4 BRITISH DESMIDIACE^E. 



central pyrenoid and a pair of lobes extending into 

 each angle. 



Zygospore globose, covered with numerous long spines, 

 broader at the base. 



Length = breadth (not including the spines) = 34-44 JJL ; 

 length of spines 4-5 [JL ; breadth of isthmus 5-7 y. ; 

 diam. zygosp., without spines, 39 ^ ; length of spines 11 pi. 



ENGLAND. Cumberland ! Westmoreland (Biss.) I 

 Lancashire ! W., N., and E. Yorks ! Leicestershire 

 (Roy}. King's Norton, Worcs ! Surrey (zygospores 

 from Puttenham Common) ! Hants ; zygospores from 

 New Forest (Roy) I Kent ! Devon (Harris). Cornwall 

 (Marquand) \ 



WALES. Moel Siabod, bog between Glyder Each and 

 Llugwy, Llyn Idwal, Llyn Padarn and Capel Curig,. 

 Carnarvonshire ! Dolgelly, Merioneth (Rolfs). 



SCOTLAND. General; zygospores from Aberdeen and 

 Kincardine (Roy & Biss.). Near Lochmaddy, N. Uist 

 and in Lewis, Outer Hebrides ! Shetlands ! In the 

 plankton ! 



IRELAND.- -Donegal ! Mayo ! Clalway ! Plankton of 

 Lough Caragh, Kerry ! Dublin and Wicklow (Arch.). 

 Armagh ! Down ! 



Geogr. Distribution.- -France. Germany. Switzerland. 

 Austria. Hungary. Servia. Portugal. Norway. Sweden. 

 Denmark. Bornholm. Finland. Poland. N. Russia. 

 Faeroes. Nova Zembla. Spitzbergen. Greenland. 

 Siberia. Central China. Japan. E. India. Australia. 

 New Zealand (var.). Madagascar (var.). Central Africa. 

 United States. Brazil. Paraguay. Patagonia. 



St. Dickiei is a most ubiquitous Desmid and frequently occurs 

 in great abundance in gatherings from bogs and marshes. It is 

 only very rarely found in plankton. By reason of its broadly 

 elliptical semicells, and slightly inflexed spines, it is a species 

 which is very easily recognised. 



Forma punctata West. 



St. Dickiei forma punctata West, Alg. W. Ireland, 1892, p. 18 ; Clare Island 

 Alg. 1912, p. 21. 



