96 МЕ. G. S. WEST ON THE FRESHWATER ALGJE 
It will be seen from the above table that the phytoplankton is richest in 
species in October and November, especially the latter month. In these 
months occur the maxima of Scenedesmus bijugatus f. areuatus, Synedra Acus 
(and var. delicatissima), Navicula Gastrum, Anabena Flos-aque (and var. 
circularis), Phormidium angustissimum, Spirulina lavissima, and Glenodinium 
Pulvisculus. In December there is a marked general decrease in the number 
of species. In January (the following month) the decrease in the Chloro- 
рһусее and Мухоррусе» is very noticeable, and concurrently a great 
quantity of Nauplius-larvee appear in the plankton. 
Plankton from the Гори River.—This river runs into Tanganyika, and two 
tubes of plankton-material were collected from it by Dr. Cunnington in 
October 1904. The phytoplankton differs very much from that of Tanganyika, 
and the species bear much resemblance to those of the surrounding pools 
and swamps, from which they are doubtless recruited. Of the thirty species 
observed in this river-plankton only one occurred in the plankton of the 
lake itself. 
The occurrence of Spherocystis Schroeteri, Chodat, is very remarkable. 
This Alga is one of the most conspicuous features of the European freshwater 
phytoplankton, and is rarely found except in the plankton of lakes. No 
specimens were observed in the collections from Tanganyika itself, nor any 
from Lake Nyasa or Victoria Nyanza, but it was present in great abundance 
in the Lofu River and the specimens were exceedingly well developed. 
The following species were observed :— 
Chlorophycez. 
(Hdogontum, sp. 
Myxonema subuligerum, (Kütz.) Hazen. 
Ulothrix tenerrima, Kütz. 
Mougeotia, sp. 
Zygnema, sp. 
Spirogyra, spp. 
Gonatozygon monotenium, De Bary. 
Closterium Venus, Kiitz. 
Pleurotenium subcoronulatum, (W. D. Turn.) W. & G. S. West. 
" elatum, (W. B. Turn.) Borge, var. conjunctum, (W. В. 
Turn.) W. & G. S. West. 
Euastrum denticulatum, (Kirchn.) Gay. 
Micrasterias americana, (Ehrenb.) Ralfs. 
Cosmarium Pseudobroomei, Wolle. 
» Dlyttii, Wille. 
" binum, Nordst. 
margaritatum, ( Lund.) Hoy. & Diss. 
nitidulum, De Not. 
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