SEA-FISHERIES LABORATORY. 247 



last pair of nepliridia is affected. In a large specimen 

 (250 mm. long-) the sixth nephridiuni of the right side is 

 normal, but the corresponding one of the left side consists 

 of a funnel only. Another specimen, 100 mm. long, has 

 only five pairs of nephridia opening on the fourth to the 

 eighth clnetigerous aniiuli, the sixth pair being totally 

 absent. These cases seem to show that the funnel and 

 the rest of the nephridiuni are, to some extent, inde- 

 pendently formed, as in the examples mentioned above 

 there are four cases in which the funnel is absent, and 

 three in which a funnel only is present. 



In worms about 17 mm. long the nephridia, which are 

 about '5 mm. long, have already assumed the adult form. 

 The funnel is" of considerable size and has well-marked 

 lips, the dorsal one bearing from three to five short, blunt, 

 conical elevations which later become the large spatulate 

 processes of the older nephridiuni. The secreting portion 

 of the first nephridiuni is a rather wide, almost S-shaped 

 tube ; that of the following nephridia is much wider and 

 sac-like. There is a rich vascular supply to all parts of 

 the nephridiuni. In a specimen 44 mm. long the 

 nephridia are about a millimetre in length (fig. 25). 

 There is little change from the condition described above 

 except that all the parts are larger ; the dorsal lip of the 

 nephrostome bears from four to seven small, blunt, conical 

 processes. Xephridia of large specimens may attain a 

 length of *8 mm. The funnel of such nephridia is large 

 and its dorsal lip bears as many as thirty-two spatulate 

 processes sub-divided distally into twelve to fifteen lobes. 



The lips of the nephrostome are lined by a single 

 layer of ciliated columnar or cubical cells, supported by 

 a thin film of connective tissue. There is a fairly sharp 

 line of demarcation between the cells of the funnel which 

 have no concretions, and the cubical, columnar, or pear- 



