160 TSTUTISH DESMTDIAOE/E. 



Var. brevius iwl. (PI. XX, figs. 11,12.) 



Cl. abrupt am 1'orma '//vr/oj- West & G. S. West, New Brit. Freslnv. Alif. 

 1894, p. ;?, t. 1, f. I. 



Cells shorter and more curved, outer margin 80-100 



D 



of arc. 



Length 60-1 07 /x; breadth 15-1 6 /A. 

 WALES. Ffestiniog, Merioneth ! 

 Georjr. Distribution. Austrian Tyrol. 



Turner has described a "var.cambricnm" of this species, 

 which lie says " differs from the type in being- regularly 

 cni'ved, and in being 1 proportionately shorter and thicker." 

 His measurements are : Length 1 14-130 ^t; breadth 14-17^. 

 The specimens were from Llyn Paclarn, Carnarvonshire (ridr 

 Turn. Desm. Notes, 1893, p. 346). We think this variety 

 must be the same as var. breriitx, although Turner's specimens 

 were a little larger. 



36. Closterium toxon West. 

 (PI. XX, figs. 13, 14.) 



Closterium toxon West, Alg. W. Ireland, 1X92, p. 121, t. 19, f. 14 ; Nordst, 

 Index Desm. 1896, p. 255 ; West & G. S. West, Desm. Singapore, 1897, 

 p. 158 ; Alga-fl. Yorks. 1900, p. 54 ; Alg. N. Ireland, 1902, p. 25. 



Cells narrow and linear, elongate, 25-30 times longer 

 than their diameter, straight for about two-thirds their 

 length, with subparallel margins, outer margin slightly 

 concave in the middle, towards the extremities gently 

 incurved and gradually attenuated, apices subtruncate; 

 cell- wall smooth and colourless ; cbloroplasts with a 

 number of small scattered pyrenoids ; terminal vacuoles 

 with two or three moving granules. 



Zygospore unknown. 



Length 220-300^; breadth 8'5-10/n; breadth of 

 apices 5*5-8 /A. 



ENGLAND. Near Bowness, Westmoreland ! Pilmoor, 

 N. Yorks ! Skip with Common, E. Yorks ! 



SCOTLAND. Sligacban in Skye, and Moidart, Inver- 

 ness ! Rbiconicb and Locb Inver, Sutherland ! Near 

 Callernisb and near Balallan, Lewis, Outer Hebrides ! 

 Plankton of Loch Nan Eun, N. Uist, Outer Hebrides ! 



IRELAND. Loughs Anna and Sproule, Donegal ! 





