497 



most varied material. At this place one can dredge the bottom 

 again and again and continually find interesting forms, with- 

 out even being troubled by corals which often in the West Indies, 

 near St. Croix for instance, renders dredging difficult. 



In the introduction to the Chlorophycese I have given a short 

 account of earlier collectors of algaB, but omitted to mention there 

 that the "Challenger" expedition also visited St. Thomas and 

 made dredgings and that some of the many Codiacese, which have 

 been found just at this island, were dredged by that expedition. 



Also several naval officers on the Danish men of war, which 

 in the course of time were stationed at the islands, have made 

 many collections there, and though these collections have a hap- 

 hazard character and, of course, generally consist of alga3 which 

 have drifted ashore or those from the littoral zone, we have, 

 nevertheless, to thank many of these collectors for the specimens on 

 which many of our first descriptions have been based. Indeed not 

 a few of the West Indian Algse were first described upon spe- 

 cimens from the Danish Isles. 



While collecting material iny procedure has always been to 

 sort the gathered material immediately on my return in such 

 a way that of each species collected some specimens were 

 dried and others laid in alcohol, and my determinations and ex- 

 aminations are chiefly based upon the last mentioned material. 

 If I therefore, with regard to the new forms, had to speak about 

 "type-specimens", in the way that word is especially used in 

 America, mine are mostly to be found in bottles and in my 

 preparations. 



Before concluding I should like to thank all those who in 

 different ways have helped me with my work. Besides those I 

 already have mentioned in the introduction to the sections treat- 

 ing of the green and the brown algse, I should like to convey my 

 warmest thanks to the specialists who have assisted me in work- 

 ing out certain groups, particularly Mme PAUL LEMOINE of Paris 

 who worked out the Melobesiese,' and Mme WEBER-VAN BOSSE 

 in Eerbeck who was so kind as to give a description of my collec- 

 tions of Rhizophyllidacede and Squamariacese. My thanks are also 

 due to Dr. HENNING E. PETERSEN who, by his great knowledge 

 of the group Ceramieae, was the best able to deal with this group. 



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