290 Wes/ : Phytopla7ikton of English Lake District. 



Soc. Bot.', XXIX., 1892, p. 172, t. 22, f. 13 ; ibid. XXXV.. 

 1903, p. 543, t. 17, f. 1-4. 



This species is fairly general in the plankton of the English 

 lakes, and a particularly fine form is abundant in Wastwater 

 (Fig. 5 e). This form attained a diameter of 80 /x with the 

 spines. 



15. Staurastrum brevispinum Breb. forma major. Cells 

 very large, but otherwise typical. Long. 59-63 /x ; lat. 52-57 /j-. 

 This form was abundant in the plankton of Brothers' 

 Water (Fig. 6 e). In size it approaches var. altum W. & G. S. 

 West, but has not the proportions characteristic of that variety. 



16. Staurastrum Ophiura Lund, in Nov. Act. R. Soc. 

 Scient. Upsala, ser. 3, VIIL, 1871, No. 2, p. 69, t. 4, f. 7. 



This species was only observed in the plankton of Easedale 

 Tarn. It has been seen in no other part of the Lake District, 

 and this is its first record for England. This is the more 

 remarkable since St. Ophiura is one of the most conspicuous 

 constituents of the Scottish and Welsh plankton. The speci- 

 mens observed were 9-rayed, and had a diameter (with processes) 

 of 142 /-i. 



17. Sph^rozosma vertebratum Ralfs var. punctulatum 

 W. & G. S. West in ' Trans. Bot. Soc. Edin.', XXIII. , 1905, 

 p. 28. 5. punctulatum West in ' Journ. Bot. ', Dec. 1891, t. 315, 

 f. I, 2. 



This variety occurred in both Brothers' Water and Enner- 

 dale Water, but was much more abundant in the latter. The 

 cells are more angular than those of the type-form, and the 

 punctulation of the cell-wall is a marked feature of the variety. 



18. Eudorina elegans Ehrenb. 



We find this member of the Volvocacege fairly general in 

 the plankton of British pools and lakes. It always attains its 

 greatest maximum in the autumn, during the decline of tem- 

 perature. 



Huitfeldt-Kaas (1. c. 1906, p. 36) has placed Spharocystis 

 Schroeteri in the Volvocaceae under the name of ' Glceococcus 

 mucosus A. Br.', but we are inclined to think that he has con- 

 fused this characteristic plankton-alga with Eudorina elegans. 

 Wesenberg-Lund also believes thisconfusion tohavetaken place. 

 We should not be surprised if Huitfeldt-Kaas had done this, 



