203 
bodywall between the succeeding mesenteries. The ectoderm follows these curves regularly. The 
entoderm (25 p.) is the same as elsewhere. 
Mesenteries. They are normal in number and course. A mesenterial musclesystem is 
entirely absent as well as mesogloeal lamellae. 
Singe-lobed mesenterial filaments are found along the primary transveral mesenteries 
only. They have the structure of the actinopharyngeal ectoderm. A pigmentation is also 
absent here. 
I have examined some parts of the polyps with reagentia macroscopically on cellulose- 
reaction, with regard to the large quantity of Algae, but there was no perceptible difference 
between these polyps and polyps of other species treated in the same manner. 
10. Sibopathes gepJmra sp. n. (PI. VI, figs. 3, 5, 6, 9, 15; PI. VII, fig. 3). 
Tentacles. They are, in cross-section, very elongated in the direction of the colony-axis, 
Ectoderm. This layer, 55 p. thick, contains many ciliated epithelial cells and only a few 
glandcells. The nematocyst-batteries are found not only on the top of the not very promiment 
and so not very conspicuous papillae, but also in the grooves between these papillae. These 
batteries are not surrounded by deeply staining glandcells, or only by a few small ones in the 
uppermost part of the epithelial layer (cf. PI. VI, figs. 3 and 6). There are no other deeply 
staining glandcells. — The nervous layer is well developed and it is found deep in the ecto¬ 
derm. There are no ectodermal musclefibres. 
Mesogloea. Its thickness is 7 p. near the base of the tentacles; this value diminishes 
gradually towards the apex of the tentacles, till practically ecto- and entoderm touch each other, 
without an intervening mesogloea; the basal parts of both layers show only an intermingling 
of fibres (PI. VI, fig. 15). — A great number of oval cells are found; these cells are of ecto¬ 
dermal origin, for the same type of cells is present in the base of the ectoderm, while often 
a cell lies partly in the mesogloea and partly in the ectoderm ; also the cell may be connected 
with the ectoderm by a canal through the mesogloea (PI. VII, fig. 3, at *). 
Entoderm. The structure is not very clear through bad preservation of this layer; 
therefore I have not always figured the limit of the entoderm, i. a. in PI. VI, figs. 9 and 15 
between the entoderm of the transversal mesenteries and that of the tentacles. — Even the 
thickness can not be exactly given, since the entoderm fills all the cavities; there is hardly any 
gastral cavity. Usually the layers become loose and larger by maceration, so that the normal 
thickness of the entoderm will be less than 40 p.. With certainty are found: many large, deeply 
staining glandcells (PI. VI, figs. 3 and 6), greater in number than the ectodermal glandcells 
or at least greater in total volume. These glandcells lie deep in the entoderm, often touching 
the mesogloea. 
Bodywall. The layers are resp. 33 p., 10 p. and r 2 (?) p. thick. I heir structure is in 
every respect the same as in the tentacles but the number of nematocyst-batteries is less, while 
great parts of the ectoderm may be entirely devoid of deeply staining glandcells. I he 
mesogloea is very variable in thickness. — The polyps are separated by an interzooidal 
