68 
small size (only 3 mm at fullest sexual maturity) for a Polyclad 
the number of adhesive cells is inconsiderable. Occurring exclusively 
near the margin of the body, they appear isolated among supporting 
cells and only to a number of 4 or 5 on a section. Consequently 
we have here more resemblance to Procerodes conditions. The 
augmentation of the adhesive zone in E. opisthoporus may easily 
be regarded as a special adaptation to the association with the 
Pagurid. 
In regard to the muscular wall, which shows the usual 
arrangement of layers, I have definitely observed the presence of 
fine transverse fibres immediately below the basement membrane. 
On horizontal sections these are easy to observe, on others the 
use of oil immersion is necessary. 
A far better preserved material has made it possible to study 
the alimentary and genital system in detail, but 1 shall 
make the discussion brief, giving only a few supplementary notes 
to the earlier description. A comparison between the type specimen 
from Galapagos and Dr. Mortensen’s material shows a divergency 
in respect to the pharynx. The side pockets of the pharyngeal chamber 
in the former are nearly absent in the latter, as seen in text-figure 
21. With regard to the location of the pharynx and mouth as 
well as to the absence of a wall protruding into the pharyngeal chamber 
from the surroundings of the mouth, there is full agreement in 
both cases. The thin, much convoluted pharyngeal fold of the 
type specimen deviates somewhat from the thick, less folded one 
in the new specimens. I cannot attach any greater importance to 
that difference, which perhaps, to a large extent, may be due 
to preservation. 
The intestine deserves special attention, as the material allows a 
chance to rectify the earlier description. The main gut reaches into 
the region of the genital apparatus. It shows the peculiar condition 
of dorsal and ventral pouches in an extremely dense arrangement. 
They predominate to such extent that the main gut does not assume 
the usual character of a tube, but of a series of hollow beads. They 
are so large that they fill up the available space inside the mus- 
cularis of the body, in dorso-ventral direction. This circumstance 
as well as the very bad preservation of the alimentary system has 
hidden the extension of the mid gut in the type specimen. Know- 
