tender, closely adhering to paper, with a slight gloss, when dry. Colour
when growing in the shade, a pale pinkish-purple, soon fading, on exposure
to sunshine, to a yellowish or greenish hue.
This is by much the most slender and dehcate, as it is also
the rarest, of the British species of Laurencia. Hitherto it has only
been found on the most southern shores of England and Ireland,
and this is probably the northern range of the species, as it is
not known on the continent of Europe, to the north of France ;
and the American specimens which have reached me are chiefly
from the coasts of Carolina and Florida. In Europe it is most
abundant in the Mediterranean Sea. Several stations are noticed
on the south coast of England, and wherever it grows it is generally
found in tolerable abundance, forming dense tufts, many
of which wül often be found in the same pool. The favourite
locality is in very shallow tide pools, fully exposed to the sun,
and frequently situated but a short distance helow high-water
mark : thus clearly showing a partiality for warmth which marks
the straggler from warmer latitudes. In such situations it frequently
becomes much discoloured, the purple hue, which is
natural to it, being exchanged for a greenish-yellow, at the same
time that the cellular substance is much softened.
I have received fine specimens from the shores of Tasmania,
where it appears to be not uncommon.
By Professor Kiitzing this species is referred to the genus
Alsidium, one of the Bhodomeleoe ; but I think few persons who
have carefully studied the species of Laurencia in a living state can
doubt its close affinity with the other individuals of that group.
Indeed some specimens of L. dasyphylla approach it so nearly
that it requires a pretty close examination to distinguish them
from strong-growing individuals of L. tenuissima. The L. striolata
of the Mediterranean seems scarcely distinct.
7
ij
Fig. 1. L aurencia tenuissima :— of the natural size. 2. Portion of a branch,
with tetraspores in the ranmli. 3. Fertile ramulus. 4. Tetraspores from
the same. 5. Apex of a branch, with ceramidia. 6. A ceramidium. 7.
Spores from the same. 8. Transverse section of the frond. w 'fon*
:A,
i 'l l