229 
acles and radial muscles of the oral disc are ectodermal, rather 
weak than strong. The ectoderm of the actinopharynx is high and 
provided with numerous giand cells and nematocysts partly 26—34 
X about 2—2,5 //, partly 14—29X3—4,5 i^i. The former nema¬ 
tocysts are sparse, the latter numerous and broader at their basal 
end, the basal part to the spiral thread is here perspicuous. 
The pairs of mesenteries are 24 (6 + 6+12 of which two pairs 
of directives) in the greater part of the body. In the uppermost 
part an incomplete fourth cycle is present. There is a great differ¬ 
ence between the 6 first pairs and the rest of them. The former are 
macrocnemes (perfect, provided with reproductive organs, strong 
pennons, filaments and acontia) the latter microcnemes (imperfect 
and without these organs). The longitudinal muscle pennons are 
very strong, circumscript, the insertions of the lamellar inner and 
outer parts of the mesenteries at the pennon stand very close to 
each other or concur. The folds of the pennons are very high and 
richly ramificated (textfigs. 28, 29), sometimes, especially in the 
directives, there is in the pennon a rather thick mainlamella from 
which the thinner folds branch off. The parietal parts of the long¬ 
itudinal muscles are well developed and form a rather distinet pro- 
jection. The parietobasilar muscles are not so broad as the former, 
but agree with them in structure (textfig. 30). Both are stronger 
in their inner parts than in the outer, where the folds are low. 
The imperfect mesenteries are narrow, in the undermost part at 
the insertions on the pedal disc considerably broader. The folds of 
their longitudinal muscles, covering the whole surface of the mes¬ 
enteries, agree with the parietal part of the muscles in the macro¬ 
cnemes (textfig. 31). The prominences of the mesogloea to which 
the muscles are attached are rather thick and in the distal part 
sometimes a little ramificated. The mesenteries of the third cycle 
are weaker than those of the second. The basilar muscles are well 
developed also on the imperfect mesenteries. The acontia are rather 
thick and contain numerous nematocysts 22—34 x about 2 {2,b) f.i, 
(22—31 X about 2// ; 26 — 34 x about 2 jti', 24—34X2 ( 2 , 5 ) /li, three 
specimens examined). Exceptionally I have here observed some small 
nematocysts 14 — 17 X 1^5 jn. In the specimen from Slipper Isl. I 
observed also a few nematocysts 26 — 34X3— 3,5 jti. They are pos- 
sibly development stages of the larger nematocysts. The species is 
dioecious. 
