a=) {9 
developed ones. They almost coincide in shape with those in L. Phi- 
lippii and L. lichenoides, but are smaller, about 500 » in diameter at 
the base, and apparently as a rule more acute. The central parts of the 
,conjugation cell‘ bear a bundle of somewhat elongated paranemata. 
The present form does not differ much from the Funafuti plant, 
which I provisionally name f. genuina. The latter has a rosy colour, 
sometimes with a feeble purplish shade, while f. purpurascens is darker 
or lighter purplish. The crust is frequently a little thicker and less ir- 
regular, but on the other hand generally with slightly smaller cells than 
in f. génuina. So also the conceptacles of sporangia being a little smaller, 
and in the few ones that I have seen not flattened in the central parts. 
Between Koh Mesan and Cape Liant on a depth of 9 fathoms (not quite 
certain); 15 naut. miles E. of Koh Chuen, 10 fathoms; the north side of Koh 
Mesan, 10—15 fathoms; between Koh Mesan and Cape Liant, 5—8 fathoms; 
the north point of Koh Chang on Coral-reefs; and Koh Kahdat in 2 fathoms 
water. 
Area: South Pacific Ocean: Funafuti (f. genwina). 
4, I. siamense Fosl. mscr. 
Thallus forming delicate, light rosy, smooth crusts or nearly 
so on divers hard objects, 30—100 » thick. Conceptacles of spo- 
rangia convex, rather prominent, 300—500, in diameter. Sporangia 
four-parted. Conceptacles of cystocarps conical, 350—600 » in 
diameter. 
f. minuta Fos). mscr. 
The crust 30-60 » thick. Conceptacles of sporangia 300— 
400 » in diameter, Sporangia 60—70 yp long, 25—30y broad. Con- 
ceptacles of cystocarps 350—450 4 in diameter. 
f. simulans Fos]. mscr. 
The crust 50—100 u thick. Conceptacles of sporangia 400— 
300 in diameter. Sporangia 140—160, long and 60--80, thick. 
Conceptacles of cystocarps 500—600 y in diameter. 
This is one of the most delicate of the species of this genus at- 
tached to hard objects. It sticks especially to Corals, but is also met 
with on stones, shells of Mollusks or even attached to other calcareous 
Algae. The colour is in a dried state a light rosy, sometimes, however, 
with a greyish-green shade. The crust is at first almost orbicular, here 
and there with slightly crenulate margin. In an old state it becomes 
more irregular in outline, and more crusts founded near each other get 
fully confluent without any visible limit, at length forming an apparently 
solitary crust up to about 12 mm. in diameter, often, however, much 
smaller, or but 3 mm. in a fertile stage (f. minuta). But sometimes it 
almost covers small shells of Mollusks (f. simulans). It is smooth and 
not or very feebly shining. The smoothness of the crust depends how- 
ever on that of the substratum, although it appears sometimes to become 
a little uneven in an old stage even on a plain substratum, partly by 
9* 
