70 BRITISH DESMIDIACE.E. 



41. Euastrum crassangulatum Borg. 

 (PL XXXIX, fig. 17.) 



Euastrum crassangulatum Borg. Desiii. Brasil. 1891, p. 37, t. 3, f. 25. 



Cells minute, 1-ir times longer than broad, deeply 

 constricted, sinus narrowly linear; semicells quadrate- 

 pyramidate, angles slightly rounded, basal angles sub- 

 rectangular, upper part of lateral margins retuse, apex 

 broadly truncate and retuse-emarginate in the middle ; 

 semicells with a protuberance in the centre, and a 

 smaller one within each basal and apical angle. Side 

 view of semicell broadly ovate, upper part of lateral 

 margins slightly retuse, apex truncate. Vertical view 

 elliptic, with a slight protuberance at the middle on 

 each side. Cell-wall thickened at all the angles of the 

 semicells. 



Zygospore unknown. 



Length 27 p, ; breadth 18 /x ; breadth of isthmus 5 /*; 

 thickness 13 p.. 



Geoc/r. Distribution. Austria (var.). Brazil. 



The typical form is not known to occur in the British 

 Islands. 



Var. ornatum West. (PI. XXXIX, fig. 18.) 



E. crassangulatum var. ornatum West, Alg. W. Ireland, 1892, p. 141"), t. 20, 

 f. 16. 



Semicells with 5 granules around the central pro- 

 tuberance and one in the middle, and with 6 others at 

 regular intervals within the margins. 



Length 27 /x; breadth 17'5jn; breadth of isthmus 

 4*5 JJL ; thickness 14 p.. 



IRELAND.- -Ballynahinch, G-alway ! 



42. Euastrum Cornubiense sp. nor. 

 (PL XL, fig. 8.) 



Cells minute, about 1-J- times longer than broad, very 

 deeply constricted, sinus narrowly linear with a dilated 

 extremity ; semicells three-lobed, incisions between the 



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