COE: TERRESTRIAL NEMERTEAN OE BERMUDA. 565 
the thick septum described above. The cylinder of cells lies 
oblique to the longitudinal axis of the proboscis for a short time, 
but soon comes to lie symmetrically nearly in the center of the pro¬ 
boscis. At the same time the canal connecting the anterior and 
posterior chambers of the proboscis is greatly reduced in size, and 
the chamber behind the septum is constricted by an ingrowth of the 
proboscis walls into a middle and a posterior chamber. The chamber 
from which the outgrowth takes place is likewise reduced in size, so 
that it surrounds the central stylet rather closely (pi. 25. fig. 21). It 
leads forward to the anterior chamber of the proboscis, into which 
it opens by a comparatively narrow tube. 
The opening is almost obliterated, or at least hidden from view, 
by an enormous growth of deeply staining gland cells (pi. 25, figs. 
20, 21), which form a broad and thick disk on the anterior margin 
• of the septum. The glands pour their secretions into the anterior 
proboscis chamber. Similar glands occur in nearly all Hoplonemer- 
tea, sometimes remaining as a disk at the posterior end of the 
anterior chamber, but more often sinking deeper into the tissues 
of the septum, and assuming the form of a wreath which surrounds 
the stylet apparatus, but situated in the peripheral portions of the 
septum. 
These glands have been commonly looked upon as themselves 
forming the secretion out of which the basis is composed, although, 
as shown above, that function belongs to other cells. Their secre¬ 
tion is poured either into the anterior chamber or into the canal 
passing through the septum, the basis being composed entirely of 
the secretions of the cylinder of cells, described above. In trans¬ 
verse section (pi. 25, figs. 22, 23) these cells are seen to be symmet¬ 
rically placed around the circular lumen filled by the basis. The 
nuclei likewise form a nearly perfect circle, all being situated at an 
equal distance from the lumen. The cell membranes are often 
inconspicuous, although a distinct line of granules of secretion can 
be seen in the interior of the cell, extending from near the nucleus 
outward to the free border of the cell (pi. 25, figs. 22, 23). 
The definite origin of the central stylet itself has not been deter¬ 
mined with certainty. Burger (’ 95 , p. 482) finds in Prosorhochmus 
that the accessory stylet pouches are each composed of a single cell 
only, the stylets themselves being formed as a secretion in this cell. 
After its formation in this manner one of the stylets passes through 
