the apices of shortened pinne, largish, binate, oval, containing many 
granules, naked, or surrounded by an imperfectly formed involucre of 
jointed ramuli. Colour, a very dark blackish, or brownish red ; becoming 
pinky, after long exposure and steeping in fresh water. Under the miero- 
scope small portions have a clear, full lake colour. Sudstance very soft and 
flaccid, adhering to paper. 
OOIIOmemrmrwmr mn 
Under Plate LXXX. of the first volume, I stated my inten- 
tions to separate the form usually considered by British botanists 
as a variety of Ptilota plumosa, from that species, as has already 
been done by Kiitzmg, 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 are sufficiently full, and the 
figures quoted sufficiently characteristic. And I much prefer the 
expressive name sericeus, which aptly defines the soft and si/hy 
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 rapestris as the most 
characteristic. 
Under Pt. plumosa I have already stated that our P#. 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 Algz, and there- 
fore mere difference of habitat cannot be insisted on as one of its 
diagnostic characters. The true difference between P#. plumosa 
and P. 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 in the 
Southern Hemisphere. 
Fig. 1. Prrtota sERICEA:—9of the natural size. 2. A plumule. 3. Young 
pimnule. 4. An older pinnule. 5. Part of a fertile pinnule, bearing 
tetraspores. 6. A tetraspore. 7. Pinnule with favelle. 8. A favella:— 
all more or less magnified, 
