PROCEEDINGS OF SOCIETIES. 297 
to it on the present occasion was to urge that Ralfs was in error 
in his description of the example from which his figure was taken 
(‘ British Desmidiee,’ p. 62). Ralfs supposed the appearance 
presented to be that of the contents of each cell of a solitary 
filament having become massed together in the cavity of each, 
without any actual conjugation having taken place. Alex. Braun, 
supposing, too, that this was hardly what had taken place in the 
specimen figured by Ralfs, suggests that it might represent a 
filament bearing the spores, but which had been detached from 
its companion filament, such as we see frequently in Zygnema, 
&e. (‘ Rejuvenesence in Nature,’ p. 296). This, however, is not 
the case, neither is Ralfs correct in supposing these spores to 
have been produced simply by the consolidation of the contents 
of the joints of a solitary filament. MRalfs’ figure, Mr. Archer 
had now no doubt, represented identically the same condition as 
that now exhibited, and he had as little doubt but that in both 
instances two filaments, not one only, were concerned in the 
process. The species conjugates in a manner quite comparable 
to that of Zygnema by mutual tubular processes, and the zygo- 
spores are formed not in the cells of one of the parent filaments, 
but in the transverse intervening space. So short, however, are 
the intervening processes uniting the opposite conjugating joints, 
and so closely approximated are their flat sides, and they adhere 
so intimately, that the whole is very deceptively like a single 
filament only, as Ralfs supposed, and the figure is indeed a most 
excellent likeness of the appearance presented. The true con- 
dition is correctly depicted by Wallich in a Bengal form (‘ Ann. 
Nat. Hist., 1860,’ pl. vii, fig. 4), where the filaments do not, 
however, approximate so closely during conjugation as those of 
D. Swartzit. 
Mr. Archer was likewise able to bring forward on the present 
occasion the zygospores of Xanthidiwm fascieulatum, of Closterium 
juncidum, of Closteriwm lineatum, and Closterium acutuwm, each 
presenting their own marked and characteristic form. 
He was likewise able to present two forms not hitherto met with 
in Ireland—Docidium baculum (Bréb.) and Euastrum circulare, 
var. 3 (Ralfs). As to the former (D. baculum), although it is 
said by Ralfs to be rather common in Wales, yet it almost looked 
as if it wasnot going to turn up in this island, its place seemingly 
being taken by the frequent Docidiwm Ehrenbergii ; yet here was 
a gathering made near Carrig Mountain in which it occurred 
pretty abundantly. As to the other form not hitherto met with 
here Huas. circulare, var. (3 Ralfs = Luas. sinwosum (Lenormand), 
it seems quite a distinct thing from Euwas. circulare (Hass.). 
This was the first time Mr. Archer had ever seen any of the 
forms included by Ralfs under Hassal’s name, Evastrum circulare, 
yet a glance showed it was very distinct indeed from any of the 
commoner related forms, and not only so, but he felt pretty well 
satisfied that the forms a, B, y, were themselves distinct from one 
another. Only a very few specimens turned up from a bog near 
