343 



doubtedly connected by Lntermediate ones oughl to be united, 

 and aro onlv 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 hånd so manv species new to the flora have been 

 found thai they have helped almost to donble 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 

 Færoes, besides the description of the ditTerent alga-associations, etc. 

 1 hope to be able to give some notes on the plant -geographical 

 position of the Færoese alga -flora compared with those of the 

 nearest adjacent counlries. 



It is here my pleasant duty to express my sincere gralitude to 

 the many who have in various ways helped me in this work. My 

 thanks are more particularlv due to Dr. E. Bornet, who kindly 

 helped me with regard to the determination of some Caltithamnion ; 

 to Mr. M. Foslie, who determined my collection of calcareous 

 algæ; to Dr. Kuckuck, who, duringa short visit I paid to Heligoland, 

 gave me valuable advice especially with regard to my Færoese 

 species of Ectocarpus ; to Professor Sauvageau for his kind assi- 

 stance in connection with my Myrionemaceae and Sphacelariaceae; 

 and to Mr. Joh s. Schmidt for determining the greater part of my 

 blue-green algæ. Above all I would express my warm thanks to 

 Dr. Ro s en vinge for his constant kind assistance which was of 

 great value to me on account of his wide experience and knowledge 

 of the Northern Algæ, 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 particularlv Dr. 

 Nordstedt; Major Reinbold; Dr. Rostrup and Professor W i Ile. 



List of abbreviations 1 . 



J. Ag., Spec. Alg. = J. G. Agardh, Species genera et ordines 

 Algarum. 



Aresch., Phyc. Scand. = J. E. Areschoug, Phyceæ Scandinavicæ 

 marinæ. Upsaliæ, 1850. 



Farl., New Engl. Alg. — W. G. Farlow, Marine Algæ of New Eng- 

 land and adjacent coast. Washington 1881. 



1 Of the title of books and of names most commonly used. 



