642 WILLIAM A. HASWELL. 



sperms of various stages. From this runs forwards an irre- 

 gular median channel without well-defined walls ; this contains 

 bodies similar to those in the testis itself, and is traceable as 

 far forwards as the base of the penis. The female aperture is 

 present ; it leads into a cavity from which runs backwards on 

 the right side a wide irregular channel representing the ovary, 

 but containing no cells that are recognisable as follicle cells 

 or ova. 



The remarkable disposition of the reproductive organs de- 

 scribed above is one which is not paralleled, so far as I can 

 ascertain, in any other Turbellarian, and is perhaps sufficient 

 in itself, apart from the other points of diflference, to render 

 necessary the separation of the present form from Pro- 

 rhynchus as at least generically distinct. 



In Prorhynchus stagnalis, according to v. Grafi*,^ the 

 testis is not sufficiently known ; the female opening is in the 

 middle of the ventral surface; the ovary is an elongated body 

 in the posterior blind portion of which are numerous germs 

 of ova, while further forwards are the ripe ova surrounded by 

 yolk-cells. In P. sphyrocephalus the same author states 

 that a similar condition of things obtains. 



None of the specimens of Prorhynchus hygrophilus 

 obtained by Vejdovsky had the testes developed. He assumes 

 that they were in a degenerate condition, and that Pro- 

 rhynchus is a proterandrous hermaphrodite. He adds, 

 however, that from the statements of v. Kennel and Braun it 

 may be looked upon as determined that the testes of Pro- 

 rhynchus are developed as small rounded follicles on both 

 sides of the intestine. Of these the latter author has described 

 two or three pairs, while v. Kennel characterises them as 

 vesicles sometimes in close contact with one another, some- 

 times separate, at first in a single series, later arranged in 

 several irregular rows extending not quite as far as the pos- 

 terior end of the body. 



Vejdovsky had found only three such follicles, and these not 

 in a state of functional activity, in the form of longish round 



^ Loc. cit., p. 266. 



