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The species of the genus Ceramium, unless, with earlier writers,
we reduce the multiplied forms presented to the eye to three or
four types, are not only very numerous, and very widely dispersed,
but are so closely connected together by doubtful looking
varieties, that their study and disentanglement becomes a task of
much difficulty. Until of late years British authors have been
contented to recognise but three, C. rubrum, C. diaphanum and
C. ciliatum ; to which, in the ‘ Manual ’, I ventured to add two
others. But now, since Kützing has published, though with less
perfect materials to work upon than exist in British Herbaria,
no less than forty-two which he divides into six genera (!) ; the
attention of British botanists has been aroused, and many new
Ceramia added to our list.
Among these is the subject of the present plate, which having
been published in two collections of dried specimens, is pretty
generally known to British botanists, though perhaps not under
the name here given. I believe it was first detected by Mrs.
Griffiths, from whom I received specimens several years ago,
and hy her has always been regarded as a well marked species,
distinguished from those most nearly allied to it, by a certain
harshness to the touch, or rigidity, as well as by its very patent
forking. In these respects it diifers from C. fastigiatum, which
it most nearly resembles.
Of the synonyme of Kützing, I feel confident, having submitted
a specimen to that author ; but by him C. nodosum is placed
in his genus Hormoceras, the character of which is to have immersed
tetraspores, whereas, I find these to be erumpent, a
character which would place it in Gongroceras, Kütz. Possibly
Kützing’s specimens had not mature fruit.
Occasionally, tufted, root-like fibres issue from the swollen
joints, as I find on Miss Ball’s and Miss Gower’s specimens.
Kg. 1. Ce r a m iu m n o d o sum :— o f the natural size. 2. Upper portion of a
filament. 3. Portion of a fertile frond, witli favellæ. 4. Portion of a
fertile frond with tetraspores :— all more or less UgUi