STUDIES OX THE ECTOPAHASITIC TREMATODES OF JAPAN'. (37 



but as their course is always more or less winding, they are not seen 

 in cross-sections exactly between the intestine and the ventnd nerve, 

 but are often situated more on one side, right or left, as the case mny 

 be. One of the two main vessels, the larger one, opens to the exterior 

 mostly with an extremely small pore in the anterior part of the body 

 on the dorsal side, close to the lateral border. This is also the case in 

 Onclwcotijlc, the paired terminal sacs described by Taschenberg^^ 

 beino-, as alreadv stated, nothinu" else than the suckers. In Microco- 

 tijlc, I have not been able to observe the excretory vessels in specimens 

 mounted in toto. and therefore have not drawn them in the figures ; 

 but I could always recognize the two main vessels in serial cross- 

 sections. In this genus, the excretory openings are situated nearly on 

 the same level with the genital opening: in 21. ckgaufi it is 5 sections 

 (each nr 10 /z), and in M. caudala 10 sections in front of the genital 

 opening ; while in 21. >>eha.-ilis it opens on the same level with it. 

 Lorenz speaks of a small papilla on which the excretory vessel 

 opens ; but I have not observed any in my sections. In this genus, 

 there is no distinct terminal sac, the vessel presenting just a perceptible 

 enlargement before it opens to the exterior. In DicUdophora also, the 

 excretory openings are nearly on the same level with the common 

 genital opening: c. (j.. in Diclid. sessiUa it is about 7 sections (each=z 

 10 fJ.) behind it ; but in this o-enus there is a tolerablv lar2:e. eirü'- 

 shaped terminal sac (PI. X, fig. 5), which opens directly to the exterior. 

 In Axine, Oncliccotijlc. and Hcxacotijh', the excretory openings are at 

 so]ne distance in front of the C(jmmon genital opening, and the two 

 main vessels present each only a slight enlargement before opening to the 

 exterior. In 2Io)iocotijlc, there is a large terminal sac of an ellipsoidal 

 form, which communicates ^vith the exterior by means of a short 

 canal proceeding from its dorso-lateral border a little before the middle 



1). Taschenberg— Weitere Beiträge, p. 13. 



