PROCEEDINGS OF SOCIETIES. 231 
supported on an extremely delicate stipes, which becomes itself 
dichotomously divided with every self-division of the elliptic cells, 
the aggregate family forming a group of a more or less rounded 
figure, and the dichotomously branching stipes radiating from 
a common centre or starting-point, where once stood the primary 
cell of the family. The cells are themselves ultimately set free 
as zoospores. Two other species of Dictyospherium are distin- 
guished from the first found form, D. Ehrenbergianum, by the 
very different form of the cells and much greater size. Now the 
plant at present exhibited agrees with D. Khrenbergianum (Nag.) 
by the cells being supported on a slender linear stipes and by 
being set free as zoospores. It differs therefore (generically ?) 
by the stipes not being forked or branched, and by these being 
attached (not to each other starting from a common centre), but 
independently to various other alge (Desmidiew). The cells here 
are round, not elliptic as in the plant mentioned. It is perhaps 
just possible that the figure of “ Phycastrum pilosum (Nag.)’’ as 
given by Nageli might represent a Staurastrum having attached 
thereto some such similar but smaller growth, although by Nageli 
regarded as spines appertaining to the Desmid itself. 
Dr. John Barker exhibited a minute unicellular production 
which he would provisionally refer to the genus Chytrydium. 
This consisted of a very slender, fusiform, colourless, usually 
arcuately curved cell, acute at the basal, somewhat truncate at 
the apical extremity, immersed in the external gelatinous invest- 
ment (from which this organism may possibly for a time have 
derived its nutriment), and sometimes seemingly in contact 
with the filament itself, of Didymoprium Grevillii. Numbers of 
these fringed several of the filaments of that desmidian, round 
which they curved, and though, doubtless, to be regarded as para- 
sitic, these seemed to remain attached for days or weeks without 
causing any very appreciable injury to the joints, although finally 
some had become effete and brown. No rootlike attachment, as 
in some species of Chytridium could be noticed. Some of these 
showed their contents separated into a number of minute rounded 
portions arranged within these very slender cells in a single file ; 
but no discharge of zoospores had been seen. 
Mr. Archer showed Chytridium endogenum (A.Braun) inhabiting 
the interior of an effete Closteriwm lunula, partly with contents, 
partly evacuated by the zoospores, and well showing the charac- 
teristic neck of this species partially and fully protruded through 
the outer wall of the host-Closterium. 
Dr. Moore showed some Scytonemez lately gathered in the 
West at Chilomore Lake ; two forms very distinct of Sirosiphon 
(one S. ocellatum) and of Scytonema. Without authentic speci- 
mens it would be most difficult to arrive at a satisfactory deter- 
mination of the species as named by authors, although the dis- 
tinctness of the forms themselves now shown, and as they usually 
present themselves, is very evident. 
Dr. M. H. Collis exhibited specimens of cheloid tumour stained 
