ON DIPLOZOON NIPPOXICUM, N. SP. 185 



if we consider that the intestine is destitute of nny distinct 

 wall, and that when the testis is nearly empty there is ahnost nothing 

 that would prevent the entrance of the ova into the cavity of the 

 testis by way of the intestine. I therefore believe, notwith- 

 standing his positive statement to the contrary, that the canal in 

 question opens also in Polystomum into the intestine at the point where 

 he represents it as arising from the testis. In Dactijlogijrus a similar 

 canal opens externally on the dorsal side, at a short distance from 

 the right lateral margin of the body. In Dipl. paradoxum this canal 

 is very long and undergoes numerous convolutions, but in nipponicum 

 it is shorter and nearly straight, and the internal surface is clothed 

 with cilia. Its nature and function, if it has any, I hope to be able 

 to treat of later. At a little distance from the point where 

 it receives this canal, the oviduct receives also the yolk-duct (yd). 

 After this it continues its former course, and then, making a sudden 

 turn anteriorly, opens into the uterus. 



The uterus, under which I include both the " Ootyp "' and the 

 " Eiergang " of the German writers, is a cylindrical tube with a dis- 

 tinct wall which is thickly beset for the greater part of its length with 

 long cilia on its internal surface. It shews an ovoidal enlargement at 

 its origin, the " Ootyp," then diminishing in diameter proceeds an- 

 teriorly, following the same course as the vas deferens, and opens ex- 

 ternally by a small aperture on the ventral side just at the angle 

 formed by the ventral side of one individual with the dorsal side of 

 the other, at the top of a conical elevation which is sometimes very 

 small, sometimes larger and very conspicuous. Just before opening, 

 it presents a second enlargement in which a single egg is usually found 

 during the period of reproductive activity. "II y a à l'origine de ce 

 conduit (i. e., of the uterus) une sorte de pylore," says v. Beneden.^' 



1) V. Beneden — 1. c. p. 43. 



