92 Proceedings of the Royal Irish Academy. 
Acanthocystis spinifera (Greeff). 
In my preceding Paseiculus, I gave a description of a new form 
appertaining to the genns Acanthocystis (Carter), named by me Acan- 
thocystis Pertyana,'^ and on discussing its relations and resemblances, 
under the head of Affinities and Differences," I had naturally occasion 
to contrast that form with the one it most approaches, the above-named 
A canthocystis spinifera (Greeff), f and I drew attention to the distinctions 
between the two forms which, indeed, still appear to me to hold good. 
That occasion afforded me, also, the requisite opportunity to give a 
resume of Greeff's views and ideas as to the supposed or conjectured 
further developmental stages, or at least assumed modified conditions, 
of his form. He conceived, namely, that the yellow globules occur- 
ring in the body-mass of A. spinifera, becoming extruded therefrom, 
involved in a hyaline covering, then give off opposite pencils or tufts 
of very slender and delicate pseudopodia, and at last acquire character- 
istics of which he gives figures. J Further, he conceived that those 
afterwards may become combined into considerably larger groups, the 
slender and delicate pseudopodia being now confined to the outer or 
circumferential parts of the cluster or aggregation of such bodies, of 
which he also gives a figure. § The first of these forms, as I then ad- 
verted to, is identical with that previously named Diplophrys Archeri 
(Barker), II and the second with Cystophrys oculea (mihi),^ and I fol- 
lowed up a review of that portion of Greeff's memoir, by some considera- 
tions which appeared to me to render his views hereupon, as yet at least, 
improbable, and therefore to indicate that those names should stand. 
Amongst those considerations opposed to Greeff's conjecture touch- 
ing A. spinifera and the other forms alluded to, was adduced the 
negative, and far the least important one, indeed — that is, that whilst 
the latter occur with -us not very uncommonly, the former had not 
yet been found in this country. 
"^ow, the object of the present additional brief note is threefold — 
first, to correct what turns out to be a misstatement on my part as to 
the non-occurrence of Acanthocystis spinifera in this country ; in the 
next place, to point out certain features in the accompanying drawings, 
(PI. xii.. Figs. 7, 8), which seem to be of possible interest in connexion 
with this elegant form ; and lastly, to draw attention to two drawings 
(PL xii.. Fig. 9, and PL xiii.. Fig. 10), which I take the oppor- 
tunity to insert in the Plates, of the little organism, already alluded to 
by me, possessing so great a resemblance to a Diplophrys, pseudopodia 
retracted and surrounded by an aggregation of foreign bodies,^'"* 
* " Quarterly Journal of Microscopical Science," vol. x., N. S., pp. 101-3. 
t Greeff: " Ueber Radiolarien unci Eadiolarien-artige Rhizopoden des siissen 
Wassers," in Schultzes " Archiv fiir mikrosk. Anat." Bd. v., p. 493, t. xxvii.. Fig. 
20-3. 
X Log. cit., fig. 26-28. § Ibid., fig. 29. 
II " Quarterly Journal of Microscopical Science," vol. viii., p. 123. 
^ Ibid., vol. ix., N.S., p. 265. 
** Ibid., vol. ix., N. S., pp. 323-4, and vol. x.,N. S., pp. 102-3. 
