111'
the apices of shortened pinnæ, largish, binate, oval, containing many
granules, naked, or surrounded by an imperfectly formed involuerc of
jointed ramuli. Cohur, a very dark blackish, or brownish red ; becoming
pinky, after long exposure and steeping in fresh water. Under the microscope
small portions have a clear, fuU lake colour. Substance very soft and
flaccid, adhering to paper.
Under Plate LXXX. of the first volume, I stated my intentions
to separate the form usually considered by British botanists
as a variety of Ptilota plumosa, from that species, as has already
been done by Kiitzing, and I now fulfil that promise. I am
compelled, however, in deference to an earlier botanist, to adopt
a different specific name from that imposed by Kiitzing. That our
plant is really the Fucus sericeus of Gmelin, as well as the F.
Ptilotus and F. pectinatus of Gunner, admits of scarcely a doubt.
The descriptions of these authors arc sufficiently full, and the
figures quoted sufficiently characteristic. And I much prefer the
expressive name sericeus, which aptly defines the soft and silky
substance of this species, to the much more modern elegans, which,
however applicable in the abstract, is scarcely characteristic of a
plant which is probably the least elegant of the beautiful genus
to which it belongs. Had I been at liberty to choose a specific
name, I should certainly have proposed npestris as the most
characteristic.
Under Ft. plumosa I have already stated that our Pt. sericea
“ invariably ” grows on rocks. This is using rather too strong
an expression, for though it very generally does grow on rocks,
it is sometimes found on several of the smaller Algæ, and therefore
mere difference of habitat cannot be insisted on as one of its
diagnostic characters. The true difference between Pt. plumosa
and Pt. sericea must be placed in the different structure of the
ramuli, these being much more simple in the present plant.
Two other species, with similarly jointed ramuli, are found iu the
Southern Hemisphere.
I , '
Fig. 1. P tilota see icea :—of the natural me. 2. A plumule. 3. Young
pinnule. 4. An older pinnule. 5. Part of a fertile pinnule, bearing
tetraspores. 6. A tetraspore. 7. Pinnule witb favellæ. 8. A favella:—
all more or less magnifed.
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