398 E. S. GOODRICH. 



Reasons have been given above for considering the dorsal 

 ciliated organ as a genital duct not fully developed. It would 

 be premature, however, to try to come to any definite con- 

 clusion on the subject of its functions and homology until we 

 know both its development and its fate. But I should like to 

 point out that the Capitellidge, the only other Polychsetes 

 possessing a uephridium described in detail which resembles 

 that of Nereis, also have in many segments a large ciliated 

 patch of coelomic epithelium, which becomes funnel-shaped 

 and functions as a genital duct (Eisig, 6). Most of the Poly- 

 chgeta, however, have large-funnelled nephridia which may 

 function as carriers of the genital products. On the other 

 hand, the latest researches on the development of the nephridia 

 in the Polychsetes (Meyer, 8) and in the Oligochsetes (Vejdov- 

 sky, 10) seem to show most conclusively that these organs 

 were developed phylogenetically from nephridia similar to those 

 of the Planarians, which were provided with flame-cells, and 

 did not open internally. Now Meyer has shown (8) that the 

 large funnels in the tubicolous worms which he studied are 

 developed independently and as outpushings of the ccelomic 

 epithelium which join and fuse with the blind end of the 

 nephridium. May not this funnel be the same as the genital 

 ducts of the Capitellids and other worms (Oligocheetes) ? I 

 should consider, then, that in most Polychsetes the nephridium 

 is a compound organ formed from the fusion of a tube with an 

 outpushing of the ccelomic epithelium, as Meyer holds ; and 

 further, that in the Capitellids this funnel is partly nipped ofi" 

 as the genital duct, while in the Oligochsetes, and perhaps in 

 the Lycoridea also, this coelomic funnel either has never joined 

 the nephridium at all (most of the lower Oligochasta, Euchy- 

 trffiids, Naids, &c.), or that it is afterwards mostly or entirely 

 separated off" as a genital duct. 



It must be remembered that if we assume that in the Chseto- 

 pods the genital ducts are simply modified nephridia, and at 

 the same time consider that their nephridia, which open into 

 the coelora, were derived from nephridia without internal 

 nephrostome, but provided with flame-cells; — if we assume 



