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the entoderm is clearly limited against the ectoderm at the free actinopharyngeal border. 
Halfway down the actinopharynx the entoderm contains a very thin layer of circular muscle- 
fibres. There is no pigmentation. 
Mesenteries. They are normal in number, course and structure. In some places the primary 
transversal mesenteries contain unilateral mesogloeal lamellae, visible in somewhat oblique 
horizontal sections. They are always without musclefibres. 
Mesenterial filaments occur along the primary transversal mesenteries, but also along the 
primary sagittal ones. The former are very much branched and convoluted. They contain darkbrown 
pigment, but in a small quantity only; the glandcells are the same as in the actinopharynx. 
Parasites. There are symbiotic Algae in the entoderm of the tentacles and the bodywall. 
They are brown, rounded or pearshaped, with a diameter of 7 p. 
Together with a great uniformity in many regards, the examination of both varieties 
of Eucirripathes spiralis shows differences in anatomical structure, although of no very great 
importance. As was not expected, the thickness of the various layers is greater in var. aphani- 
pathoides than in var. striata , especially in the bodywall, although in the latter variety the 
polyps give an impression of being much larger and more heavily built (cf. the systematic 
part). The ectoderm differs in deeply staining glandcells, which are of two types in var. apha- 
nipathoides , the more deeply staining one of which only is present in var. striata. Var. apha- 
nipathoides has a larger number of glandcells in the oral cone, while var. striata has a 
bodywall and oral cone, which are similar in this respect. 
The entoderm contains more glandcells in var. striata than in var. aphanipathoides 
where they are almost absent; var. striata only has an entodermal muscular system and some 
symbiotic Algae, while a brown pigmentation occurs in some places in var. striata only. 
The actinopharynx is more heavily built in var. striata ; var. aphanipathoides misses 
the slight musclefibres and the slight pigmentation of var. striata. 
The mesenteries of var. striata have mesogloeal lamellae and a more developed system 
of mesenterial filaments, even along the sagittal mesenteries, than var. aphanipathoides. Var. 
striata has some pigment in the filaments, but the other variety not. ■— Generally var. striata 
is richer in glandular elements and pigment with a beginning of a muscular system. 
7. Eucirripathes muscnlosa v. Pesch. 
Tentacles. The ectoderm (26 p.) has almost entirely disappeared. The remaining part 
contains only a few deeply staining glandcells or none at all. There are nematocyst-batteries. 
There is a thin layer of longitudinal musclefibres against the mesogloea. The mesogloea 
(5 — 10 p) is a homogeneous layer, with very rare transversal fibres but without any cells. The 
entoderm (20—26 p) has only rare deeply staining glandcells. There is a very slight layer 
of circular musclefibres. 
Bodywall (PI. Ill, figs. 4, 7 and 9). The ectoderm (33 p) has local crowdings of 
deeply staining glandcells (PI. Ill, fig. 4) but never to such a degree as to form a continuous 
mass. 1 here is a slightly developed layer of musclefibres, directed from the polypar base towards 
