INTRODUCTION. 



1 his treatise is based upon material collected during my three visits to the 

 Danish West Indies in 1892, 1895—96 and now most recently in 1905 — 06. During 

 my stay there I have myself collected a rather large material of algæ, and 

 further from Mr. O. Hansen at St. Croix I have received several collections of 

 algæ, among them Caulerpas, for which I here bring him my best thanks. Like- 

 wise, Dr. Th. Mortensen who together with me visited the islands in 1905 — 06 

 has given me several collections of algæ from his dredgings, for which I am 

 much indebted to him. 



For the determination of my material of Caulerpa I have naturally first of 

 all consulted the collections of the Botanical Museum, Copenhagen. Likewise 

 during repeated visits to Lund I have been able by the kindness of Professor 

 O. NoRDSTEDT to usc the Herbarium of Agardh. Further I have had the collection 

 of the Botanical Museum in Hamburg on loan. And finally Mme. Weber van Bosse 

 has had the great kindness to lend me from her large Caü/er/)a-collections material 

 of the comprehensive species Caulerpa racemosa and C. ciipressoides and a few 

 other species. 



The figures are for the most part drawn by Mr. mag. sc. Ove Rostrup under 

 my inspection. Miss Karen Boye has drawn the figures 23, 29 and 30 and I have 

 myself drawn the figures 1, 3, 4, 27. 



44" 



