140 BRITISH DESMIDIACE.E. 



Length 39-41 ^ ; breadth 40-42 [j, ; breadth of isth- 

 mus 11 (JL. 



ENGLAND. Baildon Moor and Roundhay Park, Leeds, 

 W. Yorks ! 



SCOTLAND. Whitestripes, Aberdeen ; near Clochnaben, 

 Kincardine (Roy & Biss.). Scalloway, Shetlands ! 



IRELAND.- -Derryclare Lough, Co. Galway ! 



Geogr. Distribution. Sweden. Faeroes. 



This variety is distinguished by its larger size, and its apex is 

 also much more convex than in the typical form. 



139. Staurastrum Haaboeliense Wille. 

 (PL CXLII, figs. 19, 20.) 



Staurastrum Haaboeliense Wille, Norges Ferskv. Alg. 1880, p. 42, t. 2, f. 27 ; 

 Wolle, Desm. U. S. 1884, p. 131, t. 42, f. 51-53 ; De Toni, Syll. Alg. 1889, 

 p. 1207 ; West, Alg. N. Wales, 1890, p. 18 ; Alg. W. Ireland, 1892, p. 181 ; 

 West & G. 8. West, Alg. N. Ireland, 1902, p. 52. 



Cells small, about li times broader than long, deeply 

 constricted, sinus acute, opening widely ; semicells 

 narrow elliptic-fusiform, slightly attenuated at the 

 angles, forming short stout processes tipped with a 

 group of tiny spines, and with 3 or 4 concentric series of 

 denticulations. Vertical view triangular, sides slightly 

 concave, angles produced and truncate. 



Zygospore unknown. 



Length 15-1 8 [JL ; breadth 24-27 pi ; breadth of isth- 

 mus 5-7 [i . 



ENGLAND. Codale Tarn, Westmoreland ! 



WALES. Capel Curig, Carnarvonshire ! 



IRELAND. --Near Glenties, Co. Donegal ! Ballyna- 

 hinch, Co. Galway ! 



Geogr. Distribution.- -Norway. Australia. United 

 States. 



This species is distinguished from St. hexacerum by its relatively 

 shorter, fusiform semicells, and its rather stronger denticula- 

 tion. 



