MAEINE BIOLOGICAL STATION ON PUFFIN ISLAND. 11 



F. siliquosus in its lower part, along with many shell fish ; 

 (3) ''regio Corallinarum," with C or allina officinalis, many 

 ascidians, sea-anemones, molluscs, worms and sponges; 

 and (4) " regio Laminariarum," with nudibranchs, star- 

 fishes, ascidians, Helcion, Caprella, Nympho7i and Echini. 

 The close correspondence between this classification and 

 that of the French observers is very remarkable. 



Ten years later A. S. Orsted, in an important essay,* 

 showed that in the Strait of Oresund, near Copenhagen, 

 three zones could be distinguished, both by the charac- 

 teristic plants and the animals. To these he gave the 

 names : — (1) "Eegio Chlorospermearum," the belt of green 

 sea weeds, extending from high water mark down to a 

 depth of two to five fathoms, and corresponding to the 

 ''Eegio Trochoideorum " amongst animals. The upper 

 part of this zone is the subregion of the Oscillatorias, and 

 the lower part the subregion of the Ulvas and Confervas. 

 (2) is "Eegio Melanospermearum," the belt of olive-brown 

 sea-weeds, extending down to depths of seven or eight 

 fathoms, and corresponding to the ''Eegio Gymnobran- 

 chiorum " amongst animals. Here also there are tw^o 

 subregions, an upper of Fucoids and Zostera, and a 

 lower of Laminaria. (3) is "Eegio Ehodospermearum," 

 the belt of purple-red sea- weeds, extending from eight to 

 twenty fathoms, and corresponding to the " Eegio Buc- 

 cihoideornm " amongst animals. As Vaillant has since 

 pointed out, the somew^hat abnormal conditions of marine 

 life in the landlocked Strait of Oresund may account for 

 the want of exact correspondence between these zones and 

 those established on the more exposed coasts of France and 

 Norway, but Orsted's first region evidently corresponds to 

 the three upper zones of the French observers. 



* De Regionibus Marinis. Havnise, 1844, 



