720 Scientific Proceedings, Royal Dublin Society. 
Histology. 
Ectoderm.—There is a thin cuticle on the lower three-fourths 
of the capitulum; it is absent on the thin upper part of the wall. 
The ectodermal surface is everywhere exceedingly irregular, 
giving rise to numerous ectodermal lacunz in the: mesoglea. 
The general character of the ectoderm shows nothing unusual. 
On the tentacles, there are numerous stinging cells, both thin 
and thick walled. Ectodermal muscles are only present in the 
tentacles and disk, where they are well marked. 
No cinclides could be seen. 
Mesoglea.—The mesogloea of the body-wall shows an inner 
deeply stained dense layer; made up of fibres running both trans- 
versely and longitudinally, and an outer layer not stained so 
deeply, made up of fine fibres which cross each other, forming a 
loose reticular structure. The mesogloea of the tentacles contains 
numerous cells. The ectodermal muscles, which are very well 
marked, sink somewhat into the mesogloa, but are not enclosed by 
it, and cannot be called mesogleeal. 
A few strands of muscle are prolonged from the sphincter into 
the mesogloea of the disc, but in other places the mesogloea of the 
disc is thin, and there is no mesogleal muscle. 
In all sections of the upper part of the body-wall, irregularly 
rounded bodies of varying size are seen, mainly in the mesoglea, 
but in some places in the endoderm. These bodies stain deeply 
with carmine, and are made up of fine granules, most of which 
are very small and highly refracting, a few of them are larger, 
and may be also highly refracting, but are occasionally much 
darker than the other granules. Some of the smaller bodies seem 
to be made up of a few of these granules surrounded by dense 
deeply stained mesoglea, but other small ones do not differ in any 
way from the larger and presumably older bodies. I have de- 
scribed these with the mesoglea, as they are a striking feature in 
sections of the body-wall, but they also occur, though not so 
frequently inthe endoderm. The mesoglcea of the gullet and septa 
shows no special features; the mesoglveal strand of the acontia is 
almost circular. 
Endoderm.—The endoderm is of the usual type; gland cells 
are not very abundant. Alge are everywhere present. The 
