70 ON THE GENERA ANADYOMENE AND MICRODICTYON. 
This genus is described from a single specimen in the British Mu- 
seum, collected by Mr. Menzies; it has evidently been torn by the 
waves on the edges, and is not in such a good state as one might wish. 
There are three, or rather the parts of three, oblong fronds, a smaller 
one from each side of the base of the larger, each of the three sup- 
ported by a thin articulated filament, arising from an elongated stem 
an inch or so in length, with opposite branches. 
As fixed on the paper with gum, the three fronds seem to coalesce 
at the edge, where they touch or overlap, but this may be only from 
the manner in which the specimen is mounted, and I fear that if it were 
attempted to be re-spread, the specimen might be injured, so we must 
wait until more specimens are obtained to settle the form of the edges 
of the frond and other particulars relating to it. 
There can be no doubt that its habit is very different from that of 
the species of the genus Microdictyon, and that it is a beautiful Alga. 
I can hardly understand how it has remained so long undescribed, 
but I cannot find any reference to it in any work within my reach. 
1. Phyllodictyon pulcherrimum. 
Han. Gulf of Mexico, Archibald Menzies, £sq.,1802, Herb. Brit. Mus. 
The fronds are ten inches long and about three inches wide. 
The Cladophora (?) anastomosans, Harvey, ‘ Phycologia Australica,’ 
. 101, is nearly allied to this genus. It must form a genus to which 
the name of P/erodictyon may be applied. It differs from PAyllo- 
dictyon, in which all the joints of the oblong frond are of nearly the 
same length, in the broad triangular shape of the frond, produced by the 
different length of the joints of the stipes and of the main branches. 
These joints gradually and regularly diminish in length as they approach 
the margin of the frond, “the former is stipitate, dichotomously bi-tri- 
pinnate, the pinne and pinnule opposite and horizontally patent, the 
alternate pinnules here and there anastomosing,” and “arising from a 
wall of irregular branched filaments.” — Dr. Harvey believes the single 
specimen described and figured, which was cast ashore near Fre- 
mantle, Swan River, to be the young state of a species that is more 
netted in its adult age; the form of the frond and the length of 
= the basal joint cannot be altered in the growth, and therefore Pfero- 
dielyon anastomosans must always be easily distinguished from Phyllo- 
— . Dr. Harvey mentions Cladophora composita ; this is a section of the 
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