(34 BRITISH DESMIDIACE^. 



Xanthidium fasciculatum Ehrenb. a Ralfs in Ann. Mag*. Nat. Hist, xiv, 

 1845, p. 466, t. 12, f. 3 a-d ; Brit. Desm. 1848, p. 114, t. 20, f . 1 : De 

 Not. Desm. Ital. 1867, t. 4, f . 36 ; Nordst. Desm. Brasil. 1870, p. 230 ; 

 Delp. Desm. subalp. 1877, p. 168, t. 13, f. 20-22 ; Turn. Alg. Strensall 

 Common, 1883, f. 12 ; Wolle, Desm. U. S. 1884, p. 93, t. 22, f. 4, 5. 



A", polygonum Hass. Brit. Freshw. Alg. 1845, p. 360, t. 89, f. 4 [figure 

 poor] . 



X. antilopseum (Breb.) Kiitz. Spec. Alg. 1849, p. 177; Breb. Liste Desm. 

 1856, p. 134 ; Lund. Desm. Suec. 1871, p. 75 : Kirchn. Alg. Schles. 1878, 

 p. 155 ; Wolle, Desm. U. S. 1884, p. 94, t, 23. f . 1, 2 ; Cooke, Brit. Desm. 

 1887, p. 132, t. 46, f. 2 ; Hansg. Prodr. Algenfl. Bohm. 1888, p. 192 ; De 

 Toni, Syll. Alg. 1889, p. 920; West, Alg. N. Yorks. 1889, p. 293 ; Alg. 

 N. Wales, 1890, p 291 ; Alg. W. Ireland, 1892, p. 165 ; Alg. Engl. Lake 

 District, 1892, p. 730 ; Liitkem. Desm. Attersees, 1893, p. 547 : Roy & 

 Biss. Scott. Desm. 1893, p. 244; 1894, t. 3, f. 13; W. and G. S. West, 

 New and Int. Freshw. Alg. 1896, p. 156 ; Alg. S. England, 1897, p. 484; 

 Alga-fl. Yorks. 1900, p. 67 ; Borg. Freshw. Alo-. Faeroes, 1901, p. 229; 

 W. & G-. S. West, Alg. N. Ireland, 1902, p. 31 ; Scott. Freshw. Plankton, 

 I. 1903, p. 527 ; Him, Desm. Finland, 1903, p. 23, t. 2, f . 33 ; W. & G. S. 

 WestjTreshw. Alg. Orkneys and Shetlands, 1905, p. 23; Further Contrib. 

 Freshw. Plankton Scott. Lochs, 1905, p. 72 ; Comp. Study Plankton 

 Irish Lakes, 1906, p. 85 ; Borge, Beitrage Alg. Schweden, 1906, p. 28 ; 

 Teodoresco, Mater, flor. alg. Rouman. 1907, p. 182 ; W. & G. S. West, 

 Brit. Freshw. Phytoplankton, etc., 1909, p. 180; Phytoplankton Engl. 

 Lake District, 1909, p. 138. 



X antilopaeum var. hirsutum Gay, Monogr. loc. Conj. Montpellier, 1884, p. 

 77 ; Note Conj. du midi de France, 1884, p. 340. ' 



A', spinulosum Benn. Freshw. Alg. Engl. Lake Distr. 1886, p. 10, t. 2, f. 17 

 [figure erroneous] ; Cooke, Brit. Desm. 1886, p. 132, t. 46, f. 4; De Toni, 

 Syll. Alg. 1889, p. 928. 



X. antilopeeum var. ornatum Anderss. Sverig. Chlor. 1890, p. 13, t. 1, f. 6. 



X. fasciculatum var. ornatum Schmidle, Beitr. Algenfl. Schwarzwald. u. 

 Rheineb. 1893, p. 94, t. 4, f. 6. 



X. anlilopseum var. fasciculoides Liitkem. Desm. Attersees, 1893, p. 547 

 [ = X. fasciculatum Ralfs, 1848, t. 20, f. 16 ; X. antilopseum (Breb.) Kiitz. 

 in Wittr. & Nordst. Alg. Exsicc. No. 574.] 



X. antilopeeum var. Schmidlei Borge in Nuova Notarisia, 1895, vi, p. 25. 



Cells of medium size, about as long as broad (without 

 spines), deeply constricted, sinus somewhat variable 

 in depth (according to form of basal half of semicell), 

 shortly linear with a slightly dilated extremity ; semi- 

 cells subellip tic-hexagonal, all the angles very slightly 

 rounded, sides and apex usually straight, each of the 

 four exposed angles furnished with a pair of simple, 

 straight or slightly curved, fairly long spines, central 

 area of moderate size, generally round (more rarely 

 elliptic), thickened and variously scrobiculated. Side 

 view of semicell circular or subcircular, with a slight 

 thickening at each side, and a pair of diverging spines 

 on the apical margin. Vertical view elliptic, with a 

 slight thickening (often somewhat protuberant) at the 



