716 EDWIN S. GOODRICH. 



The Adult Nephridium. — Already Hatschek (16) and 

 Fraipont (7) have given a detailed account of the nephridium 

 of Polyg'ordius. In most respects I can only confirm their 

 description, but, with regard to the structure of the nephro- 

 stome itself, my observations do not quite agree wi,th those of 

 Fraipont. He describes the nephridial canal as ending in 

 front in a funnel having a flattened brim of considerable 

 width, derived from the coelomic epithelium. In fact, in a 

 previous paper (10) I interpreted his description as favour- 

 ing the view that the excretory organ of Polygordius is, as in 

 so many Polychgetes, of double origin. 



I have been, however, quite unable to find any trace of 

 such a peritoneal funnel in living or preserved specimens of 

 P. neapolitanus, although many of those I examined had 

 nearly ripe genital products in the coelom.^ The nephridium 

 in this worm runs forwards just below the region where the 

 oblique muscles join the body-wall (fig. 47), and ends in front 

 of the next septum in a small nephrostome. Its short 

 anterior lip projects into the coelom, and is scarcely, if at all, 

 ciliated. The longer posterior lip, on the contrary, bears a 

 powerful bunch of long cilia (fig. 46). The nephridium of 

 P. appendiculatus appeared to be quite similar. 



The Larval Nephridium. — In his very important work 

 on the development of worms, Hatschek described the so- 

 called head-kidney of Polygordius as a branched organ, 

 opening internally by small funnels provided with peculiar 

 stiff processes joined together by a web. Subsequently 

 Fraipont (7) showed that the branches are blind, that a large 

 nucleus is situated at the apex of each, and that the stiff 

 processes are hollow tubes. 



I had long suspected that these structures were really of the 

 nature of solenocytes. It was not, however, till this summer 

 that I was able to confirm this surmise. On examining some 

 living larvJB at Trincomalee, the general structure of the organ 

 was found to be very much as described by Hatschek and 



' The luiiieii of the uepliridial caual is exceedingly small, being not only 

 narrower than the nucleus of the ovum, but even than its nucleolus! 



