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. 
nme 
This is by much the most slender and delicate, as it is also 
the rarest, of the British species of Zawrencia. 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 gene- 
rally found in tolerable abundance, forming dense tufts, many 
of which will 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 below high-water 
mark : thus clearly showing a partiality for warmth which marks 
the straggler from warmer latitudes. In such situations it fre- 
quently 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 Rhodomelee ; but I thnk few persons who 
have carefully studied the species of Zawrencia m a living state can 
doubt its close affinity with the other individuals of that group. 
Indeed some specimens of LZ. dasyphylla approach it so nearly 
that it requires a pretty close examination to distinguish them 
from strong-growing individuals of LZ. tenwissima. The L. striolata 
of the Mediterranean seems scarcely distinct. 
Fig. 1. Lavrencra TENUISSIMA :—of the natural size. 2. Portion of a branch, 
with tetraspores in the ramuli. 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. 
