243 
I he anterior and posterior halt of the polyp may be different in dimensions ( Euant . 
ericoides and Eucirr. contorta). The anterior side is the most developed. — The entoderm of 
the mesenteries rarely contains deeply staining glandcells. 
1 he position ot the mesenteries, as well as their musclesystem and the development of 
the sexual cells, are more in accordance with Brook’s opinion about the position of the axes 
of the polyp than Schultze s opinion. Especially in Eucirr. contorta and Euant. ericoides it 
is very clear that the corporal axis, which is at right angles with the longitudinal axis of the 
colony, divides the polyp in symmetrical halves, which is not the case for the corporal axis, 
which coincides with this colony-axis. 4 he musclesystem is arranged symmetrically in regard to 
the longitudinal axis of the actinopharynx. 1 he very unequal development of the primary 
transversal mesenteries and the neighbouring secondary mesenteries, which is always striking in 
every species, as well as the absence of these secondary mesenteries in the Homoeotaeniales 
are a great obstacle lor Schultze s opinion about the coincidence of the sagittal axis with the 
short axis of the actinopharynx (the colony-axis). According to Schultze the mesenteries in 
question would be the directive mesenteries. 
Mesenterial filaments, ihey are to be found not only along the primary transversal 
mesenteries, as is mentioned by other authors, but also (in several species) along the primary 
sagittal mesenteries and even along the secondary mesenteries (i. a. Eucirr. contorta and 
Stic hop. vanabilis). However they attain their maximum development along the transversal 
mesenteries, where they are straight along the upper part of the mesentery, but convoluted 
and even branched to a rather high degree, along the lower part : along the other mesen¬ 
teries they are always straight and unbranched. — Their shape, in cross-section, is round, 
oval or kidney-shaped ; when they are much broader than the mesentery there is often a con¬ 
striction of the mesentery at the base of the filament, but the mesentery may also broaden 
gradually into the breadth of the filament. — Their structure is clearly the same as of the 
actinopharyngeal ectoderm; they stain as deeply, the same glandcells are present and the pigmen¬ 
tation is often very striking. They may be pigmentated when the rest of the polyp is free 
from pigment. Ihey are single-lobed, with an large crowding of pigment at the limit between 
the ectoderm and the mesenterial entoderm. Sometimes the entoderm surrounds the filament 
cup-like (as with Eucirr. contorta and Stickop. solorensis). With Aphanip. indistincta the ecto¬ 
derm is found on the eniodermal side of the mesogloeal fork in the filament ; perhaps this is 
a beginning of the formation of more lobes. In Euantip. dichotoma the actinopharyngeal gland¬ 
cells are even to be found especially outside the mesogloeal fork and less between it. The 
fork-angle may be acute of obtuse. — There are no nematocyst-batteries; only in one species 
the filament contained single nematocysts. 
In one case the mesenterial filaments were not in connection with the actinopharynx- 
ectoderm as is normal with other species, but they were separated from the free border of 
the actinopharynx by a narrow part where the ectodermal cap was lacking. 
When the filaments are not continued to the end of the mesentery, the peripherical 
part of the free border may show an entodermal and mesogloeal swelling, without pigment 
or glandcells, but with many oval cells in the mesogloea. 
