1902.] FEMALE ORGANS OF EUDRILUS. 97 



into which the funnels of the gonad-ducts open. This fact appears 

 at first sight to be fatal to my hypothesis. I am not, however 

 convinced that it is necessarily so. In Dr. Bergh's fio-ure ^ 

 illustrating the first origin of the funnel (text-fig. 20, 0, p. 96), 

 it will be noticed that this sperm- duct funnel originates as a 

 thickening of the peritoneal covering of the nephridial funnel. Here 

 it may be urged that the peritoneal covering of the nephridium 

 is not the funnel itself, but a layer simply enwrapping it, and not 

 related to it any more than is the peritoneal covering of the kidney 

 in a vertebrate to be looked upon as a part of the kidney itself. It 

 may be pointed out, however, that what is called " peritoneum " 

 in these Annelids is apparently not quite to be compared to the 

 cellular lining of the coelom in a vertebrate in every case. For 

 example, in Rhynchehnis Vejdovsky has shoAvn ^ (text-fig. 20, B, 

 p. 96) that the vesicular cells involving the nephridium are deri- 

 vatives of the actual nephridium itself, and not of any peritoneal 

 covering. The nephridium, in fact, is not covered by a layer 

 independent of itself. An even more striking fact is afibrded 

 by the condition of the nephridial funnel in the Discodrilid 

 Branchiohdella. In a species of this genus, Mr. J. P. Moore ^ 

 has figured (text-fig. 20, A, p. 96) an absolute continuity between 

 the cells of the small funnel of that worm and a long thin 

 cell enveloping the funnel outside and thus presenting the 

 appearance of a peritoneal layer. Mr. Moore has remarked not 

 only upon the " direct continuity " of these cells, but also upon 

 the resemblance of the nucleus of this " peritoneal " cell to those 

 of the funnel-cells which " is very striking." It appears to me 

 that these various considerations show that it is at least premature 

 to regard the gonad - funnels of the Oligoch^ta as essentially 

 different from the nephridial funnels. None of the facts which I 

 have called attention to hei-e are at variance with the older view 

 of the intimate connection between nephridia and genital ducts 

 in the Oligochseta '. 



1 Zeitsclir. f. wiss. Zool. xliv. pi. xxi. iig. 19. 



- Entwickelungsgeschichtliche Untersuchiuigen, 1888-92, pi. xxvi. figs. 11, 12, 13. 



3 Journ. Morpli. xiii. pi. xxi. fig. 10. 



* The connection between the gonad-funnels and the nephridial funnels may be 

 indeed not without analogj' to the connection between certain cartilages in the 

 vertebrate skeleton with subsequent ossifications. The line between membrane-bone 

 and cartilage-bone is not always plain and easy to draw, and there are cases where a 

 bone originally formed in cartilage comes to be later a product in part or entirely 

 of membrane independent of the cartilage. A condition of apparently total in- 

 dependence is thus produced, which masks the real connection. This is possibly the 

 case with the bones investing the palato-pterygoid arch in the higher vertebrates. 

 And other instances might be quoted from this and other organs and sj'^stems. 



Proc. Zool. See— 1902, A^ol. II. Ko. VII. 



