264 
eliana will sufficiently indicate. Hardly anything can be 
prettier than the gradual expansion, under one’s eye, of an 
example of the form referable to Schultze’s A. porrecta, pre- 
senting itself first as a little shapeless sarcode-lump, and then 
extending into a wide-spreading, reticulose, densely ramifying 
combination of several little trees, under a higher power quite 
filling the field of view. 
From the naked forms represented by the more familiar 
Actinophrys, the subarborescent character of the pseudopodia 
would alone readily distinguish our rhizopod, even though it 
did not possess the central cells. In our new form there does 
not appear any body or structure equivalent to the so-called 
‘ nucleus,’ as that term is applied to the peculiar body in 
Amoeba, Difflugia, and some other forms to be described 
hereafter in a future part of this paper. The absence of a 
test shuts out this form from a few whose pseudopodia may 
otherwise resemble it. There is, moreover, in our form no 
‘ contractile vesicle.’ As regards, then, other rhizopods des- 
titute of a test, it is distinguished from Actinophrys by the 
subarborescent character (so to call it) of the pseudopodia 
and by the central cells. From Raphidioplirys, whose pseu- 
dopodia are still more delicately slender than those of Acti- 
nophrys, and do not fuse at all, it is distinguished by the 
absence of the spicula and the presence of the central cells — 
in fact, the possession of the central cells shuts our form out 
from every other fresh-water genus, not to speak of the other 
wide distinctions drawn attention to. 
It might suggest itself, then, as I have alluded to, that 
these very central cells might point to an affinity of the 
marine forms comprised under Haeckel’s ‘ Radiolaria,’ that 
is, if the cells in our form were thought to be at all the re- 
presentatives of the so-called ‘ yellow cells’ which pervade 
that great group, with the exception of Haeckel’s family 
therein — the ‘ Acanthometrida.’ As we have seen, these 
central cells are, like the ‘ yellow cells’ of the great majority 
of the Radiolaria, true c cells,’ 1 in the strictest sense or appli- 
cation of the word ; that is to say, they possess a nucleus, 
nucleolus, contents, and a wall, and so do the ‘ yellow cells,’ 
as described by Haeckel ; and, what is equally important, 
both agree in the mode of self-division of the contents. In 
short, the central cells in the rhizopod now brought to notice 
are, if the expression be allowable, to all intents and pur- 
poses. homologous with Haeckel’s ‘ yellow cells,’ except that 
they are not of a yellow colour; at least, not yellow, contents 
and all, as depicted by Haeckel, yet still the cell-wall has a 
1 Haeckel, op. cit., p. 84. 
