abits and structur Jotylaspis insignis Leıpy. 
Habit 1 structure of Cotyla insignis L € 
lumen, a second oval part of nearly the same size with a large 
central cavity, often containing concretionary structures and above 
these a fibrous portion running inward into the parenchyma. The 
lower part has a very narrow lumen surrounded by a lining cuticle 
which is a continuation of that of the outer surface, its wall is 
very thick owing to the presence of muscle chiefly longitudinal 
fibres which attach below to the wall of the tube and above to the 
second part of the organ. In addition to the longitudinal fibres 
there are circular fibres surrounding the passage in the centre of 
this part of the organ. The passage of the lower part of the organ 
leads up and opens into a relatively large cavity in the middle 
part, the cuticle is continuous with a lining of moderate thickness 
composed of cuticle outwardly but of nucleated epithelium on the 
inner side. A few muscle fibres surround this part but they are 
not numerous as in the lower part. The interior cavity sometimes 
contains a single concretionary object, as in the section from which 
Fig. 32 was taken, in other cases it is empty and in still others 
it contains several such objects. The upper surface of the central 
part is in connection on its inner side with a mass of non-staining 
fibrous material, closely resembling in appearance the structure of 
the nerve trunks, I am inclined to regard it as a trunk of nerve 
fibres running at least to the muscles of the organ and perhaps 
partly sensory as well. 
The complexity of these organs and their presence in so many 
of the members of this family indicate an important function for 
them, but of their physiology there is very little known. VOELTZKOW 
reports that in Aspidogaster conchicola they are protrusible, but in 
C. insignis I could not find any evidence that they are, having 
watched living animals frequently to see them everted without ever 
viewing the act, and having attempted to evert the organ by 
pressure without success. Pressure would push the organ down a 
little way, and the outer part be caused to protrude very slightly 
but not at all like VorLTzkow’s fig. 15 b. The cavity of the central 
part varied much as to its contents in different organs of the same 
and of different cases: in some there is a single large object, as in 
Fig. 34, in others a number of small ones, and in still others the 
cavity is empty. This indicates that secretions are going on the 
products being removed from time to time. I think that the muscles 
described above may be used in discharging these products, the 
longitudinal fibres may act as dilators of the outlet, needed to 
