220 
There are unicellular parasites in the entoderm of the base of the tentacles, near the 
surface of this layer, but there are no symbiotic Algae. 
21. Aphanipathes Sibogae sp. n. 
I he numerical date are deduced from a series of sections through a polyp, which was 
loosened from the axis, so an adult polyp; the description partly refers to younger polyps 
from the top of the colony, the axis of which was intact in an other series. 
Tentacles, dhe ectoderm (50 p) has nematocyst-batteries, surrounded by deeply 
staining glandcells, on the top of the papillae. Sometimes the nervous layer is on a high 
level with and distinctly separated from the mesogloea, but at other places this layer almost 
touches the mesogloea. There is a layer of longitudinal musclefibres. 
The mesogloea is 5 p at the top of the tentacle and 30 p. at its base. It is a homo¬ 
geneous layer without cells or fibres. The entodermal side has circular ridges with small secon¬ 
dary lamellae. 1 he entoderm (35 p.) has hyaline glandcells only, but hardly any deeply 
staining ones or none at all. There is a layer of slightly developed circular musclefibres. 
Bodywall. The ectoderm varies from 10 — i6p. in thickness. Its structure is like the 
tentacular ectoderm, but the nuclei are less in number and they are lying at a lower level. 
I here are also nematocyst-batteries, but they are not so numerous as in the tentacles. There 
are no musclefibres. The mouth is situated at the same level as the rest of the bodywall so 
that the oral cone is absent. Around the small rounded mouth the nematocyst-batteries are 
more crowded than elsewhere, still not so much as in the tentacles. The polyps are separated 
by an interzooidal septum, the lower border of which is fused with the axial sheath, so 
that the polyps are absolutely separated one from the other. Usually this septum has a free 
lower border in other species. 
The axis has a wall of 33 p. with a lumen-diameter of 50 p. The spines are 130 p. long, 
which is rather much, since the diameter of the entire colony-top is only 175 p., a large part 
of which is occupied by the axis. They lift the bodywall very high and they project far through 
the various parts of the polyps. The sheath of the spines is fused with the bodywall, the three 
layers of which become very thin in these places. On the older parts of the colony the body- 
wall is not so highly elevated by the spines, by all means not exceedingly so when compared 
with other genera. — The ectoderm and entoderm are less than 3 p, the mesogloea less than 
1 p. The connecting septum is short. 
The actinopharynx curves immediately towards the body wall-entoderm and lies parallel 
with the bodywall, almost touching it, as to obliterate almost the entire lumen between both 
entodermal layers. In the toppart of the colony the actinopharyngeal ectoderm is very much 
folded, but in the older parts of the colony these folds are absent and the ectoderm is straight. 
The thickness is 50 p,; together with the actinopharyngeal glandcells some small, deeply staining 
glandcells of an other type also occur. Pigmentation is entirely absent. Near the mouth, in the 
mouth itself and in its immediate vicinity there is a very dense crowding of the type of gland¬ 
cells, which usually surrounds the nematocyst-batteries. — The entire actinopharynx is almost in 
