64 PROCEEDINGS OF SOCIETIES. 
organization of the plant, as he had mentioned at the meeting of 
the club on the 19th January last; and it seemed to him at least 
probable that here, too, they bore a relationship to the torulose 
filaments corresponding to that of the similar threads in C. ebe- 
neum ; that is, that C. Arnottit may be, in truth, when found in 
fruit, proved to be a lichen, the slender accompanying threads 
representing the fibrous element in a typical lichen, and the 
torulose filaments themselves, here the marked and conspicuous 
part of the plant, the gonidial element. This, of course, until one 
or both of these plants be found in fruit, is but a conjecture, but 
one not without foundation, as Coeenogonium, in its fruit a true 
lichen, is quite as aberrant in its thallus, the structure of which 
latter seems essentially to agree with that of the plant under 
consideration. 
Dr. Moore exhibited the seeds of Disa grandiftora by reflected 
light. The reticulated outer skin of these formed very pretty 
objects. 
Mr. Archer showed fine specimens of Sciadiwm arbuscula (Al. 
Braun) new to Ireland. This remarkable little alga had been 
recorded from several localities on the Continent, but only once 
before in Britain. The record in Britain was founded on three 
minute imperfect specimens, discovered by Currey in a pool on 
“ Paul Cray Common,” in Kent (‘ Quar. Journ. of Mic. Science,’ 
Vol. VI, p. 212); but although those specimens were not fully 
developed, they were quite enough to determine the plant. The 
specimens now exhibited showed the most varied stages of growth, 
from a simple, nearly cylindrical cell, mounted on a slender 
peduncle, by which is was attached (and in this stage it might-be 
readily mistaken for a Characium), up to a complete tree-like 
structure, with tertiary umbels. Very frequently the cells 
were very elongate, and sometimes considerably curved, in this 
respect unlike the figures given by Braun in ‘ Algarum unicellu- 
larium genera nova et minus cognita,’ t. iv. But in length and 
breadth, and in general outline of the cells, in the different speci- 
mens great variety occurred; and Mr. Archer thought that there 
was no ground for assuming more than one species, although 
Braun had described three forms as distinct (loc. cit., pp. 106-7). 
There is undoubtedly great affinity between Sciadium and Ophio- 
cytium, a.young Sciadium, if detached before forming the first 
umbel, being very like some individuals of Ophiocytiwm apicu- 
latium (Nag.). But no plant of Sciadium presented itself so much 
curved as is the casein Ophiocytium (in which the cells are mostly 
spirally contorted, often forming many coils) ; not to speak of the 
umbellate mode of growth of the former, by the gonidia remaining 
in the form of an umbel at, and becoming developed around, the 
opened apex of the parent cell, and in the latter the gonidia 
becoming wholly free and developed as separate, isolated indi- 
viduals. These specimens were taken in a pool near Bray, and 
were attached chiefly to Gdogoniwm tumidulum and to Vaucheria. 
