51 
the inner marginal eyes, may be directed forwards, upwards, or 
backwards, while, on the other hånd, the marginal eyes of the 
outer edge always, as far as I have been able to find in the series 
of sections, have the opening of the cup turned toward the edge 
of the margin. This orientation of the cups seems to follow 
general principles. 
The frontal sensory furrow runs near the anterior edge of the 
body, and reaches the marginal edge of the animal at the level 
of the brain (text-fig. 14, sf). 
Bo dy-Wall: The epidermis, which as usual is higher dorsally 
than ventrally (Plate II a, Fig. 4), is characterized by a noticeable 
scarcity of rhabditi. Instead, the giand cells, with a fine granular, 
erythrophile secretion, occur in great numbers. This is particularly 
the case on the ventral side in a submarginal band, where they 
are clustered in masses. The cilia are long, but are not densely 
arranged (Plate II a, Fig. 4). In spite of the contracted State of 
the animal, which is reflected in the siender shape of the epithelial 
cells, the cilia may at times reach a greater length than the cell 
bodies. The basement membrane is thick and has a homogeneous 
appearance (when preserved in formaldehyde). Except for the thick 
ventral inner longitudinal muscular layer, which, lateral to the 
median line, exceeds all the other layers together in thickness, the 
muscularis of the body is rather thin. But its fibres are very coarse. 
Dorso-ventral musculature has average development. Parenchyma- 
tous tissue not abundant. 
Sucker: The epithelium of the disc of the sucker is more 
than three times as high as the ventral epidermis. With its enorm- 
ous mass of secretion (from subdermal giands) and total lack of 
cilia, it presents a striking contrast to the epithelium devoid of 
secretion in the stem, where the ciliated cells show only ordinary 
height. Already in the stem of the sucker the basement membrane 
is as thin as a line, and it was not possible to trace it on 
the adhesive disc with the staining technic used. It stands to 
reason that this unusually developed sucker would have a particu¬ 
larly robust and stout musculature, and this can easily be traced 
back to where it to a great extent originates from the ventral inner 
longitudinal muscular layer. It must also be pointed out that the 
latter does not reoccur caudal to the sucker. The sucker contains 
4 * 
