192 BRITISH DESMIDIACE^E. 



ably longer than usual, and their margins are crenulate 

 rather than denticulate. 



Zygospore spherical with numerous spines, broad at 

 the base, and tapering to a fine, slightly bifid apex (Roy). 



Length, without processes, 45 (JL ; including the pro- 

 cesses, 80 pi ; breadth, without processes, about 35 [JL ; 

 including processes, 70 [JL ; breadth of isthmus 15 (JL. 



ENGLAND. Cumberland ! Lancashire ! N. Yorks (W. 

 B. Turn.}. Surrey ! Hants ! Devon ! (Harris). 



WALES. --Dolbadarn Castle !, Llyn Padarn !, and Capel 

 Curig ! (Cooke & Wills), Carnarvonshire. 



SCOTLAND.- -Inverness, Aberdeen, Kincardine, Forfar, 

 Perth, Stirling and Arran ; zygospores from Heughhead, 

 near Aboyne, Aberdeen (Roy & Biss.). Sutherland and 

 in the plankton of Loch nan Cuinne ! Plankton of Loch 

 Luichart, Ross !, Loch Shiel, Inverness !, and Loch Tay, 

 Perth ! 



IRELAND. Ballynahinch, Galway ! Lower lake of 

 Killarney, Kerry ! Adrigole, Cork ! Dublin and Wick- 

 low (Arch.). 



Geogr. Distribution.- -France. Germany. Galicia in 

 Austria. Turkey. Norway. Sweden. Finland. Poland. 

 India. Australia. New Zealand. United States. 



Var. reductum W. & G. S. West. (PL CLVI, fig. 9.) 



St.furcigerum\a.T. reductum West & G. S. West, Compar. Study Irish Lakes, 

 1906, p. 104, t, 11, f. 12. 



Processes very much shorter than in the type, upper 

 processes extremely short ; vertical view triangular, 

 sides nearly straight or very slightly convex. 



Length 43 (Ji ; breadth, including processes, 54 ^ ; 

 breadth of isthmus 21^. 



ENGLAND.- -Dartmoor, Devon (Harris). 



IRELAND.- -Plankton of Lough Corrib, Galway ! 



This variety is distinguished chiefly by the great reduction of 

 the superior processes. In one semicell they were observed to 

 be suppressed entirely. 



