132 BRITISH DESMIDIACEJE. 



ENGLAND. Skipwith Common, E. Yorks ! Dela- 

 mere, Clieshire (!><>//) Enbridge Lake, Hants (Jtoi/). 



WALKS. Capel Curig, Carnarvonsliire (/'"//) 



SCOTLAND. Sutherland, Ross, Inverness, Aberdeen, 

 Kincardine, Forfar, Perth, Fife; /ygospores from 

 Fyvie, Aberdeen, and Gammie, Kincardine (/M>//). 



di'oijr. Distribution. France. Germany. Austria. 

 Norway. Sweden. India. New Zealand. E. Africa. 



This variety differs from typical CL Dinmv. only in its 

 greater degree of curvature. The apices of the cells are 

 identical in character with those of the type form, and the 

 cell-wall is faintly coloured. The zygospores are globose and 

 smooth. It is very rarely met with even though typical CL 

 Dianfe is abundant in many districts. 



1-5. Closterium Pseudodianae Roy. 



(PI. XV, figs. 7, 8.) 



Closterium Pseudodianx Roy, Desm. Alford District, 1890, p. 201 ; Roy & 

 Biss. Scott. Desm. 1894, p. 248, t. 1, f. 4 (1893) ; Nordst. Index Desm. 

 189(3, p. 208 ; West & G. S. West, Alg. S. England, 1897, p. 481 ; Alga- 

 fl. Yorks. 1900, p. 49; Lutkem. Desm. Millstiitterst-es, 190O, p. 5. 



Cells of medium size, 14-20 (commonly 10-18) times 

 longer than their diameter, moderately curved, outer 

 margin 78-88 of arc, inner margin almost straight in 

 the median part of the cell, gradually attenuated to- 

 wards the apices, which are narrow and obtuse, with 

 a slight thickening on the dorsal margin ; cell-wall 

 smooth, colourless, or yellowish-brown ; chloroplasts 

 obscurely ridged, with a single series of -5 or (} pyrenoids; 

 terminal vacuoles with several moving granules. 



o o 



Zygospore unknown. 



Distance between apices 192-253 /A; breadth 12-14/x,; 

 breadth of apices 2 '5-3 //,. 



ENGLAND. Roundhay Park, Leeds; Cocket Moss, 

 near Giggleswick, W. Yorks ! Delamere, Cheshire 

 (Roy). Thursley Common, Surrey ! 



SCOTLAND. Ross, Aberdeen, Kincardine, Forfar, 

 Perth, Argyll (//"//) Loch Shin, Loch Inver, and 

 Rhiconich, Sutherland ! Skye in Inverness ! 



IRELAND. Adrigole and Glen Garagh, Kerry ! 



