NOTES ON SOME AQUATIC OLIGOCHATA. 203 
matheca is lined by columnar cells (fig. 26), the nuclei of 
which are usually situated near the outer margin. These 
cells are very granular, and their internal margin sometimes 
indistinct. But near the neck the cells are pyriform (fig. 27), 
as in Vejdovsky’s figures; and these cells are extremely finely 
granulated, the nucleus being in the dilated part of the cell, 
which projects into the cavity of the spermatheca, so that in 
this region the inner limit of the epithelium is quite irregular. 
The spermathece are filled with the characteristic Tubificid 
sperm-ropes (I prefer this term to spermatophores), of 
which I counted in one specimen as many as thirty-five ; 
some of which were completely formed, others incompletely. 
A completely formed “‘ rope” is shown in fig. 28, its structure 
in figs. 29—381. 
It is spindle-shaped; one end being drawn out into a point, 
the opposite end being truncated, slightly knobbed, and appa- 
rently perforated. The wall is highly refracting and forms a 
fairly thick coat, in which the heads of the spermatozoa are 
embedded (a); immediately below this is, in optical section, a 
layer of granules (0) (? sections of spermatozoa), and the interior 
is filled with loose spermatozoa in addition to those embedded 
in the wall, whose freely projecting tails give rise to the move- 
ment of the whole apparatus. When partially crushed, bun- 
dles of spermatozoa protrude from the interior through any 
breaks in the wall (fig. 30). 
Though spindle-shaped like the sperm-rope of Psammo- 
-ryctes or Limnodrilus, it lacks the peculiar “ spines”’ on 
the neck which occur in the former, and is relatively much 
longer, narrower, and more pointed than in the latter. 
The structure of spermatophore is further illustrated by fig. 
31, which is drawn from a section through a spermatheca. 
The homogeneous layer (q) is in these preserved specimens very 
highly refractive and scarcely stained. By the use of an apo- 
chromatic, and regulation of the light, the heads of the sper- 
matozoa could just be detected ; the lines representing them in 
the figure are much too coarse. 
I have added a figure of a specimen of the worm after sexual 
