FRESHWATER ALGA OF THE THIRD TANGANYIKA EXPEDITION. 81 
Report on the Freshwater Algo», including Phytoplankton, of the Third 
Tanganyika Expedition conducted by Dr. W. A. Cunnington, 1904- 
1905. By G. 8. West, M.A., F.L.S., Lecturer on Botany, Birmingham 
University. 
(PLATES 2-10.) 
[Read 20th December, 1906.] 
Page 
I. Introduction ...................................... 81 
II. The Phytoplankton ................................ 83 
III. Systematic Account of the Algz of the Collections ...... 97 
IV. General Summary of the Investigation ................ 190 
1. INTRODUCTION. 
Tar Alge collected by Dr. Cunnington during his expedition to the large 
African lakes, in 1904—5, were submitted to me for examination by Dr. Rendle, 
Keeper of the Botanical Department of the British Museum. Dr. Cunning- 
ton's collections were of an extensive nature, and consisted largely of plankton 
obtained from the three great lakes, Nyasa, Victoria Nyanza, and Tanganyika. 
А portion of the material was collected in swamps and swampy pools, and a 
few of the most interesting Alge were obtained from among the finely 
divided leaves of certain species of Utricularia. 
The plankton from Tanganyika is for several reasons of the greatest 
interest. In the first place, no plankton has previously been reported on from 
this lake, although accounts have appeared on plankton from both Lake 
Nyasa and Victoria Nyanza. The species of the phytoplankton are likewise 
of a very noteworthy character, and the phytoplankton as a whole presents 
several peculiarities which may be of some slight assistance in the elucidation 
of the Tanganyika problem. 
During recent years a considerable amount of work has been done on the 
freshwater Algw of Tropical Africa, but our knowledge of their distribution 
throughout this vast area still remains very fragmentary and incomplete. No 
colleetions have as yet been sufficiently representative, and the published 
records are both few in number and from districts widely remote from 
one another. Until much more collecting and systematic examination has 
been accomplished, it is quite impossible to draw any definite conclusions 
concerning the geographical distribution of the Alge in the fresh waters of 
Tropical Africa. 
It would appear that the study of the family Desmidiacee is likely to give 
more valuable evidence regarding a definite region characterized by African 
types than the investigation of any other family of Algze, and therefore future 
collections would have most value if made largely from the permanent and 
long-standing swamps. Notwithstanding the cosmopolitan nature of no 
LINN. JOURN.—BOTANY, VOL. XXXVIII. G 
