KUASTRUM. 63 



37. Euastrum gemmatum Breb. 

 (PI. XXXIX, fig. 19.) 



Cosmarium gemmatum Breb. in Menegh. Synops. Desm. 1840, p. 221. 



'r E nostrum papulosum Kiitz. Phyc. germ. 1845, p. 135. 



Euastrum gemmatum Breb. in Ralfs, Brit. Desm. 1848, p. 87, t. 14, f. 4 



Nag. Gatt. einzell. Alg. 1849, p. 120; Rabenh. Flor. Europ. Alg. III. 



1868, p. 180 ; Kirchn. Alg. Schles. 1878, p. 160 ; Wolle, Desui. U. S. 



1884, p. 101, t. 28, f. 3, 4 ; Cooke, Brit. Desm. 1886, p. 73, t. 35, f. 1 ; 



Hansg. Proclr. Algenfl. Bohni. 1888, p. 204 ; De Toni, Syll. Alg. 1889, 



p. 1070 ; West, Alg. W. Ireland, 1892, p. 138 ; Alg. Eng. Lake Distr. 



1892, p. 723; Roy & Biss. Scott. Desm. 1893, p. 177; Nordst. Index 



Desm. 1896, p. 129 ; West & G. S. West, Alg. S. England, 1897, p. 483 ; 



Alga-fl. Yorks. 1900, p. 65 ; Alg. N. Ireland, 1902, p. 28 ; Scott. Freshw. 



Plankton, I, 1903, p. 525. 



E. (Eucosmium) Hassallianum Nag. Gatt. einzell. Alg. 1849, p. 121, t. 7 B. 

 E. gemmatum a. typicum Racib. Nonn. Desm. Polon. 1885, p. 94. 

 Helierella gemmata Kuntze, Revis. gen. plant. 1891, p. 898. 



Cells rather small, almost l^ times as long as broad, 

 very deeply constricted, sinus narrowly linear with a 

 dilated extremity; semicells three-lobecl ; polar lobe 

 short, somewhat cuneiform, with rounded angles and a 

 retuse apex ; lateral lobes subquadrate, lateral margins 

 deeply retuse, angles broadly rounded; semicells with 

 three prominent protuberances across the broadest 

 part, one in the centre, and one within each lateral 

 lobe. Side view of semicell with the lower part widely 

 inflated, then narrowed to form a neck, which widens 

 out, forming a dilated apical portion, apex retuse, 

 apical angles rounded. Vertical view elliptic, with 

 three large rounded protuberances at each side; polar 

 lobe subquadrate (almost cruciform) with deeply retuse 

 sides and rounded angles. Cell-wall finely granulate, 

 granules especially prominent on all the rounded angles 

 and protuberances. 



Zygospore unknown. 



Length 48-70 M; breadth 38-47 /z,; breadth of isth- 

 mus 12-14/x; thickness 26-30 ju. 



ENGLAND. Cumberland! Westmoreland ! (Rolfs). 

 N. Yorks ! Lancashire ! Sussex (Rolfs). Hants ! 

 (Ealfs). Devon! Cornwall! (Ealfs). 



WALES. Capel Curig ! (Cooke fy Wills) and Grlyder 

 Fawr (Roy), Carnarvonshire. 



SCOTLAND. Sutherland ! Ross, Inverness, Aberdeen, 



