12 THE MARINE ALGAE OF ESSEX.
Laminariaceae, Ag.
LAMINARIA, Lamour.
Laminaria saccharina, Lamour, "Ess.," p. 22. Harwich,
G..P. Hope; Blackwater estuary, E. M. Holmes; Clacton, E. M.
Holmes and E. A. B.; Felixstowe, G. Massee. A curious form of
this species is found at Clacton, and was plentifully strewn on the
beach in January, 1893. The frond, instead of being more or less
rugose and bullated in the centre with undulate or curled margins,
is perfectly flat and even, like that of L. digitata, and the fructifica-
tion forms an uninterrupted band down the centre of it. I have not
seen similar specimens from the South of England, but have
gathered the same variety near Berwick. Prof J. G. Agardh, to
whom I sent Berwick specimens, thought the plant might belong to
a new species, but it seems to me preferable to regard it, at least for
the present, as a variety of L. saccharina. The Clacton plants grow
to a length of several feet, but are seldom more than two inches
wide, several specimens in my possession being hardly more than one
inch wide, although when entire they were two or three feet long,
and bear mature sori. No other species of Laminaria has been re-
ported to occur on the Essex coast, and the species of the genus are
too conspicuous objects to be overlooked by collectors.
Cutleriaceae, Thur.
CUTLERIA, Grev.
Cutleria: multifida, Grev., "Alg. Brit," p. 60. Asexual
form on cement stone rock, Felixstowe ; sexual form washed ashore,
Harwich, G. P. Hope. The sexual and asexual plants of this genus
are so different in outward form that they have usually been regarded
by botanists as belonging to two separate and totally independent
genera, the former being named Cutleria multifida, the latter
Aglaosonia reptans. As a result of M. Falkenberg's researches into
the development of the Cutleriacae, it has been proved that the oospore
of these algae does not at once reproduce a Cutleria, but a hetero-
morphous thallus in no way distinguishable from an Aglaozonia. The
Zonaria parvula of Harvey's "Phycologia Britannica," and "the
Aglaozonia reptans of more modern works on British seaweeds, is
nothing more than the asexual form of Cutleria multifida. The true
Zonaria parvula of Greville, however, appears to be a really inde-
pendent species, which produces tetraspores very- much like those of
Dictyota.