204 
septum, the lower part of which is concrescent with the axis-epithelium; there are no peristomal 
folds between the three parts of the polyp. 
The oral cone is high and may be somewhat widened at the mouth. Its ectoderm 
(55 ft) * s i n every respect the same as in the tentacles; the mesogloea, 6 ij. at the base 
of the cone, diminishes towards the top to the same degree as in the tentacles; often the shape 
of the oral cone is in the sections very much like that of a tentacle, open at its apex. — The 
entoderm (40 p. ?) is also the same as in other parts, but with a somewhat greater number 
of large deeply staining glandcells; however this is not necessary the case (PI. VI, figs. 3, 6). 
The uppermost layer of the entdderm has a greater number of nuclei so that here the colouring 
is deeper (PI. VI, fig. 6). The limit between the ectoderm and the entoderm at the top of the 
oral cone is clearly visible, since the entoderm Js macerated and the ectoderm not; this limit 
js a dotted line in PI. VI . 3 indicated by an asterisk. - — The mesogloea. is slightly dentate 
at the entodermal side as if there was an entodermal system of circular musclefibres. 
The actinopharynx is entirely absent! Perhaps for this reason the number of large 
deeply staining glandcells is greater and they are found everywhere in the entoderm. 
The axis has a wall of 36 p. thick with a diameter of the lumen of 100 p.; the spines 
project as blunt knobs 33 p. above the axis; on some places the axis contains concentric 
loose rings or rather cylinders, within the solid wall. — From the epithelial layers the ecto¬ 
derm is 10 p. or less, the mesogloea usually 2 p, but sometimes increasing to 7 p, the ento¬ 
derm 10 p. (?). The mesogloea contains cells and the entoderm has the large type of 
deeply staining glandcells, though not in a great number (PI. VI, fig. 6). The connecting 
septum between axis and bodywall is broad and contains a great number of oval connective 
tissue cells; the neighbouring mesogloea of the axis diminishes very gradually in thickness, so 
that sometimes the septum is more like a broad fusion of the axis-epithelium and the body- 
wall (PI. VI, fig. 15). I here are fusions between the sheath of tissue round the spines, and 
the bodywall. Sometimes there is hardly any gastral cavity, since over the entire circumference 
the axis-entoderm and that of the bodywall touch each other. The ectoderm of the axis 
becomes a higher cylindrical epithelium as it approaches the top of the colony (PI. VI, fig. 6). 
Mesenteries. I here are no secondary mesenteries. The primary mesenteries are not 
highly developed; the two pairs of sagittal ones are only very narrow projections at the base 
of the tentacles; in a young polyp they are practically invisible. The mesogloea-projection is 
not much longer than the thickness of the'tentacular mesogloea. These sagittal mesenteries are 
not very long ; their upper and their lower parts become narrower, since there is no actino¬ 
pharynx to which they can be fixed. The primary transversal mesenteries begin at the distal 
and proximal ends of the mouth-slit, at first very narrow, furtheron somewhat broader, but 
not much. They disappear entirely at the depression between the sagittal and lateral parts of 
the polyp, so that a section through this depression is in every respect like a section through 
a part of the colony between two polyps, except that there is no interzooidal septum. Only 
in a young polyp I could follow these mesenteries as very narrow projections in these parts. — 
The transversal mesenteries appear again in the lateral parts of the polyp; here they are 
convoluted to a high degree (PI. VI, fig. 5) while their free border is club-shaped in section. 
