The fishes of the Danmark Expedition. 641 



on the other hand, though often occurring at less than ca. 100 m 

 (in the fjords the clay is mostly mixed with sand nearest the shore, 

 but pure further out), has a much greater extension in greater 

 depths. In the form of clay, sand (sometimes a few stones and 

 shells) or a mixture of both, it covers the deeper channels in the 

 fjords (e. g. at over 100 m in Lillebælt and Storebælt) and most of 

 the sea-bottom (except the above-mentioned banks with hard bottom) 

 in the deeper parts of the coastal plateau and outside this, as has 

 been shown by the Danmark and earlier Expeditions (see Böggild's 

 Chart in "Belgica" (Croisière océanographique dans la mer du Groen- 

 land 1905. Bruxelles 1909)). 



We may return again to Danmarks Havn to give a general 

 outline of the vegetation of the bottom. As a special work 

 on the algae collected on the Expedition has already been given ^, 

 I shall merely give here a general, floristic account of the algal 

 vegetation in Danmarks Havn and neighbouring waters, based on 

 the results of my dredgings. Both for the fishes and for the other 

 marine animals the algal vegetation is so important, that a little 

 more detained description of it will be of use, especially as I am 

 able to give a fairly complete and exact picture of it, which has 

 not been attempted from the botanical side (and it would have been 

 difficult to do so owing to the absence of direct observations). 

 Keeping first of all to the hard bottom, we find that all 

 algal vegetation is lacking in the uppermost ca. 2 m at the places, 

 where the ice has been free to rub against the foot of the cliffs, 

 whilst a few algae {Fusus inflatus L.) are found at sheltered places 

 (clefts in the rocks, shallow bays with rocks on the bottom), where 

 they often grow right up to the surface of the water, hi a little 

 deeper water (down to ca. 5 m) this typical, littoral alga is accom- 

 panied by others (Enteromorpha proliféra, Rodochorton Rothii, Calo- 

 thrix scopulorum etc.) and together they form the true littoral 

 region, which can thus be taken to lie between — 5 m. At 5 m 

 the character of the algal vegetation changes, the Chlorophyceae 

 being less prominent and Fucus common; in addition to the latter 

 we now find also the other Phaeophyceae (Laminaria saccharina, 

 L. solidung ala, Alaria Pylaii etc.) which give this region its character 

 and form the most copious vegetation of the arctic sea. Whilst this 

 Laminaria region is thus a continuation of the littoral region, it 

 on the other side completely changes its character at a depth of 

 ca. 15 m, the brown algae becoming replaced by red and calcareous 



^ On the Marine Algae from North-East Greenland, Ъу L. Kolderup-Rosenvinge 

 (Danmarks-Ekspeditionen til Grønlands Nordøstkyst 1806—08. Bd. III. Nr. 4. 

 Kbhvn. 1910). 



