STRUCTURE OP UROCHJITA AND DICHOGASTER. 
245 
dently represents one of the latter. The funnels of the 
mucous gland of the nephridia of the anterior segments are 
in the first place much larger than those of the posterior 
nephridia ; their structure also is different. The funnel itself 
(PI. XXIII, fig. 5) is composed of the same columnar ciliated 
cells with large nuclei, but it does not at once communicate 
with the narrow tubule ; the latter is dilated into a wide cavity 
of considerable length. This portion of the nephridium is not 
to be confounded with the funnel although its lumen is of the 
same size; its walls are tolerably thick and exhibit a faint 
transverse striation, and contain oval nuclei embedded at 
intervals. The structure of this part of the nephridium shows 
that the lumen, although it is extremely wide, is nevertheless 
intracellular ; it is simply a dilatation of the tubule. 
This dilatation of the nephridial tubule recalls an analogous 
dilatation which Bourne (12, figs. 51, 52, 53, 54), has 
described and figured in Leeches, only in these animals the 
lumen appears to be intercellular. 
I have always observed this dilatation to be filled with what 
are apparently degenerating corpuscles, the nuclei of which 
were deeply stained by borax carmine. Bourne has observed 
similar contents in the corresponding part of the nephridium 
in Leeches. 
In the genus Thamnodrilus (Beddard, 3) the funnels 
of the anterior nephridia also differ from the funnels of the 
posterior nephridia. 
In a few segments I observed two nephridial funnels, but this 
branching of the nephridium appears to be rare. 
Perrier states that the nephridial funnel is contained in the 
same segment as the nephridium itself. In a paper upon the 
structure of an Australian species of Urochseta (4) I pointed 
out that the funnel, as is usually the case among the Oligo- 
clucta, was situated in the segment anterior to that which is 
occupied by the rest of the nephridium. InUroclueta hystrix 
I find a justification for Perrier’s statement; the nephridia are 
sometimes entirely contained in one segment and sometimes 
are not. In the second case the funnel is in the segment in 
VOL. XXIX, PART 3. NEW SER. 
R 
