No. 10. Notes on the Phytoplankton of Victoria Nyanza, 

 East Africa. By C. H. Ostenfeld. 



1. General Remarks. 



From Dr. Alexander Agassiz I received some few plankton samples 

 from Lake Victoria Nyanza, East Africa, with the request to examine 

 their microflora. As I have, quite recently, published a paper on the 

 same subject I agreed with pleasure to the proposal, and I extend to Dr. 

 Agassiz my sincere thanks for placing this material at my disposal and 

 for giving me permission to illustrate it so richly. 



The samples in question were collected on the 21st and 23d of Feb- 

 ruary, 1908, respectively, and their main interest lies in this early date, 

 as the knowledge of the plankton of this large lake hitherto has been 

 based upon collections from April (1905, Dr. Cunnington), October 

 (1892, Dr. Stuhlmann), and November (1904, Dr. Borgert) ; further- 

 more the earlier collections were from places in the northern and west- 

 ern parts of the lake \ while Dr. Agassiz's samples were taken in the 

 harbor of Mwanza and off Shirati, both places on the southern shore of 

 the lake. 



I have had five samples at my disposal, but as they are from only the 

 two localities just mentioned, I prefer to take them as corresponding to 

 but two numbers. I do not know with certainty the number of silk 

 gauze used, but I have been informed that it is rather wide-meshed, 

 which perhaps may explain, to some degree, the scarcity of some of the 

 smaller phytoplanktonts. 



The above given dates of earlier plankton collections show how little 

 we know the plankton of Victoria Nyanza. The few (7) samples col- 

 lected by Dr. Stuhlmann in 1892 have been examined — with regard to 

 the phytoplankton of which only I speak here — by Prof. W. Schmidle 2 ; 

 three samples from the third British Tanganyika Expedition of 1905 



1 As to the collection made by Dr. Stuhlmann, it was taken " an verschiedenen 

 Stellen des Sees." 



2 Schmidle, W., Botan. Jahrb., 1898, 26, p. 1-59, pi. 1-4 ; 1902, 33, p. 1-33. 



