152 BEITISH DESMIDIACE^. 



p. 201 ; De Toni, Syll. Alg. 1889, p. 1025 ; Borg. Desm. Brasil. 1890, 



p. 38 ; West, Alg. N. Wales, 1890, p. 290 ; Alg. W. Ireland, 1892, p. 158 ; 



Alg. Ensrl. Lake Distr. 1892, p. 728 ; Eoy & Biss. Scott. Desm., 1894, 



p. 170 ; Nordst. Index Desm. 1896, p. 190 ; West & G. S. West, Alg. S. 



England, 1897, p. 491 ; Alga-fl. Yorks. 1900, p. 71 ; Alg. N. Ireland, 



1902, p. 40 ; Scott. Freshw. Plankton, I, 1903, p. 527 ; Borge, Alg. erst. 



Eegnell. Exped., II. Desmid. 1903, p. 100; West & G. S. West, Comp. 



Study Plankton Irish Lakes, 1906, p. 85. 



Euastrum ornatum (Ralfs) Focke, Phys. Stud. 1847, I, p. 41 [t. 1, f. 2 ?]. 

 Cosmarium ornatum Ralfs, forma, Lund. Desm. Suec. 1871, p. 28 ; Borge, 



Beitriige Alg. Schwedeii, 1906, p. 41. 



C. ornatum var. anglica Racib. Noun. Desm. Polon. 1885, p. 72. 

 C. ornatum var. suecica Racib. I.e. p. 72 ; Liitkem. Desm. Millstiittersees, 



1900, p. 68, t. 1, f. 24. 

 Ursinella ornata Kuntze, Revis. gen. plant. 1891, p. 925. 



Cells small, as long as broad, deeply constricted, 

 sinus narrowly linear witli a slightly dilated apex; 

 semicells reniform, with slightly produced, truncate 

 apices, basal angles and lower parts of sides broadly 

 rounded, upper parts of lateral margins immediately 

 below the apex sometimes very slightly retuse, apex 

 broadly truncate and straight ; lateral margins with 

 7-9 prominent granules, slightly reduced in size just 

 below the apex and often not reaching so far as the 

 upper angles, apex with about 7 marginal granules ; 

 with a number of conspicuous granules within the 

 lateral margins, often in short oblique series, and with 

 one or two series of granules (variable both in size and 

 number) within the apex ; with a granulated protu- 

 berance in the centre of each semicell, granules con- 

 spicuous and variable both in size and disposition 

 (sometimes arranged in short vertical series and some- 

 times more or less concentrically disposed). Side view 

 of semicell depressed-subcircular, with a very slightly 

 produced and truncate apex. Vertical view elliptic- 

 oblong, with broadly rounded poles, and with a broad, 

 granulate tumour at the middle on each side ; central 

 region of apex smooth. Chloroplasts axile, one in each 

 semicell, with two pyrenoids. 



Zygospore globose, and furnished with stout spines, 

 arising from a broadly conical base, and furcate-emar- 

 ginate at the apex. 



Length 32-41 ^t ; breadth 33-41 /t ; breadth of 



