STAURASTRUM. ()!) 



the apex, the centre of which is usually smooth. Ver- 

 tical view triangular, sides straight, "angles obtusely 

 rounded. Chloroplast axile, with a central pyrenoid in 

 each semicell, and a pair of plates extending into ea-li 

 angle. 



Zygospore large and spherical, provided with numerous 

 short stout processes, repeatedly branched at the apex. 



Length 60-84(1 ; breadth 52-57 [i ; breadth of isth- 

 mus 16-18 [i ; diam. zygosp., without appendages, 57 ;i ; 

 with appendages, 80 JJL. 



ENGLAND. Scawfell, Cumberland (with zygospores) ! 

 Bowness and Helvellvn, Westmoreland ! Cocket Moss, 



/ 



near Giggleswick, Cautley Spout and Penyghent, W. 

 Yorks ! Mickle and Cronkley Fells, N. Yorks ! Keston 

 Common, Kent ! Dartmoor, Devon ! Near St. Just, 

 Cornwall ! 



WALES. Snowdon, Llyn Iclwal and Yr Orsedcl, Car- 

 narvonshire ! 



SCOTLAND. Scourie, Sutherland ! Glen Tilt, Perth ! 

 Wigtown ! 



IRELAND. Carrantuohill, Co. Kerry ! Slieve Donard, 

 Down (at 2000 feet) ! 



Geogr. Distribution. Germany . Portugal . Finland. 

 K. Africa. 



St. pymmidatu-m is distinguished from St. muncatiun by the 

 more definitely truncate-pyramidate form of its semicells, and 

 by its more robust conical spines. It is a common species in 

 upland boggy districts. St. trapezicum Boldt, var. 

 spinosum Schmidle (in ; Hedwigia,' 1895, p. 81, t. 1, f. '25), is 

 probably a form of this species. 



Var. coilon West. (PL CXXXVIII, fig. 13.) 



St. pymmidatum var. coilon West & G. S. West, New Brit. Freslnv. Alg. 

 1894, p. 11, t. 2, f. 46. 



This variety differs from the type in its more numerous 

 granules ; in the vertical view the lateral margins are 

 furthermore concave, and the angles subacute. 



Length, without spines, 72 -5 [i ; with spines, 80 y.; 



