202 
Usually these cells are lying very deep in the entoderm, against the mesogloea, but they are 
found also at a more superficial level. 
Mesenterial filaments (PI. IV, fig. i). They are found along the primary transversal 
mesenteries only; they are convoluted. Their structure is the same as that of the actinopharyn- 
geal ectoderm. The actinopharyngeal type of glandcells makes it possible to discern the limit 
of the filaments against the mesenterial entoderm, although there is no pigmentation, which 
gives the sharp limit in other cases. The deeply staining glandcells are more rare in the lateral 
parts of the filament, which is separated from the mesentery by a constriction. There are 
numerous hyaline glandcells besides, but no nematocysts. The mesenterial mesogloea at the 
base of the filament is dissolved into fine fibrillae. A fine granular nervous layer is found 
between these fibres. 1 here are some spindle-shaped cells with rounded nuclei, in the base of 
the epithelium. These cells are surrounded by a sort capsule. 
9. Hillopathes ramosa (v. Pesch). 
Tentacles, dhe ectoderm (55 p.) contains deeply staining glandcells, which are prin¬ 
cipally found around the conical nematocyst-batteries. The nervous layer is well developed but 
musclefibres are absent. In its thinner part the mesogloea (2 — 5 p) shows no homogeneous 
layer between the bases of ectoderm and entoderm. The thicker parts are homogeneous, and 
the mesogloea does not contain cells, but there are bundles of very thin transversal fibrillae, 
connecting ectoderm and entoderm, at the base of the tentacles, near the transition into the 
peripheric bodywall. The entoderm (65 p) contains a large quantity of colourless symbiotic 
Algae, very much crowded together, especially in the superficial epithelial layer. Their diameter 
is 5 — 7 p. — There are no musclefibres. 
Bodywall (PI. Ill, fig. 2). I he ectoderm (30 p) contains deeply staining glandcells, 
but no nematocysts. I here is no muscular layer. The mesogloea varies in thickness from 
a few p to 13 p; it is a homogeneous layer. While the ectodermal side of the mesogloea is 
not very irregular, the entodermal side has formed an interzooidal septum (130 p deep), 
covered with entoderm and broadened at is free border. Right and left of this complete septum 
are found a large number of incomplete septa, but only as more or less high excrescences of 
the mesogloea; the entodermal surface remains straight (PI. Ill, fig. 2). The entoderm is 
the same as in the tentacles. The deeply staining blepharoplasts in the superficial layer are to 
be distinguished, as well as the cilia in many places. 
The Axis-epithelium is entirely lost by the removal of the polyps from the axis. In some 
places the bodywall is slightly elevated. Here the entoderm is thinner and a second mesogloeal 
layer is grown together with that of the bodywall. Probably these places are fusions between 
the sheath of the spines and the bodywall. The axis-ectoderm is thicker at the base of the spines. 
The actinopharynx is rather short since there is only a very low oral cone. It has a 
sagittally elongated slit-like lumen, 13 p broad with a long axis of 900 p. The ectoderm 
( 2 5—35 !->■) contains only a few deeply staining glandcells. Pigmentation is entirely absent. The 
nervous layer is well developed. The mesogloea (max. 2 p) is sinuous, approaching the 
