102 BKITISH DESMIDIACE^. 



The latter forms have been termed by Nordstedt " forma 

 glabriuscula' (vide PL XL VII, fig. 7). The lateral lobes in 

 some forms are widely separated and spreading, but in others 

 they are more compact and the incision between them is 

 narrow. 



11. Micrasterias rotata (G-rev.) Ralfs. 

 (PL XL VIII, figs. 1-6.) 



Micrasterias furcata Ag. in Flora, 1827, p. 643 [Description bad and 

 quite unrecognizable ; Agardh's original specimens have been found 

 to be partly M. rotata']. 



? Euastrum Rota Ehrenb. Entwick. Lebends. d. Infus. 1832, p. 82 [Descrip- 

 tion bad and too brief] ; Ehrenb. Infus. 1838, p. 161, 1. 12, f. 1 [Figures 

 include M. rotata, M. apiculata var. fimbriata, and M. truncata']. 



Echinella rotata G-rev. in Hooker's Brit. Fl. 1833, II, p. 398. 



Cosmarium stellinum Corda in Aim. de Carlsbad, 1834, p. ISO. 



Eutomia rotata Harv. Man. Brit. Alg. 1841, p. 187. 



Micrasterias rotata (Grev.) Ralfs in Ann. Mag. Nat. Hist. 1844, p. 259, 

 t. 6, f . 1 ; Hass. Brit. Freshw. Alg. 1845, p. 385, t. 90, f . 1 ; Kalfs, Brit. 

 Desm. 1848, p. 71, t. 8, f. 1 a (and 6 ?) ; Arch, in Pritch. Infus. 1861, 

 p. 727, t. 1, f . 20 ; in Quart. Journ. Micr. Sci. 1868, p. 294 ; Kabenh. 

 Flor. Europ. Alg. Ill, 1868, p. 108 cum fig. xylogr. ; Lund. Desm. Suec. 

 1871, p. 12 ; Delp. Desm. subalp. 1873, p. 82, t. 4, f . 1 ; Kirchn. Alg. 

 Schles. 1878, p. 162 ; Wolle, Desm. U.S. 1884, p. 109, t. 34, f . 1, 2 ; Cooke, 

 Brit. Desm. 1886, p. 57, t. 24; Hansg. Prodr. Algenfl. Bohm. 1888, 

 pp. 209, 253; De Toni, Syll. Alg. 1889, p. 1126; West, Alg. N. Wales, 

 1890, p. 286 ; Alg. W. Ireland, 1892, p. 134 ; Alg. Eng. Lake Distr. 1892, 

 p. 722 ; Eoy & Biss. Scott. Desm. 1893, p. 174 ; Nordst, Index Desm. 

 1896, p. 226 ; West & G. S. West, Desm. Singapore, 1897, p. 163 ; Alg. 

 S. England, 1897, p. 484 ; Alga-fl. Yorks. 1900, p. 66 ; Alg. N. Ireland, 

 1902, p. 30 ; Scott. Freshw. Plankton, I, 1903, p. 525. 



Didymidium (Micrasterias) rotatum Eeinsch, Algenfl. Frank. 1867, p. 149. 



Helierella rotata Kuntze, Kevis. gen. plant. 1891, p. 899. 



Micrasterias rotata var. acutidentata Benn. Freshw. Alg. S.W. Surrey, 

 1892, p. 9, t. 2, f. 10 [Figure incorrect]. 



Cells large, a little longer than broad, subcircular in 

 outline, very deeply constricted, sinus narrowly linear ; 

 semi cells 5-lobed, interlobular incisions narrowly linear; 

 polar lobe gradually widening upwards, with concave 

 sides, often slightly projecting, apex retuse-emarginate, 

 angles slightly produced and bidentate ; lateral lobes 

 unequal and broadly cuneate, each divided into two 

 lobules by a deep incision ; superior lateral lobes 

 larger than inferior lobes, each lobule subdivided into 

 four equal emarginate (or bidentate) parts by three 

 incisions, the median one being the deepest ; lobules of 

 inferior lateral lobes divided into two (sometimes four) 



