40 A. C. OUDEMANS., 
simply perforated, neither pointing towards the periphery 
nor inwards. 
In a specimen, cut sagittally, the nephridial canals were better 
coloured, but neither in transverse nor in longitudinal sections 
could I observe cilia in the canals. On the sagittal sections I 
could not find any openings in the skin, but I did find the 
ducts within the basal membrane. If I have seen well, these 
ducts open into the upper longitudinal canal where a transverse 
canal also falls into it. 
On these better coloured sagittal sections I saw that 
tke canals have walls of one single row of cells, the nuclei 
of which, intensely coloured, lay on the bottom of the cells, 
as Von Kennel represents it, of Notospermus (Cere- 
bratulus). 
Already I have mentioned that the foremost ducts were wider 
and better developed than the hindmost, so that the first were 
easily found, the latter only with difficulty. It appears that 
with the growth of the animal also the cesophageal region 
grows, and probably preserves the same relative length to the 
whole body, e.g. one third of its total length. The nephridial 
system appears to grow gradually with the esophageal region. 
We are further inclined to conclude, if we observe the differ- 
ence between the foremost and hindmost ducts, that the fore- 
most part of the cesophageal regions and thus also of the 
nephridial system, is the oldest, the hindmost the youngest. 
At any rate Valencinia displays, not only in its diverticula 
of the intestine, in its transverse vessels and in its genital 
organs, a clear internal segmentation, but also in the cesopha- 
geal region a certain degree of metamerism is visible in the 
nephridial system, which is formed like two ladder-shaped 
systems on each side, having on the level of each step a pair of 
excretory ducts. 
5. Polia curta, Hubr. Figs. 11, 12, 43—51. 
Two lacunz in the head, which terminate blindly anteriorly, 
communicate above the proboscidian sheath, then beneath at, 
spread themselves over the brain, inclose the posterior lobes and 
