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the base of ecto- and entoderm. On the entodermal side the mesogloea is very sinuous with 
large circular ridges, broadened at their tops and bearing secondary ridges here. The ento¬ 
derm, 40 tx thick, has no deeply staining glandcells. The musclefibres are absent; the preser¬ 
vation is not very good, as is also the case with the ectoderm. 
Bodywall. The ectoderm, 40 p. thick, has the same structure as in the tentacles; its 
thickness varies according to the thickness of the mesogloea (PI. VI, fig. 1). In front of the 
connecting septum the ectoderm suddenly diminishes into a very thin layer in the groove of 
the mesogloea. The mesogloea is 33 p. thick in the neighbourhood of the axis, but at a 
greater distance from this the thickness diminishes, with frequent slight increasings on the 
ectodermal side (PI. VI, fig. 1), to 7 p. in the neighbourhood of the tentacles; this is just the 
reverse of the condition in other genera, where the mesogloea of the tentacles is always much 
larger here than in the bodywall. The mesogloea is smooth on the entodermal side; it is 
homogeneous with some oval cells; usually there is a layer of fibres parallel with the ectodermal 
base, and nearer to the entodermal side; this layer does not follow the curves on the ectodermal 
side. The entoderm, 40 p. thick, is the same as in the tentacles. 
The oral cone, which may be constricted at its base, has the same anatomical structure 
as the described parts; only in the lateral walls the mesogloea is thicker (13 p) than in other 
places; there are no curves on the ectodermal side. 
The axis, the lumen of which has a diameter of 280 p with a wall of 26 p. (170 p and 
10 p at the top of the branch) has a fibrillose intima; the spines (30 p) are shut at their base 
and solid. The axis-ectoderm is max. 12 p, the entoderm 20 p, while the mesogloea 
is 20 p, which is rather a great deal compared with other genera. The sheath around the 
spines nowhere adheres to the bodywall. The connecting septum is either very broad and 
short, so that sometimes it is more like an extensive fusion of bodywall and axis-epithelium, 
or thin. Near the top of the branches the axis has two lateral, very broad connecting septa 
(PI. VI, fig. 1), which are very massive. Between them lies a part of the gastral cavity, opposite 
to which is found the thinner part of the body wall-ectoderm with a groove in its mesogloea 
on the ectodermal side. In one place the bodywall is even ruptured, but probably this is an 
artificial opening. — Each time this double connection is substituted by a single median septum, 
but furtheron again a double septum may be found. It gives the impression as if the invagination- 
process of the axis does not proceed in a regular manner from the top towards the base of the 
colony; sometimes the invagination is very advanced (single connecting septum), at other places 
the invagination is shallower (a double septum), so that the layer in the cavity opposite the 
groove (PI. VI, fig. 1) might be ectoderm and not entoderm, and this cavity might not be a 
part of the gastral cavity; this point is not to be decided by the anatomical structure. — In 
the area between two polyps an interzooidal septum is found with a free border; I can find no 
peristomal fold between the parts of a polyp. In one series of sections there is a constriction 
between the sagittal and lateral parts of the polyps but not between two polyps. In other 
series a constriction is nowhere to be found; the oral cone is visible (so the middle or 
sagittal part of the polyp), while the ova are also visible (so the lateral part of the polyp) in 
the same section. 
