684 



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

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

 published much later (1879) by Professor Warming. Lyngbye 

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

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

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

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

 a number of specifically characteristic species, partly from Denmark, 

 partly from the Faeroes 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 Floridece as the 

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

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

 occur in the depths mentioned. Thus Fucus loreus, Scytosiphon fihim 

 lomentarius and Callithamnion arbuscula are mentioned as belonging 

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

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

 has never been found in the Faeroes; to this zone he also refers 

 Callithamnion arbuscula. It seems as if his memory had been 

 failing him, and most likeW his strength had alread}^ 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 Faeroes. 



In 1844 0rsted published his well-known work, »De Re- 

 gion ibus Marinis«, in which, 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: y>Subregio 

 Oscillatorinearum« above, »Subregio Ulvacearum« below; secondl\% »Re- 

 gio Algarum olivacearum s. Melanospermearum« , consisting of »Subregio 

 Fucoidearum et Zosterce marinw« and y>Subregio Laminariearum« 

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

 and lower in 7 to 8 fathoms; finally, Regio Algarum purpurearum 

 s. Rhodospermearum, in depths of 8 to 20 fathoms. 0rsted seeks 

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

 degrees of penetration of the light 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 algae of 



