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subject of the present description belongs. It contains, according
to A g a r d h , only the species venosa, lacerata, Bonnemaisoni,
punctata and ocellata. But then the Fucus ulvoides
of T u r n e r , which nobody seems to understand, must be referred
to it also, if it prove really distinct from !>. ocellata.
Another plant, again, belongs to this group, which is probably
different from T u r n e r ’s F. ulvoides. I mean an Alga found
at Plymouth hy Miss H i l l , and noticed by Mr T u r n e r in
his observations upon the last-named plant, of a thicker substance,
and abundantly furnished with very minute sori. Of
this species, however, I have not seen entire specimens. The
only plant in the group with which the D. Bonnemaisoni immediately
comes in contact, is D. lacerata, as they are both nerved
or veined towards the base of the frond; at least this character
is but rarely absent, though it varies greatly in degree. Both
species are apt to be inconstant iu their form ; hut that of lacerata
is more or less linear; while in Bonnemaisoni it is at
first more or less wedge-shaped, the summit afterwards frequently
expanding and widening, till the general outline is often
roundish or reniform. The best specific distinction, however,
is obtained from the fructification, which is marginal in JO. lacerata.
A curious appearance of what might be called pseudo-fructification,
has been detected upon D. Bonnemaisoni, by the
acute observation of Miss H i l l , and is represented at figs. 3.
and 8. I can only conjecture it to be a morbid enlargement of
the part from some unknown cause. The first discovery of this
species as a native of Britain, is undoubtedly due to my celebrated
friend Mrs G r i f f i t h s , and to the lady above mentioned.
Fig. I. D. Bonnemaisoni, with sori. Fig. 2. Ditto, with capsules. Pig. S.
Ditto, with the appearance observed by Miss H ill; natural size. Fig. 4.
One o f the sori. Fig. 5. Sporidia from ditto. Fig. 6. A capsule. Fig. 7.
Seeds from ditto. Fig. 8. Appearance observed by Miss Hill. Fig. 9.
Granules emitted by ditto when divided, from the morbidly enlarged and in-
crassatcd cellular s t r u c t u r e magnified.
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