OLIGOCHATA OF TROPICAL BASTERN AFRICA. 229 
publication, arrived at the same results. His results, how- 
ever, were not the outcome of a study of the young stages, 
but of a comparison of the structure of the several regions in 
the adult. He found that the epithelial lining of the sac 
stopped abruptly at a point not far removed from the external 
aperture, and gave place to a layer of cells of an entirely differ- 
ent character, and like the peritoneal epithelium. It may, I 
think, be regarded as certain that a great part of the compli- 
cated system of spaces surrounding the ovary, and communi- 
cating with the exterior, in the Eudrilide are derivatives of the 
celom, but it is also clear that a variable tract of what has 
been termed the spermatotheca is really an invagination of 
the epidermis, and is therefore comparable to the spermato- 
thecee of other worms. I shall recur to this subject in describ- 
ing the anatomy of some species of Eudriloides. The deve- 
lopment of the sac a shows how the oviduct comes to be partly 
enveloped by it; as it is simply a part of the celom, there is 
nothing to be surprised at in the fact that the oviduct lies 
within it. 
§ Affinities of Pareudrilus. 
This genus evidently is referable to the second of the two 
sub-families into which I divide the Eudrilide (see below). 
It has no integumental sense-organs of the characteristic form 
found in Eudrilus and other allied genera. The sperm- 
ducts are not dilated at their junction with the funnels. 
There are no calciferous glands. It is the only genus in this 
sub-family besides Nemertodrilus which has paired repro- 
ductive apertures. A very marked peculiarity of the present 
genus is arrangement of the nephridia. This is only paralleled, 
so far as we know at the present time, in the West African 
genus Libyodrilus. In that genus there is a complex 
system of integumental nephridial tubes. Nevertheless it is 
not perhaps the only other genus in which this peculiarity 
occurs. In the description given by Michaelsen of Mega- 
cheta tenuis, it is stated that the nephridiopores could 
not be discovered; so, too, with Notykus and Metadrilus. 
