343 
doubtedly connected by intermediate ones ought to be united, 
and are only to be regarded as forms or varieties of one and the 
same species. This has naturally reduced the number of the species, 
but on the other hand so many species new to the flora have been 
found that they have helped almost to double the number; some 
I have been obliged to describe as species new to science. 
In a later work on the alga-vegetation along the coast of the 
Faeroes, besides the description of the different alga-associations, etc. 
I hope to be able to give some notes on the plant-geographical 
position of the Faeroese alga-flora compared with those of the 
nearest adjacent countries. 
It is here my pleasant duty to express my sincere gratitude to 
the many who have in various ways helped me in this work. My 
thanks are more particularly due to Dr. E. Bornet, who kindly 
helped me with regard to the determination of some Callithamnion; 
to Mr. M. Foslie, who determined my collection of calcareous 
algae; to Dr. Kuckuck, who, during a short visit I paid to Heligoland, 
gave me valuable advice especially with regard to my Faeroese 
species of Ectocarpus; to Professor Sauvageau for his kind assi¬ 
stance in connection with my Myrionemaceae and Sphacelariaceae ; 
and to Mr. Johs. Schmidt for determining the greater part of my 
blue-green algae. Above all I would express my warm thanks to 
Dr. Rosenvinge for his constant kind assistance which was of 
great value to me on account of his wide experience and knowledge 
of the Northern Algae, especially those of Denmark and Greenland. 
Lastly, I must mention those who by lending me Exsiccata or ori¬ 
ginal specimens of species which are wanting in the Botanical Mu¬ 
seum in Copenhagen, rendered me great help, more particularly Dr. 
Nordstedt; Major Reinbold; Dr. Rostrup and Professor Wille. 
List of abbreviations 1 . 
J. Ag., Spec. Alg. = J. G. Agardh, Species genera et ordines 
Algarum. 
Aresch., Phyc. Scand. = J. E. Areschoug, Phyceae Scandinavicae 
marinae. Upsaliae, 1850. 
Farl., New Engl. Alg. — W. G. Farlow, Marine Algae of New Eng¬ 
land and adjacent coast. Washington 1881. 
1 Of the title of books and of names most commonly used. 
