testis, immediately uniting with the other and forming the vas 

 deferens. This proceeds forwards with numerous complicated convolu- 

 tions as represented in fig. 3, PI. XXVI, and finally entering the 

 penis at its base and traversing nearly its whole length finally opens 

 near its apex. Prostate gland very large, vesicular, elongated, just 

 behind the penis. 



Habitat — Gill of Lethriaus spJ (Jap. Kuchibi-dai). 



Locality — Hagi . 



Date— August 1889. 



2. Epihdelta ovata, n. sp. 

 ,(P1. XXVI, figs. 4-8.) 

 Body squarish-oval, a little broader in the posterior part, flat, 

 about 2 mm. long. Anterior siiclcers elliptical, connected with each 

 other by a thin membrane. Posterior sucker elliptical, with its long- 

 er axis at a right angle to the long axis of the body, with a 

 marginal membrane, with a pair of notches on its anterior and 

 posterior margins, due to the insertion of muscular fibres at these 

 points; with three pairs of hooks of the form represented in fig. 5, 



