I'l.nsTMHirM. 170 



Cells very narrow and greatly elongated, 85-95 times 

 longer than their diameter, almost straight for above 



r^ o 



half their length, very gradually and almost im- 

 perceptibly attenuated from the middle to the apices, 

 which are slightly incurved, acute or acutely rounded, 

 and very narrow ; cell-wall smooth and colourless ; 

 chloroplasts with from 6 to 8 pyrenoids ; terminal 

 vacuoles very long and containing one (or two) moving 

 granules. 



O 



Zygospore unknown. 



Length 440-590 /x, ; breadth 5-7 ^. 



ENGLAND. Northumberland (Tiiffrn \Vcst). York- 

 shire (Cookr). Crosby Warren, Lincolnshire ! (Fotrln-}. 

 Leicester (-??#//). Devon (7>V;///r/7). 



SCOTLAND. Near Tain, Ross ; Dinnet Moss, Aber- 

 deen (Roil $' 7//W'//). Kirkwall, Orkneys! 



I[;KI,A\I). Arderry Lough, Galway ! Dublin and 

 AYicklow (Airlirr"). 



i'. Distribution. Italy. Faeroes. 



Var. subpronum >/<>!>. (PI. XXIII, figs. 4, 5.) 



Closterium subpronum West, New Brit. Freshw. Alo-. 1894, p. 3, t. 1, f. 3 ; 

 G. S. West, Alga-fl. Cambr. 1899, p. 113; West & G. S. West, Alya-H. 

 Yurks. 19LKJ, p. 5(i ; Alg-. N. Ireland, 1902, p. 25, t. 2, f. 1, 2. 



Cells commonly more elongate than in the type, 

 straight, very slightly curved, or sigmoid, 85-1-14 

 times longer than their diameter, median portion of the 

 cell with subparallel margins, then gradually attenuated 

 to the apices, which are very narrow, much drawn out 

 with parallel margins, and obtuse at the extremity ; 

 chloroplasts only extending half way from the middle 

 to the extremity of the cell ; one moving granule in the 

 terminal vacuole. 



Length 392-716 ju,; breadth 3- 7-5'2 /*; breadth of 

 apices 1'G //,. 



ENGLAND. Malham Tarn, AY. Yorks ! Pilmoor, N. 

 Yorks ! Sandholme, E. Yorks ! AYicken Fen, Cam- 

 bridge ! 



