ARCHER—ON RHIZOPODA. 265 
The foregoing view of the case as regards forms such as those on 
Plates VIII. and IX., seems to receive a very strong confirmation 
from certain freshwater Rhizopoda brought forward only a few weeks 
ago by Greef, in a paper full of close observation and close reasoning 
founded thereon,* some of which forms are identical with mine, and 
certain others very closely related, and which latter do actually seem 
te possess a true central capsule. I allude to the forms falling under 
his new genus Astrodisculus (A. ruber, A. flavescens, A. flavocapsula- 
tus, Greef). This valuable and interesting paper of Greef’s opens up 
some new points, and, as is seen, brings to notice some instructive new 
forms. 
Upon a species appertaining to one of the genera—Acanthocystis 
(Carter), a valuable paper has likewise previously appeared by Grena- 
cher,} with whom, so far as his observations are concerned, Greef 
seems tocoincide. Perhaps it would be of advantage to English readers 
briefly to allude to the points made out in both. 
As, however, some of the species Greef himself either describes or 
alludes to are actually identical with certain of those described by 
myself in the preceding sections of this communication, before the ap- 
pearance of his paper (as well as previously in a cursory manner in the 
“Proceedings of the Dublin Microscopical Club’’), I shall, perhaps, 
most fittingly allude to his account of them and of the forms most 
immediately related in a paragraph following the diagnosis of each of 
the species themselves under the head of ‘‘ Affinities and Differences.”’ 
Not essaying, then, to place our forms under headings of any of 
the proposed Classes or Orders, I shall simply attempt to give their 
generic and specific character, with a view to facilitate their more 
speedy recognition when encountered by other observers. 
But, before proceeding to do so, I would draw attention to the cir- 
cumstance that, whilst partaking with other forms of a common “ helio- 
zoan’”’ or ‘‘actinophryan” nature, there is, moreover, one additional cha- 
racter or point of structure in which the forms located in the three 
genera now soughtto be constructed by me, Raphidiophrys, Heterophrys, 
Pompholyxophrys, along with the genus Acanthocystis (as well as, pos- 
sibly (?), Greef’s new genus Astrodisculus), all mutually coincide—I 
mean, at least, as it appears to my own observation. I think, then, 
that in the forms included under the genera just named, the body-mass 
is in all composed of two distinct regions or strata of sarcode, sharply 
marked off, one within the other, the outer surrounding the inner as a 
complete investment. These two sarcode regions are distinguished by a 
sharp line of demarcation, and present considerable differences of ap- 
pearance, colour, and consistency. The outer region appears to me to 
be the softer, and more plastic and polymorphous, the inner to be more 
* «Ueber Radiolarien und Radiolarien-artige Rhizopoden des stissen Wassers,”’ in 
Schultze’s ‘‘ Archiv fiir mikroskopische Anatomie,” Band v., Heft 4, Oct. 1869 [pub- 
lished since the preceding portion of the present Paper was written ]. 
+ ‘ Zeitschrift fur wissensch. Zoologie,” Band xix., p. 288, T. 2, fig. 25. 
