150 BRITISH DESMEDIACE^. 



isthmus 9-14 /x; diam. zygosp. without spines 22- 

 25 ju,, with spines 37-40 p.. 



ENGLAND.- -Borrowdale, Cumberland ! Thursley 

 Common, Surrey ! New Forest, Hants (with zygo- 

 spores) ! Near St. Just and Halgavor Moor, Corn- 

 wall ! 



WALES.- -Capel Curig !, and Grlyder Fawr (Roy), 

 C arnar von shire . 



SCOTLAND.- -Eoss, Aberdeen, Kincardine, Forfar, 

 Perth ; zygospores from Aberdeen and Kincardine 

 (Roy Bisseti). Glen Nevis, Inverness! 



IRELAND. Lousrh Clobber, and Erri^al, Donegal ! 



O o o ' o 



Adrigole, Cork! Dublin and Wicklow (Archer). 



Geor/r. Distribution.- -Qerm&ny. Bavaria. Sweden. 

 Nova Zembla. Spitzbergen. Greenland. United 

 States. 



St. lanceolatum is a rare species with very distinct 

 characters. The quadrangular forms appear to he mostly 

 confined to arctic areas. 



In the above description we have combined the three 

 forms (f. minor, f. media, and f. major) mentioned by Nord- 

 stedt in his ' Desm. Arctoae/ p. 33,- as it is unwise to draw 

 arbitrary lines of demarcation such as would be required to 

 separate these forms. 







Var. compression W. & G. S. West. (PI. CXXI, 



fig. 7.) 



St. lanceolatum var. compression W. & G. S. West, New Brit. FresliAv. 

 Alg. 1894, p. 11, t. 1, f. -22 ; Some N. Amer. Desni. 1896. p. 261 ; Alg. S. 

 England, 1897, p. 493. 



Cells somewhat compressed, sinus narrower espe- 

 cially at the extremity ; apex of semicells flattened ; 

 sides of vertical view more distinctly concave. 



Length 1 7-3-17-5 /i; breadth 21-21-2 /*; breadth of 

 isthmus 7 '5 JJL. 



ENGLAND.--New Forest, Hants ! 



SCOTLAND.- -Lewis, Outer Hebrides ! 



Geogr. Distribution.- -United States. 



