496 
The specimens referred to var. arctica are marked by having 
a thick, transverse section, most commonly about 35 //, hut varying 
from 29 p to 45 p. In this instance also the thallus are saccate at 
the base and gradually divide into more or less deeply cleft seg¬ 
ments of uncertain number. 
Finally, to var. intestirxiformis Rosenv. I have only felt justified 
in referring a few single specimens from Klaksvig; they agreed 
fairly well with Rosenvinge’s description, and resembled also the 
Greenland specimens. 
Monostroma Grevillei occurs on sheltered, but most frequently 
on fairly exposed coasts, where it is met with near low-water mark 
and at half-tide level. It grows by preference in shallow hollows, 
which contain just a little water left by the receding tide. In such 
localities it often forms large green growths; it grows by choice 
most usually on Gorallina , but may also be found attached to other 
algEe: Fucacece, etc. as well as to rocks. It is more particularly a 
spring alga and has been observed in great abundance in April, 
May, June and July but may also occur later on; and fruiting 
specimens occurred in those months. It had already been found 
by Lyngbye, as his herbarium contains a small specimen from 
Kvivig, gathered June 9th. and called by him Ulua plicata (Hydropliyt., 
p. 30) which is unquestionably this species. 
Judging from its many habitats, this species is probably common 
along the coasts of the Faeroes. 
168. M. undulatum Wittr. Monostr., p. 46, tab. 3, fig. 9. 
f. typica Foslie, Contrib. I, p. 114. 
/. Farlowii Foslie, 1. c. M. pulchrum Farlow New. Engl. Alg., p. 41. 
The specimens referred to the typical form agree well with 
Foslie’s description, a transverse section of the monostromatic 
part of the frond showing a thickness of about 20—56//. 
The specimens referred to f. Farlowii were, on the other hand, 
thinner, about 18—27 p thick. They also agreed well with Foslie’s 
description and bore a fairly close resemblance to an original 
specimen of M. pulchrum Fosl. preserved in the museum in Co¬ 
penhagen. 
This species occurs littorally at half-tide level and near low- 
water mark, or sublittorally in shallow water. It is met with on 
exposed coasts as well as in sheltered localities, and grows some¬ 
times as an epiphyte on other algae especially Corallina and some¬ 
times directly on rocks. 
