THE NEPHRIDIUM OF LUMBRICUS. 319 



the funnel is deeply incised at the front, and the cells forming 

 this part are apparently quite continuous with the other mar- 

 ginal cells ; but I think that it is very probable that the funnel 

 of Urochseta is formed on the same plan as in Lumbricus. 

 Perrier was unable to distinguish any nuclei in the wall of the 

 widely dilated portion of the tube immediately below the margin 

 of the funnel — between, that is, the nuclei of the marginal 

 cells and those of the intra-cellular tube itself, — and suggests 

 that the marginal cells are extremely elongated. 



Beddard (3 and 6) regards this dilated region as being intra- 

 cellular. In the former paper he gives figures of sections 

 through the funnel of the ordinary nephridia, in which there 

 is — contrary to Perrier's figure — no very marked dilatation of 

 the tube ; but the funnel appears to consist (fig. 7) of several 

 rows of non-perforated cells (although such is, perhaps, not 

 intended, and probably is not the case). Of the peptonephri- 

 dium, Beddard (6) figures the funnel, and there he shows the 

 perforated cells (? = " grooved cells ") diverging from one 

 another, so as to give rise to a^very wide '^intra-cellular^' tube 

 before the actual aperture is reached. The whole margin is 

 formed by one row of marginal cells, and he makes no 

 mention of the incurving of the margin represented by 

 Perrier. 



For Pontodrilus, Perrier (27, pi. xiv, fig. 12) figures only 

 the side of a nephrostome covered by coelomic epithelium, and 

 gives little detail in the text; from it I cannot be sure whether 

 the perforated cells reach to the marginal cells simply as in 

 Perichseta, or whether there is any widening of the tube, as 

 in Urochseta. 



In Rhinodrilus (Thamnodrilus), Beddard (la, p. 161) 

 gives a figure of a complete nephridium,and describes the funnel 

 as an "elongated, folded membrane, composed of ciliated 

 columnar cells." I have removed a nephridium from a speci- 

 men of the same species (Rh. gulielmi) ; and I can confirm 

 this statement, but will add that the funnel is quite similar to 

 that of Lumbricus (with marginal cells, centripetal and cen- 

 trifugal cells) if we imagine it to be, not circular, but drawn 



