STAURASTRUM. 15 



slightly convex, upper angles subacute, and tipped 

 with a very delicate spine. Vertical view triangular, 

 very rarely biradiate, lateral margins in the triangular 

 form straight or slightly concave, angles rounded, each 

 with a minute spine. 



Zygospore compressed, rectangular, angles produced 

 and each lodged in one of the four semicells of the con- 

 jugating cells, whose form they simulate. 



Length, without spines, = breadth without spines = 

 10-15 (z ; breadth of isthmus o'o-6'o u ; length of spines 

 2-4 (j. ; length of zygospore 20 [JL ; breadth 13;ji. 



ENGLAND. --Near Bowness, Westmoreland (Biss.). 

 Delamere, Cheshire (Roy). Dartmoor, Devonshire 

 (Harris). 



WALES. Glyder Fawr, Carnarvonshire (Roy). 



SCOTLAND. --Not uncommon : zygospore from near 

 Aboyne, Aberdeen (Roy & Biss.). Sutherland ! 



IRELAND.- -Lough Anna, Lough Machugh and near 

 Glenties, Donegal ! Adrigole, Co. Cork ! Dublin and 

 Wicklow (Arch.). 



Geogr. Distribution. Servia. Galicia in Austria. 

 Sweden. Finland. Greenland. New Zealand. United 

 States. Colombia. 



This species is very similar to the preceding one, from which 

 it can scarcely be distinguished in the sterile condition (see above). 

 It is fairly widely distributed in the British Isles, but is probably 

 frequently overlooked. It is very much more common in the 

 western parts, however, than in other localities. The biradiate 

 form is known from Austria. 



49. Staurastrum connatum (Lund.) Roy Biss. 



(PL CXXX, figs. 6-8.) 



Staurastrum dejectum var. connatum Lund. Desm. Suec. 1871, p. 60, t. 3, 

 f. 28 ; Wille, Norges Ferskv. Alg. 1880, p. 41; Turn. Freshw. Alg. E. India, 

 1893, p. 106. 



St. hexacanthum Gay, Monogr. loc. Conj. 1884, p. 67, t. 2, f. 9 (forma). 



St. connatum Roy &^Biss. Jap. Desm. 1886, p. 237 ; De Toni, Syll. Alg. 1889, 

 p. 1138 ; Borg. Desm. Brasil. 1890, p. 44 ; West, Freshw. Alg. W. Ireland, 

 1892, p. 171 ; Roy & Biss. Scott. Desm. 1894, p. 18 ; West & G. S. West, 

 Alga-fl. Yorks. 1902, p. 96 ; Alg. N. Ireland, 1902, p. 43 : Freshw. Alg. 

 Ceylon, 1902, p. 175 ; Hustedt, Desm. et Bacill. aus Tirol, 1911, p. 339. 



