COSMAKIUM. 237 



Cells rather small, about ly times as long as broad, 

 deeply constricted, sinus narrowly linear with a dilated 

 extremity ; subtrapeziform-reiiiform, basal angles 

 rounded, sides coiiyex and crenulate, with about 

 2 small entire crenulations near the basal angles and 



o 



about 4 larger emarginate (or bigranulate) crenula- 

 tions on the rest of the lateral margin, apex truncate 

 and delicately 4-crenulate, apical angles commonly 

 yery slightly emarginate ; within the margin minutely 

 granulate, granules radially and concentrically dis- 

 posed, the two or three series next the margin biuate, 

 those nearest the centre single; in the centre aboye 

 the isthmus with a granulate tumour (surrounded 

 by a small clear space), granules in 4-5 subyertical 

 series and about 4 in each series. Side yiew of semi- 

 cell oyate, with a tumour near the base at each side. 

 Vertical yiew somewhat narrowly elliptic, with a 

 granulate tumour at the middle on each side. Chloro- 

 plasts axile, with two pyrenoids. 



Zygospore unknown. 



Length 26-38 ^ ; breadth 23-32^; breadth of 

 isthmus 6'6-12ju; thickness 14'5-20 /x. 



ENGLAND.- -Cumberland ! Westmoreland ! W., X., 

 and E. Yorks ! Essex! Cambridgeshire! Middle- 

 sex ! Surrey ! Kent ! Cornwall ! 



WALES. Llyn Osrwen. and Llanrhwchwyn near 



/ O e/ 



Llanwrst, Carnaryonshire ! 



SCOTLAND.- -Rhiconich, Sutherland! Iron Hill, 

 Banff, near Mill of Muchells, Kincardine (Roy 

 Bissett). Perth ! Lewis, Outer Hebrides! Orkneys ! 

 Xeugles Water and Loch Brindister near Lerwick, 

 Shetlands ! 



IRELAND. Donegal ! Derryclare Lough, Gal way ! 

 Lower Lake of Killarney, Kerry ! Armagh ! Down ! 

 Londonderry ! 



Geogr. Distribution.- -France. Germany. Galicia 

 in Austria. Italy. Finland. \T. Russia. Faeroes. 

 Greenland. Central China (yar.). Ceylon. Central 

 Africa (form). W. Indies. 



