176 BRITISH DESMIDIACE^:. 



IRELAND. Lough G-artan, Donegal ! Tipperary 



(Archer) . 



Geogr. Distribution. Gralicia in Austria. Poland. 

 S. Russia. Norway. Sweden. Denmark. 



32. Cosmarium depression (Nag.) Lund. 

 (PI. LXII, figs. 2-5.) 



Euastrum (Tetracanthium) depressum Nag. Gatt. Einzell. Alg. 1849, 

 p. 114, t. 7 C, f. 2. 



Cosmarium depressum (Nag.) Lund. Desni. Suec. 1871, p. 38 ; Kirchn. 

 Alg. Schles. 1878, p. 148 ; Wolle Desm. U. S. 1884, p. 64, t. 50, f . 10-12 ; 

 Hansg. Prodr. Algenfl. Bohm. 1888, p. 195 ; De Toni, Syll. Alg. 1889, 

 p. 940 ; Roy & Biss. Scott. Desm. 1894, p. 45 ; Nordst. Index Desm. 

 1896, p. 101 ; West & G. S. West, Freshw. Alg. Orkneys and Shetlands, 

 1905, p. 20. 



Staurastrum convergens (Ehrenb.) Menegh. (3 inermis Jacobs. Desm. 

 Daneni. 1876, p. 203. 



Cosmarium Scenedesmus Delp. Desm. subalp. 1877, p. 5, t. 7, f . 28-34 ; 

 Wolle, Desm. U. S. 1884, p. 59, t. 50, f . 7-9 ; De Toni, Syll. Alg. 1889, 

 p. 956 ; West, Alg. N. Wales, 1890, p. 288 ; Add. Alg. W. Yorks. 1891, 

 p. 246 ; Alg. W. Ireland, 1892, p. 145 ; Alg. Eng. Lake Distr. 1892, 

 p. 725 ; Nordst. Index Desm. 1896, p. 229 ; West & G. S. West, Alg. S. 

 England, 1897, p. 486 ; Alga-fl. Yorks. 1900, p. 73 ; Alg. N. Ireland, 

 1902, p. 33 ; Scott. Freshw. Plankton, I, 1903, p. 526. 



Ursinella depressa Kuntze, Eevis. gen. plant. 1891, p. 924. 



U. Scenedesmus Kuntze, 1. c. p. 925. 



Cosmarium Scenedesmus Delp. forma punctata West, Alg. W. Ireland. 

 1892, p. 145 ; Turner, Freshw. Alg. E. India, 1893, p. 60, t. 8, f. 61 

 [" (3 punctat um "] . 



Cells rather small, a little broader than long, deeply 

 constricted, sinus narrowly linear, opening outwards ; 

 semicells depressed, transversely subelliptic, apex con- 

 vex-truncate, sides of semicells rounded. Side view of 

 semicell circular. Vertical view elliptic, ratio of axes 

 about 1 : 2*2. Cell-wall finely punctulate. Chloro- 

 plasts axile, each with one pyrenoid. 



Zygospore globose or ellipsoid, smooth. 



Length 3 7-43 ^ ; breadth 40-50 ju ; breadth of isth- 

 mus 12-14 u; thickness 17*5-20^; diam. zygosp. about 

 35 /u. 



ENGLAND. Malham Tarn, AY. Yorks! Skip with 

 Common, E. Yorks ! Epping Forest, Essex ! Thursley 

 Common, Surrey ! 



AA r ALES.--Capel Curig, Llyn Idwal, and Llyn Ogwen, 

 Carnarvonshire ! 



