90 MR. С. S. WEST ON THE FRESHWATER ALG 
| | | 
| Gneci | Хула | Victoria Tan- | 
Species. Nyasa. Nyanza. | ganyika. 
DOS. 
д а | 
МҮХОРНҮСЕЖ (continued). 
Merismopedia elegans, A. Br....................... x 
” » Var. remota, VA. D. ,......... X 
» eruginea, Breb. ....................| х 
» glauca, (Khrenb,) Nag. .............. | x 
» punctata, Meyen .................... | x 
Gomphospheria aponina, Kiitz..................... ho... T x 
lacustris, Chodat .................. | х х 
| Microcystis viridis, (A. Br.) Тешт................. | x x 
” eruginosa, Kiitz. .................... | x | x 
» elabens, (Bréb.) Кїїш................... .... |... x 
„ incerta, Lemm. ...................... ess | x 
Chroococcus minimus, (Keissler) Lemm. ............ x | | 
> turgidus, (Kiitz.) Nig, ................ | poses | x 
» pallidus, Nàg. ........................ | | х 
| 
Peridiniez. | 
Glenodinium Pulvisculus, (Ehrenb.) Stein. .......... | .... .... x | 
Peridinium africanum, Lemm., sp. п. .............. | x x | 
" berolinense, Lemm., var. apiculatum, Lemm., x | 
var. n. | 
Peridiniopsis Cunningtonii, Lemm., sp. п. .......... MEE .... x | 
Ceratium Hirundinella, О. Е. Müll, forma .......... ees | X | | 
1 
Phytoplankton of Nyasa.—This lake lies between 9° 30' and 14° 25! S. lat., 
its long axis running almost north and south. It is about 400 miles long, 
with an average width of 25 miles, and is 1570 ft. above sea-level. Its area 
is about equal to that of Tanganyika. The phytoplankton has been fairly 
well investigated by Schmidle from material collected at intervals from April 
1898 to Dec. 1900 by Dr. Fülleborn. Schmidle reported upon the species he 
found in the plankton, the periodicity of the genera so far аз he was able to 
work it out, and the vertical depth to which the various genera extended in 
the lake. Nyasa is shallow at the north end and very deep towards the south 
end, no bottom having been found in several places at 1200 feet. Schmidle 
states that the phytoplankton extends in no trifling quantity to fully 300 ft. 
from the surface, and at this depth consists principally of Diatoms, with a 
few Chlorophycese and Myxophyceæ. 
In Dr. Cunnington's material, collected in June 1904, Chlorophyces were 
not very abundant, and those which did oceur were mostly representatives of 
the Protococcoidez. Only three Desmids were observed, one of which— 
Staurastrum leptocladum forma africanum—was in moderate abundance. Forms 
of Pediastrum simplex and species of Соїаѕітит were very abundant, and іп 
some of the collections Closteriopsis longissima was fairly common. The 
Diatoms comprised relatively few genera, of which Melosira, Cyclotella, 
