For the sake of completeness I give again here the con- 

 tents of these papers though in somewhat shortened or sometimes 

 also somewhat altered form. 



Compared with the chlorophyceous algal flora in northern 

 waters that found at the islands here in the tropical sea has proved 

 to be very rich in forms, much richer than those in the temp- 

 erate and cold seas. To be sure some forms are wanting here, 

 thus it is remarkable that e. g. Ulothrix, so common in northern 

 seas, has not been found, but on the other hand several famihes 

 are represented which are not at all found or only with a single 

 representative in the northern waters. 



And while in the northern seas the Chlorophycex with the 

 exception of the Ulvacex and some forms of Cladophoraceae are 

 not of much importance as regards the copiousness of the vege- 

 tation, in the tropics the Chlorophycese are of great significance 

 and this applies not only to the above-mentioned Ulvacese and 

 Cladophoracese, which at the shores of the Danish West Indies 

 are often abundantly developed, but especially to representa- 

 tives of the three families: Codiacese, Valoniacese and C aider pacese. 

 These which are quite or nearly absent in northern seas, are here 

 in the tropics luxuriantly developed and represented by a great 

 number of forms. And by the ability of many of these species 

 to grow" in loose, sandy or muddy bottom, being often present 

 in enormous masses there, they also contribute greatly to the 

 luxuriance of the vegetation. 



As another difference from the northern seas I may also 

 point out that while in the tropics several of the Chlorophycese 

 are able to grow abundantly even at a depth of about- 20 

 fathoms, in the northern seas, in any case at the Faeroes, I have 

 found some few Floridese only at this depth; the Chlorophycese 

 here stop in the uppermost part of the sublittoral region, except 

 only Gomontia and Ostreobium. 



As many of the tropical Chlorophycese furthermore are in- 

 crusted by chalk, they also contribute greatly to the deposits 

 in the sea not only in bays and lagoons but also in the more 

 open sea, and even the gravel along the shores is much mixed 

 with remains of these algae, sometimes almost consisting of these 

 alone. 



On account of the numerous coral reefs surrounding St. 

 Croix it has often been difficult to dredge off the shores of this 

 island; nevertheless, successful dredgings have been undertaking 

 e. g. in the sea round Buck Island, in White Bay and oiT Frede- 



