286 NATURAL HISTORY SOCIETY OF DUBLIN. 
As regards this species Greef suggests that the round dots seemingly 
in the extra-capsular region may actually be the superficially posed 
discoid bases of exceedingly fine and delicate spicula, comparable to 
those of Acanthocystis; but in the present instance he leaves this quite 
as matter of doubt. I would venture to think that the placing side by 
side in one genus of a spicule-bearing form with others destitute of 
spicules would be incorrect. But he distinctly attributes spicules to the 
last form he records under this genus—namely, 
A, radians (Greef ).* 
Sarcode of inner body colourless, and enclosing several (two to 
three) ‘“‘central capsules,” filled also with finely granular, colourless 
substance; outer region of a slightly brownish hue, and containing se- 
veral acicular, very slender and delicate radial spicula, reaching from 
the periphery of the inner body to the outer surface. 
The presence of these spicula would, I venture to think, place this 
form in a distinct genus, and, in fact, very close to Acanthocystis. In- 
deed, I would almost query if the form here recorded might not be truly 
a state of Greef’s A. spinifera, with the outer (sareode) region more 
conspicuous than usual, and more than one ‘‘ central capsule” present, 
and no yellew bodies developed. The tint of colour shown in Greef’s 
drawing as belonging to the outer marginal region is seemingly the 
same, or nearly so, of that prevalent in the outer sarcode stratum of my 
own Heterophrys Fockii, or in Raphidiophrys viridis, where it is un- 
doubtedly mobile and changeable, and no siliceous “ skeleton’’ or 
‘‘shell.” If Greef’s views were correct, then these spicula, contrary to 
analogy, would not be surrounded by sarcode by which deposited, but 
one siliceous structure penetrating and embedded in another. 
It will not be thought out of place to endeavour here to present as 
brief an epitome as I can of Cienkowski’s previous and Greef’s later 
observations on the but recently described Rhizopod, Clathrulina 
elegans (Cienk.), as, doubtless, any fresh views or new points as regards 
an organism seemingly so comparatively rare, and at the same time of- 
fering several interesting considerations with respect to its position and 
affinities, must be accounted of interest. 
This pretty fresh-water form was made the type of a new genus by 
Cienkowski,} and as yet has been recorded, so far as I know, but by that 
author himself, from near St. Petersburg, and from two localities in Ger- 
many; by Haeckel, from near Jena; by Greef, from near Bonn ; and by 
myself (since by others) from two or three localities in Ireland, and one in 
* Loe. cit., t. xxvii., figs. 36 and 36a. 
+ Cienkowski, ‘‘ Ueber die Clathrulina, eine neue Actinophryen-Gattung,” in 
‘* Archiv fur Mikroskopische Anatomie,” Bd. iii., 1867, p. 311, t. xviii. 
