270 NATURAL HISTORY SOCIETY OF DUBLIN. 
if perforated, and an outer hyaline one. Of any further development 
of this state Greef has not seen any indication. It is difficult to con- 
dense his long and interesting account so as to do fair justice to the 
matter ; but the foregoing may, I trust, convey an epitome of his prin- 
cipal observations. 
I myself would argue, as Greef does in one place, that in Acantho- 
eystis turfacea, Just as little as in A. Pertyana, is there anything around 
the central sarcode body which might be denominated a special mem- 
brane. The so-called ‘ lorica’’—‘‘ biegsamer Panzer’’—‘“ verdichtete 
Rindenschicht”—can be but the expression of the mutually approxi- 
mated discoid bases of the radial spines being held together with a con- 
siderable amount of coherence by means of some intervening bond, not 
readily perceptible. One meets not unfrequently portions of the peri- 
phery of a defunct Acanthocystis, perhaps as much as a fourth or fifth 
of a circle (nay, whole globes sometimes), all the sarcode clean gone, 
and nothing but a greater or less number of radial spines left, and those 
still cohering by their discoid bases, the shafts radiating in the same 
manner, just as they would if they stood at the periphery of a stall liv- 
mg example. See also Greef’s fig. 15 of an “‘ encysted” state of this 
form, where the peripheral system of spines, still mutually coherent, 
stand off a distance from the contracted inner sareode body, the latter 
now surrounded by its special investments. But Greef’s views, ex- 
pressed in his account of this outward boundary (page 488), do not seem 
to me to coincide with those previously expressed (page 484). The 
following extract gives the spsissima verba used by Greef in the latter 
place referred to :—‘‘ Ich meinerseits habe keine bestimmte Anzeichen 
finden konnen, die mit Sicherheit eine besonders abgegrenzte und 
erhartete Rindenschicht, oder was doch wohl dasselbe sagen will, 
eine Membran bekunden, wohl aber mehrere die auf die Abwes- 
enheit einer solchen schliessen lassen.’”? And he adduces as evidence 
of the foregoing view the fact (not unfrequently to be seen), that large 
finger-like sarcode projections are capable of being extruded through 
the outer boundary, these withdrawn, and the place of their exit effaced, 
and the spines again all normally im sité. He also refers as addi- 
tional evidence to the extrusion of green granules by a separation of the 
spines, by an intervening opening, which again disappears. All this is 
just, andaccording to faet ; but I think the foregoing extract does not seem 
to accord with the following, in alluding, in the encysted state (fig. 15), 
to the very same outward boundary where the bases of the spines touch 
and form a hollow globe, now standing off, leaving a vacant margin 
around the encysted body :—‘‘ Die Oberflache dieses Saumes wird viel- 
mehr durch eine zarte und glashelle aber starre und undurchdringliche 
Kieselhiille gebildet, in oder unter welcher die Fussplattchen der Sta- 
cheln festsitzen.”” It does not appear that they can truly be held im- 
bedded in a rigid pellucid siliceous coat, from the strong reasons pre- 
viously adduced. The intervening bond of union, whatever it may be, 
has then no connexion with the central sarcode body, for the spines can 
independently maintain their mutual position ; and yet this with greater 
