OLIGOCHATA OF TROPICAL EASTERN AFRICA. 243 
back to about the 25th segment behind the clitellum; a 
peculiarity about it was the fact that the last half or rather 
_ less of the gland was double, the two portions, however, 
running in close contact. Whether, as seems likely, this is a 
mere abnormality I am unable to say; but I may point out 
that in Eudrilus each atrium is normally divided into two 
separate tubes by a continuous longitudinal septum. 
The sperm-sacs are very remarkable. On the dorso- 
lateral surface of the intestine I observed a pair of fine tubes 
running a fairly straight course, which I put down at first as 
being the sperm-ducts, thinking that they terminated in the 
atrium. They do as a matter of fact terminate close to the 
atria, but quite independently of them. These slender tubes 
are the sperm-sacs. One of them, that of the left side, was 
distinctly varicose, being dilated here and there into oval 
chambers. Traced forwards, they appeared to end in the 
immediate neighbourhood of the funnels. Hach sperm-sac 
was accompanied by a blood-vessel. It is a pecularity of this 
genus to possess long sperm-sacs, which in Polytoreutus 
magilensis are of enormous extent, but in no other species 
are they of the extreme tenuity exhibited by Polytoreutus 
Finni. This state of affairs may be simply due to the fact 
that the sperm did not happen to be present in any great 
amount; but this is unlikely, as the worm was in all other 
respects fully mature. Besides, this is not the only case of a 
worm possessing such extraordinarily long and thin sperm- 
sacs. I have described elsewhere the sperm-sac of the Geos- 
colicid genus Trichocheta, which are of precisely the same 
character as those of the present species of Polytoreutus. 
On the other hand, it will be recollected that there are a 
number of different degrees in the development of the sperm- 
sacs in this genus which may perhaps be interpreted as dif- 
ferent grades of development of the sacs. In Polytoreutus 
magilensis the sperm-sacs are at first extremely narrow, 
and later become much wider. In Polytoreutus kilindi- 
nensis, described on a preceding page of the present paper, 
the narrow region of the sperm-sacs is reduced greatly, nearly 
