478 EDWIN S. GOODRICH. 



mial coelom, &c. He then treats of the nephridia and genital 

 ducts, and it is with this part of the question that I wish more 

 especially to deal in this paper. Meyer holds that the ne- 

 phridium of the Platyhelminths is represented by the so-called 

 head-kidney in the first segment, and by the tube of the 

 nephridium in the trunk segments of the Annelids, while the 

 genital duct of the Platyhelminths is represented by the wide 

 funnel of the trunk nephridium which develops, independently 

 of the tube from each genital or ccelomic follicle, and becomes 

 grafted on to it afterwards. Unfortunately, the author restricts 

 his remarks almost entirely to the Polychsetes and those forms 

 which appear directly to lead up to them. Although the 

 theory has been at all events partially adopted by other writers 

 (Lang, 71; Korshelt and Heider, 67), no one, as far as I am 

 aware, has pushed it to its logical conclusion, and applied it to 

 all the groups of Coelomata. This is what I shall attempt to 

 do in this paper. First of all, however, there is one thing to 

 be noticed with regard to Meyer's general statement about 

 the nephridial funnel, namely, that since the publication of 

 his own researches on the Polychseta, and of those of Vejdovsky 

 and others on the Oligochaeta, there can be no doubt that the 

 nephridial funnel in the latter forms part of the true nephri- 

 dium (is, in fact, derived from the end-cell), and is not a 

 grafted genital duct, as is the case in some at least of the 

 Polychseta. 



An unprejudiced review of the well-established and recently 

 ascertained facts concerning the development of the excretory 

 organs and genital ducts of the Coelomata must, I think, 

 inevitably lead us to the conclusion that we have been confus- 

 ing two organs of totally difi'erent origin under the one name 

 nephridium — the one organ the true nephridium, the other 

 the morphological representative of the genital duct, which 

 may be called the peritoneal funnel, to avoid confusion. 

 Further, that while on the one hand in certain groups such 

 as the Planaria, Nemertina, Hirudiuea, Chsetopoda, Rotifera, 

 Entoprocta, besides the genital ducts or peritoneal funnels, we 

 find true nephridia in the adult ; on the other hand, in such 



