58 BRITISH DESMIDIACEJE. 



Euastrwn (Cosmarium) quadrntum Nag. Gatt. einz. Alg. 1849, p. 114. 

 Didymidium (Cosmarium) quadratum Eeinsch, Algenfi. Frank. 1867, 



p. 113. 



Cosmarium quadratum a. genuinum Kirchn. Alg\ Schles. 1878, p. 146. 

 Dysphinctium quad i-o turn (Ealfs) Haiisg'. Prodr. Algenfl. Bohm. 1888, p. 



244; De Toni, Syll. Alg. 1889, p. 882; Schmidle, Beitr. Algenfl. 



Schwarzwald. u. Kheineb. 1893, p. 25 ; Weit. Beitr. Algenfl. Eheineb. u. 



Schwarzwald. 1895, p. 72. 



Cells of medium size, about twice as long as broad, 

 with a fairly deep constriction, sinus narrow at the 

 apex but somewhat open towards the exterior; semi- 

 cells subquadrate, slightly narrowed upwards, basal 

 angles rounded, sides slightly retuse, upper angles 

 broadly rounded, apex convex. Side view of semicell 

 ovate or elliptic-pyramidate. Vertical view elliptic, 

 ratio of axes 1:1*4. Cell- wall smooth. Chloroplast 

 axile, with two pyrenoids, and usually with four (or 

 more) somewhat irregular (but on the whole) longi- 

 tudinally-disposed plates. 



Zygospore unknown. 



Length 48-64 /.i ; breadth 25-3 7 /n ; breadth of 

 isthmus 12-23 ji; thickness 18-28 /u. 



EXGLAND. Westmoreland! (Bissett). Cumberland ! 

 Lancashire! W. N. and E. Yorks ! Essex! Cam- 

 bridgeshire ! Oxfordshire ! Surrey ! Kent ! Hants ! 

 Wilts ! Devon ! Cornwall ! Monmouth ! 



WALES. Snowdon (up to 3000 ft.), Moel Siabod, 

 Llyn Bochlwyd, Llyn Idwal, Llyn Gwynant, Llyn 

 Cwlvd, Y r Foel Eras, and Yr Orsedd, Carnarvonshire ! 



e> 



Dolgelly, Merioneth ! 



SCOTLAND. Sutherland !, Ross, Inverness, Banff, 

 Aberdeen!, Kincardine, Forfar!, Perth!, Argyll!, Fife 

 (Roy $ Bissett). Orkneys! Shetland! General in the 

 Outer Hebrides ! 



ICELAND.- -Donegal ! Mayo! Galway ! Kerry! Lon- 

 donderry ! Down (up to 2000 ft. on Slieve Donard 

 and Slieve Commedagh) ! Dublin and Wicklow (Archer). 



G*'<~njr. Distribution.- -France. Germany. Austria and 

 Galicia. Xorwav. Sweden. Denmark. Bornholm. 



tj 



Finland. Russian Lapland. X. Russia. S. Russia. 

 Faeroes. Iceland. Nova Zembla. Spitzbergen. 



