PROCEEDINGS OF SOCIETIES. 
Dublin Miceoscopical Club. 
Novemher, 1879. 
Chroococcaceous alga from Leicester ^exhibited. — Mr. Archer ex- 
hibited examples from a small collection of a Chroococcaceous algal 
form, kindly forwarded him by Mr. Holmes, of London, which had 
occurred in considerable quantities in the water supply of the town 
of Leicester. This, regarded from what might be called a mor- 
phological point of view, and taken as it stood, would be referable 
to the genus Coelosphserium, Nag., but it was clearly not iien- 
tical with the common Ccelos'pliceriwn Kutzingianwn, Nag., of 
which Mr. Archer exhibited some examples for comparison and 
illustration. He might mention that the latter form, when taken 
from running water, as these examples were, seems to possess 
notably smaller constituent cells than in the form taken fron 
standing pools. In C. Kutzingianum, however, the individual 
cells are globose. In Mr. Holmes’ plant they were elongate, 
considerably larger, of a different tint and internal appearance. 
The fission of the cells took place in the direction of the longer 
axis, that is, radially, as regards the aggregate group or 
rotund colonies, whereby the constituent cells came to 
stand themselves radially, that is, pointing to the common 
centre. It may be a question, indeed, how far Ccelosphaerium 
can be correctly regarded as a generic type ; for instance, the 
clearly allied form referred to Bacterium by Lankester, his 
B. rubescens, would appear to temporarily put on a Coelo- 
sphserium-like condition — nay, also a Merismopsedia-like, a 
Clathrocystis-like, and other phases. Since arrival many of the 
“ CoelosphaBrium ” aggregations had become broken up the cells, 
still living and subdividing, the fission still in the lougitudinal 
direction ; in that state the as yet not disconnected pairs of cells 
called to mind the appearance of a pair of cotyledons of some 
seed — say a bean — opened, and as yet held together by the em- 
bryo. Of course, this plant possessed considerable affinity to 
such as Microspora {Clathrocystis') ceruginosa, agreeing, too, with 
it, as would appear, in its copious occurrence when met with ; 
but the elongate form of the cells and different tint were striking. 
A very slight pressure was sufficient to drive away from a colony 
a number of the constituent cells, and then, or when apparently 
normally broken up, of course the separated cells might pass for 
a species of Synechococcus (where the line of fission, however, is 
transverse), but just as, well the same might be said for the 
separated cells of a Clathrocystis, which might pass for, say, 
Chroococcus minor. It does uot seem at all unlikely that under 
some different impulses the vegptating cells of this group may 
