10 BRITISH DESMIDIACE^E. 



was quite omitted. This scrobiculated area occupies the whole 

 of the central tumour and the adjacent parts of the cell-wall. 

 It is distinguished from C. Botrytis by the broader apices 

 of the semicells, by the larger and regularly arranged granules, 

 and by the tumid and scrobiculated central area of the semi- 

 cells. 



228. Cosmarium ochthodes Xordst. 

 (PI. XCVIII, figs. 1-3.) 



Cosmarium ochthodes iSordst. Desm. Arctose, 1875, p. 17, t. 6, f . 3 ; Desni. 

 Ital. 1876, p. 28 ; Wille, Ferskv. Alg. Nov. Semij. 1879, p. 35 ; Wolle, 

 Desm. U. S. 1884, p. 76, t. 14, f. 4? (not fig. 3); Cooke, Brit. Desm. 1887, 

 p. 109, t. 41, f. 3 ; Boldt, Desm. Gronland, 1888, p. 29 ; De Toni, Syll. 

 Alg. 1889, p. 992 ; West, Alg. N. Wales, 1890, p. 290; Anderss. Sverig. 

 Chlor. 1890, p. 14 ; West, Alg. Engl. Lake Distr. 1892, p. 728 ; Borg. 

 Ferskv. Alg. Ostgronl. 1894, p. 13 ; Koy & Biss. Scott. Desm. 1894, p. 

 169 ; Norclst. Index Desm. 1896, p. 187 ; West & G. S. West, Alg. S. 

 England, 1897, p. 490 ; G. S. West, Alga-fl. Cambr. 1899, p. 219 ; West 

 & G. S. West, Alga-fl. Yorks. 1900, p. 83; Liitkem. Desm. Millstattersees, 

 1900, p. 10 ; Borg. Freshw. Alg. Fseroes, 1901, p. 228 ; West & G. S. 

 West, Alg. N. Ireland, 1902, p. 40 ; Larsen, Freshw. Alg. E. Greenland, 



1904, p. 87 ; West & G. S. West, Freshw. Alg. Orkneys and Shetlands, 



1905, p. 21 ; Teodoresco, Mater, flor. alg. Bouman. 1907, p. 180. 

 C. Botrytis A. d. ochthodes Klebs, Desm. Ostpreuss. 1879, p. 39. 



? ? C. Botrytis var. squamosum Schaarschm. Magyar. Desm. 1883, p. 263. 

 Ursinella ochthodes Kuntze, Kevis. gen. plant. 1891, p. 925. 



Cells rather large, from 1-J- to almost 1-J times as 

 long as broad, deeply constricted, sinus narrowly linear 

 with a dilated extremity ; semicells ovate-pyramidate 

 from a flat base, basal angles obtuse or scarcely rounded, 



o / 



sides convex and upwardly converging to a rather 

 narrow, truncate apex (sometimes slightly retuse) ; 

 sides conspicuously crenate or only undulate, crenations 

 1113 (commonly 12), small and rounded at the basal 

 angles, but larger and flattened above. Side view of 

 semicell obovate. Vertical view elliptic. Cell-wall 

 densely covered with flattened warts of somewhat 

 indefinite outline (irregularly circular), disposed in 

 rather irregular radial and concentric series, and 

 gradually becoming less distinct towards the centre of 

 the semicell, which is also often punctulate. Chloro- 

 plasts axile, with two pyrenoids in each semicell. 



Zygospore globose, furnished with a few short, very 

 thick spines (about 1 1 visible around the margin) ; 

 apices of spines obtuse or slightly emarginate. 



