I GO JJ7s/: Phytoplankton of English Liike District. 



disposition (^var. asfenoneUoiJcs). A few specimens of Ccrafium 

 hirundinella make their appearance. 



June 190S. — Water-temperature S.3^X. (=4;^F.V A 

 marked .•l5/€rf07i^//a-p>lankton, A.gracillima reaching a maximum 

 greater than the Xov.-Jan. maximum. Tahellaria fcncstrata 

 var. astenonelloides fairly numerous, but Melosira granulata 

 quite disappeared. A few Desmids have appeared, and also 

 the first bits of Anabcrna Lcmmcrmannii. Plenty of Crustacea, 

 btit all of one species — Bosmina longirostris. Rotifers becoming 

 e\'ident. 



July 190S. — Water-temperature ii.b^C (=53^F.). A 

 Crustacean plankton, with a large amotmt of Bosmina longiros- 

 tris, Daphnia longispina, and Copepods. A few Desmids are 

 fairh^ e\ident, and also a thin species of Spirogyra. Ccratiiini 

 hiriindinella quite common, and a few individuals of Ca^Ios- 

 phcerium. Masses of floating spores of Anahcena Lemnierinannii. 

 Rotifers increasing in numbers. 



August 190S. — ^^'ater-temperature I2.7^C. (=55^F.). A 

 Crustacean plankton, with a gradtially improving phytoplank- 

 ton. Desmids becoming numerous and Ceratium hirundineUa 

 plentiful. Peridinium Willei abundant. Microcystis csruginosa 

 occurred in the plankton-collections for this month, but 

 onl3' a few specimens were seen. 



General Remarks upox the Periodicity. 



The first publication dealing with the periodicity of British 

 phytoplankton was by Fritsch, who recorded the results of a 

 somewhat incomplete series of collections made in the river 

 Thames.* The next publication was by Bachmann, who gave 

 an account of periodical collections made by Father Cyrill in 

 Loch Ness from July 1904 to May 1905.- 



In Windermere, the dominant constittients of the phyto- 

 plankton are ChloropM'ce^e and Diatoms, the Myxophyce^e 

 never at any time being conspicuous. In all, 65 species have 

 been observed, of which 30 (or 46.1 per cent.) are Chlorophycece, 

 23 (or 35.4 per cent.) Bacillarie^, 7 (or 10.7 per cent.) Myxo- 

 phycse, 3 (or 4.7 per cent.) Flagellata, and 2 (or 3.1 per cent.) 

 Peridinicce. 



* F. E. Fritsch, " Further Obs. on the Phytoplankton of the R. Thames." 

 Ann. Bot. XVII,. Sept. 1903. 



t Bachmann, " \>rgleichende Studien iiber das Phytoplankton von 

 Seen Schottlands und der Schweiz,' Archiv. fiir Hydrobiol. u. Plankton- 

 kunde, III., 1907, pp. S5-SS. 



Xaturalist, 



