36 BRITISH DESMIDIACEJL 



dilated at the extremity and slightly open outwards ; 

 semicells subpyramidate in outline, more or less three- 

 lobed ; polar lobe quadrate-cuneate, apex convex 

 with a deep and open median notch, a short, blunt 

 spine at each outer angle, and a thickening at each 

 angle of the apical notch ; lateral lobes bilobulate, 

 upper lobule rounded and submamilliform, or sub- 

 quadrate and emarginate, upwardly directed, lower 

 lobule emarginate or bluntly tridentate, horizontally 

 disposed ; semicells with a large protuberance in the 

 centre above the isthmus, a large rounded wart on 

 each side of the apical incision and near the base of 

 the polar lobe, a small wart within each lower lateral 

 lobule, and one or two small granules within both 

 upper and lower lateral lobules. Side view of semi- 

 cell ovate-pyramidate, apex rounded, with a prominent 

 protuberance on each side near the base, and a wart 

 on each lateral margin half-way between the basal 



O il 



protuberance and the apex. Vertical view elliptic, 

 with angular poles and a large protuberance in the 

 middle on each side. Cell-wall smooth. 



Zygospore globose, furnished with simple, blunt 

 spines. 



Length 39-49 /a ; breadth 25-35*5 /< ; breadth of 

 isthmus 6*5-8 fj. ; thickness 20-24 /u. 



ENGLAND.- -Westmoreland ! (Rolfs}. JN". and E. Yorks I 

 Lancashire ! Warwick (Wills). Sussex (Rolfs). Hants 

 (Bennett). Devon! Cornwall ! (Ralfs). 



WALES. Capel Curig, Carnarvonshire (Roy). Dol- 

 gelly, Merioneth (Ralfs). 



SCOTLAND. General but scarce ! (Roy fy Bissett). 



IRELAND. Mayo ! Galway ! Kerry ! Dublin and 

 Wicklow (Archer). 



Geogr. Distribution. France. Germany. Galicia in 



Austria. Norwav. Sweden. Denmark. Bornholm. 



. 



Finland. Poland. N. Russia. Faeroes. Spitsbergen. 

 Greenland. India. Ceylon. Burmah (var.). Aus- 

 tralia (var.). New Zealand (var.). Madagascar (var.). 

 United States. 



