Fronds densely tufted, from four to eight inches high, as thick as a crow’s 
quill, cylindrical, rising with a simple stem from one to three inches in 
length, then forked, and afterwards repeatedly and closely dichotomous ; 
the axils rounded. Apices of equal length ructification, of two kinds on 
distinct plants; 1, fleshy warts of a pale pimky colour, from a quarter to 
half an inch in length, bursting out irregularly from various parts of the 
branches, composed of vertical, dichotomous, moniliform, slender filaments, 
among which are thickly scattered large, oval favelle, containing a densely 
compacted cluster of conical spores. 2, oblong ¢etraspores, divided cross- 
wise, scattered at intervals among the filaments of the periphery of the frond, 
through all the upper branches of plants which produce them, vertical, 
deeply sunk. Colour a dark brownish red. Swéstance cartilaginous. 
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The genus Polyides is remarkable for its singular fructification, 
which strikingly differs both in appearance and structure from 
that of any other of the Rhodospermee. In appearance the con- 
ceptacular fruit most nearly resembles what are called zemathecia, 
but the distinct and isolated favel/e which it contains are very 
different from the contents of those imperfectly organized excres- 
cences. Here, in what-look hike irregular warts, we have most 
perfectly formed and symmetrically arranged spores. The ¢e¢ra- 
spores, which are now, I believe, described for the first time, were 
discovered by Mrs. Griffiths, whose researches into the fructifi- 
cation of the Algze are beyond all praise, and to her I am in- 
debted for specimens, producing this description of fruit. It is 
found in winter, but on plants which do not form warts. 
Polyides rotundus has a wide range in the northern hemi- 
sphere, bemg found through most of the cold and temperate lati- 
tudes of the Atlantic. It is perhaps the only species of the 
genus ; the P. D’ Urvillei of Bory bemg a doubtful species, very 
possibly not a congener. 
I follow Greville in retaming the specific name adopted in the 
great work of Turner, the foundation of modern Phycology, in 
place of that selected by Agardh from Bauhin’s ‘ Pizaw’, though 
to the latter the mere priority may belong. ‘The truth is, that 
the strong resemblance between Polyides rotundus and Furcellaria 
Jastigiata (Fucus lumbricalis, Gm.), has caused their synonymy 
to be so confused in the works of early writers, that it is a ques- 
tion to which of them Bauhin applied the name /umbricalis. 
Even Linneeus confounded one with the other. 
Fig. 1. Potyrpes rotunpUws :—of the natural size. 2. Transverse section of the 
frond, and of awart. 3. A favella. 4. A spore from the same. 5. One of 
the filaments of which the wart is composed. 6. Transverse section of a 
frond, with ¢etraspores. 7. Tetraspores :—all more or less highly magnified. 
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