OLIGOCHATA OF TROPICAL EASTERN AFRICA. 249 
of the corresponding organ in the Tubificide than is the penis 
in the Eudrilide and other terrestrial Oligocheta which 
possess an organ of this kind. The atrium is lined by a single 
layer of cells, a feature which is also found in Ocnerodrilus 
and in some other genera. The sperm-duct has a very short 
course, opening on to the exterior in the next segment to that 
which contains the internal funnel. It is quite possible, how- 
ever, that Tetragonurus shares this peculiarity with M onili- 
gaster. So, too, with the oviducal pores. Moniligaster is 
not alone among earthworms in the fact that they are in front 
of the sperm-duct pores. In both Allurus and Tetragonurus 
the oviducal pores are nearly certainly (in Allurus quite cer- 
tainly) in front of the sperm-duct pores. Dr. Rosa has 
rebuked me for laying much stress upon the fact that the male 
pores of Moniligaster are so far forward as the boundary 
line of Segments x/x1, a position which of course recalls the 
very anterior position of the corresponding apertures in the 
generality of the “ Limicolz.” It is true that the difference 
between an opening upon the 10th and 11th segments and one 
upon the 12th segment is not a very great one, but the differ- 
ence, such as it is, is in the direction of the lower Oligocheta, 
and not in the reverse direction. 
So much, then, for Moniligaster. The only point in 
which it differs in an important way from the aquatic forms is 
in the relatively small size of the ova. The Annelid which 
forms the subject of the present communication is the only 
known example of an Annelid with marked affinities to the 
terrestrial Oligochzeta which has that hitherto distinctive 
character of the lower Oligocheta—large ova filled with yolk. 
It resembles the aquatic Oligocheta in the following points: 
1. Clitellum consisting of a single layer of cells. 
2. Ova very large and full of yolk, few in number, and 
occupying several segments. 
3. Atrium lined by a single layer of epithelium, and covered 
by masses of pear-shaped cells ; sperm-ducts open into it. 
4. Longitudinal muscular layer of body-wall consists of a 
single row of plate-shaped fibres. 
