OLIGOCHATA OF TROPICAL EASTERN AFRICA. 215 
entiated condition. The integumental plexus appears to be 
much less developed in Eudriloides than in Libyodrilus. 
After finding that this species of Eudriloides showed the 
above mentioned resemblances to Libyodrilus, I examined 
other species, with a view to discovering how far they agreed 
with the present. In Pareudrilus something of the same 
kind seems to occur (see below). In Stuhlmannia varia- 
bilis I traced the nephridial duct into the body-wall at the 
inner pair of sete ; instead of opening on to the exterior opposite 
to the point where it entered the body-wall, the tube passed 
along the body-wall below the circular muscular layer, and 
eventually opened on to the exterior on a level with the outer 
pair of sete. In one instance, at any rate, I feel sure that the 
tube did not extend further than this point, but whether there 
was more than one opening on to the exterior for each 
nephridium I am not able to say with certainty. I think 
that in Eudriloides Cotterilli the same state of affairs 
is found. In the two latter cases the small size of the 
worms was a matter of difficulty ; the corresponding fineness 
of the tubes rendered their discovery a matter of greater diffi- 
culty than in Eudriloides brunneus. Iam almost inclined 
to think that all those species of Eudrilids in which Michaelsen 
has described ventral nephridiopores will be found to have a 
nephridial system like that of the species described here. One 
is tempted, in the instances brought forward here, to associate 
the complexity of the integumental plexus with the size of the 
worm. In Libyodrilus and in Eudriloides brunneus, 
which are the two largest species in which the nephridial 
system has been investigated, it is apparently the most com- 
plex; in Stuhlmannia, at any rate, it seems to be less 
complex. The only time that I was able to follow out the 
tube from the point where it entered the body-wall to its 
external pore, it seemed to me to pass straight from opposite 
the inner pair of setz to the aperture on a level with the outer 
pair of sete. In this connection Professor Hubrecht’s! inter- 
1 «The Nephridiopores in the Earthworm,” ‘ Tijdschr. Ned. Dierk. Ver.,’ 
ser. 2, vol. ii, p. 226. 
