ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 601 



They give instances of three distinct plankton communities : — (1) the 

 Desmids of the British plankton ; (2) those of Victoria Nyanza ; (3) 

 those of Victoria, as exemplified by the Yan-Yean reservoir. 



Phytoplankton of the English Lakes.* — W. and G. S. West con- 

 tinue their report on the phytoplankton of the English lake district. 

 They complete the tables begun in the last part, and then give details as 

 to the periodicity of the plankton of Windermere, month by month. 

 The dominant constituents are Chlorophyceas and Diatoms, the Myxo- 

 phyceae never at any time being conspicuous. In all sixty-five species 

 have been observed. The plankton of Windermere has three fairly 

 distinct phases : — 1. January to April (cold period). Melosira granulata 

 phase. During February and March the phytoplankton is at its 

 minimum. 2. May to July (vernal rise of temperature). First maximum 

 of AsterioneUa gracillima in May and June. 3. August to December 

 (autumnal fall of temperature). The Desmid phase extends from August 

 to November, and is most noticeable in September and October. In 

 November is a second maximum of AsterioneUa gracillima. The Chloro- 

 phyceae attain their maximum abundance in September and October. 

 The diatoms do not attain a universal maximum at one definite period of 

 the year, but the various plankton-species reach their maxima at different 

 periods. 



The authors suggest that the great maxima of AsterioneUa, which 

 occur in the British Isles, may be due to the favourable spring and 

 autumn temperatures, and the fact that at those seasons the food supply 

 would be greatest. Few of the Myxophyceaj occur in Windermere, and 

 of these Gozlosphserium Kiltzingianum is the most conspicuous. Only 

 two species of Peridiniere are recorded, Geratium hirundinella and Peri- 

 din i urn Willei. Seven figures of the latter are given. Three Fla^ellata 

 are recorded. 



The authors! then proceed to give a systematic account of the more 

 noteworthy species among the phytoplankton of the English lakes. Of 

 the twenty-eight species so treated, one is here described for the first 

 time (Dinobryon crenalatum), one is new to Britain {Elakatothrix gela- 

 tinosa), and thirteen are new to England. 



A table is appended in which the comparative frequency or absence of 

 each species during each month in the year is shown. 



Peridiniese of Sutton Park, Warwickshire.^ — G. S. West has been 

 making more or less continuous observations of the general periodicity 

 and life-histories of the alga? which occur in Sutton Park, Birmingham. 

 Seven species of Peridinieae have been observed in the pools and bogs. 

 Only one of these, Glenodinium uliginosum, is a bog species, the other 

 six having been found in the helioplankton of a sheet of water of about 

 16 acres. Notes are given on each of the seven species recorded, one of 

 which, Peridinium anglicum, is new. The periodicity of the various 

 species is shown on a chart. 



• Naturalist, No. 623 (1909) pp. 186-193 (1 fig. and 1 chart). 



t Tom. cit., pp. 260-7 (1 fig.). 



J New Phytologist, viii. (1909) pp. 181-96. 



