FAUNA OK THE AFRICAN LAKES. 511 



teristic of the ocean were to be fonnd, this wouhl afibrd very 

 valuable evidence concerning the ancient hi.stoiy of the lake. 



It was with this end in view that a Third Tanganyika Expe- 

 dition (68) was organised by the Committee, with the conduct of 

 wliich I had the honour of being entrusted. One of tliO principal 

 objects of this expedition was tlierefore to make a careful collec- 

 tion of the water plants of Tanganyika, at the same time 

 collecting in Nyasa, with the idea of afibrding a comparison with 

 a more normal African fresh-water lake. My instructions also 

 provided " That other groups of organisms likely to throw light 

 on the Taiiganjaka Problem, and especially fishes, shall not be 

 neglected." Including observations on various points of intei-est, 

 the work before the expedition Avas thus sufficientlj'^ extensive, 

 although matters of geology and geography were outside the field 

 of enquiry. 



I left England in the spring of 1904, proceeding via the 

 Zambezi and Shire rivers to Lake JSTyasn, whei-e a few weeks were 

 spent in collecting. My stay on and around Tanganyika lasted 

 about eight months, which wei'e fully occupied in making collec- 

 tions and observations as far as facilities ofiered. Returning to 

 the coast by way of the Victoria Nyanza, an opportunity was 

 afforded of obtaining representatives of the flora of that lake for 

 purposes of comparison with the plants collected in Nyasa and 

 Tanganyika. 



It may at once be stated that the flora of Tanganyika fails to 

 exhibit cjuite the remarkable features which some had expected 

 it to show. As regards the higher aquatic plants, a comparison 

 of the species from Tanganyika with those from Nyasa and 

 Victoria Nyanza does not throw any light on the hj'pothesis of a 

 marine origin for Tanganyikn. The fresh-water A]giB of the 

 lake, however, have pioved to be a strange and interesting 

 assembly, a considerable number being peculiar to Tanganyika 

 while several show undoubted marine affinities. The lower forms 

 of vegetable life which occur thus tend to confirm the unique 

 biological nature of the lake. 



On the zoological side, my collections have added not a little 

 to the number of forms knoAvn from the lakes, the results 

 appearing as a sei'ies of memoirs principally in the Proceedings 

 of the Zoological Society. For the fiist time systematic tow- 

 nettings were made in Tanganyika on an extensive scale, and as 

 a result, detailed information is to hand about whole groups of 

 organisms, only the bare existence of which in the lake was 

 known before. Thus reports have now been publislied on the 

 smaller Crustacea (Copepoda and Ostracoda) as well as on the 

 Rotifera, while in addition the groups Rranchiura and Hydrach- 

 nida are new records from the lake. 



In completing this brief review of the zoological exjiloiation of 

 Tanganyika, it is only necessaiy to I'efer to the Belgian expe- 

 dition to that lake and to Lake Mwero undertaken by the late 

 Louis Stappers. This expedition visited Tanganyika in 1912- 



