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the basal growth of the spines is exceedingly more than the apposition at the apex of the spine, 
possibly in connection with the greater thickness of the axial ectoderm at the base of the spines. 
Origin of the axis. I he invagination, which will yield the epithelial layers of the axis, 
may originate on two places, either on a little distance below the colony-top (9 p. in Euant. 
dichotoma , 75 ij. in Stick, vanabilis ), so that the top itself is a cylinder of ectoderm, mesogloea 
and entoderm, or the invagination takes place at the extreme colony-top, so that the last cross- 
sections always contain the axis and its layers (. Aphan . indistinct A Through the invagination 
and the following growth a broad knob of ectoderm originates, surrounded by mesogloea and 
entoderm, connected with the bodywall through a narrow septum of mesogloea and entoderm. 
At a greater distance from the top a colourless horny matter is found, forming an intricate 
mass with the invaginated ectoderm. Still further from the top this ectoderm arranges itself into 
a high cylindrical epithelium, at first irregular in thickness, but furtheron from the top regular 
in thickness, while the axis gets its normal shape and yellow colour: the wall is thin, the lumen 
is wide; Aphan. indistincta shows a divergation of this type of axis, in the top-part of the 
branches, more like Dendrobrachia fallax. — At first the connecting septum changes into a 
broad fusion of bodywall and axial sheath, but furtheron it grows narrower. — At last the 
axial ectoderm lessens in thickness and becomes the usual thin layer. 
Actinopharynx. In its middle part the actinopharynx has a sagittally elongated slit-like 
lumen, which is more rounded in the upper part of the actinopharynx and which widens very 
perceptibly in its lower part, while the actinopharyngeal wall is curved towards the bodywall. 
One of the species has a sagittally elongated lumen in one polyp and a transversally elongated 
one in the other polyp. — The free border of the tube descends to a lower level along the 
primary sagittal mesenteries, but the greatest width is found along the primary transversal 
mesenteries. — In the slit-like part the sagittal ends form a sort of sulcus, but without a 
special anatomical structure. — The free border of the actinopharynx may curve upwards and 
outwards, but in other species it follows the axial sheath; sometimes the wall is almost in con¬ 
tact with the bodywall, along the entire length of the tube. These differences are dependent 
on the shape of the oral cone. — The entire wall of the actinopharynx may be longitudinally 
folded (apart from the ectodermal folds). In Aphan. indistincta these folds are curved and 
fused together, so as to make a narrower tube at the distal transversal side. This tube also 
contains ectodermal folds. — The ectoderm is longitudinally folded, usually without connection 
with the places of attachment of the mesenteries. The number of these folds may increase 
very much in the lower part of the actinopharynx; in some cases these folds are absent in 
the lower part, while they are numerous in the upper part, with the young polyps only. — 
The ectoderm stains very deeply, which in the first place is caused by the numerous small 
actinopharyngeal glandcells, near the surface of the ectoderm and by deeply staining glandcells, 
which are connected with the base of the epithelium by a thin stalk, which may be swollen 
in its lower part. Sometimes a larger type of deeply staining glandcells is found in the neigh¬ 
bourhood of the mouth (some Euantipathes- and Aphanipathes- species), while also large alveolar 
glandcells may occur in the epithelial base. — A dark pigment is found, especially in the lower 
half of the actinopharynx, in Stichopathes- and Eucirripathes- species. This pigment increases in 
