THE NEPHRIDIA OF THE POLYCHJITA. 727 



gajolae and Tremomastus, Fig. E) ; but even in this case the 

 funnel still develops an opening to the exterior^ through 

 which alone the genital products are shed. Lastly in 

 Clistomastus, where the generative cells escape through the 

 rupturing of the body-wall, the genital funnels are found only 

 in a more or less rudimentary state, and do not normally open 

 to the exterior.^ 



In figs. 31 and 32 I have represented some transverse 

 sections of Notomastus latericius, showing that in this 

 species the large genital funnels open to the exterior (at the 

 level marked by an asterisk *), and are quite independent of 

 the nephridium and its nephrostome, several sections inter- 

 vening between the end of the latter and the beginning of 

 the funnel. 



The HesionidiB present some very important variations 

 of structure. Hesione (Fallacia) has a very large genital 

 funnel, not known to open to the exterior ; but which is 

 connected at one point Avith the open nephrostome of the 

 nephridium. The exit of the genital products has not been 

 observed (Fig. G). 



In the genera Tyrrhena, Ophiodromus, and Irma, we find a 

 gradually closer and closer union established between the 

 funnel and the nephrostome. In Irma, where the genital 

 funnel is very well developed, it is so completely fused with 

 the nephridium that the two organs can no longer be dis- 



' These facts concerning the Capitellidae are all drawn from Eisig's mono- 

 graph (5). The case of Clistomastus is so important in connection with 

 Nereis and the Hesionids that his statements deserve to be quoted at length. 

 About Clistomastus Eisig writes, page 146 : — " Aber — in einzelnen Falhen sind 

 doch Spuren der Schlauche .... in den letzten drei Thorax-Segmente 

 vorhanden. Diese Spuren sind erstens auf die Liebeshohle beschrankten und 

 stellen daun peritoneale Wucherungen dar, die zwar noch an die Form der 

 Genitalschlauche eiinnern, aber doch jedwederausseren Miindungen entbehren. 

 Zweitens konnen diese Spuren umgekehrt ansschliesslich aus mangelhaft 

 ausgebildeten Poren bestehen, welche den Hautmuskelschlauch uich durch- 

 brechen oder, wenn sie das thun, doch nur in iiberaus kleine und undeutlich 

 ausgebildete Genitalschlauche iibergehen .... In noch setteueren Fallen 

 endlich . . . erreichen aber auch bei Clistomastus die Geuitascblauche eiue 

 voUkommeuere ausbildung." 



