The Morphology of Coeloplana. 65 
this infundibular canal has disappeared and the lower part of the 
stomodaeum has become modified as the pharynx. From the in- 
fundibulum the two perradial canals, as in the Cydippida, lead 
directly into the roots of the tentacles, but before entering the 
tentacle base they spread out in an enclosing network or system of 
sinuses surrounding the sheath, as described before. A glance at 
the text figures (C and D) will show the probable origin of all these 
“sinuses”. We have only to imagine the stomodaeal canal bent 
upward and under the sheath (a natural result of the flattening. of 
the body) and the splitting off of the adradial canals from the 
interradial canals to be continued down to the perradial canal and 
we would have the tentacle sheath enclosed on three sides by canals, 
the confluence of branches of which would give the enclosing network 
mentioned. The other two adradial canals would be left free and 
would run from the perradial canal to the periphery (Fig. D). In 
Coeloplana the proximal portions of these canals seem to have joined 
in the sagittal plane to form one one stem canal, which is, however, 
frequently cleft to the infundibulum (vide ante page 52). From 
these main trunks arise the anastomosing branches of the gastro- 
vascular system as previously described. The Cydippid meridional 
canals have disappeared in Coeloplana. 
D. Summary. 
We may summarize the morphological facts described in the 
foregoing pages as follows: 4 
1. The epithelium is similar to that in pelagic Ctenophores 
with the exception of the cilia on the ventral surface. 
2. The epithelial gland cells apparently pass through the same 
cycle of changes as described by Samassa for the Ctenophores. 
3. The coloration is due to iridocyte-like pigment cells in the 
subepithelial structures. 
4. The gastrovascular system consists of a capacious thickwalled 
pharynx leading upwards into an infundibulum underlying the sense 
organ. From this two canals arise, in the tentacular plane, enclosing 
the tentacle sheathes in an anastomosing network. Two others in 
in the sagittal plane arise in the same way but soon divide so as 
to form four canals converging towards the tentacles, roughly in 
the form of a figure “8”. 
5. The arrangement of these canals has apparently been derived 
Zool. Jahrb. XXIV. Abt. f. Anat. 9 
