EUASTRUM. 21 



Cells small, about If times longer than broad, deeply 

 constricted, sinus narrowly linear with a dilated extre- 

 mity ; semicells three-lobed ; polar lobe prominent and 

 outstanding, quadrate-cuneate, angles rounded, apex 

 truncate with a narrow median incision of some depth ; 

 lateral lobes bilobulate, lobules rounded, separated by 

 a widely-open sinus, the upper one not projecting so 

 far out as the lower ; semicells with three protuberances 

 across the base and two across the centre. Side view 

 of semicell pyramidate with a quadrate base, upper 

 part of lateral margins slightly retuse, apex rounded- 

 truncate. Vertical view elliptic, with three protube- 

 rances on each side, and the two central ones showing 

 above and between them ; polar lobe oblong-rect- 

 angular, poles retuso-emarginate. Cell-wall finely 

 punctate, puiictulations often scarcely visible. 



Zygospore unknown. 



Length 56-78 ^ ; breadth 35-46 ^ ; breadth of 

 isthmus 9-15 \L ; thickness 21-30 /*. 



ENGLAND. Cumberland ! Westmoreland ! (BaJfs). 

 W. and X. Yorks ! Lancashire ! Surrey ! Hants ! 

 (Ralfs). Devon! 



WALES. Capel Curig, Snowdon, and Llyn-y-cwm- 

 ifynon, Carnarvonshire ! 



SCOTLAND. General, but rare (Roy $ Bissett). Rhi- 

 conich and Loch Gulag 1 . Sutherland ! L. Luichart, 



o ? ' 



Ross ! Outer Hebrides ! Shetlands ! 



IRELAND. Donegal ! Galway ! Kerry ! Dublin and 

 Wicklow (Archer). 



(reoc/i'. Distribution. France. Germany. Austria 

 and Galicia. Italy. Xorway. Sweden. Denmark. 

 Poland. S. Russia. Faeroes. India. Ceylon (var.). 

 Siam. Singapore. Java. Australia. Xew Zealand. 

 Central Africa. Sandwich Islands. United States. 

 Guiana. Brazil. 



Much confusion has existed concerning the nomenclature 

 of this characteristic Euastrum. It has been referred by 

 many authors to "Euastrum circulars Hass." as a variety, 

 but the latter species does not exist, HassalFs figure being 



