684 



At the same period (1836) Lyngbye was dealing with the algæ- 

 vegetalion in a paper entitled »Rariora Codana«, which was only 

 piiblished much later (1879) by Professor Warming. Lyngbye 

 makes a division into three Zones : firstly that of the Ulvaceæ, reaching 

 from the surface of the sea to a depth of 30 feet, secondly that of 

 the Florideæ, as far down as from 30 to 60 feet, and finally that of 

 the Laminar iaceæ, from 50 to 90 feet. For each zone he mentions 

 a number of specifically characteristic species, partly from Denmark, 

 partly from the Færoes and from Norway. Lyngbye's division 

 does not however seem quite satisfactory to me. It would have 

 been most natural to determine the zone of the Florideæ as the 

 lowest one, as in J.Agardh's division. Besides, several species (I 

 refer only to the Færoese specimens mentioned by Lyngbye) do not 

 occur in the depths mentioned. Thus Fiiciis loreiis, Scytosiplwn fdum 

 lomentarius and Callithamnion arbiiscula are mentioned as belonging 

 to the zone of the Florideæ; they are, however, all littoral. Lami- 

 naria agarum is given as in the zone of the Laminariaceæ , but it 

 has never been fonnd in the Færoes; to this zone he also refers 

 Callithamnion arbuscula. It ~ seems as if his memory had been 

 failing him, and most likely his strength had already grown less 

 as it was but a short time before his death (compare Warming' s 

 introduction [60, page 3]). It must be remembered also, that he 

 wrote his paper many years after his visit to the Færoes. 



In 1844 Ørsted published his well-known work, »De Re- 

 gion ibu s Marinis«, in wdiich, relying on the above-mentioned 

 work of J. Agardh, he gives a detailed description of the algal 

 vegetation of the Sound. He subdivides this into firstly, »Regio 

 Algarum viridium s. Chlorospermearum« , reaching from the surface 

 of the sea to a depth of 2 to 5 fathoms and embracing: »Snbregio 

 Oscillatorinearum« above, »Snbregio Uluacearum« below; secondly, »/?e- 

 gio Algarum olivacearum s. Melanospermear nm c<,conshi'mg of »Snbregio 

 Fncoidearnm et Zosteræ marinæ« and »Snbregio Laminariearnm« 

 below it, and whose upper limit Hes in depths of 3 to 5 fathoms 

 and lower in 7 to 8 fathoms; fmally, Regio Algarnm pnrpnrearnm 

 s. Rhodospermearnm, in depths of 8 to 20 fathoms. Ørsted seeks 

 the chief explanation for this distribution of the Algæ in the varying 

 degrees of penetration of the hght through the water, and, in connec- 

 tion with this, in the different colour of the light at different depths. 



In addition to these authors, Areschoug, Kleen, Ekman 

 and others have also contributed to our knowledge of the algæ of 



