66 JAMES Francis ABBOTT, 
from the Cydippid Ctenophore type by such an alteration of the 
Cydippid canal system as would naturally come about in the adoption 
of littoral habits by a pelagic form. 
6. There is no circumperipheral canal and the multitude of 
small canals throughout the body are to be considered merely as 
arborizations of the main canals mentioned above. 
7. The canals are lined with loose vacuolated endothelial cells 
that bud off into the lumen of the canals. 
8. The pinnate tentacles with their “adhesive cells” (colloblasts) 
are practically identical with those of typical Ctenophores. 
9. The method of formation of the colloblasts is as follows. The 
chromatin substance in the original mother cell arranges itself in a 
central mass, which we may call the nucleus and a number of 
smaller masses (“nucleoli”) which arrange themselves in a hemisphere 
about the former. Each nucleolus cleaves off the adjacent cytoplasm 
into blotks (but without the formation of cell walls) so that the 
original cell has a mulberrylike appearance. This forms the cap of 
the cell. The cytoplasm differentiates into the spiral cord and the 
central filament of the developed cell and by its elongation the cell 
attains the shape and size typical of its kind. The “nucleoli” 
disintegrate leaving only the central nucleus at the base of the cup. 
The developed colloblast arises then from one undifferentiated cell 
and not from the union of two. 
10. Phagocytes are to be found in the tentacle sheath, filled with 
the ingested fragments of colloblasts. 
11. The otolith is typical of the Ctenophora and is supported 
by brushes of cilia arising from the wall of the cup. 
12. There is a rudimentary nervous system with four ganglia 
symmetrically disposed about the otolith capsule. 
13. The weight of the morphological evidence supports the 
assumption that Coeloplana is a very highly specialized Ctenophore 
related to, or derived from the Cydippida. *) 
1) The true position of Coeloplana and its relationship with other 
groups cannot be certainly decided until its development has been worked 
out. Unfortunately the writer has been unable to shed any light upon 
this matter. The only times when it was possible for him to collect were 
spring and late summer and it is possible that the animals attain sexual 
maturity at a different season or that they may reproduce at greater 
depths or in a different environment from that in which they were found. 
