62 BRITISH DESMIDIACE^. 



p. lf>o. t. f>2, f. 0; De Toni, Syll. Alr. 188!), p. lir>(> ; Gutwin. Fl<>r. 

 .don. >\\ < Julie. 1892, p. 73 ; Roy & Biss. Scott. Desni. ISO.'J, p. 18 ; Liitkem. 

 Desm. ]\Iillslattersees, 1900, p. 22; Com ere, Desm. de France, 1901, 

 p. 171, t, 12, f. 6 ; W. & G. S. West, Alg. N. Ireland. 1902, p. 48. 

 >V. i>U<>Kiun b. Brebissoaii, Ivabenh. Flor. Europ. Alg. 1808, p. 212. 



Cells small, about as long as broad, or sometimes not 

 quite as long as broad, deeply constricted, sinus acute, 

 widening outwards; semicells elliptical or elliptic-fusi- 

 form, angles rather acutely rounded, cell-wall provided 

 with numerous fine, acute spines, which are more 

 crowded and longer near the angles, around which they 

 are arranged in concentric circles. Spines in front view 

 of semicell arranged in longitudinal rows, becoming 

 smaller and more distant towards the centre of the face. 

 Vertical view usually 3- (-5-) angular, sides distinctly 

 -concave, angles acutely rounded, spines wanting in the 

 centre of apex. 



Zygospore according to Cleve's figure spherical with 

 numerous complex spines. 



Length, without spines, 34-48 [i ; breadth, without 

 spines, 40-62 pi; breadth of isthmus 13[j.; length of 

 spines at the angles about 2*5^ ; diam. zygosp. 72^. 



ENGLAND. Near Bowness, Westmoreland (Bissett). 

 Leicestershire (Roy). Sutton Park and Harborne, War- 

 wicks ! Hants (Roy). 



WALES. Capel Curig and Glyder Fach (at 2200 feet), 

 Carnarvonshire ! 



SCOTLAND.- -Ross, Aberdeen, Kincardine, Forfar, 

 Perth, Fife (Roy & Biss.). 



IRELAND. Mayo ! Dublin and Wicklow (Arch.). 

 Lough Derryadd, Armagh ! 



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

 Austria. Hungary. Servia. Norway. Sweden. Den- 

 mark. Finland. N. Russia. Nova Zembla. Spitsbergen. 

 Greenland. United States and Alaska. Patagonia. 

 Antarctic. 



Good figures of St. Brebissonii have always been wanting, 

 and it is evident that different workers have had different 

 conceptions of the species. The figure given (PL CXXXVII, 

 fig. 4) is copied from a drawing by the late Dr. Lutkemiiller. 



