THE NEPHRIDIA OF THE POLYOHvETA. 719 



internal end is more or less branched, and the solenocytes 

 restricted to the branches. 



No genital funnels occur in the quite anterior segments, in 

 a varying number of which nephridia alone may be present. 

 From about the ninth segment (Asterope) traces of the 

 genital funnel may be seen as a thickened ciliated patch on 

 the anterior face of the septum near the nephridium. Pass- 

 ing backwards, this increases in size, and bulges into the 

 segment behind in the form of a blind ciliated sac. In 

 Vanadis the funnel is long and almost tubular in shape. At 

 maturity the sac enlarges, becomes filled with spermatozoa 

 or ova, fuses with the nephridial canal about halfway down its 

 course, and finally opens into it, allowing the ripe genital pro- 

 ducts to pass to the exterior by the nephridiopore (Alciope). 



Phyllodocinse. — The nephridium closely resembles that 

 of the preceding sub-family ; but the blind internal end is 

 more branched, the lumen being even subdivided in some 

 cases (Eteone) into primary and secondary canals. The 

 solenocytes are generally set in rows chiefly on the dorsal 

 surface of the lobed extremity. In Phyllodoce Paretti, 

 however, they are grouped only at the tips of the branches. 

 In most cases the tubes of the solenocytes support the cell- 

 bodies at their distal free ends; but, in Phyllodoce lami- 

 nosa, the cell-bodies are bent round so as to rest on the 

 nephridium. In this species, also, cilia are developed on the 

 ccfilomic surface between the rows of solenocytes. 



The genital funnels develop, except in a few anterior seg- 

 ments, as thickenings of the peritoneum lining the septum 

 dorsal to the nephridium, which become bell-shaped and 

 ciliated, grow backwards towards the nephridial canal with 

 the wall of which they become fused, and open at maturity 

 into its lumen. The ripe genital products are thus enabled 

 to escape through the nephridiopore. 



Nephthyid^ (Part I, p. 188, and Part III, p. 715). 



The species Nephthys scolopendroides, and N. cfeca, 

 have been studied. The nephridium consists of a long 



