104 PROCEEDINGS OF SOCIETIES. 
had been originally ordinary clay-slate, but had been hard- 
ened by contact with trap-rocks, so as to resemble ‘“ Lydian 
stone.” It was seen under the quarter-inch objective that the 
constituents now consisted of minute grains of silica cemented 
by a colourless glass or uncrystalline felspar, which contained 
black grains, probably of magnetite; these black grains imparted 
a dark shade to thestone. Mr. Hull believed that the argillaceous 
components of the slate (the alumina, &c., and lime) had been 
sufficiently heated to undergo fusion, but the original grains of 
silica remained unaltered and were now bound together by a 
glassy cement, which sufficiently accounted for the superior hard- 
of the ‘‘ baked” over the unaltered slate. 
A New Bat-tick—Mr. R. M. Barrington exhibited a specimen 
of a bat-tick, Ixvodes scotophili, anew species found by him on 
Scotophilus Leisleri (taken in Co. Armagh in some abundance, an 
interesting fact in itself). 
Chlorochytrium Lemne, Cohn, new to Freland—Mr. Archer 
showed the new parasitic alga lately described by Professor Cohn 
(“Ueber parasitische Algen,” in ‘ Beitrige zur Biologie der 
Pflanzen,’ p. 87, t. 11; also ‘ Quart. Journ. Micr. Scz.,” Vol. XIII, 
N.S., p. 366), which inhabits the fronds of Lemna trisulca and 
named by him Chlorochytrium Lemne. These examples were 
found lately in some pools at Raughlan, close to Lough Neagh, 
near Lurgan. This was the first record (Mr. Archer thought) 
subsequent to Cohn’s of the oceurrence of this remarkable and, 
in its bearing, highly interesting little alga; it is probably, how- 
ever, not uncommon, though Mr. Archer had looked for it since 
the publication of Professor Cohn’s memoir, but without success 
until the present occasion. Prof. Cohn’s examples were met with 
by him in some examples of the Lemna kept in a room over 
winter, and upon examining them in the month of May. Those 
now shown were met with in the open field and in the month of 
August. 
15th October, 1874. 
Examples of Irregular Sessile Foraminifera Structure exhibited. 
—Professor Macalister, M.D., exhibited several sections of the 
remarkable irregular sessile rotalian genus Polytrema from the 
shell of Zridena, and others from the tube of Chetypterus. The 
sections, both vertical and longitudinal, exhibited the foraminiferous 
nature of this form, which had been described by Lamarck as a 
Millepora. One of them also exhibited a tubular intercameral 
eanal, like the stolon canals of Orbztolites, with a section of which 
it was contrasted. 
Some Diatoms from Antarctic Sea exhibited.—Rev. E. O’Meara 
brought under notice some slides mounted by Mr. Carter from 
material collected in the Antaretie circle. Though not put up 
for the purpose of finding Diatomaceous forms, still several 
species of great interest were found, some specimens of Coc- 
