658 GERARDA STIASNY-WIJNUOFF 



or even before the brain. The ovaries are developed in the 

 usual way. These facts can easily be understood as we know 

 the testes of Platyhelminths to be developed all over the body. 

 The arrangement of the gonads in primitive Anopla without 

 intestinal pouches is absolutely irregular, as shown by Biirger 

 in Tubulanus (8, PI. iv, fig. 2). Two interesting facts are to 

 be mentioned : the gonads are placed in several irregular rows, 

 and the gonopores lie on the dorsal surface. In the Anopla 

 we can follow the development from this stage without intes- 

 tinal diverticula to the pseudo-metameric arrangement in 

 Lineus and Cerebratulus, where always one gonadial sac lies 

 between two intestinal pouches, opening to the exterior by 

 one row of dorsal gonopores. 



In Enopla the Bdellomorpha display the same irregular 

 position, as for instance Tubulanus polymorphus, and 

 have dorsal gonopores. The Hoplonemertini show a great 

 variety of arrangement. First we have to look at the Mono- 

 stilifera, of which Geonemertes, Nemertopsis (Text-fig. 22, a), 

 Prosadenoporus, Prosorochmus have a number of gonads 

 between two following intestinal pouches, the first stage of 

 arrangement that follows on the above-described displacement 

 of Tubulanus polymorphus in the Anopla. All these 

 worms are more rounded than the flat Malacobdella and the 

 Tubulanidae. In consequence the gonopores partly lie more 

 laterally, but always above the nerve-cords. The next stage is 

 the reduction of the number of gonads per pseudomere to one 

 on each side, as in P r o s t o m a c o r o n a t u m (8, PI. ii, fig. 3) 

 and Amphiporus species. At last we get a still greater reduction 

 of this number as in A. pulcher (8, PI. xiii, fig. 6). 



In the Polystilifera we know two genera of Eeptantia, 

 Uniporus and Drepanophorus. Uniporus (Text-fig. 22, h) 

 has in each pseudomere two to five gonadial sacs with dorsal 

 pores and exhibits in consequence a very primitive feature. 

 In Drepanophorus we know the great regularity in which 

 intestinal pouches and gonads alternate, one sac between two 

 pouches. But the gonopores lie laterally (Text-fig, 23, a) 

 as in D . w i 1 1 e y a n u s , c e r i n u s , i n d i c u s , or ventrally 



