10 



Ox THE Generative Organs of Drepanidot-enia Yenusta 

 (Tcenia Venusta, Bosseter, 1896). 



By T. B. Rosseter, F.R.M.S. 



(Read January 2\st, 1898.) 



Plates . 1 and 2. 



In a paper which I read before the Club at the November 

 meeting in the year 1896, on the discovery of a new Cysticercus 

 and the production of this tape-worm by feeding ducks with the 

 organisms (Entomostraca) which contained it, I purposely refrained 

 from passing any remarks on the anatomy of the creature. I 

 then stated that this, and more especially with reference to the 

 genital organs, would form the subject of a special paper. These 

 latter have now been worked out by me as far as the limited 

 material, owing to the scarcity of the worm, would permit. 



The tapeworm which I exhibited on that occasion was an 

 immature one. In this instance, that from which I have prepared 

 my specimens for examination was one of two worms which I 

 reproduced in the early spring of last year (1897) by again feeding 

 ducks from material obtained from Gorstley Wood pond. By 

 this I mean Ostracoda known to be infected, not only with 

 this Cysticercus, but likewise with other Cysticercoids, and from 

 which, besides other tapeworms, I w\^s able to obtain two, and 

 only two, Drepanidotsenia (Trenia) Yenusta. These w^ere sexually 

 mature. Both of them had passed into that stage when the 

 proglottides of the Strobila have become merely uterine egg-sacs 

 for the developing Oncospheres. One of these I have sealed up, 

 preserving it as a ' type specimen ' ; the other I have subjected 

 to preparation for the purposes of this paper. 



The method employed is simplicity itself w^hen applied to the 

 larger Mammalian Tsenise, w^hether of man or animals, such as 

 Tcenia solium, or Bothriocephulus latus of the foi-mer ; or Tcania 

 serrata, or T. expansa of the latter, But the technique presents 

 many difficulties in such a case as the present one. I did not 



