88 
Proceedings of the Boyal Irish Academy. 
''nucleus," the presence of tlie " central capsule," and of the nume- 
rous exceedingly slender filiform (not short digitate or conical) pseu- 
dopodia of that genus, as far as I can see, completely place the forms 
referrible to it apart from the present and amongst " Eadiolaria." I 
have no doubt that I have now myself met with more than one 
Astrodisculus-form, but so sparingly, that I have yet had no opportunity 
to submit them to any tiling like a safiicient examination. But though 
the Amphizonella-forms are then "Amoeban," in their affinity, they 
seem generically quite distinct from all such recorded previous to 
Greeff's memoir, by the special and peculiar character of the outer 
coat. Possibly, further research may disclose transitory stages in 
development of the forms referrible here, which may present con- 
ditions falling short of those assumed as typical in the present state 
of knowledge about them, but as yet I venture to think the genus 
must be taken as a " good" one. 
It seems exceedingly probable that the form named by Auerbach,^ 
Amoeba hilimhosa, ought to be referred here ; this has not, however, so 
far as I am aware, been ever rediscovered. Many of the characteristics 
described for it seem to j)oint to a community of structure with such 
as the present, and, therefore, in fact, to its necessary exclusion from 
Amoeba pro2)er, notwithstanding that Aiierbach has endeavoured to 
demonstrate that "allAmoebce are encompassed by a universally-closed 
membrane, which is structureless, very extensible, and perfectly 
elastic." To combat this view, however, is no part of the object of 
this communication, nor to give a resume of Auerbach's now well- 
known^ memoir, to which I would refer, however, as interesting in 
connexion with the present forms. Still, however, Auerbach's experi- 
ments, with re-agents or otherwise, do not seem to have produced a 
separation of the body proper from the closely-investing covering, that 
is, they do not seem to demonstrate their, so to say, independent 
character. 
Descanting, however, upon this outer, doubly- contoured investment, 
which he was inclined to regard as nothing else than the presupposed 
cell-membrane, which he would ascribe to all Amoebae, and, alluding 
to the mode of projection of the pseudopodia and the thinning off and 
interruption of the investment where they occurred, Auerbach goes on 
to say : — " AUein indem ich langer beobachtete, wurde ich iiber diese 
Ansicht bedenklich. l^amentlich war mir das Yerhalten der Contouren 
an der Basis der Fortsatze ein Stein des Anstosses. Ich hielt es fiir 
unwahrscheinlich, class eine dicke Zellenmembran an einer so scharf 
begranzten Stelle so sehr sollte verdiinnt werden konnen. Deshalb 
warf ich mir die Erage auf, ob ich nicht vielleicht Bhizopoden mit 
einer membranosen Schale vor mir hatte, welche an gewissen Stellen 
fiir auszustreckende Portsatze durchlochert ware." And, with the 
light thrown by the knowledge of the form described in the present 
* Auerbach, " Ueber die Einzelligkeit der Amoeben," in Siebold and Kolliker'a 
** Zeitscbrift fiir wissenscb. Zoologie." Bd. vii., p. 374 (1856). 
