102 
Proceedings of the Royal Irish Academy. 
''skin" (Fig. 11), and thus, at all events, to a considerable extent 
falling in with the authors' description of their form. 
But when our form is treated with acetic acid the body completely 
retracts from the integument, and it is shown as an independent, 
colourless, and smooth coat or case, or — may we call it — ^^test?^^ (see 
Eig. 12), thus proving a characteristic not claimed for their forms, at 
least to this extent, by Claparede and Lachmann, something more, in 
fact, than what would, I think, be called a mere '' skin" — might not 
our forms, indeed, be designated as '' cuirasses" ? 
Eut to advert, then, to the mutual differences presented by the ex- 
amples lately met with by me (Fig. 14), as compared with the form 
here designated Plagiophrys sphcerica (Fig. 11). I found it impossible 
to attain a good profile view of one of the former, so, like Claparede 
and Lachmann themselves, in this instance I have been obliged to be 
content with a figure drawn from the posterior aspect. Comparing, 
then, the form we are the more familiar with (Fig. 1 1 ) with that more 
recently met with (Fig. 14), we see the colour of the body, or rather 
contents, is much darker in the latter (Fig. 14) ; this indeed is pro- 
bably of but little moment ; the wall or exterior appears even thinner, 
smoother, sharper, more glossy. We see, too, the pseudopodia far more 
conspicuous, longer, here and there more broadened out, granuliferous, 
more fitful and changeable, and, so to say, of a more solid character, 
less hyaline ; but all this, it may be, requiring far more observation 
to decide as to its being specially characteristic of truly distinct forms. 
The differences under the action of Beale's fluid are more tangible. 
Specimens of the rhizopod, represented by Fig. 14, upon being treated 
with this re-agent immediately collapsed, and assumed the crumpled 
appearance indicated by the outline shown by Fig. 15. In a few 
minutes this crumpled form began to expand, and speedily the folds 
all became obliterated, and the whole inflated, until a balloon-shape 
was assumed (Fig. 16). After a time some of the sarcode mass became 
expelled through a rather wide truncate neck-like anterior extremity, 
and the body-mass became distinctly retracted from the outer case 
(test ?) ; the nucleus took a bright red colour. Sometimes, but by no 
means in every instance, there was to be seen a brighter, smaller, 
'' nucleolus-like" (?) dot within. In the instance figured, a couple of 
yellow oil-like globules presented themselves, very like the yellow 
globules of Acantliocystis spinifera (Grreeff), and, in my opinion, seem- 
ingly largely going to prove that in that form these cannot be at all 
properly regarded as homologous with "yellow cells." The other speci- 
mens (Fig. 11), those of the presumed P/^,^'. sphmrica, also treated with 
the carmine fluid, behaved somewhat differently. '^o collapse or 
crumpling-up of the total rhizopod took place ; on the contrary, rather, 
by degrees a slight expansion. JN'or was it for a very considerable time, 
comparatively, that the nucleus took its dye completely, nor was 
there any apparent retraction of the body-mass from the outer en- 
velope, nor did the latter become balloon-shaped, but its anterior 
border assumed a very broadly conical figure, no very evident apical 
opening offering itself to view. But that there is, and indeed, as 
