Jo THE JOUKNAL OF BOTA1TC 



are in existence; hut, in the light of our present knowledge, they 

 need a drastic revision. In recent years sundry papers have been 

 published by various authors on West Indian algology, but the 

 real investigators of the region are Dr. Marshall A." Howe and 

 Dr. F. Btfrgesen. The former has collected extensively in Porto 

 Rico, Jamaica, Cuba, &c, and has published complete local lists in 

 Dr. N. L. Britten's Floras of the Bahamas and Bermuda, besides 

 other important papers. Dr. Borgesen, on the other hand, has 

 confined his researches to the Danish West Indies. This small group 

 of islands was transferred to the United States in 1917— a lasting 

 source of grief to the majority of the Danish people! From its 

 geographical position this group afforded a convenient entity for 

 algological investigation and for a special monograph — a task which 

 was undertaken with patriotic and scientific enthusiasm by the author 

 of the present volumes. His collections were made during three 

 visits — February to March 1892, December 1895 to January iS'.x;, 

 December 1905 to April 1906,— the present monograph of his' results 

 being issued in yearly parts from 1913 to 1920. It comprises the 

 Chlorophyceae (90 species), Phseophycese (15), and Rhodophyceae ( 192 ), 

 the Cyanophycea; being omitted. The section Melobesiere'is the work 

 of Madame Lemoine, and the Khizophyllidaceaj and Squamariacea' are 

 contributed by Madame Dr. Weber van Bosse. Every species, and in 

 some cases the genus, is fully and critically discussed' and illustrated 

 by excellent figures of habit and structure. The ecological aspect of 

 the flora was to have been studied during a special visit in 1915 ; but 

 this was prevented by the outbreak of the Great War. 



A period of publication extending over eight years naturally 

 necessitated the addition of an appendix. This comprises 73 pages 

 and contains a revised list of the species, in which are inserted 

 descriptions of many novelties and revisions of certain genera in the 

 light of the most recent investigations. 



A few instances will be of interest. Eleven species of Galaxaura 

 are recorded and discussed in the text, their values and positions being 

 based on Kjellman's monograph ; but in the appendix they are reduced 

 to five, as a consequence of Dr. Howe's investigations (191 S), which 

 revealed the dimorphic character of each natural species, and showed 

 that what had hitherto been regarded as two distinct species are but 

 the sexual and tetrasporic generations of one and the same. 



The treatment of Acrochcdtium is of equal interest. Owing to 

 their microscopic size, the West Indian members of this epiphytic 

 genus had mostly escaped notice. In the present work twenty-live 

 sj ecies are recorded, all but one of which are novelties detected by the 

 author's keen eye. A helpful key to the specific characters is supplied 

 and is founded on the distinctive features afforded by the base of the 

 Acroclttelium in relation to the host- plant, thus following on the 



lines of Bornet. Sexual organs were detected in one species only 



A. Sargassi. 



Interesting also is the discussion of Rhizoclonium, a genus hitherto 

 specially characterised by the presence of lateral rhizoids and by the 

 absence or extreme rarity of the original attachment— the basal end- 

 rhizoid ; but in all the many specimens examined by Dr. Borgesen 

 there were no lateral rhizoids at all, and in most of the specimens the 



