4 



nearly so much as I could have wished in this direction, and I am by no means 

 blind to the defects in my work just in this respect. But it is also quite clear to 

 me, that if I do not wish to postpone the publication of my work until an uncertain 

 future period, thus running the risk of never getting it finished, I must have it 

 published, even if my investigations are not complete on many points. 



On account of the extent of the work I have decided to have it published in 

 small portions , to begin with the Rhodophycese. Of this family the well-known 

 specialist, the conservator Mr. M. Foslie, several years ago undertook to determine 

 the Melobesiece and Mag. sc. Mr. Henning E. Petersen undertook to work up the 

 genus Ceramium. Mr. Foslie has already given the preliminary results of his 

 work in several publications, but they will be dealt with in more detail in the 

 present memoir. Mr. Petersen's work on the genus Ceramium was really destined 

 to be embodied as a part of the same, but as it was finished before mine and was 

 of considerable extent it was preferred to have it published separately ^ 



Besides the two mentioned groups of red Algae a large portion of the blue-green 

 Algai I have collected was worked up by Dr. Johs. Schmidt in 1899^'. It may also 

 be mentioned here, that mainly on the basis of my own collections and investiga- 

 tions I have been able to enumerate not a small number of species, which have not 

 been known before in the Danish waters, in my work on the Algaj in Rostrup's 

 Guide to the Danish flora 



My thanks are due to many persons, who during the many years that have 

 passed since I began my investigations have rendered me valuable assistance in 

 different ways. I would here mention especially the different captains, the late 

 fisheries supervisor Mr. A. Bloch, Commander P. Grove, the former fisheries super- 

 visor Mr. Holstein, the present fisheries supervisor Mr. W. Larsen, Captain Rosen- 

 kilde, the retired Captain C. Trolle; further the director of the Danish Biological 

 Station Dr. C. G. Joh. Petersen and Dr. Johs. Schmidt; also Dr. F. Borgesen, Dr. 

 Th. Mortensen, Dr. C. H. Ostenfeld, Mag. A. Otterstrom , Mag. Ove Paulsen 

 and Mag. Henn. Petersen, who have placed their collections of Danisli marine 

 Algae at my disposal. 



I desire here also to express my best thanks to the Directors of the Carlsberg 

 Fund for the assistance they have given to defray various expenses in connection 

 with the publication of this work, especially the charts and photographs of plants. 



1 Henning E. Petersen, Danske Arter af Slsegten Ceramium (Roth) Lyxgbye. K. D. Vidensk. Selsk. 

 Skr. 7. R. 5. R. No. 2 1908. 



'- Johs. Schmidt, Danmarks blaagrenne Alger {Cyanophyceae Daniae) I. Hormogoneae. Botanisk 

 Tidsskrift Bd. 22. 



^ E. RosTRUP, Vejledning i den danske Flora. Anden Del. Blomsterlese Planter. K0benhavn 1904. 



