4.14 PROCEEDINGS OF SOCIETIES. 
invisible to the naked eye, but became apparent when viewed 
with the ordinary lens. 
Navicula subcincta, Schmidt, exhibited, new to Ireland.—Rev. 
E. O’Meara exhibited a form of Navicula which he found several 
years since in a gathering made by Professor E. P. Wright at 
Arran Island, County Galway, and specimens of which he had 
subsequently found in stomachs of Ascidians taken by Mr. A. G. 
More in Broadhaven Bay, in same county. This form Mr. 
O’Meara had considered undescribed, and named it in his private 
list Navicula Cleveana, but happening to glance at a recently 
published paper by Schmidt, in a work (‘Die Botanischen 
Engebnisse der Nordseefahrt’) lying on the table (for quite 
another purpose) at the time of the meeting, he at once recog- 
nised as that described by the distinguished author referred 
to as Navicula subcincta. This name has, therefore, the priority 
of publication, and so is entitled to stand as the designation of 
the species, of which the following is the description :—Valve 
slightly constricted; ends somewhat cuneate; rounded at the 
extremities. Median fascia broad, inflexed at the ends, and 
slightly constricted at the middle; external fascia broad acute, 
unstriate. Striated band marginal, divided into equal portions 
by a longitudinal suleus. Striew costate, parallel in the middle, 
slightly radiate towards the ends. Length 0:0042”, greatest 
breadth 0°0016”, breadth at constriction 00015”. 
Mougeotia glyptosperma, De Bary, stained by Logwood.—Mr. 
Archer showed an example of foregoing, mounted by Professor 
Thiselton Dyer, after having stained it with logwood. It thus 
formed a striking object, and this plan seemed calculated to make 
a good permanent preparation. 
Singular and unprecedented Case of Conjugation between two 
distinct, but allied, Desmidian Species—Mr. Archer drew atten- 
tion to two or three cases of conjugation between two distinct, 
‘but allied, Desmidiex,—a similar case he had indeed never before 
seen or heard of. The species of these alge always conjugate 
like with like. Even those closely resembling, but still distinct, 
Staurastra, confounded under the name of Stawrastrum dejectum, 
though crowded together in the same gathering, sometimes one 
only of the forms, sometimes all of them, being in the conjugat- 
ing state, still in them conjugation takes place only like with tke. 
And soon. But, mirabile dictu! here was Euastrum didelta and 
Euastrum humerosum mutually conjugated! The zygospore was 
very large, and densely covered, as is usual in the genus 
Euastrum, by long, rather thick, finger-like hyaline spines or 
processes, bluntly rounded at their apices. We must, in ex- 
planation of this singular (and, so far as Mr. Archer was aware, 
unprecedented) fact, suggest one or other of two possibilities, 
Either these two forms are only varieties of a single species, 
hence a matter of indifference whether conjugation takes place, 
didelta with didelta, or humerosum with humerosum, or didelta with 
humerosum. Or this was just a mere case of hybridisum, similar 
