94 H. JONSSON : MARINE ALGAL VEGETATION 



The positive results which are obtained with this small dredge are 

 satisfactory enough when the material is inspected with sufficient 

 criticism , but it should not be concluded with certainty from a 

 negative result (that is, when absolutely nothing comes up from the 

 bottom) that no plants grow there. In great depths, also, dredging 

 is difficult from a small rowing-boat. In some places only, in SW. 

 Iceland and E. Iceland, have I undertaken dredgings in a depth of 

 about 80 metres, and the result has been negative. In those places 

 where the plummet revealed a clayey bottom, it was certain that 

 no plants were growing there. Off S. and SW. Iceland I have met 

 with no vegetation at a greater depth than about 40 metres, but in 

 Rey5arfj6r5ur in E. Iceland, on the other hand, I have come across 

 plants at as great a depth as about 60 metres. This might indicate 

 that the vegetation extends further downwards in E.Iceland; but 

 as the observations are too few, this point must remain undecided 

 until further investigations are forthcoming. 



It was a fairly common occurrence, especially in the fjords of 

 E. Iceland, to encounter sunken fragments of algae (often strictly 

 littoral species) and of mosses in depths of more than 22 metres. 

 In SeySisfjorQur I came across leaves of Betula and Salix at a depth 

 of 14 — 20 metres. 



C. H. Ostenfeld (the Ingolf Expedition) found Lithothamnion 

 laeve in great quantities at a depth of 88 metres off the north coast 

 of Iceland, and R. Horring (on board the "Diana," off E. Iceland) 

 found Lithothamnion tophiforme at a depth of 70 metres. In depths 

 of from 60 to about 100 metres Horring found, in addition, frag- 

 ments of various algae, amongst which were strictly littoral species, 

 and of mosses which had evidently fallen to the bottom. In order 

 to draw the attention of future investigators to this matter it must 

 further be mentioned that Horring brought home in spirits a 

 young plant of Laminaria saccharina from a depth of from 81 to 

 104 metres (Mjoifjortmr, 14.5. 1898, St. XIII) and on the label was 

 written "In the trawl were many large Laminarice which had been 

 torn away from the bottom." The Laminaria brought home appeared 

 normal, and, if it had fallen to the bottom could only have lain 

 there for a short time. What is most likely is that the trawl passed 

 over an uneven bottom, and that the Laminaria^ grew at a lesser 

 depth than that mentioned; or is it possible that the deep-water 

 form of Laminaria saccharina ranges so far downwards? I leave it 

 to future investigation to decide this question. 



