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folia, the meshes of the reticulations longer, and the dots of
fructification more oblong.” “ It is much easier,” adds this
acute observer, “ to see the difference than to describe it in
words.” The most obvious difference lies in the colour P. plantaginea
being of a clear dark brown; P. latifolia always very
pale. P. plantaginea also is usually much narrower, and greatly
more tapering, truly cuneate at the base, and much less wavy;
but I possess specimens as broad and as little tapering below as
many referred to P. latifolia. Nor am I very confident, after an
attentive comparison of a multitude of specimens, whether there
is any absolutely distinguishing character between the two except
colour, if that be admitted as sufficient. Late in the season P.
latifolia becomes as coarse and thick as P. plantaginea, and will
not in the least adliere to paper. A specimen, from Trieste, in
Sir W. J. Hooker’s herbarium is identical with those from Devonshire
; but Dr. J. Agardli states that his Mediterranean specimens
are thicker than British ones: it is therefore obvious that the
substance varies as much in the Mediterranean as I have observed
it to do in our seas.
The genus Punotaria is exactly analogous among Dictyotese to
Ulva in UlvaceEe, and so cldsely do its species resemble the Ulvie
in form and substance, that without reference to fructification,
or without a close examination of the structure of the frond, a
young botanist might sometimes confound the species of one genus
with those of the other. It requires also a careful examination
to distinguish at all times between Laminaria debilis and Punc-
taria latifolia, the form and colour of both being nearly identical.
The Laminaria is, however, to the naked eye, more glossy and
adheres much less firmly to paper; and its structure, instead of
being reticulated is closely cellular.
-natural size. 3. Base of the F ig . 1 . P u n o t a r ia lATiFOMA: .--- ------------------------f--r-o- nd and scutate
rxououti j- -^miioaugiynibiyfihecudi.. 3. Portion voaf the frond, show.. ing t-h--e-^ r--e--t-i-cifrated ^structure,
and spots of fructification, vertical view magnified. 4. Sorus, lateral
view;— magnified.