162 W. V,. EENHAM. 



them. Each nephridium is a large organ, almost filling the 

 cavity of the somite ; this size is due to the great development 

 of large vesicular cells in which the tube is embedded, as in 

 Pontodrilus, Criodrilus, Libyodrilus, Tubifex, and 

 other worms. 



The nephridia are absent in the first twelve somites. The 

 first one lies in Somite xiii, and has its funnel in Somite 

 XII ; in one specimen, however, I noted a nephridium in this 

 latter somite. 



The general character of the nephridium agrees with that 

 which I have described^ for Lumbricus and other worms. 



Sparganophilus agrees, however, with Criodrilus in 

 lacking a muscular duct ; the " wide tube " perforates the 

 body-wall (fig. 8, ne. d.), as I have figured for Criodrilus 

 (loc. cit.), and opens in front of the innermost chaeta (fig. 

 11, ne. p.). 



In the structure of the funnel, however, the present worm 

 exhibits a rather more complicated condition than any hitherto 

 figured, in the possession of an extra row of small cubical 

 cells round the margin. As in Lumbricus, the funnel con- 

 sists of a large " central cell" (figs. 31, 32, c.) surrounded by a 

 series of " marginals " {m.) arranged in a fan-shaped way, and 

 diminishing in size towards each side, where they pass round 

 to form an incomplete ventral lip ; outside these marginals are 

 set the cubical "extra-marginals" [ex. m.), which appear as a 

 single row of cells when the funnel is seen from in front, but are 

 really three or four rows deep, and passing round to the back of 

 the funnel, graduate into the flat coelomic cells normally 

 present. The arrangement is represented in figs. 31, 32, one 

 of which represents a longitudinal section, the other a trans- 

 verse section of a funnel. 



In many cases I have observed in front of the funnel a 

 large spherical mass (fig. 33), consisting of a number of nuclei 

 — most of them deeply stained, irregular, and highly refract- 

 ing, others with but little chromatin in them — embedded in a 



' Benham, "The Nephridia of Lumbricus," 'Quart. Jouni. Micr. Sci.,' 

 vol. xxxii. 



