454 Dansk Botanisk Arkiv, Bd. 3. Nr. 1. 



of the typical Aer. repens. As to the occurrence of the sporangia 

 a difference, too, seems to be present as the pedicels, bearing 

 the sporangia in Aar. repens, are often placed directly upon the 

 main filament, while in the plant upon Griffithsia these, in the 

 scanty material found, are always placed upon the lowermost 

 cells of the side-branches. 



By its large, widely spreading system of endophytic fila- 

 ments our plant, too, reminds very much of Aar. Nemalionis 

 (De Not.) Bornet, but it is, nevertheless, very different when 

 compared with Rosenvinges i) exhaustive description, the Acr. 

 Nemalionis being a much taller, more robust and much more 

 ramified plant. 



The Grijfithsia in which this plant was growing was dredged 

 in about 5 fathoms of water in the month of January. 



St. Croix: Near Buck Island. 



28. Acrochætium phacelorhizum Borgs. 



29. Acrochætium Collinsianum Borgs. 



Syn. Acrochætium Liagoræ Borgs., p. 57. 



In the year of 1914 Mme Weber in the Marine Algæ of "The 

 Percy Sladen Trust Expedition" 2) has described a Chantransia 

 Liagoræ found on Liagora Hawaiiana. The Acrochætium (Chan- 

 transia) Liagoræ, which I described a year later in the first part of 

 this volume, must therefore have another name, and I propose to call 

 it Acr. Collinsianum in honour of the well known American phy- 

 cologist, Mr. Franc S. Collins, who has contributed largely 

 not only to our knowledge of the American Acrochætium species, 

 but to our knowledge of American algal flora in its entirety. 

 I deeply regret to say that it will not only be in honour of 

 Frank S. Collins, but also in memory of him. Because, after 

 the MS. had left my hands and gone to the printers, Dr. Howe 

 informed me by letter that Collins, the enthusiastic algologist, 

 had suddenly died. His death is a great loss to science, but I 

 also feel it as a deep personal one, having corresponded with 

 F. S. Collins during many years. 



1) RosENviNGE, L. KoLDERUP, The marine algæ of Denmark, Part I, 

 Rhodophyceæ, p. 126. 



2) In The Transactions of the Linnean Society of London; 2. ser. Zoology, 

 vol. 16, part. 3, London 1914. 



