188 EDWIN S. GOODEICH. 



Sections show that, as already mentioned, the lip of the 

 nephrostome is directly continuous with the ventral prolonga- 

 tion of the ciliated organ. Since this connection is, I believe, 

 of considerable morphological importance, I have figured it in 

 detail. A transverse section of the two organs is shown in 

 fig. 12 (an enlarged view of part of fig. 10), a frontal section 

 in fig. 22, a sagittal section in fig. 16, and a transverse in 

 fig. 13. From these it will be seen that the ventral prolonga- 

 tion of the ciliated organ is distinguishable from the lip of the 

 nephridial funnel, — the cells of the former being small, deeply 

 staining, and not ciliated ; those of the latter being ciliated, 

 less deeply staining, and larger. The convex outer surface of 

 the large cells forming the funnel can be seen in the living 

 tissue (fig. 17). 



Passing downwards, a section through the wide tube (fig. 4) 

 shows that the lumen is intra-cellular, and the cilia arise from 

 various places round the inner surface ; cil., fig. 6, represents a 

 section through the convoluted mass, where the lumen is cut 

 through seven times. The whole organ is, of course, covered 

 with ccfilomic epithelium (c. ep.). 



Such nephridia occur in all the segments of the body 

 occupied by the ciliated organs. 



Tyrrhena. 



In Tyrrhena Claparedii the condition of the ciliated 

 organ and of the nephridium is very much the same as in 

 Hesione. As in the latter, the nephridial funnel is in direct 

 continuity with the ventral prolongation of the ciliated organ. 

 The nephridium is of simpler structure, the tube being very 

 little convoluted. The ciliated organ itself is in the same 

 position, but it is less elongated in shape, and its ciliated 

 surface has fewer ridges. 



Nephthys. 



The Ciliated Organ. — When describing the ciliated 

 organ of the Lycoridea^ I stated that I had been unable to 



1 Loc. cit. 



