I20 JJ'cs/ : Phyioplankton of EngiisJi Lake District. 



number, but included some particularly fine specimens of 

 Staiirastriim jaculiferiim. Cocconema gracilc and a few other 

 Diatoms were observed. The most interesting member of the 

 phytoplankton was Elakatothrix gelatinosa Wille, this plankton- 

 alga not having been observed from smy other lake in the 

 British Islands. 



We are receiving periodic collections from this lake, and 

 the August and September collections, 1908, contained quan- 

 tities of Elakatothrix. 



8. Brothers' Water, Westmorland. September 1906. Altit. 

 520 feet. A small lake about three-quarters of a mile long by a 

 quarter of a mile broad. Its greatest depth is about 70 feet. 

 The dominating constituents of the September plankton were 

 Desmids and the spiny Flagellate Mallomonas longiseta. In 

 fact, the latter was so numerous that the plankton could be 

 correctly termed a Mallomonas-plankton. The principal Des- 

 mids were Staiirastnim Arctiscon (very common), a large stout 

 variety of St. brevispinum, X. antilopcBum var. triquetrum, and 

 Cosmarium depressum. Ceratium hirundinella was common, 

 and a few specimens of C. cornutum were observed. Large 

 ■colonies of Dinohryon cylindricum var. divergens occurred rather 

 sparingly. Many Crustacea and Nauplii were present, and the 

 three Rotifers Anurcea cochlearis, Notholca longispina, and 

 Polyarathra platyptera were equally abundant. Fine specimens 

 of Acanthocystis chcetophora were frequent in the plankton. 



9. Hayes Water, Westmorland. September 1906. Altit. 

 1383 feet. A small mountain lake with rocky shores, about a 

 ■quarter of a mile long, lying under the western slopes of the 

 High Street Range. It contained a mixed plankton of which 

 Gymnodinium paradoxum was the most conspicuous constituent. 

 Oscillatoria tenuis and Tahellaria fiocculosa were both common. 

 There were few Desmids, but Ankistrodesmus Pfitzeri was plen- 

 tiful, mostly in process of formation of autospores. As would 

 be expected, much dark-coloured organic matter was in sus- 

 pension in the water. 



10. Red Tarn, Westmorland. May 1903. Altit, 2356 feet. 

 This is a small mountain lake, about a quarter of a mile square, 

 ■on the eastern side of Helvellyn, and immediately below the 

 summit (3118 feet). The surroundings are rocky, and there is 

 no possible source of contamination. The plankton was mixed 

 in character. Dinohryon cylindricum and Tahellaria fiocculosa 

 were equally common. Of the other Diatoms, Synedra radians' 



Naturalist 



