Dr. Diimimond, who discovered it cast on shore at Larne, in
August, 1806;—unless, as Dr. Arnott supposes, it he the TJlm
rubens of Hudson, a synonyme which I think better referable to
Dudresnaia divaricata.
It is common on many parts of the coasts of England, Scotland,
and Ireland, and is found in the Isle of Jersey by Miss
White; but appears to be, in some districts, less common than
M. virescens. This, Mr. Ralfs remarks, is the case about Penzance,
in Cornwall, and on the Welsh Coast. It is frequent in
Torbay, and in other localities of the south of England; and
very abundant on the west and south-west coasts of Ireland. In
the north-east of Ireland, where it was first noticed, Mr. Thompson
finds it in profusion, and has observed, among heaps of seaweed
cast on shore “ the partiality of the Idotea cestrum, Leach,
for the gelatinous Mesogloia vermicularis, plants of which it had
very much eaten, leaving the other Algse, of which there were
many species in the heap quite untouched.”
I have given the Mediterranean station on the authority of
Professor Meneghini, who has received it from Venice and from
Trieste. It is omitted by Agardh in his Algse Mediterranese.
M. vermicularis may be considered the type of the genus
Mesogloia, as now defined by J. Agardh, consisting of that portion
of the older genus to which I formerly applied the name of
Triclwcladia, subsequently changed into Helminthocladia. When
I proposed M. multifida of Agardh, as the type of the restricted
genus Mesogloia, I was not aware that that species is identical
in structure with Nemaleon of Tozzetti. To Nemaleon, M. multifida
is therefore now referred; M. Hudsoni (of British authors)
and M. coccinea to Dudresnaia; and M. moniliformis. Griff, to
Crouania. Respecting the proper place of M. purpurea, Harv.
I am at present doubtful.
Fig. 1. Mesogloia vermicularis, (small specimen);— natural size. 2. Portion
of the filaments, axial and peripherical, of which the frond is composed.
3. Apex, with its spore, and cluster of rUtimate f i b r e s '