94 KARM NARAYAN BAHL • 



the condition of nephridia in the posterior region of tlic body 

 of Allolobophora antipae is remarkably similar to 

 that in the whole length of the body of Pheretima. On 

 the formation of communications between the supra-intestinal 

 ducts and the lumen of the gut, the essentials of the ' entero- 

 nephric ' system are completed. 



The formation of secondary septal and integumentary 

 nephridia is not difficult to explain. The septals are, no doubt, 

 traceable to the same source as the primary nephridia, i.e. to 

 the cell-group making its way into the intersegmental septum. 

 The ])rimary nepln'idium already has a pre-septal funnel, 

 while, of the succeeding secondary ones, most have a post- 

 septal funnel, there are some with a pre-septal funnel. It 

 is possible that the original ' funnel-cell ' has something to 

 do with the pre-septal or post-septal position of the funnel. 

 If the funnel is formed from the original ' funnel-cell ' or 

 a derivative of it, we get a pre-septal funnel ; l)ut if the funnel 

 is formed from one of the other cells which takes up the 

 character of the ' funnel-cell ', a post-septal funnel results. 



As regards the secondary integumental nephridia, their 

 separation from the primary nephridia and from one another 

 has gone much deeper and further than that shown in the 

 developing nephridia of Megas col ides (17) and Mah- 

 benus (8). They are coeval in origin, but not connected in 

 any part of their development. 



Both the buccal cavity and the pharynx, forming that por- 

 tion of the alimentary canal wdiich lies in the first four segments 

 of the body, belong to the stomodaeum ; and since the latter is 

 morphologically external, the pharyngeal nephridia opening 

 into the stomodaeum may be said to open on the ectoderm. 

 But the facts of development do not help us in understanding 

 the possible course of evolution of these nephridia. We cannot, 

 for example, assume that these nephridia are really integu- 

 mentary, but have come to occupy their present position and 

 relationship on account of the anterior portion of the worm 

 being formed into an ' introvert ' or a stomodaeum. This 

 assumption does not work in giving us the adult structure 



