I 



IVes^ : Phytoplankton of English Lake District. 121 



and Cocconema ventricosum were the most noticeable. Large 

 numbers of small Desmids were present, of which Cosmarium 

 ahhreviatum var. planctonicum was the most abundant, although 

 Staurastrum denticulatum and bi- and tri-radiate forms of St. 

 jacuUferum were exceedingly common. Peridinium Willei was 

 frequent, and a few specimens of Anurcea cochleans were ob- 

 served . 



11. Ullswater, Westmorland. May 1903 and September 

 1906. Altit. 476 feet. /\bout jh miles long by three-quarters 

 of a mile broad. Average depth S^, feet ; maximum depth 205 

 feet. This is one of the larger lakes, mostly with rocky shores, 

 and its upper end is situated among high mountains. The 

 water is somewhat contaminated by the hamlets of Patterdale 

 and Glenridding, and also by the water running from the Green- 

 side Lead Mines. As a result of this slight contamination, the 

 plankton is great in bulk, but poor in quality for the size and 

 situation of the lake. It is an Asterionella-plankton both in 

 May and September. In May little else exists besides the enor- 

 mous quantity of Asterionella formosa, only a few specimens of 

 Tabellaria floccnlosa and Dinobryon cylindricum var. divergens 

 being observed. In September the great mass of Asterionella 

 has amongst it a sprinkling of other Diatoms, a few Desmids, and 

 a considerable quantity of Dinobryon cylindricum var. divergens. 

 Tabellaria floccnlosa occurs in long chains and Tabellaria 

 fenestrata var. asterionelloides is frequent. The Desmids are 

 chiefly Spondylosium pulchrum var. planum, Staurastrum 

 brevispinum (large variety), and St. cuspidatum var. maximum. 

 Oocystis lacustris and Sphcsrocystis Schroeteri, both of which are 

 typical plankton-species of the Protococcoidese, were not un- 

 common. Anurcea cochlearis was also present. 



12. Hawes Water, Westmorland. September 1906. Altit. 

 694 feet. About two and a half miles long by about three- 

 eighths of a mile broad. It is rather an isolated lake, with a 

 maximum depth of 103 feet, and an average depth of about 

 40 feet. The September plankton was somewhat mixed, but 

 was mostly a Diatom-plankton , icith a large admixture of Ccelos- 

 phcerium Kutzingianum. The Diatoms were chiefly zig-zag 

 chains of Tabellaria fenestrata, Cocconema gracile, C. cymbiforme, 

 and Synedra Acus. Ceratium hirundinella was common, and 

 sterile filaments of Mougeotia elegantula were frequent. A few 

 Desmids were observed, amongst which Staurastrum jactiliferum 

 was the most abundant. Others were St. denticulatum, Arthro- 



iqog March i. 



