ARCHER—ON RHIZOPODA. 253 
tions in the preceding pages, the present does not demand a new genus 
for its reception, as it falls, as will be seen, in my own opinion at least, 
as a new species under the genus Gromia (Dvj.). 
Those, indeed, who are acquainted with the much larger represen- 
tatives of the genus, such as even the comparatively small Gromia 
fluviatilis, and conceiving that form magnified 400 diameters, that is, 
to the scale of the accompanying drawings (PI. X., figs. 7-11), being 
that to which all my previous figures have been made, might hardly 
be disposed to regard these two as strictly congeneric; or they might, 
on the other hand, regard the present as, perhaps, simply a young 
state of Gromia fluviatilis. But the present has other and further re- 
semblances, to which I shall draw attention after having first given 
some account of it. Nay, this inert, at first glance nearly lifeless- 
looking organism, might also be taken for some species belonging to 
the fungal genus Chytridium, and not as appertaining to animal life 
at all, only that it occurs free in the water, and not living parasitically 
(as would a Chytridium) on some confervoid or other host. 
But if I was for a little somewhat puzzled by the Chytridium-like 
appearance of this form, rendered the more misleading by its occurring 
in the gathering chiefly amongst the branches of Iicrothamnion Kiitz- 
ingianum (Nag.), a short examination soon dispelled that idea, and 
made it certain that I had indeed a true Rhizopod before me. Amongst 
the ramifications of almost every example of this little alga in the 
gathering—never, indeed in any way attached to them—occurred this 
little Rhizopod, either singly or in groups of two, three, four, five, six, 
or even more; and it 1s sufficiently remarkable that I but seldom met 
with them in any other situation in the gathering at large; so that 
whilst they lasted I presently found that the quickest way to meet 
with specimens was to look out for a plant of the Microthamnion, and 
then search with a ‘“‘ quarter-inch” amongst its branches for the little 
Gromia, which, however, owing to its minuteness, and being thus 
often above or below the plane of the focus, readily eluded observation. 
I can in no way account for the proclivity of this little Rhizopod for 
poising itself amongst the branches of the alga referred to, between 
which it sent its own ramifying pseudopodia in various directions. 
Those who will take a look at the drawing (PI. X., figs: 9, 11) 
may, perhaps, forgive my momentary misconception that I had a 
Chytridium before me, the pseudopodia being, perhaps, somewhat like 
the root-processes of the organisms appeartaining to that type, the test 
corresponding to, and resembling not a little, the orbicular body of a 
Chytridium plant, which at maturity becomes ultimately the sporan- 
gium. But a more prolonged observation showed a slow, but not the 
less actual, flow of the granules along the branching, and here and 
there incorporating pseudopodia; nay, the circumstance that two, 
three, or four, or even more individuals, might not unfrequently be 
found united by a mutual fusion of their pseudopodia in a more or less 
reticulate manner, and seemingly carrying on a common life, abun- 
dantly proved the true nature of this organism. 
