KUASTEUM. 75 



basal angles, the retuse portion of the lateral margin 

 being nearer the apex; apex "widely convex and retuse- 

 emai'O'inate in the middle. Side view of semicell 



o 



quadrate-pyramidate, inferior and superior angles 

 rounded, sides and apex retuse. Vertical view oblong- 

 rectangular, angles rounded, poles retuse, with a pro- 

 minent protuberance at the middle on each side ; polar 

 lobe rectangular, angles round, sides and poles retuse. 



Length 34*5 p,; breadth 22 p, ; breadth of apex 

 18 ft : breadth of isthmus 9*5 ^ ; thickness 17 /*. 



SCOTLAND. Near Tarbert, Harris, Outer Hebrides ! 



This variety somewhat resembles the previous one, but the 

 general outline of the semicells is rather different, and the 

 side and vertical views differ greatly in the amount of the 

 retuseness of the poles. 



46. Euastrum validum West and Gr. S. West. 

 (PI. XL, figs. 21, 22.) 



Euastrum validum West and G. S. West, Some X. Anier. Desm. 1896, 

 p. 245, t. 14, f. 32, 33 ; Freshw. Alg. Ceylon, 1902, p. 156. 



Cells minute, 1-g- times longer than broad, very deeply 

 constricted, sinus narrowly linear with a dilated extre- 

 mity ; semicells truncate-pyramidate, lateral margins 

 retuse. inferior angles inflated, superior angles some- 

 what rounded and sometimes slightly thickened ; apex 

 broad, truncate-convex, einarginate and thickened in 

 the middle; semicells with a small papilla within each 

 basal angle, a large granule in the middle, close to the 

 isthmus, and a small scrobiculation near the centre. 

 Side view of semicell ovate, with a granule near the 

 isthmus on each side; vertical view elliptic, with a small 

 papilla on either side of each pole. Cell- wall smooth. 



Zygospore unknown. 



Length 26-5-30 /*; breadth 19-22 p.; breadth of 

 apex 13*5-14'5 //,; breadth of isthmus 4'4-4'5/x ; thick- 

 ness 1011 p. 



SCOTLAND. Rhiconich, Sutherland! Loch Diracleet, 

 near Tarbert, Harris, Outer Hebrides ! 



Geogr. Distribution. Ceylon. United States. 



