OLIGOCHZTA OF TROPICAL EASTERN AFRICA. 237 
The setz seem to be asin other species of the genus. There 
seems to be a tendency for the ventral setz to be defective 
upon the segments which bear the genital pores; I refrain, 
however, from giving any details, since 1 am not certain how 
far this deficiency may be normal. 
The nephridiopores are lateral in position. 
There is no median genital papilla such as occurs in P. 
violaceus. 
The clitellum extends over Segments x1v—xviul, being 
only developed upon the anterior half of the last segment. 
Behind the clitellum is a median area bounded by the ventral 
setz, which looks like an extension of the clitellum ; it has the 
same tumid appearance, and the boundary lines between the 
segments are there uot apparent. This area reaches from the 
18th to the 21st segments ; when the worm is seen in profile it 
is seen to project somewhat. It is very possible that this area 
serves the purpose of the genital papilla in Polytoreutus 
violaceus. 
The anterior of the two median and unpaired genital open- 
ings is situated on the border line between Segments xvui/xvi11; 
it is a widish aperture with crenated margins; behind it is a 
transverse groove which runs for a considerable distance right 
and left; this groove is not, as might be supposed, the boundary 
line of Segments xv11/xvi11; it can be easily seen that the 
furrow between these segments is anterior to it and bisects the 
genital pore already described. Immediately behind the groove 
referred to is the posterior genital aperture; this is much less 
conspicuous than the anterior pore, and has not crenated 
margins. 
The internal structure of this species is very similar to that 
of the last, but there are certain recoguisable differences. 
There are six specially thickened septa; the first of these lies 
behind the 5th segment, and the last behind the 11th segment. 
As appears to be usual in the family Eudrilide, these septa are 
not much connected together by threads. 
The gizzard lies in the 5th segment, and is small; the 
calciferous glands, of a white colour, are in Segment x11; the 
