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to imply a structure different from that in the genus I have
named Monema. Schizonema lacustre of A g a r d h seems also
to be a true species. But respecting S. Grateloupii, corym-
hosum and ramosissimum, I have no means of deciding whether
they belong to Monema or Schizonema.
Gloionema has been justly observed by Captain C a r m i c
h a e l to differ from S. Smithii in a generic sense, only by
its simple form. Perhaps some other character may hereafter
be found to distinguish i t ; for if a plant (of which I have my
doubts), it is certainly distinct from Schizonema. I do not see,
however, bow the genus Hydrurus can be sustained; for the
character, “ Frons gelatinosa filis coadunatis hyalinis granula
elliptica seriatim continentibus composita,” seems to apply
strictly to Schizonema. Hydrurus Vaucherii, A g. probably
belongs to Schizonema; but my copy of V a u c h e r ’s work is
unfortunately not at band for consultation. Hydrurus penicillatus,
as far as I can judge from dried specimens, I agree
with A g a r d h really forms a distinct genus ; but its character
will require to be modified.
Parasitic upon one of my figures I have represented at a,
Exilaria fasciculatum {Diatoma fasciculatum, A g.), which
I was so fortunate as to observe fixed to a base similar to that
in Exilaria fulgens.
If
Fig. 1. Schizonema Smithii, natural size. Fig. 2. Portion o f a frond. Fig. 3.
Termination of a frond. Fig. 4. Geminate granules, viewed in fron t and
profile. Fig. 5. Granules after separation ; magnified.
A*
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