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 Rhodophyceæ. Of this family the well-known 
specialist, the conservator Mr. M. FosLiE, several years ago undertook to determine 
the Melobesiee and Mag. sc. Mr. HENNING E. PETERSEN undertook to work up the 
genus Ceramium. Mr. Fosie 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 Algæ a large portion of the blue-green 
Alge I have collected was worked up by Dr. Joxs. 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 Algæ 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. Brocn, 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. Jon. PETERSEN and Dr. JoHs. Scamipr; also Dr. F. Borcesen, Dr. 
TH. Mortensen, Dr. C. H. OSTENFELD, Mag. A. OTTERSTROM, Mag. Ove PAULSEN 
and Mag. Henn. PETERSEN, who haye placed their collections of Danish marine 
Algæ 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. 
+ HENNING E. PETERSEN, Danske Arter af Slægten Ceramium (Roth) Lynepye. K. D. Vidensk. Selsk. 
Skr. 7. R. 5. B. No. 2 1908. 
2 Jous. Scaminr, Danmarks blaagronne Alger (Cyanophyceae Daniae) |. Hormogoneae. Botanisk 
Tidsskrift Bd. 22. 
° E. Rosrrup, Vejledning i den danske Flora.»Anden Del. Blomsterlose Planter. København 1904. 
