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“ So far as our acquaintance with these little Algffi reaches, there appear
to exist four (if not five) distinct, yet kindred forms of figured ‘ Chroo-
coocaceEe ’—their remarkable shapes preclude their being regarded as
‘ Lichen-gonidia,’ but whether mature plants or stages in the growth of
any more complicated structure remains a problem. Ours are at least
forms which here and there recur, and one can at once recognise them as
always offering the same charaotersitics and as maintaining their apparent
individuality. Whether they are ‘ speoies ’ or not, it may be a matter
of convenience, should observers meet them elsewhere, and be able to
throw a light upon them, to have at least a means of their recognition;
for these reasons it occurs to me as desirable to record them under
Eeinsoh’s genus.”—W. Archer in Qrevillea i., p . 44.
T e trapedia C ru x -M ich a e ll. Beinsch Alg. Mitt. Frank,
Cells quadrate, lateral margins entire, with two shallow concavities,
each extending half the length of the side, thus producing
an obtuse-angled central prominence, deeply incised at
the angles, incisions diagonal, rectilineal, deep, acute below,
slightly expanding upwards, thus bisecting the angles, and
dividing the cell into four broadly cuneate segments, the upper
angles of which are subacute (the incisions ultimately completed,
and the cell breaking up ?) ; in side view lanceolate,
ends acute.
S iz e . Cells •008-'012 mm. diam.
Archer in Grevillea i., p. 45. Reinsch Algenflora, t. i., fig. 6.
In running water (very scantily) near Mullingar, Co. W est-
meath, Ireland.
Flate L X X X V I I . fig. 8. Cells magnified 600 diam.
T e trapedia R e in sch ia n a . Archer in Grevillea I., p. 46, t. 3, / .
11-13.
Cells quadrangular, two opposite margins excavated by a
wide triangular sinus, thus subdividing th e cell into two broadly
cuneate segments connected by a wide isthmus, and somewhat
convex on their lower margins ; the other two opposite margins
of the cell, th a t is the upper margins of the segments, very
slightly concave at the middle, somewhat raised towards the
acute outer an g le s; in side view oblong, constricted at the
middle, ends rounded.
S iz e . Largest cell ’OOTh-'Ol mm. diam.
In moor pools, Co. Dublin and Wicklow.
Plate LXXXVII. fig. 9. Cells magnified 600 diam.
Te trapedia se tig e ra . Archer in Grevillea i., p . 46, t. 3, fig. 14-17.
Cells triangular, the lateral margins somewhat deeply excavated
by a broad rounded sinus dividing the cell into three
lobes, rounded at the ends, and each terminated by a very
delicate straight bristle, in length about equal to the diameter
of the c e ll; in side view oblong, somewhat inflated at the
middle at each side, ends round, and each seen tipped by the
bristle.
S iz e . Cells without bristles •0062--0075 mm., including the
bristles -016--02 mm., from end to end.
In moor pools, Co. Dublin and Wicklow.
PUte L X X X V I I . fig. 10. Cells magnified about 600 diam. After
Archer.
Genus 90. SYNECHOCOCCUS. Nag. (1849.)
Cells oblong, usually single, sometimes 2-4 connected in a
series constituting a family. Cell membrane thin, cell-contents
blue green ; now and then yellow or pale orange. Tegument
absent. Division in one direction only.
Syirechococcus c ra ssu s. Archer Micr. Journ. 1867,p . 87.
Cells broadly elliptic, about one h a lf longer than broad ; cell
wall very thin.
In shallow pools. Bray’s Head, Ireland.
Larger than the largest of Nageli’s species (S. æruginosus), from which
it is also distinguished by its elliptic or egg-shaped cells, somewhat
narrowing towards the gradually rounded ends, and not cylindrical, with
rounded truncate ends.
No figures or measurements of this species have been published, and
only the hare description reproduced above.
Genus 91. G1OE 0TH EC E . Nag. (1849.)
Cells cylindrical-oblong, rounded at the ends ; division transversal
in one direction. Other characters as in Glæocapsa.
Tegument very thick, lamellose.
G loe o th e c e c y s tife r a . (Bass.) R alh. Alg. Fur. Ii., 61.
Cells oblong-cylindrical, 2-4 associated in families ; involved
in a special universal tegument which is globose or oval, l |- 8
times as long as broad. Cell-contents verdigris green.