other. These branches are soon so finely branched that they can not be followed. The ectoderm 
contains a very dark pigmentation as a sharp limit against the entoderm; distally this pigmen¬ 
tation is gradually less dark, while the middle of the ectoderm contains hardly any pigment. 
In this not-pigmented part large hyaline glandcells occur but nematocysts are absent everywhere. 
The left and right corner of the filament-section, towards which corners the mesogloeal branches 
are directed, are deeply stained just as the actinopharynx-ectoderm. Since the filament is only 
single-lobed, without a nematocyst-glandular part and two ciliar parts, it is difficult to compare 
it with a complete filament; probably we have a combination of both parts here, but yet 
without nematocysts. The filaments do not occur along the entire free border of the transversal 
mesenteries; in its distal part this border is free from an ectodermal cap. These parts are 
swollen (PI. I, figs. 5 and 10). — The broadened mesogloea contains a very large number of 
cells (fig. 10) and sometimes there is no sharp limit between these cells in the mesogloea and 
the same type of cells in the entoderm (fig. 5). In these distal parts of the mesenteries there 
are slightly developed musclefibres on both sides of the mesogloea, and all of them parallel 
with each other and with the free border. In view of the polyp-schema (fig. 254) this can be 
explained by the longitudinal musclefibres diverging in the shape of a fan in the basal part 
of the transversal mesenteries by the broadening of these mesenteries. So they are in that part 
of the mesentery which is next to the bodywall subparallel with the transversal fibres. 
Parasites. In several places the entoderm of the bodywall and the tentacles contains 
Algae (diameter 7 — 10 p.). The ectoderm of the bodywall contains Algae (diameter 3 p„) at a 
very low level in the epithelium; their colour is yellow greenish. 
We regret that Brook’s anatomical description of the polyps of Cirripathes propinq^^a Br. 
(which I joined to Eiicirripathes aiiguinci ) are very incomplete through bad preservation. Brook’s 
data of the thickness of the various layers in the tentacles do not differ very much from those 
of Eucirr. anguina , while Brook also describes mesenterial musclefibres and others, but without 
a definite direction. 
2. Eucirripa thes nana v. Pesch. 
Tentacles (PI. I, figs. 9, 12, 13 and 17). The ectoderm is papillose with a thickness 
of 45 p at the utmost. There are no musclefibres, or only very slightly developed ones; mesogloeal 
lamellae are absent also. The thin nervous layer is found very near the mesogloea. The 
epithelium contains large nematocyst-batteries, not only on the top of the papillae but in the 
intervening grooves also. These batteries consist of nematocysts, arranged in the shape of a 
fan; the batteries are surrounded by deeply staining glandcells, while there is an increased 
number of epithelial nuclei below the batteries. Usually these nuclei are somewhat elongated. 
Figs. 12 and 17 on PI. I give the structure of these batteries; the glandcells surround the 
battery at every side; the nematocysts are separated one from the other, but there are no special 
sustaining cells to be seen; some cells are smaller and thinner but without any difference in 
quality. The mesogloea varies from 27 p. at the tentacular base to 2 p. or less at the top. 
There are circular ridges on the entodermal side, at the top of the tentacle (PI. I, fig. 9). 
