IVes^ : Phytoplankton of English Lake District. 289 



This distinctive variety has only previously been observed 

 from the Scottish lakes. It was abundant in Grasmere and 

 Windermere, especially in the latter, in which it was quite a 

 conspicuous feature of the plankton. It also occurred in 

 Hawes Water. Long. 56-61 /x ; lat. sine spin. 56-62 cum 

 spin. 92-97 /z. (Fig. 5 A). 



11. Staurastrum anatinum Cooke & Wills var. Lager- 

 HEiMii (Schmidle) nob. St. Lagerheimii Schmidle in Bih, till 

 K. Sv. Vet.-Akad. Handl. Bd. 21, No. 8, 1898, t. 3, f. 10. St. 

 Landmarki Huitfeldt-Kaas, 1. c. 1906, pp. 54, 155, t. 2, f. 32, 

 33- 



This variety differs only from typical St. anatinum in the 

 shorter processes, which are scarcely more than half the normal 

 length. It occurred in Ennerdale Water and in Easedale Tarn. 

 Long. 53-65 /X ; lat. cum proc. 72-88 /x. St. anatinum and 

 several of its varieties occur abundantly in the British lake- 

 plankton. The var. Lagerheimii is known from Norway and 

 Northern Sweden (Finmark). 



12. Staurastrum Arctiscon (Ehrenb.) Lund, in Nov. Act. 

 R. Soc. Scient. Upsala, ser. 3, VIII., 1871, p. 70, t. 4, f. 8. 



This handsome Desmid appears to be very general in the 

 British plankton, although exceedingly rare in other situations. 

 It was particularly abundant in Brothers' Water. 



13. Staurastrum cuspidatum Breb. var. maximum West 

 in ' Naturahst,' Aug. 1891, p. 247 ; W. & G. S. West in ' Journ 

 Linn. Soc. Bot.', XXXV., 1903, p. 545, t. 17, f. 13. St. cuspi- 

 datum Breb. var. longispinum Lemm. in * Botan. Centralbl. 

 Bd.', LXXVL, 1898, p. 4 (sep.). St. Daaei Huitfelt-Kaas, 

 1. c. 1906, pp. 55, 155, t. 2, f. 30, 31. 



In the plankton of all the British lake-areas this large variety 

 of St. cuspidatum occurs in abundance. It exhibits consider- 

 able variability in the length of the spines, although they are 

 invariably stronger than in typical St. cuspidatum. Surround- 

 ing the base of each large spine is a ring of about six large 

 pores, through each of which a short projecting piece of denser 

 mucilage can frequently be seen extending into the surrounding 

 and less dense gelatinous envelope. These structures are 

 sometimes very conspicuous, and have caused Huitfeldt-Kaas 

 to describe them as spines. 



14. Staurastrum* jaculiferum West in ' Journ. Linn. 



1909 Aug. I. 



T 



