2958.
DESMONEMA Dillwynii.
Dillwyn’s Desmonema.
CR YPTOGAMIA Alga.
Gen. Char. Plants suberect, fasciculated, branched.
Branches of two kinds; primary branches each with a connecting cell at its base; secondary branches without connecting cells. Filaments more or less coherent. Endochrome annulated.
Spec. Char. Filaments cohering mostly in pairs, bluish green, becoming brown plant. at the base of the
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m-
I- HE present genus approaches very closely to Calothrix,
(taking C. fasciculata, Ag. as the type of that genus,) but
differs in possessing, besides the ordinary branches of Calothrix,
each of which has a connecting cell at its base, other
branches without connecting cells and formed by dislocation
of the endochrome and subsequent elongation of each separated
portion. We propose to include in the genus, besides
the present species, Scytonema cirrhosum, t. 2920, which we
had included in our genus Ccenocoleus (see description of
t. 2940), but which further careful examination shows to belong
to Desmonema, some of its branches having connecting
cells at their base, which is not the case in C. Smithii. For
the specimens now figured we are indebted to the kindness of
wMer .h aRvael fds,e rwivheod hmasu cahls oa ssfuisrtnanischee.d us with notes, from which
Plant minute, flaccid, much-branched, seldom a quarter of
an inch in length, varying in colour from brown to bluish
green. Filaments usually cohering in pairs. Sheaths inconspicuous,
except those of the older filaments at the base of the
plant, which become thickened and of a reddish brown colour.
Endochrome annulated, more evidently so in the recently