ARCHER—ON RHIZOPODA. 289 
show a decided resistance to reagents, and are seen to be superficially 
covered by very minute spinelets, giving a somewhat pilose appearance 
to the surface. I do not think the cysts seen in Irish examples have 
shown this characteristic. Greef argues that both perforate globe and 
stipes are doubtless (?) siliceous, for they likewise withstand the action 
of concentrated sulphuric acid. 
Touching the systematic position of this interesting Rhizopod, Greef, 
as did Cienkowski and myself, of course suggests its relationship to the 
Ethmospheerida, and that close to the marine Heliosphera, justly re- 
marking that if such a perforate ‘‘ skeleton” were met with, as that 
possessed by this form, in the sea or fossil, no one would hesitate to 
place it amongst Polycystina proper. But then we know the living 
animal, and it has no ‘‘central capsule,” unless, indeed, the questionable 
“ nuclear” body be its representative, nor (less significant or important 
indeed) has it ‘‘ yellow cells.” Greef, indeed, suggests besides that 
this central body (I think not at all always present, or at least percep- 
tible) may be, perhaps, rather the representative of the not always 
present, so denominated ‘‘ inner vesicle’’ (‘‘ Binnenblase’’) of the typical 
marine Radiolaria. The stipes, too, is seemingly unique, and I had 
imagined the genus would have been better named in allusion to that 
character than to the fenestrate shell, a character pervading so very 
many of its marine relatives. The absence of the ‘central capsule” 
has indeed a possible parallel in one marine form, Coscinosphera ciliosa 
(A. Stuart),* possible only, indeed, because even the form referred to. 
may yet, according to Stuart himself, be seen actually to have a central 
capsule. 
Greef finally makes some suggestions as regards the seeming incli- 
nation to formation of colonies presented by Clathrulina, if indeed the 
fact of the individuals sometimes mutually standing off from one ano- 
ther, and attached to each other by the bases of the stipes, as they 
might be to foreign objects, deserves to be so called, and he builds a 
hypothesis on that circumstance. But I imagine there is in this fact 
no analogy to such an organism as Carchesium. I venture to think the 
younger examples, originating from the germs evolved from the lower 
and first produced individual, are merely to a great extent accidentally 
located attached to the latter, the locomotion of the germs ceasing 
and development commencing before they succeed in reaching a more 
distant or a foreign object on which to establish themselves. Some- 
thing like what may perhaps be cited as a kind of growth in minute 
Algee, forming a parallel to that of Clathrulina referred to, is that seen 
in Sciadium arbuscula, as a constant characteristic of the species, and 
in Ophiocytium majus as an exceptional circumstance. In the latter, 
the young plantlets produced by the development of the germs are 
sometimes stationed, at least temporarily, at the summit of the parent 
cell-walls, or along its length, or one upon another, and attached by 
* “ Zeitschrift fur wissensch. Zoologie,” Bd. xxvi., p. 328, t. xvili. 
