724 . EDWIN S. GOODRICH. 



pore iu the mter-segmental groove near the base of the para- 

 podium, corresponding to the segment in which the funnel 

 opens. These organs function both as kidneys and as genital 

 ducts. 



Geneeal Conclusions. 



Hitherto in this paper I have scarcely ventured beyond the 

 domain of facts, but I now propose to point out some of the 

 more important theoretical conclusions which may be drawn 

 concerning the homology of the Polychaete nephridium and 

 its relation to the genital funnel. 



The Genital Funnel. — First of all as to the genital 

 funnel. Is it, as I have elsewhere contended (10), the mor- 

 phological representative of the genital ducts of other Anne- 

 lids ? Or is it, as some would appear to believe, merely a 

 specialised portion of the nephridium, a much enlarged 

 nephrostome which may become separated off from its duct ? 



For various reasons the first of these views seems to me to 

 be the only reasonable one. It is not advisable here to go 

 into the general question of the homology of the genital ducts 

 or funnels of the other Annelids, a subject which I have 

 already dealt with in some detail in the paper referred to 

 above (10), but it may be pointed out, that, where the 

 anatomy and development of the genital funnel in these forms 

 is understood, it is found to arise from the ccelomic epithe- 

 lium, being in fact merely a specialised, ciliated, funnel- 

 shaped outgrowth of the ccelomic follicle, designed to afford 

 an outlet for the ripe genital products. 



From the facts described in Parts I, II, and III, and others 

 we were already acquainted with, we are now in a position to 

 state that in the Polychseta also a specialised, ciliated, funnel- 

 shaped segmental region of the ccelomic epithelium is deve- 

 loped, which forms a duct to lead the genital products to the 

 exterior. Moreover, that this funnel may secondarily acquire 

 other functions than the merely genital, and in this case is 

 generally early developed in the immature animal (Nephthys, 

 Glycera) ; that it may even occasionally cease to function as 



