9 



in the neighbouring countries. Bornholm's algal flora has thus been investigated, in 

 connection with that of the inner Baltic, by Krok ' who gave valuable information 

 regarding this region, not investigated until then. During the years 1870 — 1875 two 

 expeditions were made from Kiel respectively to the Baltic and to the North Sea, 

 on which occasions some dredgings were also made in the Danish waters, mostly 

 in the Great Belt, and reports on these have been given by P. Magnus^. By these 

 dredgings the existence of Algae at great depths was determined in the Great Belt, 

 among which were some species not found before in the Danish waters (Antitham- 

 mion Plumula, Chylocladia clavellosa (Loinentaria clavellosa), some Liihothamion-specieH 

 and the new species Callithamnion {Rhodochorton) membranaceum Magn.). 



The marine Alga? have not in general been included in the Danish local florae, 

 or only the most obvious mentioned en passant; in J. P. Jacobsen's list of the 

 plants'' found in L?es0 and Anholt only some few species of marine Algae from 

 each of these islands have also been mentioned. Collin's work on the marine 

 fauna ^ of the Limfjord contains some remarks about the flora of this fjord, in 

 which some of the most important species in the composition of the flora are 

 mentioned, partly from the information given by J. P. Jacobsen. The number of 

 the species stated is however also here too small to be of any importance in flo- 

 ristic regard. One of the species mentioned, Rhodomenia mamillosa {Gigartina ma- 

 millosa (Good, et Woodw.) J. Ag.) is however of interest, as it had not previously 

 been found on the coasts of Denmark. 



For two smaller groups however we find special contributions in the literature. 

 The Characece, which in this country have not usually been studied in connection 

 with the other Algae, were included in two editions af Lange's manual ' and were 

 later exhaustively studied by P. Nielsen, especially in South West Sealand''. In 

 1880 I published a preliminary report on the submarine FoHc/ie/ja-species , the 

 number of the known Danish species being thereby augmented'. 



Collections employed for the present work. 



My work is naturally mostly based upon my own collections, but it need 

 hardly be said that 1 have also employed all the marine Algae accessible to me 



' Til. O. B. N. Krok, Algfloran i inre Ostersjon ocli Bottniska viken. Ofversigt af K. Vet. Akad. 

 Forhandl. 1869. 



' P. MAGNU.S, Botaiiische Untersuchungen der Pommerania-Expedition vom 3. bis 24. August. Aus 

 dem Bericht iiber die Expedition.... Pommerania. Kiel 1873. 



P. Magnus, Die botanischen Ergebnisse der Nordseefahrt voin 21. .lull bis S). Septbr. 1872. II. 

 Jabresber. der Kommission z. Uiiters. d. deutsch. Meere in Kiel. Berlin 1874, 



' .1. P. .Iacobsen, Fortegnelse over de paa L;es0 og Anbolt i 1870 fuiidne Planter. Botan. Tids- 

 skrift. 11. Bind 1879. 



^ Jonas Collin, Om Limfjordens marine Fauna. Kjobenhavn 1884. 



' JoH. Lange, Haandbog i den danske Flora. 2. edition 1859, 3. edition 1864. 



'' P. NiRLSEN, Exsiccatsamling af Characeer, navnlig fra Danmark. 1869. Idem, SydvestsjwUands 

 Vegetation. Botanisk Tidsskrift 2. R. 2. Bd. 1873. 

 ' Botanisk Tidsskrift Bd. 12, p. 11. 



I). K. 1). ViilensU. Selsk. Skr., 7. ItiL-Uke, ii;itin \ ideiisk. dk Jiuitlleni. AI'd. VII. 1. 2 



