OLIGOCHATA OF TROPICAL EASTERN AFRICA. 235 
thecal sac, but never in between. I find it difficult to under- 
stand this. The spermatothecal apparatus is so large that it 
must, one would think, perform some function not performed 
by spermatothecz which are smaller in size ; for instance, those 
of Eudrilus. The presence of spermatophores needs more 
room, supposing that there is about the same amount of sperm. 
But the restriction of the spermatophores to the anterior end 
of the spermatothecal apparatus is still unexplained. In Poly- 
toreutus coeruleus and in Polytoreutus magilensis the 
oviduct is dilated near to the opening into the egg-sac. In this 
dilatation are lodged bundles of sperm. Michaelsen has sug- 
gested that this looks as if the ova were fertilised in the egg- 
conducting apparatus. The facts described in the present paper 
support this contention, but unfortunately throw no further light 
on the exact place where fertilisation takes place. The spermato- 
thecal sac is lined throughout with a layer of very tall columnar 
cells, the nuclei of which are near to the attached base of the 
cells. In the anterior part of the spermatothecal sacs where 
the spermatophores are lodged these latter are seen to lie 
partly among the cells, having, as it were, thrust their way in 
between them. There were, however, no indications that the 
cells lining the sacs are in any way responsible for the forma- 
tion of the spermatophores. 
The ovaries of Polytoreutus ceruleus have been de- 
scribed by Michaelsen as lying in a spherical chamber which 
itself lies at the extreme end of each of the two branches in which 
the spermatothecal sac ends anteriorly. The epithelium lining 
this chamber is believed by Michaelsen to be the ovarian epi- 
thelium. This spherical pouch is attached to the Septum 
x11/x111 by a strand of connective tissue. In Polytoreutus 
violaceus the position of the ovarian chamber—if I am right 
in so calling it—is rather different. At the point where the 
large terminal chamber of the spermatothecal pouch comes 
nearest to the Septum x11/x111 there is a minute sac attached 
to its wall, and formed of a muscular coat with a lining of epi- 
thelium. Where this sac is in contact with the wall of the 
spermatothecal sac there is no development of muscles, so 
