(61) 



4. Fresh-water ALG.2E.*— By G. S. West, M.A., D.Sc, F.L.S. 



Plates I., II. 



So little is known of the fresh- water algae of South- West Africa, or 

 for that matter of South Africa as a whole, that the collections made 

 by Professor Pearson in 1908-1911 have proved of considerable 

 interest. The present report deals only with those collections made 

 between November, 1908, and July, 1909, mainly from the edge of 

 the South-West African Plateau, an area with little rainfall and few 

 places in which algae are able to exist. 



The algae examined were from the following regions : — 



1. Angola. On the sides of the water-conduit and tank of the 

 cable-station at Mossamedes there was a thin green stratum con- 

 sisting of an interesting aggregation of small algae, including immense 

 numbers of Ankistrodesmus convolutus, a new African variety of 

 Oocystis elliptica, and an undescribed species of Myxobactron, one 

 of the rarest genera of the Chroococcaceae. A saline marsh south of 

 the river Bero contained great quantities of Chlamydomonas marina. 



At Cazengo (3,000 feet), in a small stream in the dense forest, and 

 attached to stones, was a quantity of Bhizoclonium hieroglyphicum, 

 amongst which were numerous Diatoms. 



2. Karoo. The water in all the places collected from smelt 

 strongly of sulphuretted hydrogen. In springs at Pappekuil (950 

 feet) and Gansfontein (1,200 feet) were several Desmids and 

 Diatoms. At Benkesfontein, in a spring in which the water was 

 at a temperature of 27 , 25° C, were Mcrismopedia glauca and 

 Nitzschia Palea. 



3. Upper (or Composite) Eegion. Most of the algae collected in 

 this region were obtained from stagnant pools and drying mud in 

 the Holle Eiver (at 2,700 feet). A large form of Bhizoclonium 

 hieroglyphicum was mixed with several filamentous blue-green 

 algae, several Desmids, and a sterile Spirogyra. Attached to the 

 Bhizoclonium were quantities of Uroncma confervicolum. Numerous 

 Diatoms occurred amongst these various filamentous algae. 



* Percy Sladen Memorial Expedition in South-West Africa, 1908-1911. Report 

 No. 14. 



