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that the filaments of the Greenland specimens also vary rather con¬ 
siderably with regard to thickness, never, however, exceeding 16 [a, 
but as mentioned above, the Fseroese specimens are often much 
thicker, and in this they come very near to the extremely interesting 
aerial species of the Floridese Rhodochorton islandicnm Rosenv. 1 which 
Helgi Jonsson gathered on his native island. The Fseroese 
material, which especially resembled this species and which perhaps 
even makes it doubtful whether Rhodochorton islandicnm ought to 
retain its value as a distinct species, was also gathered by Jonsson 
during his visit to the Faeroes in 1897. As the material in question 
appears to me to be of special interest, I will describe it more fully. 
The material was gathered in Skaalefjord, late in October. With 
reference to its habitat Jonsson writes in his diary as follows: — 
»Forms a continuous covering on the rocks, and occurs most 
often above the water, but is, however, now and then washed by 
the waves«. To this I may remark that there is no doubt whatever 
that the alga growing here in the fjord where no tide is felt or 
where it is almost imperceptible, would not, during summer in 
calm weallier or when a land-breeze was blowing, be wetted by 
sea-water for a long period, even if it did not grow very far above 
sea-level, just a few inches higher making a great difference here in 
the fjord. The Fseroese material — a very small quantity \—is sterile; 
it corresponded, as a whole, closely to Rosenvinge’s exhaustive 
description and figures, but I have not come across such thin de- 
current threads as, according to Rosenvinge’s description, are to 
be found on Rh. islandicnm ; it is true that a few thin threads oc¬ 
curred intermixed, but from a biological point of view they did not 
seem to be different from the thicker ones. The thickness of the 
erect branches varied from 16 to 29 [a, i. e. between two somewhat 
greater extremes than those mentioned by Rosenvinge. The cells 
of the lower part are about as long as broad and those of the upper 
part twice or thrice as long as broad. The cell-walls are often 
very thick, as much as 5 [a. A few poorly developed filaments of 
Callithamnion scopnlornm occurred intermixed in the material. This 
Rhodochorton impressed me as being a stunted Rhodochorton Rothii 
which had altered in appearance on account of its habitat, and in 
the Fseroese material I came across the most evenly transitional 
stages between this peculiar form and typical Rhodochorton Rothii. 
1 Rosenvinge, L. K older up: Note sur une Floridee aerienne (Rhodochorton 
islandicum nov. sp.). Botanisk Tidsskrift. 23. Bind, p. 61. Kobenhavn. 1900. 
