40 McMURRICH. [Vou. II. 
which perhaps give rise to the peculiar clinging power possessed 
by the tentacles in fresh specimens. They adhere to the fingers 
quite firmly when handled, and a quite decided effort is required 
to detach them. I believe this to be due to the numerous 
nematocysts, as I discovered no glandular or suctorial structures 
in the tentacles. No sensation of stinging was observed, how- 
ever, but this does not necessarily follow the penetration of the 
hard skin of the hands by the threads of the nematocysts. In 
the lower layer of the ectoderm is a delicate nervous layer. 
The ectodermal musculature is longitudinal, and is by no means 
strong, the mesogloeal processes being quite low. On the endo- 
dermal side of the mesogloea are circular muscles, and the endo- 
derm cells contain numerous “yellow cells.” In longitudinal 
sections a fibrillar layer containing some nuclei could be ob- 
served, separated from the mesogloea by the muscle cells; it is 
evidently the endodermal nerve-layer, similar to that which the 
Hertwigs have described (’79) in Zealia crassicornis. It is most 
clearly seen just where the tentacles join the disc, becoming 
rapidly indistinct towards the apex of the tentacles, so that in 
that region it is impossible from my preparations to assert its 
presence. 
The small portion of the disc left uncovered by the tentacles 
is smooth, and structurally presents no peculiar characters, the 
musculature, like that of the tentacles, being weak. The mouth 
is large, with well-marked gonidial folds. 
The mesenteries are very numerous, varying, according to 
the size of the individual, from 100 to 200 pairs, which are 
alternately perfect and imperfect. The longitudinal and parieto- 
basilar muscles are not particularly strong, the former being 
limited to the outer portion and having the processes arranged 
in a characteristic manner. A series of elevations of the meso- 
gloea give rise to a number of radiating processes, which branch 
to a slight extent, there being a few short and stout processes 
in the intervals (Pl. IV., Fig. 1). The nearest approach to such 
an arrangement that I am aware of has been described by 
R. Hertwig in Polystomidium patens. The inner mesenterial 
stomata are present, and are comparatively large; there is no 
trace of the external stomata. The specimens examined were 
females, and the reproductive organs were present on all the 
mesenteries, with the exception probably of the directives. My 
