272 PROCEEDINGS OF SOCIETIES. 
plant now exhibited cannot be Zygogonium ericetorum, nor any 
variety, nor can it indeed fall under the genus Zygogonium at all, 
either as Zygogonium (de Bary), or as Zygogonium (Kiitz.) ; for 
as already mentioned, as will be seen from the characters above 
detailed, it must find its place truly in Mougeotia (de Bary, non 
Agardh). If, on the other hand, de Bary have really erred as 
regards his plant, the genus Zygogonium, as constituted by him, 
may possibly not stand, or at least it may have to remain contingent 
on its being necessary to retain it for the common plant Zygogo- 
nium ericetorum (Kiutz.), for it should not certainly be main- 
tained for those species of Zygnema only, which form their zygo- 
spores within the transverse tube. 
In endeavouring to identify this plant with any form already 
described, Mr. Archer ventured to think that it comes quite close 
enough to Zygogonium leve (Kiitz.) as to render it probable that 
they are indeed one and the same thing, though Kiitzing describes 
only the barren plant. And if this view be correct, adopting the 
genus Mougeotia (de Bary, non Agardh), this plant should be 
henceforth called Mougeotia levis. 
Mr. Archer had to apologise for the present somewhat round- 
about description of this plant. It is not easy without a figure to 
convey at once a definite idea of the points dwelt upon, but he 
trusted his meaning would be sufficiently apparent to observers 
who have made themselves acquainted with the peculiarities and 
the characters of these interesting Algew. Those who have be- 
come familiarised with these forms will well know that these dis- 
tinctions are by no means imaginary, and will, he thought, accord 
with him in feeling that they each possess an individuality, and 
that we can know and recognise the same thing, time after time, 
when it offers itself to observation, although we may not be always 
able to tell exactly why. And that feeling seems to be increased 
and strengthened when, as in the present instance, we are able to 
follow up the characters of a perhaps tolerably familiar form to its 
fructification, compare it in its various stages with its allies, and, 
though they are sometimes hard to describe, note its differences 
and its idiosyncracies. 
Rey. E. O’Meara exhibited a species of Coscinodiscus found 
in a frond of Vanvoorstia spectabilis, Hary., from Ceylon. In its 
general appearance it so much resembles Coscinodiscus symmetricus, 
Greville, that Mr. O’Meara was disposed to identify it with that 
species. There are, however, slight differences worthy of notice. 
In the case of C. symmetricus the fasciculi of radial beaded lines 
are seven in number, whereas in the form now presented there 
are eleven such fasciculi of lines; the marginal portion of the dise 
in the present case is smooth ; in the case of C. symmetricus it is 
striated. This form seems of exceedingly rare occurrence in the 
material, only one specimen of it having been found. 
Dr. Moore showed fine and numerous specimens, perfectly un- 
