125 
The basement membrane is 5 thick, homogeneous, stained 
with eosin, and has an oulward border of a distinet fine membrane 
stained with hematoxylin. 
The muscular wall of the body is still more feebly developed 
than in Cr. wahlbergi. On the ventral side it reaches only the 
height of the ventral epithelium, while on the dorsal side it is, of 
course (through the absence of an inner longitudinal muscular layer), 
still thinner. The muscle fibres are, on the other hånd, coarse 
and densely packed. The muscularis of the body found in the 
parenchyma compensates for the inconsiderable thickness of the 
muscular wall of the body. As a matter of faet, besides the usual 
very robust dorso-ventral muscular bundles, so many muscular 
fibres, running in different directions, are present that the tissue 
between the intestine and the compact musculature looks more 
like a sparse muscular tissue than a parenchyma. The fibres are 
as mueh as 4 thick and contain coarse fibrilles. 
Sparse pigment cells with brownish-black granules are present 
in the muscularis and the underlying tissue. It should be empha- 
sized that they also oceur, though less frequently, on the ventral 
side of the body. However, on account of the colour of the epi- 
dermis, these do not appear, at least on the preserved animal, as 
a pattern. 
Exeretory system: The discovery in this animal of numerous 
coarse, branched exeretory duets was indeed unexpected, as they 
have hitherto not been observed in any Polyclads in the State of 
preservation. Moreover, only Schulze and Lang have noted them 
in living Polyclads. Therefore, I am giving my observations below, 
although the preservation does not allow any details as to the fine 
capillaries and the terminal cells. 
The large efferent exeretory canals oceur in great numbers in 
the tissue between the ventral musculature and the intestinal system. 
The stoutest trunks may reach a thickness of 10 to 20 Thus 
they can easily be followed from section to section. These canals 
subdivide, and, as can be seen, the branches form a network with 
swellings to the above maximum thickness oceurring here and there. 
Short efferent duets running in a ventral direction proceed 
from these canals (Plate IV, Figs. 25—28). These latter duets can 
without difficulty be discerned even during their course through the 
