196 
would not, however, wish it to be thought that in these remarks 
he was contending against the genus Pleurotaenium, which pro- 
bably would hereafter be found to be a good and natural one, but 
only that our experience seems not yet sufficiently advanced for 
its reception. There can he no doubt but that the configuration 
of the endochrome is very constant and generically, if not specifi- 
cally, characteristic in these and many others of the simple Algae 
— such, for example, as the genera Mesotaenium, Cylindrocystis 
and Spirotaenia, Zygnema, Spirogyra, Drapernaldia, Mesocarpeae, 
CEdogonieae, &c. 
Mr. Tichborne exhibited a slide of Platinocyanide of Thallium, 
as a polariscopic effect. One peculiarity of this salt is that it 
shows, when viewed by polarized light, appearances similar to 
starch-granules viewed under the like circumstances. This was 
well shown by the specimens now brought forward. 
Mr. Archer exhibited specimens of a fine new Staurastrum from 
Connemara, remarkable for being probably the very largest of 
rayed or armed forms yet found in Europe, the largest of the 
Ralfsian forms being probably some 3 -^/' in expanse, while this 
reached from tip to tip of the radiating arms, ten of which, 
beautifully toothed or serrated and notched at the end, extending in 
the end view like a wheel, presented a very handsome and striking 
appearance. Mr. Archer trusted to give, on a future occasion, a 
detailed description of this species, which he would name Staur- 
astrum verticillatum. 
Mr. Woodworth showed some excellent transparent photographs 
of microscopic objects, prepared by himself, for the magic lantern, 
and which were justly much admired. 
19 th November, 1868. 
Mr. Archer desired to record the occurrence of Micrasterias 
crux-melitensis (Ehr.), Half's, in the gatherings made in Conne- 
mara, and for the first time discovered in Ireland ; it had been 
found by him in the material exceedingly sparingly. He had 
made a previous acquaintance with it from specimens obtained 
from Scotland and from Wales. It seems to be a tolerably widely 
distributed form in Europe, and it was met with by Dr. Wallich 
in Bengal ; but yet it appears to be always very sparing. 
Rev. E. O’Meara exhibited specimens of Surirella turgida, found 
in considerable abundance in a gathering from Lough Neagh, not 
far from Lurgan. He was not aware that this form had been 
found anywhere but in Lough Neagh. He showed also forms of 
Stauroneis acuta , found sparingly in Lough Neagh, and also in a 
pond near Armagh. He further directed attention to Tryblionella 
Victorice (Grunow), found in gatherings from Lough Neagh, and 
from the Ulster canal near Poyntzpass. Concerning this species 
Grunow remarks — “ I have observed this species in abundance 
amongst algae of the Victoria regia tank in Kew Gardens, at 
London, and conjecture that it has come in with the latter from 
