200 
On those parts of the transversal mesenteries, the free border of which bears the mesen¬ 
terial filaments, the musclefibres are on both sides of the mesentery parallel one with the other 
(PI. Ill, fig. 4, which is part of the mesentery from PI. V, fig. 9, in the left part of the 
gastral cavity). This is to be explained by the longitudinal musclefibres diverging fan-shaped 
from the oral one, while the transversal musclefibres retain the same direction everywhere. 
The mesenterial filaments are single-lobed. They have the structure of the actinopharyn- 
geal entoderm with a very large quantity of pigment (PI. V, figs. 8 and 9). This pigment is very 
dense on the limit of the ectoderm and the mesenterial entoderm. The filaments are found 
along the primary mesenteries. They are straight and unbranched along the sagittal mesen¬ 
teries and very much convoluted along the transversal mesenteries, but only in that part, which 
immediately follows the free actinopharyngeal border (PI. V, fig. 8), while they are straighter 
furtheron in the gastral cavity'. In PI. V, fig. 9 this difference is visible, where the filaments 
are folded in the oral cone but unbranched and straight in the gastral part. — The secon¬ 
dary mesenteries do not descend so very low into the oral cone, and they have left the 
actinopharynx long before the free border of the actinopharynx is formed. 
8. Eucirripathes Rumphii v. Pesch. 
Tentacles (PI. IV, figs. 5 and 6; PI. V, fig. 25). The ectoderm (115 p.) contains 
no deeply staining glandcells or a few only; there are rather a great deal of hyaline gland- 
cells, although less than in the other parts of the polyp. The nematocyst-batteries are very 
numerous; they are so much crowded that there is hardly any room left for the other epithelial 
cells, especially at the surface of the ectoderm; at their base there is more room since the 
batteries are conical (PI. IV, fig. 6). In PI. V, fig. 25 I have indicated, with a schematical 
cross-section through the tentacular top, how numerous, but also how large these batteries are. 
Their normal type is given in PI. IV, fig. 6. There are two types of nematocysts. One type 
is narrow (3 p.) and colourless, with an easily distinguished spiral. This type is the same as 
is found in all the other species I have examined. The second type is found in this species 
only. They are yellow in colour, and 5 p. thick. The spiral is not visible or only very indistinct, 
while there is a narrow longitudinal canal in the nematocyst. Both types are subequal in 
length, but the yellow ones may be somewhat shorter. Besides they are more brittle, since 
there are a great many broken yellow nematocysts in the sections, while this is not the case 
with the normal nematocysts. The yellow nematocysts are more numerous in the batteries on 
that side of the tentacles, which is averted from the oral cone, although they are not entirely 
absent in the batteries on the oral side of the tentacles. This is in accordance with the 
numerous darker points on one side of the tentacles, as is described in the systematic part. 
The difference between the two types is very conspicuous on a tangential section of the 
tentacles (PI. IV, fig. 5). — The batteries are surrounded by hyaline glandcells but not by 
deeply staining ones (PI. IV, fig. 6). There are very crowded nuclei below the nematocysts; 
these nuclei are also visible where a battery is attained in a lower part (PL IV, fig. 5 to 
the right!). — The nervous layer is separated from the mesogloea by a little distance only. 
