104 BRITISH DESMIDIACE^E. 



plankton, 1909, p. 172 ; Wahlburg, Bidr. kiinne. Littois-trask, 1913, 

 p. 48. 



Body of semicell smaller and relatively somewhat 

 narrower than in the type, processes very much longer 

 and very slender, rather more divergent and often 

 gracefully curved, about 1| times to twice as long as 

 the body of the cell. 



? Zygospore globose and smooth, fuscous brown in 

 colour (Turner}. 



Length, without processes, 26-29 \L ; with processes, 

 77-84 \L ; breadth, without processes, 15-17^; with 

 processes, 84-139 [i ; breadth of isthmus 8-9*5 \i ; diam. 

 zygosp. 12[j, (Turn.}. 



ENGLAND.- -Plankton of Crummock Water, Cumber- 

 land ! Plankton of Hawes Water, Grasmere, Stickle 

 Tarn and Windermere, Westmoreland ! Strensall, N. 

 Yorks ! Plankton of pools in Button Park, Warwickshire ! 



WALES. Capel Curig ! (Cooke & Wills), Carnarvon- 

 shire. In the plankton ! 



SCOTLAND.- -Loch Hempriggs, Caithness ! ; Poolewe, 

 Ross ; Dallas, Moray ; Glen Coe, Argyle (Roy & Biss.). 

 Rhiconich, Sutherland ! Loch Ness, Inverness ! Common 

 in the plankton of Sutherland, Ross, Inverness, Perth, 

 Lewis and Harris, Outer Hebrides, and of the Orkneys 



i/ 



and Shetlands ! 



ICELAND.- -Donegal ! Galway ! Kerry! Plankton of 

 Mayo, Galway, Kerry, Lough Neagh, and of Lough Beg, 

 Londonderry ! 



Geogr. Distribution. Germany. Galicia and Austria. 

 Servia. Norway. Sweden. Finland. Poland. Iceland. 

 Central China. Turkey-in-Asia. Australia. Canada. 

 Colombia. 



This variety is most commonly found in plankton, although 

 not exclusively confined to such a habitat. It is a frequent 

 constituent in plankton samples from many parts of the world, 

 and is generally distributed in the British lakes, occurring in 

 some cases in such great abundance as to form the dominant 

 constituent of the phytoplankton. 



The zygospore figured by W. B. Turner, 1893, for this variety 



