MICEASTERIAS. 99 



several of its varieties. It can be at once recognized by the 

 numerous spines inserted regularly on the margins of the 

 lobules and polar lobe, and more or less irregularly all over 

 the surface of the cell. It is somewhat variable in its relative 

 proportions. 



Var. fimbriata (Ralfs) Nordst. (PL XL VI, fig. 6 ; 



PL XL VII, figs. 3, 4.) 



Euastrnm Rota Ehrenb. Inftis. 1838 (in part), t. 12, f. Id. 



Micrasterias fimbriata Ealfs, Brit. Desna. 1848, p. 71, t. 8, f . 2 ; Arch, in 



Pritch. Iiifus. 1861, p. 727 ; Eabenh. Flor. Eur. Alg. Ill, 1868, p. 193 ; 



Kirchn. Alg. Scliles. 1878, p. 162 ; Wolle, Desm. "U. S. 1884, p. 109, 



t. 36, f. 1-8 "(various forms) ; Cooke, Brit. Desm. 1886, p. 59, t. 26, f. 1 ; 



Wolle, Freshw. Alg. U. S. 1887, p. 338 ; Hansg. Prodr. Algenfl. Bohm. 



1888, p. 210; De Toni, Syll. Alg. 1889, p. 1131; Roy & Biss. Scott. 



Desm. 1893, p. 174 ; Nordst. Index Desm. 1896, p. 124. 

 Didymidium (Micrasterias) fimbriatum Eemscli. Algenfl. Frank. 1867, 



p. 149. 

 Micrasterias apiculata (Ehrenb.) Menegh. stibsp. fimbriata Nordst. Boriih. 



Desm. 1888, p. 190 ; West, Alg. Eng. Lake Distr. 1892, p. 722 ; Nordst. 



Index Desm. 1896, p. 48 ; West & G. S. West, Alga-fl. Yorks. 1900, p. 66. 

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



Interlobular incisions narrower than in the type, 

 causing the lateral and polar lobes to become approxi- 

 mate ; polar lobe less projecting, usually with fewer 

 apical spines ; cell-wall commonly destitute of surface- 

 spines. 



Zygospore globose, furnished with slender, elongate, 

 scattered spines, mostly furcate at their extremities 

 and sometimes notched below the middle ; furcate 

 extremities with the divisions recurved. 



Length 230-255 p.; breadth 216-245 p. ; breadth of 

 isthmus 29-32 p ; diam. of zygospore without spines 

 75 ju,, with spines 125 /x. 



ENGLAND. Bowness, Westmoreland ! Cullingworth, 

 Aclel Dam, and Eldwick, W. Yorks ! Sutton Park, 

 Warwick (Wills). 



WALES.- -Capel Curig, Carnarvonshire (Cooke fy 

 Wills). Dolgelly, Merioneth (Rolfs). 



SCOTLAND. - - Scotston Moor, near Kintore, Press- 

 whin, Loch Ullachie, and near Ballater, Aberdeen ; near 

 Bridge of Feugh, Kincardine ; Meiimuir, Forfar (Hoy $ 

 Bissett). Khiconich, Sutherland ! Plankton of Loch 

 nan Cuinne, Sutherland ! (/. Murray). 



