Geo. K. Sutherland. 
<83 
ADDITIONAL NOTES ON MARINE PYRENOMYCETES. 
By Geo. K. Sutherland. 
[With Three Figures in the Text]. 
Orcadia pelvetiana nov. sp. (Fig. I, 1-4). 
YCELIUM in quibusdam locis, hyalinum; stroma nulla; 
perithecia simplicia, 110-140//. diam., globosa, mollia, pallida, 
thallo omnino immersa, ostiolo longissimo, 160-180//longo, 20-30// 
lato, cylindraceo vel fastigato, ad superficiem pertinente; asci 
clavati vel fusiformes curvatique, 50-65// x 11-13//, octospori; 
paraphyses deliquescentes ; sporidia fusiformia, curvata, circa 40 
X 4-5//, 3-septata, primo hyalina demura flavescentia. 
Hab. in thallo vivo Pelvetiae canaliculatae, Orkney and Clare 
Island. 
Sections ol Pharcidia-iniected thalli of Pelvetia, collected in the 
early part of last autumn, frequently showed spherical or more 
irregullar masses of very fine mycelium deeply buried in the 
medullary tissue. These were usually about 200// from the surface, 
and in many cases possessed imperfectly developed ostioles. The 
slender, hyaline hyphae and soft, white, immersed fruiting bodies 
were so different from the dark coloured, stouter mycelium and 
minute, leathery, superficial perithecia of Pharcidia that the two 
were obviously distinct. However, the absence of any form of 
spore made it impossible to name or place the fungus at that time. 
A subsequent examination of Ascophyllum nodosum revealed a fully 
matured species of similar habit and development for which the 
the genus Orcadia had to be created. Although this similarity gave 
a hint as to the probable position of the unknown form on Pelvetia, 
it was only later, when the mature ascigerous stage was found that 
it was proved conclusively to be another species of the new genus. 
The material was collected towards the end of autumn, primarily 
on account of its showing the late fruiting perithecia of Didymo- 
sphceria, but it enabled Orcadia to be identified and its action on the 
host to be more or less isolated. 
The localised mycelium occurs invariably interwoven with the 
very similar vegetative body of Mycosphcerella, in addition it may 
be with the diffuse Didymosphceria or the rapidly spreading Pharcidia. 
When their finer branches are so alike, as is the case in the first 
three, it is almost impossible to make out the relation of any one to 
the host, or to differentiate their individual action on its cells. 
