406 PRANK E. BEDDARD. 



of E. Meyer and of Vejdovsky (13), that in Polychseta and 

 Oligochseta the funnel is developed perfectly independently of 

 the rest of the nephridium. It was important, however, to 

 note that not only is the nephridial funnel formed by the 

 proliferation of a single cell, but that in Stylaria this cell 

 becomes ciliated and acquires a lumen before it 

 undergoes division; repeating in fact the presumed ancestral 

 condition. With regard to the presence of a single flagellum in 

 the "flame cells," Hartog has recently pointed out (10 a) that 

 the optical effect produced by the motion of minute cilia might 

 readily give the impression of a single flagellum. In the 

 adult Clepsine (Bourne 5) the funnel consists of only two 

 cells, so that it is but a stage removed from the Platyhelminth 

 funnel. The above facts lend at least some support to the 

 views that it is unnecessary to regard the funnels of 

 the Annelida as new structures. 



The facts recorded in the present paper fit in very well with 

 the supposition that the Annelid excretory system is directly 

 traceable to that of the Platyhelminth; I shall suggest, how- 

 ever, a course of development rather different from that put 

 forward by Lang. 



Lang has pointed out that in certain Planarians a commenc- 

 ing metamerism (parallel with the commencing metamerism of 

 the generative organs, &c.) is visible in the excretory system. 

 Here and there " secondary " external orifices are formed 

 through branches given off from the longitudinal trunks of 

 either side ; at first irregular, these secondary pores finally 

 become regularly disposed, and a paired arrangement even is 

 seen; the disappearance of at least the greater part of the 

 network (and the development of internal funnels) brings 

 about the conditions which occur in Lanice conchilega; in 

 this Annelid, Meyer (11) and Cunningham (6) have shown that 

 the longitudinal trunks connecting the nephridia of successive 

 segments persist; Vejdovsky also (13) has figured traces of this 

 same longitudinal duct in Anachseta; and Wilson has 

 recently (16) been able to prove that the embryo Lumbricus, 

 like the embryo Criodrilus, possesses a similar longitudinal 



