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JOURNAL OF BOTANY 



BRITISH AND FOREIGN. 



WELWITSCH'S AFRICAN FRESHWATER ALGiE. 



By W. West, F.L.S., and G. S. West, A.R.C.S. 



(Plates 365-369.) 



The algfB which form the subject of this paper were collectecl 

 some forty years ago by Dr. Welwitsch during his eight years' 

 residence in Angola. They are chiefly from the latter region, but 

 a few are from Benguella and Sierra Leone. The specimens are all 

 dried ones, and for the most part are mounted on paper. Portions 

 of all had to be soaked out for investigation, the results of which 

 have been very gratifying, as by this means, after a detailed exami- 

 nation, many of the smaller species have been observed. These 

 latter, however, had not been collected, but, independently entangled 

 among other conspicuous species, had been collected with them. 

 The Desmids had practically all been unconsciously obtained in 

 this way, few, if any, collections having been made from places 

 in which one would expect to find Desmids in abundance ; and yet 

 about 130 fine species (including fifty undescribed onesj have been 

 found as intruders amongst other algfe. From these mere samples 

 one is led to wonder as to the richness of the Desmid-flora of 

 Tropical Africa. 



Very little is known concerning the Freshwater Algre of Africa, 

 only a few small scattered papers having as yet been published ; 

 and this extensive collection — one in which almost all the groups 

 are represented — very considerably enlarges our knowledge of the 

 geographical distribution of these plants. The Diatoms, which are 

 numerous in a few of the gatherings, are left for future investigation. 



At the time these algfe were collected the great majority of the 

 species were as yet undescribed. They form part of the Welwitsch 

 collection deposited in the British Museum, and the numbers after 

 the species refer to the numbers on the sheets of this collection. 

 A few of the species can hardly be considered as freshwater ones, 

 but as they were in the collection we have included them. 



It is interesting to note that the earliest collection of algse made 

 in Africa has been found to be more extensive and representative 



Journal of Botany. — Vol. 85. [Jan. 1897.] b 



