424 
north halves run in one line and the two south halves in another, 
during the conjugative act. 
Dr. Barker brought forward a new Staurastrum, which he had 
discovered at Glengariff, Co. Cork, when in company with Mr. 
Archer and Dr. Wright last May. At first sight it looked some- 
what like Staurastrum gracile undergoing subdivision ; it is smaller 
in arms, not so long or fine proportionately. Although a true Stau- 
rastrum, it does not fulfil one of its definitions, each segment of 
the frond being somewhat longer than broad. The segments are 
T-shaped, longer than broad, ends crowned with a wreath of fine 
spines or granules ; arms horizontal, each nearly half the length of 
the segment, and terminated by three or four minute spines ; base 
of each segment inflated spherically, and marked with three or 
four rows of small spines. Frond deeply constricted in middle ; 
end view triradiate, tapering into elongate, straight, horizontal pro- 
cesses ; rough, especially at the most concave parts, between arms, 
with minute spines. Length, about ^Lth; breadth, -^Jg-th of an 
inch. He would name this species Staurastrum elongatum, in 
allusion to the great proportional length of this form in comparison 
to its expanse. 
Dr. Macalister showed Acarus bicaudatus taken from the ostrich. 
Rev. Eugene O’Meara showed Pleurostigma strigilis from a lake 
in Co. Wexford. This appears to be an exceedingly rare form in 
Ireland, being the second specimen he had as yet found. 
Mr. Archer drew attention (though unable to throw any light 
upon the specimen) to a state of a minute Coleochsete, long 
regarded and referred to by him as Pringsheim’s “seventh species 
that peculiarity, now drawn attention to, seemed to indicate a 
developmental stage. Pringsheim, in his fine memoir on this genus 
(‘ Jahrbiicher fiir wissensch. Botanik,’ Bd. ii, page 36 ; also de Bre- 
bisson, ‘Ann. des Sciences naturelles,’ 3 ser., tome i, pi. ii, fig. 6), 
describes six species, merely remarking at the end that he knows a 
seventh, which he believes to be a form mistaken by de Brebisson 
for an early condition of Coleochcete scutata. This “ seventh 
species” appears to be unique in being unicellular, each somewhat 
pear-shaped cell repeating itself by division, all the cells being 
finally free, and seemingly equivalent, each bearing one, or some- 
times more, of the curious bristles characteristic of the genus. 
Empty cell-walls are frequently found, but Mr. Archer has never 
before seen what (sometimes at least) becomes of the contents, 
imagining that they become removed as zoospores, which indeed 
may likely be often the case. In the present examples, however, 
the contents of many of the cells, after emergence through a slit or 
opening in the parent cell-wall, seemed to have become massed 
into an elliptic, compressed, spore-like body, enveloped by a sharply- 
bounded hyaline mucous covering. When the narrow view of this 
elliptic, fruit-like body is towards the observer, at each end can be 
seen a minute, somewhat wedge-shaped, or funnel-shaped opening 
in the mucous covering reaching to the cell-wall. Might this pos- 
sibly indicate the position of an aperture for the admission of 
