STAURASTRUM. 133 



Apex of semicell truncate, with a circle of small 

 granules. 



Length 25 '5 u. ; breadth 20-27 [i ; breadth of isthmus 

 8[i. 



WALES.- -Llyn Padarn, Llyn Idwal, Rhyddu, bog 

 above Capel Curig Lakes and bog between Glyder Fach 

 and Lluffwy, Carnarvonshire ! 



o \j J 



IRELAND.- -Loughs Clogher and Dunlewy, Donegal ! 

 Slievecommedagh, Down ! 



Geogr. Distribution. Austria. Scandinavia. 



Var. hirtum Nordst. (PI. CL, fig. 11.) 



St. margaritaceum var. hirtum Nordst. Alg. et Char. I, 1880, p. 11, t. 1, 

 f. 18 ; Lagerh. Sverig. Desm. 1883, p. 54 ; Borg. Desm. Brasil, 1890, 

 p. 46 (forma) ; West, Alg. W. Ireland, 1892, p. 186 ; Borge, Sao Paulo 

 Alg. 1918, p. 50. 



A variety in which the granules ornamenting the 

 cell-wall, including those at the apices of the processes, 

 are developed into short spines. 



Length 38 p ; breadth 44 ^ ; breadth of isthmus 12 JJL. 



WALES.- -Yr Orsedd, Carnarvonshire ! 



IRELAND. Carrantuohill, Kerry ! Castletown, Cork ! 



Geogr. Distribution. Scandinavia. Finland. Australia. 

 Java. Brazil. 



Var. robustum W. & G. S. West. (PI. CL, fig. 13.) 



St. margaritaceum var. robustum West & G. S. West, Alg. S. England, 1897,. 

 p. 496, t. 7, f. 14 ; Freshw. Chlorophy. Koh Chang, 1901, p. 95. 



Cells stouter than in the type, semicells, without 

 the processes, broadly elliptical, not constricted at the 

 base of the processes, but tapering gradually into them ; 

 in vertical view 4- or 5-radiate, with a small emarginate 

 verruca on either side of the base of each process. 



Length 25*5 pi ; breadth 27 [i ; breadth of isthmus 8 (JL, 



ENGLAND.- -Uxbridge, Middlesex ! 



Geogr. Distribution.- -Koh Chang, Siam. 



This variety approaches St. ornatum Turn. ( St. margari- 

 acemn var. ornatum Boldt), but has much shorter and stouter 



