ZOOLOGY AND BOTANY, MICROSCOPY, ETC 497 



French. An account in English is given by the author in the Bot. 

 Centralblatt.* 



Phytoplankton of Victoria Nyanza. f — I. Woloszynska contributes 

 to B. Schroder's " Zellpflanzeu Ost Afrikas" an account of the phyto- 

 plankton of the Victoria Nyanza. He finds a remarkable prevalence of 

 spiral, ring-shaped, globular, and boat-shaped forms, and an avoidance 

 of straight lines and surfaces. Even the usually stiff Melosira nyas- 

 sensis takes a bow-like curve. Anabsena flos-uquse is twisted like a 

 spiral ; and the short filaments of A. tanganyileae are ring-shaped or 

 spiral. The ccenobia of Scmedesmus are curved into a half-circle, and 

 the structure is net-like. Membranes surrounded by jelly are a common 

 appearance in Myxophyceee, Chlorophyceae, and even in Desmidiacea^. 

 Peridinieae are very small. Geratium hirundinella is of middle size, and 

 has three horns. The extreme variability of the plankton forms is 

 remarkable, giving rise to many transition-stages. Dinobryon is want- 

 ing. Many species appear to have been brought by rivers to the lake. 

 A periodicity seems to exist, but details are not yet forthcoming. 

 Differences in the composition of the plankton of East African lakes are 

 marked, and depend not so much on endemism, as on the respective 

 quantitative relations of the plankton constituents. Anabsena and other 

 algae form no resting-spores. In the Victoria Nyanza there are cosmo- 

 politan species, Fragilaria virescms, Gosmarium depression, Scmedesmus 

 obliquus, Anabsena. flos-aquse, Beridinium Gunningtonii ; also species 

 peculiar to the temperate zone, and others hitherto only recorded from 

 the tropics. Again, others from the East African lakes, Surirella 

 maJombse, Gloeocystis ikapose, Anabsena tanganyikse, Peridermium 

 africanum ; and, finally, some peculiar to the Victoria Nyanza only, 

 Rhizosoleuia victorise, Melosira Schroederi, and Scmedesmus bijugaUis. 

 The subgenus Anabsenopsis, common to Africa and Java, is characteristic 

 of the tropical zone. The distribution of the 135 species recorded is 

 shown in a table. New species and varieties are described. 



Bacillariese of the Lower Elbe. $ — H. Reichelt and F, Schucht 

 report on the diatoms of the recent slime-ooze in the flood area of the 

 Elbe. Samples were collected in 1902 from new stations on the Lower 

 Elbe, and the Bacillariege were named by Reichelt. The ooze from 

 Zollenspieker contains remains of fresh-water organisms ; and in one 

 of the Hamburg samples fresh-water species predominate, mixed with 

 eight North Sea species and three belonging to slightly brackish water. 

 The samples taken between Schulau and Neufeld b. Marne are rich in 

 diatoms common to the coast-zone of the North Sea in the estuaries of 

 the Elbe, YVeser, Jade, Scheldt, and Thames. Eupodiscus argus, Actino- 

 cyclus Ehrenbergii, Actinoptychus undulatus, Biddulphia rhombus, 

 Goscinodiscus Jonesianus, and Triceratium Funis are characteristic 

 species. To these may be added the North Atlantic species, Coscinodiscus 

 oculus-iridis, G. radiatus, and G. excentricus. 



* Bot. Centralbl., exxvi. (1914) pp. 619-21. 



t Hedwigia, lv. (1914) pp. 183-223 (6 pis. aud figs.). See also Bot. Centralbl., 

 exxvi. (1914) p. 618. 



% Abh. Nat. Ver. Bremen, xxii. (1914) pp. 259-66. See also Bot. Centralbl. 

 exxviii. (1915) p. 159. 



