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with wide margins, sessile on the sides of short, simple, or branched peduncles,
which rise from the ramuli near their base. Favellce mostly bilobed, involúcrate,
borne on lateral peduncles, or terminating shortened ramuli. Substance
flaccid,' adhering to paper. Colour a fine rose red, soon fading in
fresh water. Sometimes the ramuli are alternate, and then the plant becomes
C. repens of authors.
This pretty little species of Callithamnion was named by Dr.
Roth after its discoverer Mr. Dawson Turner, the celebrated
author of the Historia Fucorum and numerous other learned
works. It was first observed on the Norfolk coast ; and has
since been found on most of the shores of Furope, where it not
uncommonly creeps over the fronds of various small Algæ.
After as careful study as I have been able to give the subject,
I am persuaded that Col. repens of authors is nothing more than
an imperfectly developed state of this species, in which either the
plant is in a very young state, or, if more fully grown, the branches
are mostly alternate. I have examined numerous specimens in
which the alternate and opposite branching occurs in difierent
parts of the same specimens ; and as this is the chief character
insisted on by those who contend for two species, its failure must
destroy one of them. The form which has been called C. Turneri
exhibits the species in its most perfect state, and therefore this
name, apart from its commemorative significancy, deserves to be
retained.
The fructification of this species differs in some respects from
that of other Callithamnia, and shows an approach to Griffithsia,
especially in the involucrated favellæ. The tetraspores are, however,
not so regularly disposed as in that genus ; and the habit
is much more like that of Callithamnion.
Fig. 1. Callithamnion T u rn eri -.— o f tie natural size. 2. Branch with
tetraspores.^ 3. Bortion of the same. 4. A tetraspore. 5. Portion of a
filament with favellæ. 6. Hamulus and pedunculate favella.
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