OLIGOCHATA OF TROPICAL EASTERN AFRICA. 221 
with a rather complicated arrangement of muscular bands. 
These are illustrated in the accompanying figure (fig. 21). 
Just behind the muscular bulbus arise by a common stalk the 
two atria. At the angle on either side of their entrance 
into the terminal bulbus is a bundle of muscular fibres 
running transversely to the longitudinal axis of the body. 
These muscular fibres appear to be mainly concerned with 
the penial seta, which is enclosed by them. From each 
of these bundles of fibres arises a flat strap-shaped band of 
muscles, which passes forwards obliquely and is inserted on to 
the body-wall just in front of the edge of the muscular bulbus. 
Besides these muscles, a number of delicate fibres pass from the 
parietes to be inserted round the periphery of the bulbus. 
The latter muscles are, I take it, retractors, while the single 
strap-shaped muscle on each side, perhaps, by its action when 
contracted, protrudes the bulbus by drawing back the body- 
wall just in front of it. 
The penial seta of each side of the body lies, as already 
stated, in the mass of muscles lettered in my figure. These 
sete are very strong and rather short, in fact very short if 
compared, for example, to those of Eudrilus Cotterilli. 
They are strongly curved into an S-shape, and are a deep 
yellow colour. The free extremity is not at all ornamented, 
but it thins off like the blade of a knife, and on this thin 
edge a few transverse strie are to be noticed. The genital 
sete of this species are decidedly peculiar in form and very 
characteristic of the species. 
Pareudrilus stagnalis, n. g., n. sp. (fig. 9). 
I have had for examination a considerable number of indi- 
viduals of this worm, which is referred to a new genus. It 
presents upon a casual inspection all the characters of the 
genus Eudrilus, to which genus I was at first disposed to 
assign it. Not only are the colour and general appearance 
quite similar to those of that genus, which also appears to exist 
on the east coast of Africa, but the position of the reproductive 
pores are identical, and they are paired—a character which is 
