14 A. O. OUDEMANS. 
from the lumen. On the inner side of these cavities I have 
seen here and there small flattened nuclei. 
Thus the lacune have a wall consisting of a layer of cells with 
flattened nuclei, and a layer of hyaline basal tissue. McIntosh 
(26) makes use of the terms “granular layer” and “ basal 
layer ” or “layer of basal tissue,” where he describes the wall 
of the proboscidian sheath. 
I did not observe a communication of the two lacunz beneath 
the proboscidian sheath. 
On following the lacunze backwards one sees that they pass 
with the proboscidian sheath through the brain ring, formed 
by the ganglia and their two commissures, still resting on the 
sides of the proboscidian sheath (fig. 20). They then descend 
to a lower level. The mouth and the csophagus next become 
visible. First the lacune remain where they are (fig. 21), that 
is to say, they do not descend any further, but lie in the hori- 
zontal plane, between the stomodzum and the proboscidian 
sheath. A few slices further backwards they are separated 
from the proboscidian sheath by the cesophagus which assumes 
a semilunar shape, the two horns extending between the pro- 
boscidian sheath and the blood cavities. Now, these cavities 
lie against the intestine above the plane of the nerve trunks, 
which are perfectly lateral. Behind the cesophageal region the 
lacune descend till they come to lie against the intestine, 
beneath the level of the lateral nerves, but still imbedded in 
gelatinous stroma. However, they have become somewhat 
changed, having obtained outside of the hyaline basal layer a 
layer of circular fibres. Intentionally I use here the term 
“fibres” because I have not been able to make out whether 
they are muscular or not. It appeared to me that they were 
still “in statu nascenti.”’ They are still primitive, and I 
cannot say anything definite concerning them. They appear 
to be of the same nature as those which I shall describe after- 
wards in Carinoma Armandi (see fig. 74). I have not seen 
longitudinal fibres. Probably the fibres add to the contrac- 
tility of the vessel. 
I have seen nothing of the water-vascular, better called ne- 
